December - US EPAE. J ,' 'i AP-42 Section Number: 1 1.23 Reference Number: 3 Title: Standard Support...

E.

J ,'

' i AP-42 Section Number: 1 1.23

Reference Number: 3

Title: Standard Support and Environmental Impact Statement for the Iron Ore Beneficiation Industry (Draft)

Reed, A. K., EPA Contract No. 68-02- 1323

Battelle Columbus Laboratories

December 1976

EPA

Text Box

Note: This is a reference cited in AP 42, Compilation of Air Pollutant Emission Factors, Volume I Stationary Point and Area Sources. AP42 is located on the EPA web site at www.epa.gov/ttn/chief/ap42/ The file name refers to the reference number, the AP42 chapter and section. The file name "ref02_c01s02.pdf" would mean the reference is from AP42 chapter 1 section 2. The reference may be from a previous version of the section and no longer cited. The primary source should always be checked.

I I I I I I I I I I 1 I I I I I IE I I I

Notice

This document is a preliminary draft. the U . S . Environmental Protection Agency and should not at this stage be construed to represent Agency policy. It is being circulated for comments on its technical merit and policy implications.

It has not been formally released by

.

_ _ DO NOT QUOTE OR CITE

STANDARDS SUPPORT AND ENVIRONMENTAL IMPACT STATEMENT

THE IRON ORE BENEFICIATION INDUSTRY

December, 1976

by

A. K. Reed

Battelle Columbus Laboratories Columbus, Ohio 43201

under

Contract No. 68-02-1323" Task No. 34

Gilbert Wood Project Officer

Emission Standards and Engineering Division Office of Air Quality Planning and Standards

U.S. Environmental Protection Agency Research Triangle Park, North Carolina 27711

I I I I 1 I I. I I I I I I I I I I I I I

CONTENTS

Chapter 1 . Summary

(To be completed by t h e Emission Standards and Engineering Divis ion. U.S. EPA)

Chapter 2 . In t roduct ion . . . . . . . . . . . . . . . . . . . . Chapter 3 . The I r o n Ore B e n e f i c i a t i o n I n d u s t r y . . . . . . . .

3.1 General . . . . . . . . . . . . . . . . . . . . . . . . 3.1.1 Number. Production. and D i s t r i b u t i o n of I r o n

Ore Mines . . . . . . . . . . . . . . . . 3.1.2 Ore Types and D i s t r i b u t i o n . . . . . . . . . 3.1.3 Pro jec ted Growth . . . . . . . . . . . . . .

3.2 Processes and Thei r Emissions . . . . . . . . . . . . . 3.2.1 Mining Operat ions . . . . . . . . . . . . . 3.2.2 Benef ic ia t ion of I r o n O r e . . . . . . . . . 3.2.3 Agglomeration . . . . . . . . . . . . . . . 3.2.4 Fac tors Affec t ing Emissions From I ron Ore

P l a n t s . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . Chapter 4 . Emission Control Techniques . . . . . . . . . . . .

4 . 1 Control Device A l t e r n a t i v e s . . . . . . . . . . . . . . 4 . 1 . 1 Control of Mining Operat ions . . . . . . . . 4.1.2 Control of B e n e f i c i a t i o n Operations . . . . 4.1.3 Control of P e l l e t i z a t i o n . . . . . . . . . . 4.1.4 Control of Other Sources . . . . . . . . . .

4.2 Performance of Typical Control Techniques . . . . . . . 4.2 .1 General Aspects and Vendor Guarantees . . . 4.2 .2 F i e l d T e s t Data . . . . . . . . . . . . . .

. . 2-1

. . 3-1

. . 3-1

. . 3-1

. . 3-7

. . 3-11

. . 3-12

. . 3-13

. . 3-16

. . 3-28

. . 3-46

. . 3-48

. . 4-1

. . 4-1

. . 4-1

. . 4-3

. . 4-10

. . 4-19

. . 4-25

. . 4-25

. . 4-29

CONTENTS

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-35

Chapter 5 . Modification and Reconstruction . . . . . . . . . . . 5-1

Reconstruction . . . . . . . . . . . . . . . . . . . . . 5-1

Applicability to the Iron Ore Beneficiation Industry . . . 5-4

Chapter 6 . Model Emission Control Systems . . . . . . . . . . . . 6-1

6 . 1 Mining, Blasting, and Hauling . . . . . . . . . . . . . . 6-1

6.2 Primary Crushing . . . . . . . . . . . . . . . . . . . . . 6-1

and Ore Storage . . . . . . . . . . . . . . . . . . . . 6-2

6 . 4 Pellet Induration . . . . . . . . . . . . . . . . . . . . 6-3

6 . 4 . 1 Grate-Kiln System . . . . . . . . . . . . . . 6-4

6 . 4 . 2 Straight Grate System . . . . . . . . . . . . 6-6

5 . 1 40 CFR Part 6 0 Provisions for Modification and

5.2

6 . 3 Secondary Crushing, Screening, Conveyor Transfer,

Chapter 7. Environmental Impact

(To be completed by the Emission Standards and Engineering Division, U . S . EPA)

Chapter 8. Economic Impact

(To be completed by the Emission Standards and Engineering Division, U.S. EPA)

Chapter 9. Rationale for the Proposed Standards

(To be completed by the Emission Standards and Engineering Division, U . S . EPA)

Appendix A.

Appendix B.

Evolution of Proposed Standards (Not Included)

Index to Environmental Impact Considerations (Not Included)

Appendix C. Emission Source Test Data . . . . . . . . . . . . . . C-l/C-38 Appendix D. Emission Measurement and Continuous Monitoring

(Not Included)

Appendix E. Enforcement Aspects (Not Included)

fl I I I I I I I I 1 I I

I I I I I I I I I

I I

'I I I c I 1 I If I I 1 I I I E I. 1 1 I z I

TABLES

Number

3.1 Iron Ore Mines . . . . . . . . . . . . . . . . . . . . . . . . . 3-2

3.2 Pellet Plants . . . . . . . . . . . . . . . . . . . . . . . . . 3-5

3.3 Pellet Plant Expansions . . . . . . . . . . . . . . . . . . . . 3-6

3.4 Production of Crude Ore . . . . . . . . . . . . . . . . . . . . 3-8

3.5 Percentage of Total Crude Production by Region . . . . . . . . . 3-8 3.6 Iron Ore Mine Production and Total Shipments in 1975 . . . . . . . . 3-9 3.7 Beneficiation Methods Used by Active Iron Ore Mines . . . . . . 3-17 3.8a Summary of Emissions from Beneficiation Operations of

Several Iron Ore Plants (English Units) . . . . . . . . . . . 3-26 3.8b Summary of Emissions from Beneficiation Operations of

Several Iron Ore Plants (Metric Units) . . . . . . . . . . . 3-27 3.9a Summary of Particulate Emission Data on Pelletization

Systems (English Units) . . . . . . . . . . . . . . . . . . . . 3-43

3.9b Summary of Particulate Emission Data on Pelletizing Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-44

4.1 Emission Sources and Control Alternatives . . . . . . . . . . . 4-2 4.2 Summary of Transfer Point Sources Versus Type of

Indurating Machine Employed . . . . . . . . . . . . . . . . . 4'-19 4.3a Characteristics of Particulate Control Devices

(English Units) . . . . . . . . . . . . . . . . . . . . . . . 4-27

(Metric Units) . . . . . . . . . . . . . . . . . . . . . . . . 4-28

Devices Used by the Iron Ore Industry . . . . . . . . . . . . 4-30

Currently Used in Iron Ore Pelletization . . . . . . . . . . .

4.3b Characteristics of Particulate Control Devices '

4.4 Typical Performance Guarantees on Some Control

4.5 Summary of Field Test Data on Control Devices 4-32

4 . 6 Field Test Data on Minor Source Wet Scrubbers Used by the Iron Ore Industry . . . . . . . . . . . . . . . . 4-34

C-la Iron Ore Plant Emission Data . . . . . . . . . . . . . . . . . . . C-1 C-lb Iron Ore Plant Emission Data . . . . . . . . . . . . . . . . . . C-2

>

I

TABLES

Number

C-2a I r o n Ore P l a n t Emission Data. . . . . . . . . . . . . . . . C-3

C-2b I ron Ore P l a n t Emission Data. . . . . . . . . . . . . . . . C-4

C-3a I r o n O r e P l a n t Emission Data. . . . . . . . . . . . . . . . C-5

C-3b I r o n Ore P l a n t Emission Data. . . . . . . . . . . . . . . . C-6





C-6a I r o n Ore P l a n t Emission Data. . . . . . . . . . . . . . . . C - 1 1

C-6b I r o n Ore P l a n t Emission Data. . . . . . . . . . . . . .) . . C-12





c 17 c-4a Lron ure Fianr: Emission Daca. . . . . . . . . . . . . . . . C-9b Iron Ore P l a n t Emission Data. . . . . . . . . . . . . . . . C-18

C-loa I r o n Ore P l a n t Emission Data. . . . . . . . . . . . . . . . C-19

C-lob I ron O r e P l a n t Emission Data. . . . . . . . . . . . . . . . C-20

C-lla I r o n Ore P l a n t Emission Data. . . . . . . . . . . . . . . . C-21

C-llb I r o n Ore P l a n t Emission Data. . . . . . . . . . . . . . . . C-22

C-12a I r o n Ore P l a n t Emission Data. . . . . . . . . , . . . . . . C-23




C-14a I ron Ore P l a n t Emission Data. . . . . . . . . . . . . . . . C-27

-

I i 31

1 1 1 1 1 1 1

1 1 1 E 1 1 1 1 1

a

1 =

I' I 1 I I I E I I I. I' I I I I: I 1 I I 0

TABLES

Number

C-14b I ron Ore P l a n t Emission Data. . . . . . . . . . . . . . . . C-15a I r o n Ore P l a n t Emission Data. . . . . . . . . . . . . . . . C-15b I r o n Ore P l a n t Emission Data. . . . . . . . . . . . . . . . C-16a I r o n Ore P l a n t Emission Data. . . . . . . . . . . . . . . . C-16b I r o n Ore P l a n t Emission Data. . . . . . . . . . . . . . . . C-17a I ron Ore P l a n t Emission Data. . . . . . . . . . . . . . . . C-17b I r o n Ore P l a n t Emission Data. . . . . . . . . . . . . . . . C-18a I r o n Ore P l a n t Emission Data. . . . . . . . . . . . . . . . C-18b I r o n Ore P l a n t Emission Data. . . . . . . . . . . . . . . . C-19a I ron O r e P l a n t Emission Data. . . . . . . . . . . . . . . . C-19b I ron Ore P l a n t Emission Data. . . . . . . . . . . . . . . .

C-28

c-29

C-30

C - 3 1

C-32

c-33

c-34

c-35

C-36

c-37

C-38

FIGURES

Number

3 . 1 Location of I r o n Ore Reserves i n t h e U.S . . . . . . . . . . 3-10

3 . 2 Gyratory Crusher. . . . . . . . . . . . . . . . . . . . . . 3-18

3 . 3 Crushing P l a n t Flowsheet (U.S. Stee l - Minntac) . . . . . . 3-20

3 .4 Fine Crushing Building (Eveleth Taconi te Company) . . . . . 3-21

. 3 . 5

3 . 6

3 .7

3 . 8

3 . 9

3 . 1 0

3.11

3 .12

4 . 1

4 . 2

4 . 3

4 . 4

4 . 5

4 . 6

4 . 7

4 . 8

4 . 9

4 . 1 0

4 . 1 1

I r o n Ore C oncent ra tor Flowsheet U t i l i z i n g Autogenous Mi l l ing and F l o t a t i o n C i r c u i t s - Tilden Mine. . . . . . . 3-24

Disc-Type Vacuum F i l t e r . . . . . . . . . . . . . . . . . . 3-25

Typical Bal l ing D r u m C i r c u i t . . . . . . . . . . . . . . . . 3-32

Cross-Section of V e r t i c a l Shaf t Furnace . . . . . . . . . . 3-34

S t r a i g h t Grate Indura t ion System, McKee Type. . . . . . . . 3-37

S t r a i g h t Grate Indura t ion System, Dravo-Lurgi Type. . . . . 3-38

Gra te -Ki ln Indura t ion System. . . . . . . . . . . . . . . . 3-39

Plan V i e w of C i r c u l a r Grate Machine . . . . . . . . . . . . 3-41

Typical High-Efficiency I n v o l u t e Cyclone. . . . . . . . . . Typical Baghouse Col lec tor . . . . . . . . . . . . . . . . . 4-5

Hood Configurat ion f o r Secondary Crusher. . . . . . . . . . 4-7

Hood Configurat ion f o r Crusher-Screen Combination

4-5

. . b-6 Hood Configurat ion for VCDrating Sci-ccii . . . . . . . . . .

. . . . . 4-7

Packed-Bed Scrubber (Nat ional Dust Col lec tor Corporation, H y d r o f i l t e r ) . . . . . . . . . . . . . . . . 4-8

Company, Rotoclone) . . . . . . . . . . . . . . . . . . . 4-8 C e n t r i f u g a l Fan-Type Scrubber (American A i r F i l t e r

Hood Configurat ion f o r Ore Chute Transfer

Hood Configurat ion f o r Conveyor Bel t Transfer

A i r Flow Diagram-Dravo-Lurgi S t r a i g h t Grate M a c h i n e . . . . . . . . . . . . . . . . . . . . . . . . . . 4-12

A i r Flow Diagram-McKee S t r a i g h t Grate Machine . . . . . . . 4-13

. . . . . . . . . 4-9

4-9 . . . . . . .

.I 1 1 P I I 1 I I I I I 1 I 1 I t I 1

1 a

Number

4.12

4.13

4.14

4.15

4.16

6.1

6.2

FIGURES

Mul t ip le Tube Dry Co l l ec to r (Mult ic lone) . . . . . . . . . . . 4-14

A i r Flow Diagram-Grate Ki ln Process . . . . . . . . . . . . . 4-16

E l e c t r o s t a t i c P r e c i p i t a t o r . . . . . . . . . . . . . . . . . . 4-17

Ventur i Scrubber. . . . . . . . . . . . . . . . . . . . . . . 4-17

Combination Wet Scrubber. . . . . . . . . . . . . . . . . . . 4-20

Model P e l l e t Induration-Grate K i l n Options. . . . . . . . . . 6-5

Model P e l l e t Indura t ion - S t r a i g h t Grate Options. . . . . . . 6-7

-I- 1' I I 1 I I 1 I I I 1 C t 1 I I I u P 1 I

This document

2 . INTRODUCTION

s ' a pre l iminary d r a f t . It i a s n o t been formal ly r e l e a s e d by t h e U . S . Environ- mental P r o t e c t i o n Agency and should no t a t t h i s s t a g e be construed t o r ep resen t Agency pol icy . I t i s being c i r c u l a t e d f o r comments on i t s tech- n i c a l merit and po l i cy impl i ca t ions .

This d r a f t document p r e s e n t s in format ion on t h e i r o n o r e benef ic ia -

t i o n indus t ry . The r e p o r t desc r ibes t h e va r ious mining, concent ra t ing , ag-

glomerating, and handl ing processes ; t h e i r emissions; and some of t h e var ious

systems a v a i l a b l e f o r c o n t r o l l i n g emissions of s u l f u r oxides and p a r t i c u l a t e

matter from these processes . This informat ion be subsequent ly used as

p a r t o f t h e d a t a base f o r cons ide ra t ion of s tandards o f performance f o r new

sources (Sect ion 111 of t h e Clean A i r Act, as amended June 1 9 7 4 ) o r emissions

s tandards f o r hazardous a i r p o l l u t a n t s (Sec t ion 1 1 2 ) . E i t h e r , bo th , o r

n e i t h e r of t hese types bf s tandards may be a c t u a l l y developed a f t e r determi-

na t ion o f t h e presence o r absence of need f o r con t ro l s .

2-1

I' I I 11 I' I 1 I I I I 11 I I I II I P IE I I

3. THE IRON ORE BENEFICIATION INDUSTRY

3 . 1 GENERAL

I ron o r e b e n e f i c i a t i o n p e r t a i n s t o t h e mining, crushing, gr inding,

concent ra t ing , and agglomerating of i r o n conta in ing ores . The i r o n o r e indus-

t r y p re sen t ly mines over 6.4 Mg/s (200 m i l l i o n long tons per yea r ) o f crude t o

produce over 66,000,000 Mg (65 m i l l i o n long tons ) of i n d u s t r i a l i r o n o r e pe l -

l e t s . The i r o n o r e indus t ry p re sen t ly i s p ro jec t ed t o inc rease 30 percent by

1978. Geographically t h e major tonnages a r e produced i n t h e Great Lakes reg ion

wi th Minnesota and Michigan be ing the l a r g e s t producers.

3 . 1 . 1 Number, Product ion, and D i s t r i b u t i o n of I ron Ore Mines

- _ - ___ - . - - . __ .

___c_I

Iron o r e i s p resen t ly mined a t 4 1 mines ranging from 2 kg/s (180

long tons p e r day) t o 1 . 3 Mg/s (110,000 long tons p e r day) product ion of i r o n

ore . There are p resen t ly 1 9 p e l l e t i z i n g p l a n t s ope ra t ing wi th a r a t e d capac i ty

o f 2 . 1 Mg/s (65.75 m i l l i o n long tons p e r year ) of p e l l e t s . Table 3 . 1 l i s t s t h e

mines i n ope ra t ion i n 1974 and t h e i r r a t e d o r e product ion. Table 3 . 2 gives t h e

p e l l e t p l a n t s ope ra t ing i n 1974 a long wi th t h e i r r a t e d capac i ty o f p e l l e t s .

-

The i r o n o r e indus t ry p re sen t ly has expansions under way t h a t w i l l

t o t a l 0.76 Mg/s ( 2 3 . 6 m i l l i o n long tons per y e a r ) of p e l l e t s . The loca t ions

of the expansions and t h e i r r a t e d capac i ty are shown i n Table 3 . 3 . A s shown

the re , t h e major expansions are occur r ing i n Minnesota.

Crude i r o n o r e product ion has increased from 5.79 Mg/s (179,851,000

long tons per year ) i n 1966 t o 6.97 Mg/s (216,620,000 long tons p e r year ) i n

1975. The t o t a l product ion o f crude along wi th tonnages f o r t h e fou r major '

3-1

I 1 I I 1 I I 0 1 I 1 1 I I I I 4 I 8 I I

TABLE 3 . 1 IRON ORE MINES

Star t -up 1974 Ore Mined Operation/Location Year k g l s l t p d Mine Type

~~ - ~~

Arcturus Mine Marble, Minn.

Black River F a l l s Mine Black River F a l l s , Wisc.

But ler Taconite Nashwauk, Minn.

Canisteo Mine Coleraine, Minn.

Cedar Ci ty Mine Cedar Ci ty , Utah

Corns rock Mine Cedar Ci ty , Utah

Eagle Mountain Mine Eagle Mountain, C a l i f .

Empire I ron Mining Co.. Ishpeming, Mich.

Er ie Mining Co. Hoyt Lakes, Minn.

Eveleth Taconite Co. Evele th , Minn . Grace Mine Morgantown, Pa.

Gross-Nelson Mine Eveleth, Minn.

Groveland Mine Randville, Mich.

H i l l Annex Mine 0 Calumet, Minn.

Hull-Rus t Mine Hibbing, Minn.

Jackson County I ron Co. Black River F a l l s , Wisc.

Lind-Greenway Mine Grand Rapids, Minn.

Lone Star S t e e l Co. Lone S t a r , Tex.

NA

1969

1967

1933

1946

1953

1948

1964

1957

1965

1958

1966

1959

1917

1965

1969

1953

1947

NA

106

268

346

64

49

352

529

1 , 0 5 8

200

83

7 1

168

235

47

88

235

1 8 8

NA

9,000

22,800

29 ,450

5 , 4 0 0

4 ,200

30 ,000

45,000

9 0 , 0 0 0

17,000

7,025

6,000

1 4 , 2 5 0

20 ,000

4 ,000

7 , 5 0 0

20 ,000

16,000

Open p i t

Open p i t

Open p i t

Open p i t

Open p i t

Open p i t

Open p i t

Open p i t

Open p i t

Open p i t

Underground

Open p i t

Open p i t

Open p i t

Open p i t

Open p i t

Open p i t

Open p i t

3-2

TABLE 3 . 1 IRON ORE MINES (Cont) . .

Start-up 1974 Ore Mined O p e r a t i o n l h c a t i o n Year kgls l t p d Mine Type

Luck Mining Co. S i l v e r C i ty , N.M.

MacIntyre Deveiopment Tahawus, N . Y .

Mather Mine Ishpeming, Mich.

McKinley Mine McKinley, Minn . Meramec Mining Co. Su l l ivan , Mo.

Minntac P l a n t M t . I r on , Minn.

Nat iona l S t e e l P e l l e t P l a n t Keewatin, Minn.

Nevada-Barth Corp. Ca r l in , Nev.

P i l o t Knob P e l l e t Co. I ron ton , Mo.

Republic Mine Ishpeming, Mich.

Nev i l l e Mine Chisholm, Minn.

S t a r Lake, N . Y .

Rana Mine Kinney, Minn.

Reserve Mining Co. Si lver Bay, Minn.

Rouchleau group Vi rg in i a , Minn.

Sherman Mine Chisholm, Minn.

Sherwood Mine I ron River , Mich.

Stephens Mine Aurora, Minn.

.,... .,_..1_ ,.>.., - 1 ._ I * C W I"&& Y I V I ~ I V L L

1938 2

1942 59

1943 86

1968 200

1961 100

1967 1,294

1967 282

1960 1 4

1968 70

1956 285

1974 102

,,? L A -

1 n ,, ,. A d . 7 7

1974 42

1955 1,000

1943 NA

1948 NA

1940 19

1957 NA

180

5,000

7,300

17,000

8,500

110,000

24,000

1,200

5,979

24,200

8,650

0,5%

3,600

85,000

NA

NA

1.600

NA

Open p i t

Open p i t

Underground

Open p i t

Underground

Open p i t

Open p i t

Open p i t

Underground

Open p i t

Open p i t

nnen - 4 : r - -~-..

Open p i t

Open p i t

Open p i t

Open p i t

Underground

Open p i t

3- 3

- i I 1 I P 1 1 0 E I I I

1 I I I 2 I I I I

I -

I 1 1 1 1 I

P I' I 1 1 1 I I I I t' I 1

a

TABLE 3 . 1 IRON ORE MINES (Cont)

Start-up 1974 Ore Mined OperationILocation Year kg l s l t p d Mine Type

Sunrise Mine 1900 NA NA Underground Sunrise, Wyo.

1974 433 36,800 Open p i t Tilden Mining Co. Ishpeming, Mich. U . S . P i p e & Foundry Co. 1954 8 700 Open p i t Russe l lv i l l e , Ala.

1973 2 39 20 ,300 Open p i t Whitney Mine Hibbing, Minn.

1960 38 3,200 Open p i t Wyoming Mine Virginia, Minn.

Source: Reference 1.

3- 4

TABLE 3.2 PELLET PLANTS

Rated

Company S tart-Up Capacity

Location Year P e l l e t Sys tem Mg/s million l t p y

E r i e Mining Co.

Reserve Mining Co.

U.S. S t e e l - Minntac

But le r Taconi te

Nat ional S t e e l P e l l e t P l a n t

Eveleth Taconite Co.

Hanna Mining Co. -

Marquette I ron Min-

Humbolt Mining Co.

Pioneer P e l l e t P l a n t

Empire i r o n ?lining

Grove land

ing Co. - Republic

co.

Ti lden Mining Co.

Meramec Mining Co.

P i l o t Knob Mining

Jackson County i r o n

Bethlehem S t e e l Corp. - Grace

C i t i e s Service Co.

Kaiser S t e e l Corp.

U.S. S t e e l Corp. - A t l a n t i c Ci ty

co.

co.

Minn.

Minn . Minn.

Minn.

Minn.

Minn.

Mich.

Mich.

Mich.

Mich.

Mich.

Mich.

Mo.

Mo.

wis.

Pai

Tenn.

Cal.

WY.

195 7 / 1960

1 9 5 6 / 1 9 6 2

1 9 6 7 / 1 9 7 2

1967

1969

1965

1963

1962

1960

1965

19 6 3 1 196 7

1975

1964

1968

i 9 o 9

1 9 6 1

1972

1965

1962

Shaft furnace

S t r a i g h t g r a t e

Grate - k i l n

Grate - k i l n

Grate - k i l n

Grate - k i l n


Grate - k i l n

Grate - k i l n

Grate - k i l n

Grate - k i l n

Grate - k i l n

Shaft furnace


Shaf t furnace

Grate - k i l n



0.332

0.348

0.386

0.084

0.090

0 .077

0 . 0 6 8

0 . 0 8 0

0.029

0.052

0 .113

0.129

0.058

0 .032

r 7 n",. V . V L -

0.048

0 .029

0 .090

0 . 0 4 8

10 .3

1 0 . 8

12 .0

2.6

2.8

2.4

2 . 1

2.5

0.9

1 . 6

3 . 5

4 . 0

1 . 8

1.0

"75

1.5

0.9

2 . 8

1.5


3- 5

- l2

a

E l

P I 1

T 8 1 I i I

i

1, 1 1 t I 1

I I 1 I 1 i I I

i

1 1 II I

TABLE 3 . 3 PELLET PLANT EXPANSIONS

Star t -up Rated Capacity Company Location P e l l e t System Year Mg/s m i l l i o n l t p y

E m p i r e Mining Co. Mich. Gra te -k i ln 1975 0.058 1.8

Eveleth Taconite Co. Minn. S t a t e - k i l n 1976 0.116 3.6

Hibbing Taconite Co. Minn. S t r a i g h t g r a t e 1976 0 . 1 7 4 5.4

National S t e e l P e l l e t Minn. Grate-ki ln 1977 0.135 4 . 2 P l a n t

Inland S t e e l Co. - Minn. S t r a i g h t g r a t e 1978 0 . 0 8 4 2.6 Minorca

U.S. S t e e l Corp. - Minn . Grate-ki ln 1978 0 . 1 9 3 6 . 0 Minntac


..

3-6

producing a r e a s are given i n Table 3.4.

i n t h e four r e g i o n a l a r e a s a r e given i n Table 3 . 5 .

duct ion of o r e and t o t a l shipments f o r t h e r e g i o n a l a r e a s in 1975.

3 . 1 . 2 Ore Types and D i s t r i b u t i o n

The percentages of t o t a l crude mined

Table 3 . 6 gives the pro-

I r o n oxides a r e the most s i g n i f i c a n t mineral component of i r o n o res ;

however, o t h e r forms of i ron minerals a r e mined f o r t h e i r i r o n content . I ron

o r e d e p o s i t s a r e genera l ly categorized according t o t h e i r genes is , s t r u c t u r e ,

geologic f e a t u r e s , o r amenabili ty t o m e t a l l u r g i c a l uses . There a r e i n gen-

eral t h r e e types of deposits--bedded, massive, and r e s i d u a l . The bedded de-

p o s i t s a r e sedimentary l a y e r s t h a t have accumulated i n bodies of water. The

massive-type d e p o s i t s a r e v e i n s o r masses of i ron minerals t h a t have replaced

p r e e x i s t i n g minerals o r f i l l e d voids o r f i s s u r e s i n e x i s t i n g rock formations.

'The r e s i d u a l d e p o s i t s a r e bodies of i r o n minerals t h a t have been subjected t o

a leaching a c t i o n whereby some o f t h e nonferrous mineral c o n s t i t u e n t s have

been removed.

I ron o r e depos i t s a r e known t o occur i n a l a r g e number of s t a t e s in

the United S t a t e s . The general d i s t r i b u t i o n of known i ron d e p o s i t s i n the

United S t a t e s is i l l u s t r a t e d by Figure 3 . 1 . A s can b e noted from Figure 3.1,

t h e r e a r e 20 s t a t e s t h a t have some known occurrence of i ron o re .

The bedded i r o n formations c o n s t i t u t e the l a r g e s t i r o n formations

present ly being mined.

Superior ores .

and i r o n minerals with prominent granular o r o o l i t i c t ex tu re . They are

g e n e r a l l y a s s o c i a t e d w i t h c h e r t , s l a t e , sha l e s , and dolomite. The d e p o s i t s

are g e n e r a l l y well-defined and have broad r e g i o n a l e x t e n t and are developed

These d e p o s i t s are c h a r a c t e r i z e d by t h e Lake

Typical ly these ores c o n s i s t of interbanded c h e r t o r quartz

3-7

>

1 I 1 I P I I I I I D I I .I I 1[ I t

I I 1

i

1 I 1 8 1 1 I 1 1 1 I 1 1 I 1 1 1 1 I I I

TABLE 3 .4 PRODUCTION OF CRUDE ORE

Year Regional Product ion, thousands of tons

Year Superior S t a t e s S t a t e s S t a t e s T o t a l U.S. (a ) Lake Southeastern Northeastern Western

1966 1967 1968 1969 1 9 70 1 9 7 1 1972 1973 1974 1975

142,819 -144,754 156,832 166 ,654 1 7 0 , 0 7 1 159 ,390 155,685 1 8 3 , 6 8 1 183 ,600 185,170

7 ,042 7 , 4 6 1 7 , 6 2 1 8 ,992

10 ,376 9 ,265 9 ,186 8,493 7 ,030 7,250

11 ,365 1 0 , 3 2 9 10 ,075

9 ,575 9 , 0 2 9 7 , 6 5 1 6 , 6 1 5 6 ,806 6 , 3 6 5 5 ,150

18 ,625 18 ,479 1 9 , 3 6 0 18 ,966 19 ,666 18 ,132 13,137 17 ,795 1 7 , 1 8 3 1 5 , 0 5 0

179 ,851 181 ,023 193,889 204,187 209,142 194 ,438 184 ,623 216,775 214,178 212,620

(a ) Includes some by-product o re . Source: Reference 2 .

TABLE 3.5 PERCENTAGE OF TOTAL CRUDE PRODUCTION BY REGION

Southeastern Northeastern Year Lake Superior S t a t e s S t a t e s Western S t a t e s

1966 79 .4 3 .9 6 . 3 1 0 . 4 1967 80.0 4 . 1 5.7 10.2 1968 80.9 3.9 5 .2 10.0

4 . 4 4.7 9 . 3 4 . 3 9 .4

1969 81 .6 19 70 81 .3 5 . 0 1 9 7 1 8 2 . 0 4.8 3.9 9 . 3 19 72 8 4 . 3 5 . 0 3.6 7 . 1 1973 84 .7 3 .9 3 .2 8 .2 1974 85.7 3 . 3 3 . 0 8 . 0 1975 8 7 . 1 3 .4 2.4 7 . 1

Source: Reference 2 .

3-8

m r. rl m

ZH

$ c 0 c

z E- V 3 0 Ec: PI

2

n

w

z ZH w Fr; v

z 0 5 u)

m w : c

h

v nJ

CO

P rl nJ U 0 E-

E m m a u u m m m u 5 m

h n N i o .m

h m m z 2 .~

^ " N r l m r l m m

^ ^

h 0" o m m o m m o m ..e

-2- O, " S

h N O o m '0. '" u u m m m N

..^

m m m u o u m r l 00 drl

" ^

* ^

v

h m m a m

m u m m

mr. - - m m

v

h

or. rlu) O d

m m N U 3

I ^

m m ..^

o m -2

h

m N m m m r l U 3 - i u u

m r l

^ ^ m m

v

h Na N U c o r ! O N m u m m

. I "

v

h

. . r.r.

v

. . mv) O N O N

^ . . m d rlrl

h a m ". N d

Nu) O N m m .."

u)u) v

I

h

a Y m

Lo d m z U Y U P m m u a w m Lo m

U Z Y 0 Q V Y m d 0- c m c r l c Y a 0 4 a 4 P i a v h & V I

go 5

h m u r.u) N O

h

h - 0 P- V h Nr. dv) r.4

m N m N

h ..^

..e m m

v

h .-. u u - - h

ar.

h o m

m m r . m

^ ^

I L Z Z ^ ^ m u

. . a m m m a m

M M

E E

s s s s a a Y Y

2 2 Y Y 0 0

u u

u u Y Y a m a a

$ 5

m m

2 4-34 -0" e m u ) 4 - -

r.u w m u 0- -

U Y

hhhh 3 m e u P 0 v v v v CO

1

1 1 P I I t I I I t

c I 1 1 I I 1 1 1

i

1. 0

-

3-9

f 1

I I s I 1

a

I 1 1 I I I I 1 I I I I I

W

z 0 a Y

i n t h e pre-Cambrian rock groups.

morphosed. T h i s type o f d e p o s i t is g e n e r a l l y r e f e r r e d t o a s t acon i t e , meta-

t a c o n i t e , j a s p i l i t e , and i r o n - q u a r t z i t e and i s t y p i c a l of t h e Mesabi Range

depos i t s . Other bedded type d e p o s i t s i n the U.S. a r e i n t h e "red" o re s o r

"Clinton" d e p o s i t s found i n Alabama. These d e p o s i t s c o n s i s t of hemati te ,

chamosite, and s i d e r i t e interbedded w i t h carbonaceous s h a l e , sandstones, and

carbonate rocks.

These d e p o s i t s a r e o f t e n h ighly meta-

The massive i r o n depos i t s are divided i n t o four d i f f e r e n t types,

two o f which are being e x p l o i t e d i n t h e U.S.

Kiruna type i s t y p i c a l of the Pea Ridge d e p o s i t i n Missouri. This depos i t

i s a massive magnetite d e p o s i t t h a t appears as a n i n t r u s i o n i n t o g r a n i t o i d

and s y e n i t e rocks. These d e p o s i t s are t y p i c a l l y h igh i n magnetite with an

apprec iab le amount o f a p a t i t e present .

is r e f e r r e d t o as a contact-metasomatic type.

Pennsylvania, is an example. These types of d e p o s i t s a r e massive and vein-

l i k e conta in ing mostly magnet i te and hemat i te b u t sometimes a l s o carbonate

and p y r i t e , o f t e n assoc ia ted with skarn minerals . These d e p o s i t s occur

pr imar i ly i n l imestone, volcanic-sedimentary bas ic rocks, an6 amphi'uuiiirs.

One type r e f e r r e d t o as t h e

The o t h e r type found i n the U.S.

The d e p o s i t a t Cornwall,

The r e s i d u a l d e p o s i t s a r e of l e s s e r importance present ly . However,

one t y p i c a l d e p o s i t i s being explo i ted i n Texas and c o n s i s t s mainly of

g l a u c o n i t i c sand, qua r t z , c l ay , and s i d e r i t e .

3 .1 .3 Projected Growth

The i ron o r e i n d u s t r y i n t h e U.S. i s pro jec ted t o have an annual

growth from 1.3 t o 2.3 percent from 1968 to the year 2000. The expansion

plans a l ready announced and under c o n s t r u c t i o n show an i n c r e a s e of 0.76

%/s (23.6 m i l l i o n l t p y ) of p e l l e t s from 1975 r a t e d capac i ty t o 1978 r a t e d

3-11

1 1 d I I 1 I I I 1 I 1 I I 1 1 1 I 1 I I

,"\

capaci ty . "' This growth would r e s u l t i n a t o t a l production of p e l l e t s i n

1978 of 2.876 Mg/s (89.35 mil l ion l t p y ) . However, t h i s expanded growth i n

three years is not expected t o continue but probably w i l l drop back t o t h e

1 .3 t o 2.3 percent pro jec ted growth r a t e over the long-range per iod t o t h e

year 2000.

3.2 PROCESSES AND THEIR EMISSIONS

The f i r s t s t a g e i n the processing o f i r o n ores i s mining which in-

cludes d r i l l i n g , b l a s t i n g , and removing t h e rock. The second s t a g e i n t h e

processing reduces t h e rock s i z e by crushing and gr inding to l i b e r a t e the i r o n

minerals from t h e gangue minerals . The ground mater ia l is then t r e a t e d i n a

b e n e f i c i a t i o n p l a n t designed t o i n c r e a s e t h e i r o n content of the m a t e r i a l .

This processing can include a v a r i e t y of s t e p s such as washing, var ious grav-

i t y separa t ion techniques, magnetic s e p a r a t i o n , f l o t a t i o n , thickening, and

f i l t e r i n g . The f i l t e r e d m a t e r i a l is then mixed w i t h a binder (usua l ly ben-

t o n i t e ) and agglomerated using b a l l i n g drums, b a l l i n g cones, o r p e l l e t i z i n g

d i sc s . The agglomerated b a l l s [ p e l l e t s approximately 1.0 cm (3/8 inch) i n

diameter] a r e f i r e d i n a furnace t o produce a hard r e l a t i v e l y nondusting

p e l l e t which i s i d e a l f o r b l a s t furnace opera t ion . The f i r e d p e l l e t s a r e

cooled, s i z e d by screening , s t o r e d , and shipped t o the s t e e l m i l l s .

The p o t e n t i a l sources of p a r t i c u l a t e emissions from the i r o n ore

operat ion a r e t h e mining, crushing, and conveying of t h e o re , t h e furnace

f i r i n g and cool ing gases , and the p e l l e t handl ing, sc reening , s to rage , and

loading opera t ions .

l a t e c o n t r o l devices on most of t h e var ious sources of a i r emissions.

All p l a n t s have some v a r i e t y o r combinations of par t icu-

3-12

3.2.1 Mining Operations

3 . 2 . 1 . 1 Process Descr ipt ion. The mining of i r o n ore c o n s i s t s of

two general mining methods, underground and open p i t . The l a r g e s t tonnages of

i ron ore produced come from t h e open p i t opera t ions . I n genera l , t h i s mining

operat ion c o n s i s t s of t h r e e s t e p s ; d r i l l i n g - b l a s t i n g , loading, and haul ing.

The underground mining of i r o n o res i n the United S t a t e s i s pres-

e n t l y p r a c t i c e d a t s i x d i f f e r e n t l o c a t i o n s . I n genera l , underground mining

r e q u i r e s a higher grade of i r o n ore than needed f o r open p i t mining i n order

t o achieve comparable u n i t cos t s .

anized and the d r i l l i n g , loading, and haul ing opera t ions genera l ly are done

with wet m a t e r i a l .

Meramec Mine and t h e P i l o t Knob Mine i n Missouri .

Underground mines usua l ly a r e highly mech-

Two examples of underground mining of i ron o r e a r e t h e

Open p i t mining i s t h e most a t t r a c t i v e method of e x p l o i t i n g c e r t a i n

d e p o s i t s because i t can g e n e r a l l y be adapted t o most shapes of depos i t s . I n

addi t ion , open p i t mining can be adapted t o l a r g e tonnage output wi th f l e x i -

b i l i t y a t the lowest cos t .

Taconites i n genera l a r e s i l i c e o u s and hard t o d r i l l and fragment.

Thus, i n t a c o n i t e mines, t h e bench he ight tends t o b e h igher than i n open p i t

mining of o t h e r o r e s ; d r i l l i n g and b l a s t i n g are c a r e f u l l y engineered t o a s s u r e

good fragmentation.

The d r i l l i n g and b l a s t i n g opera t ions i n a t a c o n i t e mine are c a r e f u l l y

planned and executed because t h e c o s t s are high and t h e fragmentation achieved

a f f e c t s the opera t ing c o s t s f o r a l l the subsequent s t e p s . Three p r i n c i p a l

types of d r i l l s a r e used; j e t p i e r c e r s , r o t a r y d r i l l s , and some down-the-hole

percussion d r i l l s .

3-13

I 1 c I P I I I 1 I 3 1 P 1 1 I I I I 1 1

1

4 I I I I 1 I 1 I 1 I I 1 I I I 1 1 .I

a The j e t p i e r c i n g d r i l l i s p r e f e r r e d f o r t h e harder taconi te- type

rocks with t h e d r i l l i n g a c t i o n r e l y i n g on t h e s p a l l i n g c h a r a c t e r i s t i c s of the

rock. The j e t p ie rc ing d r i l l i n g a c t i o n s depends on the d e c r e p i t a t i o n of t h e

rock r e s u l t i n g from s t r e s s e s caused by d i f f e r e n t i a l thermal expansion. This

d r i l l induces t h e thermal s t r e s s from a burner using f u e l o i l , oxygen, o r a i r ,

and water which generates a flame temperature of 1922 t o 2644 K (3000 t o

4300 F). The d r i l l s genera l ly opera te a t 0.085 t o 0.381 cm/s (10 t o 45 fph) ,

consume from 42 t o 79 cm3/s (40 t o 75 gph) of f u e l o i l , and produce a h o l e of

23 t o 38 cm (9 t o 15 inches) i n diameter.

Rotary d r i l l s a r e genera l ly used i n those mines where t h e o r e is

r e l a t i v e l y s o f t .

usual ly l e s s consol idated than t h e ore .

now a v a i l a b l e , r o t a r y d r i l l s a r e being used more ex tens ive ly . The r o t a r y d r i l l

r e l i e s on t h e c u t t i n g a c t i o n of a r o t a t i n g cone-shaped b i t w i t h the c u t t i n g s

removed by a i r o r sometimes an air-water mixture. The d r i l l i n g r a t e depends on

t h e r o t a t i o n a l speed of t h e b i t and t h e pressure appl ied t o t h e b i t . The d r i l l

b i t l i f e can vary from 72 t o 720 ks ( 2 0 t o 200 hours) depending on the charac-

t e r i s t i c s of the o r e and the opera t ing condi t ions used i n d r i l l i n g . Dus t sup-

press ion techniques a r e genera l ly used with r o t a r y d r i l l i n g . They can include

water addi t ions t o the a i r and water i n j e c t i o n i n the upward a i r f l o w from the

b i t . The i n j e c t i o n of water i n the a i r s t ream general ly shor tens b i t l i f e and

r e s u l t s i n somewhat increased b i t cos t .

A l so they a r e used i n d r i l l i n g t h e over-burden which is

However, w i t h tungsten carb ide b i t s

The down-the-hole percussion d r i l l s a r e only used i n some s p e c i a l

circumstances and do not account f o r a l a r g e tonnage of ore ; t h e r e f o r e , they

a r e not considered important t o t h i s d i scuss ion .

3-14

The b l a s t i n g i n open p i t mines v a r i e s considerably w i t h t h e ore body,

mine plan, equipment used, d r i l l ho le s i z e , d r i l l h o l e spacing, bench h e i g h t ,

loading equipment, e t c . In general a s i n g l e b l a s t w i l l fragment from s e v e r a l

100,000 mg (hundred thousand tons) of o r e t o a 1,016,000 Mg (mi l l ion tons) and

w i l l use from 0.27 t o 0.45 kg (0.6 l b t o over 1 l b ) of explosives per 1 Mg

(1 ton) of o r e broken. Blas t ing i n some of t h e l a r g e opera t ions i s scheduled

t o occur during favorable meteorological condi t ions t o prevent the propagation

of sound waves.

Loading p r a c t i c e i n open p i t opera t ions usua l ly involves t h e use of

l a r g e shovels with 7- t o 13-m3 (9- t o 15-cubic yard) buckets f o r t h e primary

loading w h i l e l a r g e front-end loaders a r e used i n secondary or cleanup

opera t ions .

Hauling operat ions include r a i l r o a d haulage from the working f aces '

t o l a r g e t rucks o r some combination of t rucks and r a i l haulage usua l ly depend-

i ng on t h e ind iv idua l opera t ion .

356 Mg (50 t o 350 tons) ( the l a t t e r i s a pro to type u n i t i n opera t ion a t Eagle

Mountain, C a l i f o r n i a ) . The ore t ranspor ted by r a i l r o a d usua l ly i s done by u n i t

c a r t r a i n s such a s a t Reserve Mining Company where 160-car u n i t t r a i n s t rans-

po r t o r e some 80 km (50 miles) t o the c rusher s t a t i o n .

The t rucks used range i n s i z e from 51 t o

3.2.1.2 Emissions From Mining. The p r i n c i p a l mining operat ions

include d r i l l i n g , b l a s t i n g , loading o r e , and haul ing of t h e o re , a l l of which

can produce p a r t i c u l a t e emissions.

Some of the f u g i t i v e emission sources are c o n t r o l l e d t o some degree

i n t h e i r o n o r e indus t ry p r i n c i p a l l y by u s i n g water sprays a s i n the case of

d r i l l i n g and mine road dus t . Other sources of f u g i t i v e emissions such a s

b l a s t i n g and the haulage loads a re more d i f f i c u l t t o handle; i n a d d i t i o n , the

3-15

I il s 1 II I I I I I 1 1 I I I I I 1 1 1 .I

s e v e r i t y of t h e emissions usua l ly depends on the weather. There a r e p r e s e n t l y

no es t imates a v a i l a b l e of f u g i t i v e emission q u a n t i t i e s from the var ious mining

opera t ions . Only one p l a n t of t h e 1 9 p l a n t s surveyed i n t h i s s tudy repor ted

on emissions i n t h i s category. In t h i s c a s e (Eveleth Taconite Company), t h e

emissions from the t ruck dump and r a i l c a r loading and unloading pockets were

estimated t o be about 1 9 g / s (150 pounds p e r hour) while processing about 232

kg/s (825 tons per hour) of ore . These emissions sources were e i t h e r uncon-

t r o l l e d or had dry cyclone c o l l e c t o r s opera t ing .

3.2.2 Benef ic ia t ion of I ron Ore

The present-day s p e c i f i c a t i o n s for b l a s t furnace feed a r e s o s t r i n g e n t

and t h e crude o r e grades a r e i n genera l s o low t h a t p r a c t i c a l l y a l l of the crude

o r e has t o be b e n e f i c i a t e d before i t can b e marketed. The b e n e f i c i a t i o n s t e p s

and procedures required w i l l vary from simply crushing and washing t o var ious

combinations of crushing, washing, g r a v i t y and magnetic s e p a r a t i o n , and f lo-

t a t i o n . The v a r i a t i o n s used i n the o v e r a l l processes b e n e f i c i a t i n g t h e crude

o r e a r e i l l u s t r a t e d by t h e d a t a included i n Table 3.7.

major i ty of the ore i s processed through a crushing, gr inding, and a magnetic

separa t ion stage with f l o t a t i o n being appl ied i n a few cases t o make the f i n a l

concentrate .

A s can be noted, the

3.2.2.1 Crushing. . I ron o r e crushing i s genera l ly accomplished by

u t i l i z i n g gyratory-type c rushers and v i b r a t i n g screens t o s i z e t h e mater ia l .

Figure 3.2 i l l u s t r a t e s t h e gyratory-type crusher . Typica l ly , the crushing

c i r c u i t w i l l c o n s i s t of primary, secondary, and t e r t i a r y c rushers combined wi th

v i b r a t i n g screens t o s e p a r a t e t h e des i red s i z e f r a c t i o n .

Several v a r i a t i o n s i n m a t e r i a l flow and number of c rushers a r e used;

however, i n genera l , the o r e w i l l b e crushed i n a primary gyratory crusher t o

3-16

TABLE 3 . 7 . BENEFICIATION METHODS USED BY ACTIM IRON O M MINES

Grinding, primary/ Concentrating

Locat ion secondary Method

Erie Mining Co. Minn . RM- BM MS Reserve Mining Co. Minn. RM- SM MS

B u t l e r Taconi te Minn. DSAG- BM Ms National S t e e l P e l l e t Plant Minn. DSAG- BM MS Eveleth Taconi te Co. Minn . RM- BM Ms Hanna Mining Co. - Groveland Mich. RM- BM MS-Spi-Flot Marquette I r o n Mining Co. - Republic Mich. RM- BM F lo t

Pioneer P e l l e t P l a n t Mich. RM- BM W-HM-MS Empire I ron Mining Co. Mich. WAG-BM MS-Flot Ti lden Mining Co. Mich. WAG-BM SF1-Flot Meramec Mining Co. Mo RM- BM MS-Flot P i l o t Knob Mining Co. Mo . WAG- BM Ms-Flot

U . S . S t e e l Corp. (Minntac) Minn. RM- BM MS

Humboldt Mining Co. Mich. -_ _-

Jackson County I r o n Co. Wis. RM- BM Ms Bethlehem S t e e l Corp. - Grace Pa. RM- BM Ms

U,S. S t e e l C O T . - A t l a n t i c Ci ty wyo . RM- BM Ms

Source: Reference 1. Legend:

Cities Serv ice Co. Tenn. BM Flot-R Kaiser S t e e l Corp. C a l . RM- BM HM- J-MS

RM - Rod M i l l BM - B a l l M i l l DSAG - Dry Semi-Autogenous WAG - Wet Semi-Autogenous Grinding Ms - Magnetic Separat ion Spi - S p i r a l F l o t - F l o t a t i o n HM - Heavy Media W - Washing R - Roasting

SF1 - S e l e c t i v e F loccula t ion J - J i g

3-17

I 1 I I I 1 I I I 1 I 1 I' 1 I 1

CRUSHIN1

F I X E D THR0lr.T .-

6 SIJRFACE .

E C C E N T R I C

D I S C H A R G E

Figure 3 . 2 Gyratory crusher

3-18

approximately 18 cm ( 7

t o 60-inch) g y r a t o r i e s

inches) . The primary crushers a r e 137- t o 152-cm (54-

with t h e product going to a s t o c k p i l e o r primary

crusher b ins . This m a t e r i a l i s then picked up by v i b r a t i n g feeders and put

on a conveyor b e l t which, i n some i n s t a n c e s , w i l l be processed on v i b r a t i n g

. sc reens . Some p l a n t s w i l l send a l l of t h e primary c rusher discharge d i r e c t l y

t o the secondary crusher o r f i n e crushing p l an t .

The f i n e crushing p l a n t w i l l general1.y c o n s i s t of secondary and

t e r t i a r y c rushers and, i n some p l a n t s , t h e r e w i l l be a fourth-s tage crusher .

These a r e genera l ly cone c rushers . Vibra t ing screens a r e usua l ly incorpora ted

i n t o t h e flowsheet t o remove the undersize m a t e r i a l from t h e next crusher feed.

T h i s method of screening o f f t h e undersize allows the next crusher t o handle a

l a r g e r volume of m a t e r i a l than i t otherwise could. I n genera l , t h e f i n e crush-

ing p lan t w i l l produce m a t e r i a l t h a t i s pr imar i ly l e s s than 0.64-cm (1/4-inch)

s i z e . The f i n e crusher discharge i s conveyed t o holding b ins o r s i l o s to pro-

v ide feed m a t e r i a l f o r t h e gr inding c i r c u i t . Typical crushing c i r c u i t s a r e

shown i n Figures 3.3 and 3.4.

3 . 2 . 2 . 2 Grinding and Concentration. The gr inding c i r c u i t w i l l con-

G r n r r a i l ~ i ~ t a ; sis t of rod m i l l - b a l l m i l l combinations o r autogeneous m i i i s .

i s added a t t h i s po in t and the m a t e r i a l i s handled a s a s l u r r y through the

concentrator . In both cases t h e m a t e r i a l w i l l b e subjected to s i z e c l a s s i f i -

c a t i o n by screens o r cyclones and concent ra t ion by magnetic s e p a r a t o r s , g rav i ty

s e p a r a t o r s , f l o t a t i o n , o r some combination o f these methods. 1 Typical ly t h e rod m i l l d i scharge w i l l be pumped t o magnetic sepa-

r a t o r s r e f e r r e d t o a s cobbers. The nonmagnetic m a t e r i a l w i l l b e discarded t o

the t a i l i n g s . Some p l a n t s w i l l c l a s s i f y t h i s m a t e r i a l ' t o s e p a r a t e t h e coarse

t a i l i n g s from the f i n e t a i l i n g s . These p l a n t s w i l l genera l ly use t h e coarse

3-19

- -

I 1 1 I P 1 1 1 I I D 1 I 1 1 1 I 1 'I- I I 1-

I I 1 11 I I I I I I I I I I I I I I I I

3-20

I

3-21

I 1 1' 1 8 1 1 I I 1 I I

1 1 I 1 I #I I I I

I w

-

I I 11 I I I 1 I I 1 I I 1 1 I I I I 1' 1 I

- I-

t a i l i n g s f o r d ike cons t ruc t ion o r road b u i l d i n g material whereas t h e f i n e ma-

t e r ia l w i l l be pumped d i r e c t l y t o t h e t a i l i n g s th ickeners . The magnetic frac-

t i o n w i l l be pumped t o primary b a l l m i l l s and ground f u r t h e r ; t h e b a l l m i l l

d i scharge is then pumped t o c l a s s i f y i n g cyclones wi th t h e coarse material

(underflow) r e tu rn ing t o t h e b a l l m i l l and the f i n e ma te r i a l (overflow) pumped

t o rougher magnetic sepa ra to r s . The rougher magnetic sepa ra to r s d i s c a r d t h e

nonmagnetics t o t h e t a i l i n g s and t h e magnetics are ground t o a f i n e r s i z e i n

secondary b a l l m i l l s . The secondary b a l l m i l l s d i scharge t o c l a s s i f y i n g cy-

c lones wi th t h e coarse ma te r i a l r e t u r n i n g t o t h e rougher magnetic s e p a r a t o r s

o r secondary b a l l m i l l s . The f i n e r material i s pumped t o e i t h e r a dewater ing

device such as hydrosepara tors , t h i ckene r s , s iphons ize r s , e tc , o r magnetic

s epa ra to r s . I n some p l a n t s t h e r e are c l e a n e r and f i n i s h e r magnetic s epa ra to r s .

I n essence, some p l a n t s use two s t a g e s of magnetic s epa ra t ion ; o t h e r s use t h r e e

o r fou r s t ages of magnetic s epa ra t ion .

I n add i t ion t o t h e above flow schemes, some p l a n t s w i l l u se g r a v i t y

sepa ra t ion devices such as j i g s , s p i r a l s , heavy media sepa ra to r s , . f l o t a t i o n ,

o r var ious combinations o f t hese techniques. Also some p l a n t s are using auto-

geneous gr inding c i r c u i t s i n s t e a d of t h e convent ional methods descr ibed above.

I n these p l a n t s t h e o r e w i l l be ground i n t h e autogeneous m i l l and discharged

t o a double-deck screen which s e p a r a t e s t h e 2 . 5 - t o 6.4-cm (1- t o 2-1/2-inch)

m a t e r i a l which is used as gr inding media i n t h e pebble m i l l s . The p lus 6.4-

c m (2-1/2-inch) material is re turned t o t h e autogeneous m i l l , t h e minus 2.5-

c m (1-inch) material i s ' p a s s e d over a 0.840-mm (20-mesh) DSM sc reen wi th the

f i n e s bypassing t h e pebble m i l l and going s t r a i g h t t o t h e magnetic cobbers.

The pebble m i l l then d ischarges t o a c l a s s i f y i n g cyclone wi th t h e overflow

going t o t h e magnetic f i n i s h e r s and t h e underflow re tu rn ing t o t h e pebble m i l l .

I

3-22

In t h e newest p l a n t using autogeneous gr inding

a r a t i o n i s used, t h e pebble m i l l d ischarges to

th ickener , and then t o t h e f l o t a t i o n s e c t i o n .

(Tilden Mine), no

a cyclone, then a

magnetic sep-

desliming

The flowsheet of the Tilden

Mine concent ra tor i s shown i n Figure 3.5. In t h e f l o t a t i o n s e c t i o n , a com-

b i n a t i o n of chemical reagents is added t o cause the gangue PAter ia l s ( s i l i c a t e s )

t o be s e l e c t i v e l y f l o a t e d away from t h e i r o n m a t e r i a l s .

Typical ly t h e s l u r r y from t h e concent ra tor i s then f i l t e r e d u t i l i z i n g

disc- type vacuum f i l t e r s which a r e i l l u s t r a t e d i n t h e photograph of Figure 3.6.

The f i n a l product from 'the b e n e f i c i a t i o n s e c t i o n i s a f i l t e r e d i r o n

concentrate conta in ing approximately 9 percent moisture , 60 percent i r o n , and

2 t o 7 percent s i l i c a with a s i z e ranging from 80 percent minus 0.0445 mm

(325 mesh) t o 90 percent minus 0.0127 mm (500 mesh). This m a t e r i a l is t rans-

f e r r e d t o l a r g e b ins which feed the agglomeration s e c t i o n .

3.2.2.3 Emissions From Benef ic ia t ion Operations. The b e n e f i c i a t i o n

opera t ion thus c o n s i s t s of one o r a l l of t h e following: crushing, screening,

t r a n s p o r t i n g , gr inding, magnetic s e p a r a t i o n , f l o t a t i o n , thickening, and f i l t e r -

ing. All opera t ions i n t h i s s e c t i o n except f o r t h e crushing, sc reening , and

t ranspor t ing a r e done w e t (as a slurry); t h e r e f o r e , p a r t i c u l a t e emissions a r e

not a problem. I n the case of crushing and t r a n s p o r t i n g , t h e p o t e n t i a l emis-

s i o n s a r e usua l ly a t t h e feed or discharge p o i n t s of t h e c rusher or a t conveyor

t r a n s f e r po in t s . Screens can be s i g n i f i c a n t sources; thus , they are genera l ly

hooded with a c o n t r o l device a t tached .

Some p a r t i c u l a t e emission va lues were obtained i n t h i s s tudy f o r a

v a r i e t y o f b e n e f i c i a t i o n p l a n t s . These a r e averaged by category and l i s t e d i n

Table 3.8.

3-23

3- I 1 1 1 0 I I I t I I

c I I I I I 1 I

I I

I (I I I I I 1, I I 1 I I I I I I I' I I I

i I I

4 3-24 2

$ i l

-

Figure 3 . 6 Disc-type vacuum f i l t e r

3-25

1 I t 1 8 P 1 1 1 I 1: I

c I I 1 1 I 1 1 I

I .I

I I I I I I: I I 1 1 I I 1 I I I I 1 I I I

p - u l m l. 0 0

* W \ D

0 0 0 0 9 9 9

3-26

b4. 0

d a c d $4 0

s 0 m

0 U 1 4 u

5 d 3

. I

m

$4 m 0.

2 $4 m a

m . L d Y n

0 M e e o

$ a 3 M d

m r - ur. c \ o

d c o r l I I O N m m Jm

d d m m w u u u m m \ o u 000000 . . . . . I .

3-27

our. m mlm

r.r-

rlu "

. .

rl m C Y o m drl u u m 3 Zrn I 1 M M G ' c d d c c d d z z m a c c c c x x m a

1 I I 1 P c1 1 1 1 1 c1 1 1 1 1 1 1 I I I 1 1 -

I I I I I 1 I I I 4 I I I I I I I I 'I I I

The d a t a i n Table 3.8 show a r a t h e r c lear-cut d i f f e r e n c e i n par t icu-

l a t e emissions depending on t h e type of b e n e f i c i a t i o n p lan t considered.

example, assuming a t y p i c a l p l a n t w i l l process about 1000 tons per hour of o re ,

the conventional crushing and gr inding p l a n t w i l l emit about 8 g / s (65 pounds

per hour) of p a r t i c u l a t e s , and t h i s i s contained i n about 106 s tandard m 3 / s

(225,000 scfm) of gas volume. The p l a n t s using dry semiautogeneous gr inding

w i l l have up to 25 g / s (200 pounds p e r hour) of p a r t i c u l a t e s and a gas volume

about twice t h a t of conventional p l a n t s . I t should be noted t h a t a t l e a s t one

of the two p l a n t s which c u r r e n t l y u t i l i z e dry gr inding is implementing a

change t o t h e w e t autogeneous gr inding method. This w e t method apparent ly

w i l l r e s u l t i n g r e a t l y reduced emissions a s pro jec ted by the Hibbing p r o j e c t

which can have emissions a s low a s 0.78 g / s ( 7 pounds per hour) p e r 1000 Mg

For

(1000 tons) of o r e processed.

3.2.3 Agglomeration

The l a s t decade has seen a s i g n i f i c a n t i n c r e a s e i n t h e use of ag-

glomerated i r o n ores e i t h e r i n t h e form of s i n t e r o r p e l l e t s .

use of agglomerated ores r e s u l t s from the decrease i n t h e a v a i l a b i l i t y of

d i r e c t shipping o res and t h e improvement i n b l a s t furnace performance when

using agglomerated ores . The b l a s t furnace opera t ion i s not e f f i c i e n t fo r

handling f i n e s ; t h e r e f o r e , a s i g n i f i c a n t i n c r e a s e i n the production of p e l l e t s

and s i n t e r can be a n t i c i p a t e d i n t h e n e x t decade.

The increased

3.2..3.1 S i n t e r i n g . The s i n t e r i n g process was developed because o f '

the d i f f i c u l t i e s t h a t a r i s e i n the handling of f i n e o re s and concent ra tes .

Fine m a t e r i a l s c r e a t e dust problems and a r e not as e f f i c i e n t i n subsequent

operat ions such a s t h e b l a s t furnace.

by causing the f i n e p a r t i c l e s t o bond t o g e t h e r , o r agglomerate, i n t o porous

S i n t e r i n g overcomes these d i f f i c u l t i e s

3-28

pieces t h a t are s t r o n g enough t o hold t h e i r shapes i n subsequent furnace op-

e r a t i o n s and porous enough t o permit good gas d i s p e r s i o n through t h e bed.

S i n t e r i n g i s accomplished by mixing a f i n e l y divided s o l i d f u e l , such a s coke

breeze, w i th t h e f i n e o r e , i g n i t i n g t h e f u e l and burning i t wi th a forced

d r a f t through t h e mixture . This process i s used pr imar i ly f o r f i n e s gener-

a t e d a t steel m i l l s , a l though a t least two s i n t e r i n g p l a n t s are a t s e p a r a t e

l o c a t i o n s .

-

The s i n t e r i n g machine b a s i c a l l y c o n s i s t s of a number o f i nd iv idua l

con ta ine r s , termed p a l l e t s , f o r r ece iv ing and conveying t h e material. The

p a l l e t s are simply r ec t angu la r troughs w i t h w a l l s on two s i d e s , and g r a t e s t o

suppor t t h e charge.

p o s i t s and l e v e l s a bed of charge material [usua l ly about 30.5 cm (12 inches)

i n depth] under a burner which i g n i t e s t h e upper s u r f a c e of t h e charge. The

p a l l e t s then pass a number of chambers r e f e r r e d t o as wind boxes which a r e

connected t o t h e exhaust s i d e of a fan t o draw t h e h o t a i r through t h e charge

on t h e p a l l e t s . The ra te of t r a v e l of t h e p a l l e t s i s r egu la t ed so that they

w i l l a r r i v e a t t h e end of t h e wind box s e c t i o n when t h e charge has reached t h e

des i r ed temperature.

The p a l l e t s success ive ly pass under equipment which de-

I n t h i s manner, mixcures of o r e s o r concent ra tes conta in ing fuel are

i g n i t e d , and t h e i n i t i a l combustion i s propagated downward by t h e down d r a f t

through t h e wind box s e c t i o n . The flame f r o n t cont inues t o t h e bottom of t h e

charge. It should be noted t h a t t h e f i r i n g i s reversed i n some cases and t h e

wind boxes a r e opera ted i n an updraf t mode. The h e a t developed by t h e com-

bus t ion of t h e f u e l i n t h e l a y e r of charge produces t h e porous agglomerate

c a l l e d s i n t e r .

c o n s t i t u e n t s i n t h e ma te r i a l as carbonates and s u l f a t e s .

The s i n t e r i n g process a l s o serves t o decompose such undes i rab le

3-29

I I I 1 i 1 1 I I I 1 I ! I I I I 1 I I I 1 -

I I 1 I I I I I I 'I I I I I I I I !I I I I

3.2.3.2 P e l l e t i z i n g . P e l l e t i z i n g l i t e r a l l y means the forming of

l i t t l e s p h e r i c a l agglomerates. This process has become increas ingly impor-

t a n t as the ores become lower i n i r o n content and more f i n e l y disseminated

t h u s causing the b e n e f i c i a t i o n processes to work with f i n e r m a t e r i a l . The

f i n e r m a t e r i a l from minus 0 . 6 4 c m (minus 1 / 4 inch) to minus 0.0127 mi l l imeter

(0.0500 inch) i n s i z e could not be t r e a t e d i n t h e b l a s t furnaces e f f e c t i v e l y ,

t h e r e f o r e t h e forming of b a l l s , 0.95 t o 1 . 2 7 cm (3/8 t o 1 / 2 inch) i n s i z e , by

p e l l e t i z i n g has become necessary.

The p e l l e t i z i n g o r b a l l i n g c i r c u i t s t a r t s with the concent ra te

s t o r a g e b i n s which hold the concent ra te produced i n t h e b e n e f i c i a t i o n sec t ion .

This m a t e r i a l i s taken out of t h e concent ra te s t o r a g e b i n s by variable-speed

t a b l e feeders and deposi ted on a conveyor b e l t t h a t passes under a feeder

which adds b e n t o n i t e a t t h e r a t e of 4 t o 9 kg/Mg (9 t o 20 l b p e r long ton) of

concentrate . Bentoni te i s a c lay binder used t o provide s t r e n g t h ( s t rong

enough t o withstand handl ing before f i r i n g ) t o the p e l l e t s . The b e n t o n i t e and

concentrate a r e then thoroughly mixed and fed t o b a l l i n g drums or p e l l e t i z i n g

d iscs . The major i ty of the i r o n o r e p l a n t s use b a l l i n g drums; however, a few

p l a n t s use p e l l e t i z i n g d i s c s or cones. The p e l l e t i z i n g d i s c i s shaped l i k e a

l a rge saucer which is t i l t e d and r o t a t e d , thus forming b a l l s which cont inue t o

grow i n s i z e u n t i l they f i n a l l y reach t h e d e s i r e d s i z e 0.95 t o 1 . 2 7 cm (3/8 to

1 / 2 inch) a t which poin t they a r e discharged over the edge of t h e d i sc .

Several v a r i a b l e s c o n t r o l t h e opera t ion of t h e d i s c such as moisture conten t ,

bentoni te a d d i t i o n , degree of t i l t , r o t a t i n g speed, and p a r t i c l e s i z e of t h e

mater ia l being handled.

The b a l l i n g drum c i r c u i t i s s i m i l a r i n n a t u r e to the d i s c except t h e

mechanism i s a l a r g e r o t a t i n g drum, 2 . 7 t o 4.6 m (9 t o 15 f e e t ) i n diameter

3-30

and 9 .1 t o 1 2 . 2 m (30 t o 40 f e e t ) long. A t y p i c a l b a l l i n g drum c i r c u i t i s

shown i n Figure 3.7. The p e l l e t i z i n g c i r c u i t c o n s i s t s of t h e concent ra te

being fed t o the drum which i s s l i g h t l y i n c l i n e d [approximately 0.12 to

0.16 rad (7 t o 9 degrees) ] and r o t a t e d [approximately 0.13 t o 0.17 revolu-

t i o n s per sccond (8 t o 10 rpm)]. A s t h e m a t e r i a l passes through t h e drum,

the p e l l e t s grow i n s i z e and pass on t o the screen. Cut te r bars a r e used

i n s i d e t h e drum t o t r i m t h e m a t e r i a l o f f t h e w a l l of the drum; usua l ly the

drum w i l l have a 1.27- t o 1.91-cm (112- t o 314-inch) l i n i n g of concentrate .

There a r e b a s i c a l l y two types of c u t t e r b a r s , o s c i l l a t i n g and r o t a t i n g . The

o s c i l l a t i n g c u t t e r b a r o s c i l l a t e s back and f o r t h p a r a l l e l t o the c e n t e r l i n e

of the drum and has tungsten carb ide t e e t h which trim o f f the concent ra te t o

the d e s i r e d th ickness . The r o t a t i n g c u t t e r opera tes p a r a l l e l t o t h e c e n t e r

l i n e of the drum; however, the c u t t e r s now r o t a t e i n t h e oppos i te d i r e c t i o n of

the drum and i n t h i s manner t r i m t h e concent ra te o f f t h e drum. The c u t t e r bar

is necessary t o provide a smooth and r e g u l a r s u r f a c e l i n i n g on t h e drum t o

allow c o n s i s t e n t p e l l e t formation.

The p e l l e t s being discharged from the p e l l e t i z e r a r e screened with

the undersized m a t e r i a l being recycled back t o the feed end of the p e l l e t i z e r .

In never p l a n t s , o v e r s i z e p e l l e t s a r e broken and a l s o recycled t o t h e p e l l e t -

i z e r .

furnaces.

P e l l e t s of c o r r e c t s i z e a re then conveyed on t o t h e i n d u r a t i o n

The i n d u r a t i n g o r f i r i n g of t h e p e l l e t s i s accomplished by s e v e r a l

b a s i c furnace conf igura t ions and combinations. The b a s i c types p r e s e n t l y

being used a r e

0 Shaf t furnace

0 S t r a i g h t g r a t e -

3-31

1 I 1 I 0 I 1 I I I I I I 1 I 1 1 1 I c I 1

I I 1 1 I I I I I 'I I I I I I I I I I I I

; -STORAGE 8IN I

TMLE WEXR-

I I

CUTTER BAR-

* .

i

Figure 3.7 Typical balling drum circuit.

3-32

McKee type - no h e a r t h l a y e r

Dravo-Lurgi - h e a r t h l a y e r used

Grate*kiln

0 Circular g ra t e .

Each of the above indura t ing systems has a drying zone, f i r i n g zone,

and cool ing zone. However, a number of th ings a r e d i f f e r e n t such a s the of f -

gas flows, mechanical handl ing of p e l l e t s , mechanical wear, and thermal e f f i -

ciency.

k i ln" and t h e " s t r a i g h t gra te" systems. The s h a f t furnace was one of the

e a r l i e s t systems, with t h e c i r c u l a r g r a t e be ing the newest approach.

system has i t s suppor te rs and t h e i r reasons f o r using a c e r t a i n conf igura t ion .

P r e s e n t l y the l a r g e s t tonnage of p e l l e t s is produced i n t h e "grate-

Each

3.2.3.2.1 Shaf t Furnace. The s h a f t furnace i s q u i t e simple i n

design and o p e r a t i o n ; b a s i c a l l y , it c o n s i s t s of a l a r g e , v e r t i c a l steel s h e l l

which i s r e f r a c t o r y l i n e d and i n which the green p e l l e t s a r e fed i n t h e top

and flow out the bottom w i t h the gases flowing countercur ren t t o t h e p e l l e t s .

A cross s e c t i o n of a s h a f t furnace i s presented i n Figure 3.8. Typica l ly , a

furnace w i l l process 14 t o 1 7 kg/s (50 t o 60 tons per hour) of p e l l e t s and

have approximate dimensions of 2 . 1 t o 2.4 m (7 t o 8 f e e t ) wide a t t h e stock-

l i n e and appruxlmately 20 m (65 f e e t ) high:

I n the s h a f t furnace opera t ion , green p e l l e t s a r e layered i n the

top of the furnace by indexing type feeders which evenly d i s t r i b u t e the pel-

l e t s across the furnace. The p e l l e t s then begin descending down t h e furnace

t o be d r i e d and preheated by the upward flow of a i r and gases introduced a t

the bottom of the furnace. The p e l l e t s flow i n t o the b u s t l e zone where t h e

f i r i n g occurs , then continue down t h e furnace t o t h e cool ing zone where a i r i s

b e i n g introduced. Thus, the cold a i r coming in a t t h e bottom i s heated by the

3-33

I I ! I I I I I I- I- I I -

I I I I I I I I I I I I I I 'I I I I .I 1 I 'I

GIRD€R AREA

E N D V I E W

Figure 3 . 8 Cross-Section of Vertical Shaft Furnace

3-34

hot p e l l e t s descending down the furnace; t h i s , t h e r e f o r e , provides f u e l eco-

nomies i n the f i r i n g process . The average residence time f o r t h e p e l l e t s i n

the furnace is about 4 hours.

There a r e some r a t h e r severe l i m i t a t i o n s t o t h e s h a f t furnace. (3)

F i r s t , i t i s l i m i t e d t o magnetite ores . Indura t ion i s dependent upon t h e exo-

thermic r e a c t i o n of t h e magnetite. I f t h e FeO content is below approximately

18 percent , indura t ion cannot be sus ta ined . Second, i t i s d i f f i c u l t t o main-

t a i n even d i s t r i b u t i o n of t h e gases through the s h a f t , r e s u l t i n g i n ad jacent

hot and cold s p o t s e f f e c t i n g f i r e d p e l l e t q u a l i t y .

the q u a l i t y of s h a f t furnace p e l l e t s i s t h e poorest of a l l t h e p e l l e t i z i n g

systems.

Third, genera l ly speaking,

The p e l l e t s a r e discharged from the furnace by s e v e r a l means rang-

ing from continuous discharge by v i b r a t i n g u n i t s t o i n t e r m i t t e n t discharge by

hoppers and screens. The s h a f t furnaces can be f i r e d with n a t u r a l gas , f u e l

o i l , o r coa l (using an e x t e r n a l combustion chamber) and t y p i c a l l y w i l l r e q u i r e

644 t o 966 MJ/Mg (400,000 t o 600,000 Btu 's per ton) of p e l l e t s . No new

p l a n t s , however, a r e being cons t ruc ted which employ s h a f t furnaces.

3.2.3.2.2 S t r a i g h t Grate Sys tem. The s t r a i g h t g r a t e o r t r a v e l i n g

g r a r e furnace c o n s i s t s of a moving g r a t e passing through s e v e r a l zones which

inc lude drying, prehea t ing , f i r i n g , burning, and cooling.' There a r e b a s i c a l l y

two types of s t r a i g h t g r a t e machines; the McKee type and Dravo-Lurgi type.

The primary d i f f e r e n c e i n t h e two types i s t h a t t h e Dravo-Lurgi machine re-

cyc les f i r e d p e l l e t s to be layered on t h e g r a t e ( r e f e r r e d t o as a "hearth

layer") before green (unf i red) p e l l e t s a r e put on t h e grate.

g r a t e system then r e q u i r e s f i r e d p e l l e t sc reening and recyc le p lus a d d i t i o n a l

equipment t o spread the f i r e d p e l l e t s . With t h e f i r e d pe l l e t l a y e r next t o

This s t r a i g h t

3-35

I! I I I i 1 I I 1 1 I I I I

C I I I I I .I I I -

-1 I I I I I I I I I I I I I I I 1 I I I I I

the g r a t e [usua l ly approximately 10 cm ( 4 i n c h e s ) ] , the g r a t e i s n o t sub-

jec ted t o as high a temperature; t h e r e f o r e , i t usua l ly can b e cons t ruc ted out

of l e s s expensive m a t e r i a l s and i t provides longer l i f e than t h e McKee type.

However, the McKee type w i l l allow a h igher throughput f o r t h e same s i z e

gra te . The two types of s t r a i g h t g r a t e machines a r e shown i n Figures 3.9 and

3.10. A number of c o n t r o l v a r i a b l e s are a s s o c i a t e d ' w i t h t h e s t r a i g h t g r a t e

such as a i r d i s t r i b u t i o n , g r a t e speed, d i s t r i b u t i o n of p e l l e t s on t h e g r a t e ,

temperatures maintained i n t h e wind box hoods, gas volume, e t c .

3.2.3.2.3 Grate-Kiln System. The g r a t e - k i l n i n d u r a t i n g furnace

c o n s i s t s of a combination t r a v e l i n g g r a t e and r o t a r y k i l n . The t r a v e l i n g

g r a t e is used t o dry and preheat t h e p e l l e t s p r i o r ' t o the a c t u a l f i r i n g which

i s accomplished i n t h e r o t a r y k i l n . A t y p i c a l g ra te -k i ln system i s i l l u s -

t r a t e d i n Figure 3.11.

The green p e l l e t s a r e fed by r o l l f eede r s , v i b r a t i n g f eede r s , o r

vane-type feeders t o the g r a t e s ec t ion . The i n i t i a l g ra t e s e c t i o n i s used t o

dry the p e l l e t s a t a temperature of 644 t o 700 K (700 t o 800 F). The drying

zone gases come from t h e preheat zone of t h e g r a t e and the p e l l e t s a r e d r i e d

by passing t h e gas through t h e p e l l e t bed.

can be u t i l i z e d b u t most g r a t e k i l n s u t i l i z e downdraft drying.

usua l ly pass through a - p a r t i c u l a t e c o n t r o l device and a r e then vented t o t h e

Both updraf t and downdraft drying

These gases

atmosphere. The continuous g r a t e feeds the p e l l e t s t o t h e preheat zone which

is again operated i n a-downdraft mode with t h e source gas coming from the

k i l n . The prehea t zone is usua l ly maintained between 1311 and 1 4 2 2 K (1900

and 2100 F) . After the gases pass down through t h e p e l l e t bed, they typ-

i c a l l y pass through a bank of cyclone c o l l e c t o r s and then on t o t h e drying

zone. The pe l le t s coming out of t h e prehea t zone a r e now thoroughly dry of

3-36

3-37

I I 1 P 1 I I I I 1 I I I I I I I I I I I

t

,. 8 U m h m

3-38

3-39

C 0 rl V Io r 7 a C rl

rl -I

m 9) Y 3 M

I I I I 9 I 1 I I I 1 il r ,I c I d I I 3

J

I 1 k t I I I 1 I I I I I I I 1 6 I E 1 1 ~1 iI

moisture and s t r u c t u r a l l y s t rong. These p e l l e t s a r e now passed t o t h e ro-

t a t i n g k i l n which i s maintained between 1561 and 1 5 8 9 K (2350 and 2400 F) f o r

t h e f i n a l f i r i n g .

the hot gases a r e countercurrent t o t h e m a t e r i a l flow.

out of the k i l n drop i n t o an annular c o o l e r which can provide two or even

t h r e e s t a g e s of cool ing. The f i r s t s t a g e cool ing gases a r e approximately

1422 t o 1478 K (2100 t o 2200 F) and a r e used as a f i r i n g gas i n the k i l n .

The second s t a g e cool ing gases t y p i c a l l y a r e vented t o atmosphere but can b e

recuperated. The cooled p e l l e t s a r e then conveyed to shipping o r s torage .

The k i l n is f i r e d with n a t u r a l gas , f u e l o i l , or c o a l and

The pe l l e t s passing

3.2.3.2.4 C i r c u l a r Grate. The " c i r c u l a r gra te" system is essen-

t i a l l y t h e four th generat ion furnace and reported t o have incorporated a l l the

advantages of the o t h e r furnaces .

only i n one p lace , i n Mexico. No U.S. i n s t a l l a t i o n s a r e p r e s e n t l y foreseen;

however, newer i n s t a l l a t i o n s i n t h e f u t u r e may consider t h i s type of furnace.

The c i r c u l a r g r a t e furnace is opera t ing

The b a s i c s of the c i r c u l a r g r a t e machine a r e i l l u s t r a t e d in Fig-

ure 3 .12 . Opera t iona l ly , i t incorpora tes a h e a r t h l a y e r s i m i l a r t o t h a t used

i n the Dravo-Lurgi system with the except ion t h a t the same f i r e d p e l l e t s re-

main on the g r a t e and a r e not removed with each pass .

requi res only one s t ack . This system and no r e t u r n s t r a n d t h a t has t o be

heated, repor ted ly r e s u l t s i n lower f u e l consumption. AdditiDnal improvements

a re reported t o r e s u l t from t h e over-bed s e a l s which provide for a dust- and

gas-free environment. However, opera t ing d a t a a r e only now being e s t a b l i s h e d

and i t is unknown what o v e r a l l in f luence t h e system may have wi th in t h e i r o n

o r e p e l l e t i z i n g i n d u s t r y .

The gas handling system

3-40

Figure 3.12 Plan view of c ircular grate machine.

3-41

3.2.3.3 Emissions From Agglomeration. The agglomeration opera t ion

a s described c o n s i s t s of t h e b a l l i n g drum o r d i s c s e c t i o n and t h e i n d u r a t i o n

furnace sec t ion .

passed on t o t h e indura t ion furnace f o r dry ing and f i r i n g and because the.

p e l l e t forming i s done e n t i r e l y wi th t h e concent ra te being i n a wet o r damp

s t age , t he re is no r e a l source of emissions i n the b a l l i n g sec t ion .

The p e l l e t s a f t e r being formed i n t h e b a l l i n g s e c t i o n a r e

I n the furnace s e c t i o n , t h e r e a r e two main sources of p a r t i c u l a t e

emissions; t h e waste process gas exhausted from t h e furnace and t h e p e l l e t

handling equipment.

A s i g n i f i c a n t amount of da ta were obtained i n t h i s program on t h e

emissions from the indura t ion furnaces and d a t a a r e s u m a r i z e d i n Table 3 . 9

and d e t a i l e d i n Appendix C .

and i n most cases a r e reported by t h e s p e c i f i c companies involved through

f i e l d t e s t i n g a t t h e i r p l a n t s .

The data are arranged according t o furnace type

The l e v e l s of emissions, i n genera l , show a marked dependence on t h e

p a r t i c u l a r emission c o n t r o l devices used a t t h e var ious p l a n t s .

the d a t a i s f o r mult ic lone i n s t a l l a t i o n s and t h e s e p l a n t s , a t b e s t , have e m i s -

s i ons of 446 g/Mg (1.0 pound per ton) of pe l l e t s produced. Those p l a n t s us-

ing ESP c o l l e c t o r s have emissions averaging about 103 g/Mg (0.23 pound per

ton) of p e l l e t s and those with scrubbers average about 201 g/Mg (0.45 pound

per ton) of p e l l e t s . A l s o i t is evident t h a t t h e p l a n t s having no primary

cont ro l device o r simply drop-out boxes have t h e h i g h e s t emissions.

The bulk of

There appears t o be only small d i f f e r e n c e s i n gas volumes exhausted

from the var ious furnace conf igura t ions . For example, g ra te -k i ln and v e r t i c a l

s h a f t systems t y p i c a l l y average about 2.48 m 3 / s per kg per s (1500 scfm p e r

ton per hour) of p e l l e t s . S t r a i g h t g r a t e systems genera l ly have a somewhat

3-42

\-- * i w-m my A r l " m a O r . \ D . . . . . . . . Q 0 0 0 0 3 3 N

4 r n N a h

I U

0 3 E4

3

m m

m rl) m

.. 0 0 O M o r d

- L l

3 4 , " ?

0 3 3

0 U

2 2 .,-! c

U Q 3 0

$ 3:

3-43

O O 3 N m m

3 m u l eeul m r . 3 0r.a 3 3

. . .

N

'c)

3 2. U

3

U %I rd .. c 000 e m 000 bo 0 00 rd

1 , . - - Ll rd 0 3 0 e o o h m d uleN 3 u - I 4 1

2

a o m r . m N

e

Ll CT)

z I

1 I I I 1 I I 1 t C 1 ' I 6 1' 1 1 'I 1 1 f I'

4. m m m m C C C C 0 0 0 0

r l r l r l r l m m u u u u c c 4.rld.rl 0 0 U U U U Z Z rlrlrld 3 1 3 3 t:t:t:t:

m N

m 0:

m rl N rl

rl m

m m r l m m m r l m m m m m m m u m m-m-

rlrl

N u 0 o a r . u m 4- .

rim

m a a

I U

0 rl U FU

2

0 U

M C d C

2 U rl 0 D

X

3-44

m

U W

: I

a U 0 . 0 0

U

O U M u m c u 4 Mv) C

c m 4s 0

m s m d U U u m m w m r

.rl

a 8

With coa l f i r i n g i n s t e a d of n a t u r a l gas , a s i g n i f i c a n t i n c r e a s e i n

the SO2 emissions can be expected. For example, i t can b e assumed t h a t a ton

of i r o n ore p e l l e t s w i l l r e q u i r e about 528 M J (500,000 Btu) f o r indura t ion

r e g a r d l e s s of the type of indura t ion machine employed. Thus, a 1.016 Mg ( ton)

of p e l l e t s w i l l r e q u i r e about 15.9 kg (35 pounds) of c o a l f o r combustion

(assuming a h e a t i n g value of 33.3 kJ/g (14,300 Btu/ lb) and t h i s coa l w i l l pro-

v i d e about 0.64 kg (1.4 pounds) of SO2 as p o t e n t i a l emissioxs.

on u s i n g a low-sulfur Eastern Kentucky o r West Virg in ia coa l with a s u l f u r

content of 2 percent .

1

This i s based

Generally, from t h e above assumptions i t can be s t a t e d t h a t coal

f i r i n g w i l l i n c r e a s e SO2 emissions by a f a c t o r o f 23 times over n a t u r a l gas

f i r i n g , and w i l l r e su l t i n a waste gas which conta ins about 275 ppm SO2.

higher gas volume a s i n d i c a t e d by t h e average use of 3.59 m3/s p e r kg per s

(2100 scfm per ton per hour) of p e l l e t s .

It is be l ieved t h a t these d a t a a r e c o n s i s t e n t with a c t u a l condi t ions

i n t h e f i e l d and', i n genera l , agree wi th o t h e r f i e l d t e s t d a t a taken by o u t s i d e

agencfes.

3.2.3.4 Sulfur Emissions From Coal F i r ing . With the a n t i c i p a t e d

changeover t o c o a l f i r i n g of indura t ing machines, s i g n i f i c a n t q u a n t i t i e s of

s u l f u r oxide emissions a r e a l s o expected from p e l l e t i z i n g systems. Current

s u l f u r oxide emissions using n a t u r a l gas a r e very low, t y p i c a l l y averaging

about 1 2 ppm SO2 (source:

l a t e s t o about 27 g of SO2 per Mg (0.06 pounds of SO2 per ton) o f p e l l e t s

produced, assuming a gas flow of 137 m3/s (290,000 scfm).

Eveleth Taconi te Company test da t a ) . This calcu-

- .. . .

1

3-45

- 1 I 1 1 I I I I 1 3 91 1 1' I I I I I I I I I

1 I I I 0 I 1 3 i. 1 1

' I t I 3 t I, I 1 I' I

3.2.4 Factors Affect ing Emissions From I ron Ore P l a n t s

I n general the f a c t o r s a f f e c t i n g emissions from i ron o r e p l a n t s i n -

clude: moisture content of the o r e and overburden, type of o r e ( t a c o n i t e ,

hemati te , e t c ) , s i z e of b l a s t and amount of o r e processed, type o f equipment,

and opera t ing p r a c t i c e s employed such a s p l a n t maintenance and general house-

keeping.

the p a r t i c u l a t e emission, e s p e c i a l l y t h e fugi t ive- type emission. I n most

cases , these general f a c t o r s combine t o c o n t r i b u t e to a p l a n t ' s t o t a l emissions.

I n addi t ion , a v a r i e t y of geographical and seasonal condi t ions a f f e c t

The type of o r e has some a f f e c t on emissions, p r i n c i p a l l y i n the o r e

handling s t ages . This inc ludes the i n h e r e n t moisture content of the o r e and

overburden. The s o f t e r , more weathered o r e s ( red and brown o res , hemati te)

have a g r e a t e r p o t e n t i a l f o r emissions than t h e harder o re s ( t a c o n i t e s ) .

The type of equipment and o p e r a t i n g p r a c t i c e probably has t h e la rg-

est s i n g l e e f f e c t on p o t e n t i a l p a r t i c u l a t e emissions. The equipment s e l e c t i o n

is based on a v a r i e t y of f a c t o r s , some of which a r e not a l t o g e t h e r q u a n t i f i e d ;

b u t , i n genera l a r e inf luenced by the p l a n t age, t y p e of o r e processed, capac-

i t y of p l a n t , and equipment conf igura t ion . I n genera l , emissions from equip-

ment a r e a func t ion of equipment, c o n f i g u r a t i o n and a u x i l i a r y equipment, such

a s hoods, s k i r t s , and general p l a n t maintenance. The opera t ing p r a c t i c e s

employed by a p l a n t , such a s p e l l e t formation and con t ro l , furnace con t ro l ,

e t c . , in f luence the p a r t i c u l a t e emissions.

The most s i g n i f i c a n t geographical f a c t o r a f f e c t i n g p a r t i c u l a t e

emissions would be cl imate . Climate c o n d i t i o n s , such as wind v e l o c i t y and

d i r e c t i o n , r e l a t i v e humidity, and p r e c i p i t a t i o n , can a f f e c t emissions. Other

3-46

I factors could b e the general topography surrounding the plant and general

amount of vegetation around the f a c i l i t y . _ I

I 1 P

Seasonal variat ions have some e f f e c t on potential emissions. For

example, the winters i n Minnesota as opposed t o the winters i n California and

other i e s s severe seasonal changes.

a f I I 3 J I I ' I I

9 a

3-47

I 1 I I

I I REFERENCES FOR SECTION 3.

1. Engineering and Mining Journa l , November, 1974.

2. I ron Ore - 1975, American I ron Ore Associat ion.

3. The Development o f Four Generations of P e l l e t i z i n g , 0. G. Gramp, paper

I I I I I 1 I I 1 1 I I I I d I

I

presented a t CIM Conference of M e t a l l u r g i s t s , Quebec C i ty , August 26-29,

1973.

i 3-40

1 I I I I 1 I I I I 1 I I 1 1 I s I I z

4. EMISSION CONTROL TECHNIQUES

4.1 CONTROL DEVICE ALTERNATIVES

The d i v e r s i t y of t h e p a r t i c u l a t e emission sources , s i z e s , and

q u a n t i t i e s inherent i n an i r o n o r e p l a n t has r e s u l t e d i n t h e u t i l i z a t i o n

of a v a r i e t y of c o n t r o l techniques and devices .

appl icable , d u s t suppression techniques such as water sprays w i l l be used.

However, o t h e r sources are not amenable t o t h i s c o n t r o l method and r e q u i r e

hooding and t h e use of c o l l e c t i o n devices .

la te emissions and t h e c o n t r o l a l t e r n a t i v e s c u r r e n t l y i n use , o r proposed

by the i n d u s t r y a r e l i s t e d i n Table 4.1.

4.1.1 Control of Mining Operations

I n genera l , where

The various sources of par t icu-

4.1.1.1 D r i l l i n g . I n genera l t h e p a r t i c u l a t e emissions from

d r i l l i n g opera t ions are handled by w e t t i n g t h e d r i l l c u t t i n g s with water.

This dampens t h e p a r t i c u l a t e s and prevents them from becoming airborne.

Other techniques could be used such as shrouding the d r i l l h o l e and passing

t h e a i r c a r r y i n g t h e p a r t i c u l a t e s through a c o l l e c t i o n device.

t h e p a r t i c u l a t e emissions from t h e d r i l l i n g opera t ion a r e e f f e c t i v e l y

contained by water sprays o r i n j e c t i o n .

Typical ly

1 4.1.1.2 Blas t ing . E f f e c t i v e methods have not been demonstrated

f o r c o n t r o l l i n g p a r t i c u l a t e emissions from b l a s t i n g operat ions.

most companies employ good b l a s t i n g techniques and schedule t h e i r b l a s t i n g

t o occur when t h e metero logica l condi t ions are t h e most favorable .

f a c t o r s a l s o d i c t a t e a c l o s e c o n t r o l of t h e b l a s t i n g opera t ion and t h i s h e l p s

t o reduce d u s t emissions.

However,

Other

4.1.1.3 Loading and Hauling. The d u s t emissions from haul ing

4- 1

I 1 1 1 t: 1 I I I 4 1 1 1 I 1 1 1 1' I 1

TABLE 4.1 EMISSION SOURCES AND CONTROL ALTERNATIVES

Operation o r Source

Mining

D r i l l i n g

Blas t ing

Loading and Hauling

Benef ic ia t ion

Crushing

Screening

Conveying and Transfer

P e l l e t I n d u r a t i o n

Main Process Gases

Furnace Transfer Poin ts

Miscellaneous Sources

Bentoni te F a c i l i t i e s

P e l l e t Handling and Loadout

S tockpi les

T a i l i n g s Ponds

Control A l t e r n a t i v e s

No c o n t r o l Water in jec t i o n Venting of gas t o c o l l e c t i o n device

No c o n t r o l

No c o n t r o l Water sprays Water w e t t i n g of road s u r f a c e O i l c o a t i n g of road s u r f a c e

Water sprays Dry c o l l e c t o r s Wet scrubbers Baghouse

Same as crushing

Same as crushing

No c o n t r o l Dry c o l l e c t o r s Wet scrubbers E l e c t r o s t a t i c p r e c i p i t a t o r (ESP) Baghouse

Same as process gases excluding ESP

W e t sc rubbers Baghouse

Water sprays Wet scrubbers Baghouse

Water sprays

Wetting Chemicals Vegetat ion

4-2

- of ore-and overburden on t h e road are propor t iona l t o t h e amount of t r a f f i c ,

speed, and road s u r f a c e condi t ions. In genera l , dus ty condi t ions are hard

on the equipment; t h e r e f o r e , t h e mines t r y t o maintain t h e i r road s u r f a c e s

and c o n t r o l t h e i r t r a f f i c t o minimize the d u s t emissions.

The road sur face emissions c a n be c o n t r o l l e d by water o r o i l

c o a t i n g of t h e sur face o r by using chemical a d d i t i v e s and employing s o i l

s t a b i l i z a t i o n techniques.

can be q u i t e e f f e c t i v e depending on t h e general condi t ions and weather.

Road dust can a l s o be c o n t r o l l e d by p e r i o d i c a p p l i c a t i o n of chemicals (such

as C a C l ) and s o i l s t a b i l i z a t i o n a d d i t i v e s (composed of s y n t h e t i c o r n a t u r a l

petroleum r e s i n s ) .

4.1.2 Control of Benef ic ia t ion Operations

The most c m o n method i s water spraying which

2

Typical ly a b e n e f i c i a t i n g p l a n t w i l l c o n s i s t of numerous sources

of emissions a s s o c i a t c d pr imar i ly with t h e crushing p l a n t and o r e handling

f a c i l i t i e s (conveyors, feeders , sc reens , e t c ) . I n genera l , t h e r e s t of t h e

p l a n t ( f ine gr inding , magnetic s e p a r a t i o n , and/or f l o t a t i o n ) c o n s i s t s of

handling s l u r r i e s and, t h e r e f o r e , does not represent a d u s t emission

problem.

have a m u l t i p l i c i t y of dust-producing p o i n t s . As such, e f f e c t i v e emission

c o n t r o l involves a combination of water wet t ing, hooding, and t h e use of

d r y o r w e t c o n t r o l devices.

The crushing p i a n t and ore i ~ m i ~ i , ~ g f z c i l i t k z ::<I! +.miral ly -, r -- ---

4.1.2.1 Primary Crushing. Wet dus t suppression u s u a l l y begins

a t t h e primary c r u s h e r where water sprays are normally used around t h e

per iphery t o spray t h e o r e as it i s dumped i n t o t h e c rusher . For p l a n t s

using t ruck haulage, t h i s can be a n e f f e c t i v e way of reducing emissions.

The crusher is normally open a t t h e top and r e c e i v e s o r e from two s i d e s ,

thus e f f e c t i v e hooding and d u s t c o l l e c t i o n is d i f f i c u l t , al though some

p l a n t s have p a r t i a l l y enclosed the c rusher by a bui ld ing .

4- 3

-1 1 I I I 1 d I 3 1 I 1 1 I 1 1 I I

T I 1

i

I n some cases , a d d i t i o n a l water sprays a r e loca ted a t the primary

crusher discharge and i n the a r e a of t h e pan feeder and primary ore conveyor.

I n o ther cases , these emissions a r e hooded and d i r e c t e d t o a con t ro l device.

Many p l a n t s now use the dry c e n t r i f u g a l c o l l e c t o r , such a s i s shown i n

Figure 4.1, f o r con t ro l of t he primary c rushe r emissions.

a few p l a n t s have i n s t a l l e d baghouses at the primary crusher . A t y p i c a l

baghouse i s i l l u s t r a t e d i n Figure 4.2.

More r ecen t ly ,

4.1.2.2 Secondary Crushing and Screening. Typical ly , t he secondary

c rushers and screens i n an i ron ore b e n e f i c i a t i n g p l an t a r e covered w i t h a

hood and exhausted t o a con t ro l device. Screens a r e genera l ly completely

covered t o c o n t r o l p a r t i c u l a t e emissions a t t h e sur face of t he screen. I n

some p l a n t s the screen and crusher w i l l be covered by the same hood. Typical

arrangements a r e shown i n Figures 4.3 through 4.5.

The con t ro l devices used i n conjunct ion with the above hood

arrangements a r e t y p i c a l l y the wet mechanical-type scrubbers and/or

separa tors . The most c m o n systems used i n the indus t ry a r e the wet

packed-bed scrubbers a s shown i n Figure 4.6 o r t h e c e n t r i f u g a l separa tors

a s i l l u s t r a t e d i n Figure 4.7.

u n i t s i n the b e n e f i c i a t i n g p l an t a lone.

c o s t , and a r e e f f e c t i v e i n c o n t r o l l i n g emissions from these sources.

Some p l a n t s may use up t o 30 o r 40 of these

They a r e compact, have reasonable

4.1.2.3 Conveying and Transfer . Typica l ly , t he dust emissions

from conveyor b e l t s and t r a n s f e r s t a t i o n s a r e con t ro l l ed i n much the same

way as c rushe r s and screens. I n gene ra l , t h e conveyors a r e covered with a

hood which at tempts t o l i m i t t h e amount of a i r being swept over t he b e l t ,

and t h i s i s genera l ly done by using rubber s k i r t i n g .

a r e shown i n Figures 4.8 and 4.9.

depending on t i g h t n e s s of enclosure, ma te r i a l handled, d i s t ance t o con t ro l

Typical conf igura t ions

The air sweep v e l o c i t i e s vary widely

4- 4

pical h i g h - e f f i c i cy involute cyclone. Bource: Reference ?$ Figure 4 .1

Figure 4.2 T p ica l baghouse co ector. 6ource : Reference kj

4-5

I I 1 1 I d I I 1 I 1 1 1 I f I I 1 I 3

Feed

TO control device

Oversize

Undersize

Figure 4 . 3 Hood configuration f o r vibrating screen.

4-6

To . c o n t r o l device b -

I n s p e c t i o n door

o l l e c t i o n . hood

Cone crusher

Crusher d i scha rg

Belt conveyor I I

Figure 4.4. Hood conf igu ra t ion f o r secondary c rusher .

TO c o n t r o l device

C o l l e c t i o n

Cone c rushe r

Belt conveyor

I I I 5 5 1 I I I 1 I I I, I I t I I

Figure 4.5 Hood c o n f i g u r a t i o n f o r c rusher -screen combination.

4- 7

I 1 1 1 I 3 1 1 1 I 1 I 1 1 1 J 1 I 1 3

orble b ids o p n q e d in series, 01 in o plote column

Figure 4.6 Packed-bed scrubber (National Dust Collector Corporation, hydrofi l ter)

Figure 4.7 Centrifugal fan-type scrubber (American A i r F i l ter Company, rotoclone)

4- 8

From chute or b e l t

To c o n t r o l device

Conveyor b e l t f Figure 4.8 Hood c o n f i g u r a t i o n f o r o r e chute t r a n s f e r .

To c o n t r o l device

s k i r t

Figure 4 . 9 Hood c o n f i g u r a t i o n f o r conveyor b e l t t r a n s f e r .

4- 9

! device, e t c .

800 fpm) with conveying v e l o c i t i e s being 2000 cm/s (3940 fpm) and up.

These v e l o c i t i e s w i l l range from 100 t o 400 c m / s (200 t o

Again, t h e most common c o n t r o l devices used f o r conveyors and

t r a n s f e r p o i n t s are t h o s e i l l u s t r a t e d i n F igures 4.6 and 4.7

4.1.3 Control of P e l l e t i z a t i o n

4.1.3.1 Main Process Gases. The p e l l e t i n d u r a t i o n s e c t i o n is

perhaps t h e primary source of p a r t i c u l a t e emissions a s s o c i a t e d with t h e

complete i r o n o r e p l a n t complex. The a i r b o r n e p a r t i c u l a t e s generated i n

p e l l e t i z a t i o n d i f f e r from those i n t h e b e n e f i c i a t i o n opera t ions i n t h a t

t h e product m a t e r i a l is o r e concent ra tes and t h e waste gas s t reams genera l ly

a r e hot . Equal ly important is t h e f a c t t h a t very l a r g e g a s volumes a r e

generated by t h e i n d u r a t i o n furnace and e f f e c t i v e c o n t r o l of p a r t i c u l a t e s

involves both good hooding and c o l l e c t i o n , and e f f i c i e n t removal. The

c o n t r o l techniques used by t h e indus t ry a r e geared b a s i c a l l y t o t h e type of

indura t ing furnace employed i n each p a r t i c u l a r p l an t . Thus, t h e b a s i c

furnace conf igura t ions w i l l b e discussed s e p a r a t e l y .

4.1.3.1.1 V e r t i c a l Shaf t Process. Curren t ly , t h r e e p l a n t s

employ the vertical s h a f t furnace f o r i n d u r a t i o n of t h e i r i r o n o r e pel le ts .

There are b a s i c a l l y two main sources of emissions from t h e v e r t i c a l - s h a f t

furnace. The top gases or f i r i n g gases e x i t a t t h e top of t h e furnace and

a r e t y p i c a l l y passed through mult ic lone c o l l e c t o r s . The bottom gas which

is used f o r p e l l e t cool ing is c o n t r o l l e d by dry cyclones, mul t ic lones , o r

w e t s c r u b b e r s .

There are b a s i c d i f f e r e n c e s i n c o n t r o l techniques a s s o c i a t e d

wi th t h e v e r t i c a l s h a f t process over t h e more conventional s t r a i g h t g r a t e

o r gra te -k i ln systems. One f a c t o r i s t h a t a l a r g e number of i n d i v i d u a l

u n i t s must b e c o n t r o l l e d ( t h e Erie Mining Company p l a n t h a s 27 v e r t i c a l

4-10

s h a f t l i n e s ) and another i s t h a t t h e gases a r e t y p i c a l l y much h o t t e r .

Bottom gases , f o r example, can e x i t a t 772 K (930 F); thus many p l a n t s

use waste h e a t exchangers f o r recovery of t h i s energy. The c o l l e c t i o n

device must b e adaptab le t o a l a r g e f l u c t u a t i o n i n gas temperature and

p a r t i c u l a t e loading.

4.1.3.1.2 S t r a i g h t Grate Process . This process is b a s i c a l l y

one of two types -- Dravo-Lurgf system o r t h e McKee system. However, from

a p a r t i c u l a t e emissions s tandpoin t , t h e r e are only s u b t l e d i f f e r e n c e s

between t h e two systems. In both, t h e r e a r e two main waste gas streams

generated as shown i n Figures 4.10 and 4.11.

box exhaust) is pul led from the down-draft drying and preheat s e c t i o n s

of t h e g r a t e machine.

are recycled from t h e f i r i n g zone by t h e recupera t ion fan.

t h e f i r i n g gases go through a m u i t i p l i c i t y of dry cyclone c o l l e c t o r s on

each s i d e of t h e machine before e n t e r i n g t h e recupera t ion f an and t h i s

r e p r e s e n t s t h e f i r s t s t a g e of emission cont ro l .

One process gas s t ream (wind-

These gases c o n t a i n products of combustion which

Typica l ly

A f t e r passing through t h e downdraft drying zone, t h e most

common p r a c t i c e i n c o n t r o l l i n g emissions from t h i s source is Ei re use u; a

m u l t i p l e tube, d r y cyclone c o l l e c t o r (mult ic lone) . A t y p i c a l mult ic lone

conf igura t ion i s i l l u s t r a t e d i n F igure 4.12. Some p l a n t s employ t h e

mult ic lone preceded by a dropout box f o r coarse p a r t i c u l a t e s and t h i s

repor ted ly is e f f e c t i v e i n reducing wear on t h e mul t ic lone with improved

performance.

t h e Dravo-Lurgi process a l l use mul t ic lones f o r c o n t r o l of t h e windbox

exhaust. The two p l a n t s u t i l i z i n g t h e McKee process , however, have no

c o n t r o l device on t h e windbox exhaust .

The t h r e e p l a n t s surveyed i n t h i s program which u t i l i z e

4-11

t t I 1 I I I I I

I I I I

I I 1 I I I I

i

i

I I 1 I

1

i' 1

I I

c

c

t I

I

al

Y) 2 i

- I

4-12

W a W I n w 0 2 5 0 t-

4 - 1 3

1 1 I 1 5 1 1 I 1 I I I * I E

1 I d I I I I

i

4 Solids

Figure 4.12. Multiple tube dry collector (multiclone).

4-14

The o t h e r main process gas from t h e s e machines i s t h e hood 'I

exhaust which is used f o r i n i t i a l drying of t h e green p e l l e t s .

has prev ious ly been used f o r t h e cool ing s e c t i o n s of t h e machine t o recover

h e a t energy and reuse i t f o r t h e drying s t e p . Typica l ly , emissions from

t h i s source a r e much lower than f o r t h e windbox exhaust because t h e damp

p e l l e t bed a c t s much l i k e a f i l t e r f o r removing p a r t i c u l a t e s and because

oniy minor awounts of f i n e s are g c m r a t e d i n these s e c t i o n s .

do n o t employ a c o n t r o l device f o r t h e hood exhaust.

however, can be s i g n i f i c a n t s i n c e a l a r g e q u a n t i t y of gases a r e used even

i f a l o w p a r t i c u l a t e concent ra t ion r e s u l t s .

Taconi te Company), w i l l use a w e t scrubber on t h e hood exhaust.

This gas

Most p l a n t s ,

The emissions,

One proposed new p l a n t (Hibbing

The only remaining waste process gas from s t r a i g h t - g r a t e machines

i s t h a t used f o r second-stage cool ing of t h e f i r e d p e l l e t s and t h i s occurs

i n s e v e r a l of t h e e a r l y McKee machines. Modif icat ions have beet1 proposed,

however, to e l i m i n a t e t h i s as a source of p a r t i c u l a t e emissions. The

proposed changes w i l l involve r e c y c l i n g of t h e gas f o r h e a t recuperat ion.

4 . 1 . 3 . 1 . 3 Grate-Kiln Process . As shown i n Figure 4 . 1 3 , the

min waste gases from t h e gra te -k i ln system t h a t are generated i n f i r i n g ,

? r e h e a t i n g j and drying, a r e combined i n t o a s i n g l e emission po in t . These

gases a r e very s i m i l a r t o t h e windbox exhaust gases from t h e s t r a i g h t

g r a t e machines.

The p l a n t s surveyed i n t h i s s tudy , which employ t h e gra te -k i ln

system a r e us ing a number of d i f f e r e n t c o n t r o l devices f o r t reatment of

t h i s waste gas e f f l u e n t .

c l o n e c o l l e c t o r shown i n Figure 4 . 1 2 .

management a r e u t i l i z i n g an e l e c t r o s t a t i c p r e c i p i t a t o r (ESP) f o r c o n t r o l of

these gases . This device, i l l u s t r a t e d i n F igure 4 . 1 4 , h a s shown very high

Again t h e most common method is t h e dry multi-

Two p l a n t s under t h e Cleveland-Cliffs

4-15

=--

I 1, I 1 D B 1 I I li 1 I E 1) I 1. 1 I 1 I I 1

~

I I 3 .f I I I 1 1 s; I I I (I I d I I I I 1 I

t_, J-

4-16

rl

$4 rl 4

m rl

G,

High tension support frame

High voltage inwlators

collector plates

Discharge electrodes

Discharge Wire wnights

--t

ionizer Collecting plate

PRINCIPLE OF ELECTRO- STATIC PRECIPITATION

P i s r e 4.14 Eleccrostst ic precipitator.

Figure 4.15 Venturi scrubber.

4-17

I 1

0 1 I 1 1 li b I 11 1 i I 1 I I I

a

I

I t I 1 I 1 I is I I I 11 1 d I I I I 1 1

c o l l e c t i o n e f f i c i e n c i e s and very few opera t ing problems i n t h e s e v e r a l

years i t has been i n use i n these p l an t s .

I n a d d i t i o n t o t h e ESP, two p l a n t s have i n s t a l l e d w e t scrubbers

f o r c o n t r o l of t h e waste gas stream. One u n i t i s a spray-impingement-

type scrubber designed f o r Cleveland-Cliff ' s Pioneer P e l l e t P l a n t .

u n i t has not been completely s a t i s f a c t o r y according t o p a s t emission

tests but , on occasion, can give very good c o l l e c t i o n e f f i c i e n c y . The

o t h e r u n i t is a ventur i - type scrubber employed by Eveleth Taconi te Company

which has a pressure drop of about 23 cm (9 inches)of water.

p r i n c i p l e i l l u s t r a t e d i n F igure 4.15 provides f o r very high c o l l e c t i o n

e f f i c i e n c i e s on t h e f i n e p a r t i c u l a t e s generated i n t h e g r a t e - k i l n process .

The Eveleth p l a n t is under expansion which w i l l inc lude a l a r g e r gra te -k i ln

l i n e and a v e n t u r i scrubber w i l l b e used h e r e a l s o .

This

The v e n t u r i

The remaining process emission source f o r t h e gra te -k i ln system

a r e those gases used f o r second or th i rd-s tage cool ing of t h e f i r e d p e l l e t s .

This i s i d e n t i f i e d a s t h e c o o l e r exhaust i n Figure 4.13. General ly , most

p l a n t s do not use a c o n t r o l device f o r t h i s source because, t y p i c a l l y , t h e

gases a r e very low i n p a r t i c u l a t e emissions. More recent ly , however, t h e

newer or proposed p l a n t s w i l l employ some type of c o l l e c t o r on t h i s source.

4.1.3.2 Furnace Transfer Poin ts . In a d d i t i o n t o t h e main

process emissions descr ibed above, t h e r e a r e s e v e r a l o t h e r sources of

p a r t i c u l a t e emissions generated i n t h e p e l l e t i z a t i o n process .

these a r e a s s o c i a t e d wi th t h e t r a n s f e r of p e l l e t s from one s e c t i o n of the

machine t o another and t h e c h a r a c t e r i s t i c s of t h e source a r e a g a i n d i c t a t e d

by t h e type of indura t ing machine employed. Table 4.2 s u m a r i z e s t h e usua l

t r a n s f e r po in t sources a s s o c i a t e d with each machine.

B a s i c a l l y

4-18

TABLE 4.2 SUMMARY OF TRANSFER POINT SOURCES VERSUS TYPE OF INDURATING MACHINE EMPLOYED

Dravo-Lurgi McKee Grate-Kiln V e r t i c a l Shaf t S t r a i g h t Grate S t r a i g h t Grate Process Process

Hearth and S i d e Grate Feed Grate Feed P e l l e t Recycle Layout System

Grate Discharge Grate Discharge Grate Discharge Product Screen and Transfer

Product Screen Product Screen Cooler Discharge and Transfer and Transfer

Product Screen and Transfer

Typica l ly , t h e p a r t i c u l a t e emissions generated at each of the

p e l l e t t r a n s f e r po in ts can be s i g n i f i c a n t and nmst p l a n t s employ hooding

and t h e use o f a c o l l e c t i o n device t o c o n t r o l these emissions. The c o n t r o l

devices used w i l l vary from p l a n t t o p l an t but in most cases some type of

w e t scrubber w i l l be employed.

~ackerl-be(! sc1-.lhher previoiirly i . l l u s t r a t e d in Figures 4.6 and 4.7.

r e c e n t l y , many p l a n t s have been i n s t a l l i n g t h e Ducon "dynamic scrubber"

which i s i l l u s t r a t e d i n Figure 4.16.

s t a g e c o l l e c t o r and r e p o r t e d l y has c o l l e c t i o n e f f i c i e n c i e s up t o 99.5 percent

Some p l a n t s u t i l i z e t h e "Rotoclone" o r

More

This device is a combination three-

i n the 1 t o 2 u m (40 t o 79 micro-inch) range. It is being used ex tens ive ly f o r

p e l l e t p lan t i n s t a l l a t i o n s and a l s o t o some e x t e n t in many b e n e f i c i a t i o n p l a n t s

f o r c o n t r o l of crushing, screening, and conveyor t r a n s f e r .

4.1.4 Control of Other Sources

4.1.4.1 Bentoni te F a c i l i t i e s . Almost a l l i r o n o r e b e n e f i c i a t i o n

p l a n t s make use of bentoni te c l a y s as a binder in t h e i r i r o n ore pel le ts ,

and dus t emissions c o n s i s t i n g of b e n t o n i t e are o f t e n a problem. There a r e

4-19

1 I I f t E

I 1 1 I I ! 8' I I I 1 1 I

:I

I [I 'I I I I I I1 1 I I I 11 1 11 I I 1 I 1

CLEAKEDGAS

SCRURBING LIQUID ItdlRODUCED INTO E Y E OF FAN

SLUDGE OUTLET

Figure 4.16 Combination w e t scrubber (Source: The Ducon Company)

4-20

b a s i c a l l y two sources of emissions; one is t h e b e n t o n i t e unloading s t a t i o n

. 1 I I l 0 1 s 1 1. 11 I I 9- I

I I I 1 1 I 1 I

a

where t h e b e n t o n i t e is pneumatically conveyed from r a i l c a r s and i n t o

s t o r a g e silos.

b e n t o n i t e is mixed with t h e i r o n o r e concent ra tes p r i o r t o t h e b a l l i n g

drums.

,The o t h e r source is t h e blending s t a t i o n s where t h e

Most p l a n t s c u r r e n t l y u s e a baghouse f o r c o n t r o l of the b e n t o n i t e

emissions and, depending on s i z e , e i t h e r m u l t i p l e u n i t s o r a s i u g l r

baghouse may b e employed.

t o one c o l l e c t o r .

used i n s t e a d of t h e baghouse.

Usual ly , t h e blending s t a t i o n s a r e a l l ducted

In a few p l a n t s , a high-eff ic iency w e t scrubber is

E f f i c i e n t l o c a l cap ture and containment of b e n t o n i t e d u s t i s

pandatory f o r t h e i r o n o r e p l a n t s t o provide f o r worker s a fe ty .

e f f i c i e n c y c o l i e c t o r s a r e r o u t i n e l y u t i l i z e d because of t h e f i n e p a r t i c l e

s i z e of the b e n t o n i t e material.

High

4 .1 .4 .2 Pe l le t Load-Out. Most i r o n o r e p l a n t s s h i p t h e i r

p e l l e t s by r a i l c a r s which are either loaded d i r e c t l y from t h e i n d u r a t i n g

furnaces o r from s t o c k p i l e s . The loadout f a c i l i t i e s and a l s o screening

s t a t i o n s f o r t h e f i n a l p e l l e t s c o n s t i t u t e sources of p a r t i c u l a t e emissions.

These sources are t y p i c a l l y c o n t r o l l e d by t h e use of wet sc rubbers such

a s t h e "rotoclone" o r Ducon un i t s .

a baghouse f o r t h i s purpose.

t h i s area.

A f e w p l a n t s have proposed t h e use of

However, some p l a n t s e x e r c i s e no c o n t r o l s i n

4.1.4.3 Stockpi les . P a r t i c u l a t e emissions from t h e conveying

of f i n a l p e l l e t s t o s t o c k p i l e s a r e most genera l ly c o n t r o l l e d by d i r e c t

water spraying of t h e m a t e r i a l .

as t h e p e l l e t s leave t h e furnace s e c t i o n of t h e p l an t .

t y p i c a l l y placed i n t h e open atmosphere and emissions have n o t been quant i f ied .

The u s e of water sprays begins immediately

S tockpi les a r e

4-21

I 1 I. I 1 1 I {I 1 1 I. I

1 1 1 I 1 I I I I I

4.1.4.4 T a i l i n g s Ponds. The t a i l i n g s areas a r e p o t e n t i a l

sources of f u g i t i v e emissions.

ground cover and v e g e t a t i o n t o reduce wind l i f t and eros ion of t h e t a i l i n g s .

I n some p l a n t s t h i s i s q u i t e e f f e c t i v e l y and ex tens ive ly accomplished.

The i n d u s t r y usua l ly tries t o provide

4.1.4.5 S u l f u r Oxides. A s pointed out i n Chapter 3, t h e

p e l l e t i z a t i o n systems a r e a l s o a p o t e n t i a l source of s u l f u r oxide

emissions i f c o a l is used f o r f i r i n g of t h e macines. Generally t h e s e

emissions w i l l b e r e s t r i c t e d t o t h e waste gas exhaust only ( f i r i n g gases ) ;

t h e e f f l u e n t gases as pro jec ted i n Chapter 3 w i l l conta in about 275 ppm

SO f o r a t y p i c a l g r a t e - k i l n system. 2 Because n a t u r a l gas is t h e predominant f u e l being used,

c o n t r o l techniques for SO2 a r e not c u r r e n t l y used by t h e i r o n o r e indus t ry .

However, t h i s s u b j e c t has received widespread development i n o t h e r i n d u s t r i e s ,

p a r t i c u l a r l y t h e power genera t ion i n d u s t r y . Applicat ions i n r e l a t e d

i n d u s t r i e s , such a s s i n t e r i n g p l a n t s , a l s o have been made i n Japan. Thus,

t h e techniques used in t h e s e i n s t a n c e s should b e a p p l i c a b l e t o t h e U.S.

i r o n o r e indus t ry .

Many techniques and process modi f ica t ions have been i n v e s t i g a t e d

i n r e c e n t y e a r s f o r t h e c o n t r o l of s u l f u r oxide emissions.

a r e descr ibed i n d e t a i l in the l i t e r a t u r e and i n r e c e n t symposia.

It seems f a i r l y clear, however, t h a t f o r i r o n o r e p e l l e t i z a t i o n a p p l i c a t i o n ,

one of the w e t scrubbing techniques probably would be most a p p l i c a b l e .

This r e s u l t s from t h e f a c t t h a t scrubbing systems a r e g e n e r a l l y more

e f f e c t i v e on d i l u t e gas s t reams (275 ppm SO2) and cons ider ing t h a t recovery

of s u l f u r o r o t h e r s u l f u r compounds probably is n o t warranted.

scrubbing systems be l ieved t o b e most a p p l i c a b l e a r e those us ing c a u s t i c ,

These methods

(1, L 3 )

The

4-22

lime, or l imestone scrubbing o r t h e double a lkal i system.

a p p l i c a t i o n under cons idera t ion , it i s est imated t h a t a 90 percent removal

of SO could b e achieved.

For t h e

2

4.1.4.5.1 Caust ic Scrubbing. Several modi f ica t ions of t h i s

process have been developed and are c u r r e n t l y i n use on an i n d u s t r i a l

s ca l e .

a t St. Louis, Missouri , which u s e s t h e process on two b o i l e r s fed with

A no tab le example i s t h e General Motors Chevrolet Assembly P l a n t

The system u t i l i z e s (3) c o a l conta in ing 3.2 percent s u l f u r and 10 percent ash.

cyclones and e l e c t r o s t a t i c p r e c i p i t a t o r s t o f i r s t remove f l y ash from

t h e f l u e gas stream. Af te r p a r t i c u l a t e removal, t h e flows are combined

and passed through a three-s tage Peabody impingement scrubber with

chevron demisters. The e f f i c i e n c y of SO removal is be l ieved t o b e greater

than 90 percent . S u l f i t e i s oxidized t o s u l f a t e .

2

The only major problem with t h i s process is t h a t t h e e f f l u e n t ,

sodium s u l f a t e s o l u t i o n , must b e f u r t h e r t r e a t e d o r disposed o f . A t

t h e GM p l a n t , t h e s o l u t i o n i s simply discharged t o t h e M i s s i s s i p p i River.

Apparently, t h i s is being allowed as a t l e a s t an i n t e r i m measure due

t o the l a r g e d i l u t i o n obtained.

A modification of ;his process , commonly c a l l e d t h e Yellman-

Lord process , has been used ex tens ive ly in Japan f o r t reatment of b o i l e r

f l u e gases. Here t h e scrubbing medium is sodium b i s u l f i t e i n s t e a d

of sodium s u l f i t e . The b i s u l f i t e is then d ispropor t iona ted by h e a t

t reatment followed by recovery of SO a s s u l f u r i c ac id . Processes f o r

s u l f u r recovery, however, are not be l ieved a p p l i c a b l e t o the i r o n o r e

indus t ry .

2

4.1 .4 .5 .2 Lime-Limestone Scrubbing. The most s u c c e s s f u l l y

opera t ing processes on b o i l e r s t o d a t e have g e n e r a l l y employed l ime as

4-23

. -

I t 1 1 0 1 1 I IN 11 1 I I 1 I I 1 I 1 1 I I

I 1 I I I I I

I C

II I I I %I I

I I

I I I I I I

t h e scrubbing medium.

t h e Chemic0 i n s t a l l a t i o n a t t h e Mi tsu i Aluminum Company i n Japan and more

r e c e n t l y the i n s t a l l a t i o n a t L o u i s v i l l e Gas and E l e c t r i c ' s Paddy's Run

S ta t ion . (3)

hydroxide scrubbing b u t t h e product is a calcium s u l f a t e s ludge which

avoids t h e problems of s o l u b l e sa l t d i s p o s a l . This , of course, b r i n g s up

new problems of s ludge d isposa l .

The f i r s t major la rge-sca le demonstration was

These processes are both very similar t o t h e s i m p l e sodium

4.1.4.5.3 Double A l k a l i Process. Perhaps t h e most advanced

scrubbing concept now be ing t e s t e d on a commercial s c a l e is t h e double

alkali process. I n t h i s process, s o l u b l e sa l ts such as those of sodium

o r ammonia a r e used in t h e p r i m a r y c i r c u i t , bu t l i m e o r l imestone is used

i n the secondary c i r c u i t .

Nippon Kokan, one of t h e l a r g e s t s teel producers i n Japan,

has developed an a m o n i a scrubbing process t o combine a m o n i a i n coke-

oven gas w i t h SO

A prototype p l a n t with a capac i ty of 42 Std m /s (88,500 scfm) of waste

gas has been o p e r a t i n g a t Keihin Works i n the following two ways:

(1)

ammonium s u l f a t e ; (2) amnonium s u l f i t e is t r e a t e d wi th l i m e t o

p r e c i p i t a t e calcium s u l f i t e , which is oxidized by a i r i n t o gypsum, and

t o recover ammonia, which i s re turned t o t h e absorbing system. Waste

gas from t h e s i n t e r i n g p l a n t t y p i c a l l y conta ins 250 t o 500 ppm SO

and about 95 percent removal can b e achieved.

by an e l e c t r o s t a t i c p r e c i p i t a t o r p r i o r t o the scrubbing system.

( 1) i n a waste gas from an i ron-ore s i n t e r i n g p l a n t . 2 3

ammonium s u l f i t e formed by t h e r e a c t i o n i s oxidized t o produce

2

The gases are f i r s t cleaned

One p o t e n t i a l problem wi th t h i s process a s i t might apply

t o t h e U . S . i r o n o r e i n d u s t r y , is t h a t a s a l a b l e gypsum o r ammonium s u l f a t e

f e r t i l i z e r must b e produced. A l t e r n a t i v e l y , however, a calcium s u l f a t e s ludge

could b e disposed of s i l i l a r l y t o t h e s t r a i g h t l ime scrubbing systems.

4-24

4.2 PERFORMANCE OF TYPICAL CONTROL TECHNIQUES

4.2.1 General Aspects and Vendor Guarantees

There are numerous f a c t o r s which i n f l u e n c e t h e e f f i c i e n c y of

c o l l e c t o r s t o r e m v e p a r t i c u l a t e s from gas streams.

of t h e four b a s i c types of c o l l e c t o r s depends on knowledge o f t h e equipment

g iv ing o f f t h e gas as w e l l as the gas i t s e l f . A genera l summary o f f a c t o r s

which inf luence t h e type of equipment t o be i n s t a l l e d on t h e process as

w e l l as t h e f a c t o r s which a f f e c t t h e d e v i c e ' s opera t ion follows:

The s e l e c t i o n of one

Volumetric Flow Rate of Gas - Range and frequency of v a r i a t i o n

- Continuous o r discont inuous

Gas Temperature - Pressure - Moisture Content - Range, frequency, and d u r a t i o n of v a r i a t i o n s

P a r t i c u l a t e s S p e c i f i c Gravi ty - Any s i g n i f i c a n t v a r i a t i o n s between p a r t i c u l a t e s

P a r t i c u l a t e C h a r a c t e r i s t i c - S o l i d , l i q u i d d r o p l e t , hydroscopic,

S i z e D i s t r i b u t i o n of P a r t i c u l a t e s - Any v a r i a t i o n s

e l e c t r i c a l r e s i s t i v i t y , r e a c t i v i t y , etc

P a r t i c u l a t e Concentration - Weight per u n i t volume and v a r i a t i o n s

Chemical Composition of G a s - SO2, nyi rocar loua , ~ j rganks , e tc

The cyclone and mult ic lone d r y c o l l e c t o r s a r e s e n s i t i v e t o change

i n p a r t i c l e s ize and concent ra t ion , gas v e l o c i t y , and v o l u k .

i n s t a l l a t i o n of dropout boxes o r enlarged zones g e n e r a l l y increase t h e

e f f i c i e n c y of t h e device.

dewpoints may h inder t h e device ' s e f f i c i e n c y .

The

The presence of moisture o r gases reaching t h e

The w e t mechanical c o l l e c t i o n devices , such as v e n t u r i scrubbers,

packed-bed-type, and t h e c e n t r i f u g a l sc rubbers , are u s u a l l y very e f f i c i e n t

and i n general are s e n s i t i v e t o temperature changes o r concent ra t ion w i t h i n

des ign limits. The chemistry of t h e g a s can a f f e c t t h e scrubber due t o t h e

4-25

a I I 1 1 I 1 I 1 I 1 I

I I I I I I I 'I 1 I I I (I' I 3 I I I I I I

formation of a c i d s which causes excessive wear.

v a r i a t i o n s can be designed i n t o w e t scrubber

I n genera l , l a r g e flow

a p p l i c a t i o n s .

The baghouse c o l l e c t o r i s one of t h e most e f f i c i e n t c o l l e c t o r s ;

however, a number o f f a c t o r s p a r t i c u l a r l y a f f e c t i t s operat ion. Some of

these a r e as follows:

Ai r -c lo th r a t i o

P a r t i c l e s i z e and s i z e d i s t r i b u t i o n

Gas volume

Temperature of gases

Dewpoint of gas , t h e gas o r device cannot drop below t h e

dewpoint

Mechanical a s p e c t s such a s bag c leaning cycle t i m e , wear on

bags, etc.

Probably one of t h e most c r i t i c a l v a r i a b l e s i n a baghouse o p e r a t i o n

as r e l a t e d t o i r o n ore p l a n t s i s t h e gas temperature and dewpoint. Thus,

f o r a p p l i c a t i o n t o furnace exhaust gases, t h e baghouse o p t i o n w i l l r e q u i r e care-

f u l assessment of types of f a b r i c s , c o n f i g u r a t i o n s , e t c .

The e l e c t r o s t a t i c p r e c i p i t a t o r (ESP) has a very high e f f i c i e n c y

on f i n e p a r t i c l e s and i s fundamentally independent of the v e l o c i t y of t h e

gas stream flow.

s e n s i t i v e t o gas d e n s i t y and electrical conduct iv i ty .

e l e c t r i c a l conduct iv i ty (or r e s i s t i v i t y ) are a c r i t i c a l f a c t o r a f f e c t i n g

t h e e f f i c i e n c y of a n ESP.

The ESP i s less s e n s i t i v e t o p a r t i c l e s i z e but i s h i g h l y

Large v a r i a t i o n s i n

Curren t ly , t h e i r o n o r e i n d u s t r y i s u t i l i z i n g a l l four of t h e

b a s i c types of c o l l e c t o r s ; namely, mechanical c o l l e c t o r s , f a b r i c f i l t e r s ,

wet scrubbers , and e l e c t r o s t a t i c p r e c i p i t a t o r s . Several b a s i c

c h a r a c t e r i s t i c s of each of these c o n t r o l devices a r e shown i n Table 4.3.

4-26

rl 0 c z 8

W

F4 c

m u

W

rl

0 m V

rl

0 V

0

E

m A

0 YI A

2 2

0 0

I V 0 m

m m

m e I m r l F r

O^ 0 0 b b

rlrl A h

m o N r l I h m

m

0

V m

U V

- v 0 r.

4 h

0 rl A

el

m V m

-3 h

- z YI

d

0 A

rl

V

$4 W U rl 4 w M m m

4-27

r l r l r l m

O o o m w m m m v v v v

0 YI \o

I 0"rl

A h

rl

r l r l r lo h h h h

m m y l r l N

V

..

+l

m m I YI m

rl V

rl

0 h

rl

V

M e rl U m $4 W a 0

rl m 1 10 1 $4 m -u C 3 x 0 e W .d U .d w w W

U

5 U $4 W a 0 m h rl W U

El 2 0 $4 a a m

m -e W U U a rl rl 0 U

W N d m W 4 U

4.8

i d U

a a 0

2

e d

- w m o

10

I 1 I 0 1 ,I I I l 0 I I 1 I I 1 I I I 1 I

I I I I I I I I I I

I I I I I I I I I I I I

4

0 m V

m U N V

U U 0

u rl i A

C m A

x z

0 m o m

1 0

m v

\D U N r l c l a

m b U N

d-3 -3-3 u3\D

nn . . N N

A h

m 0 N r l

I A m

VI

0 m A

\D m V m

U U LD

n N

A

0 4 A

cl

m m A

ID m m A

n m m

N

0 h

rl

V

c l c l c l m

\D U

U

m

m m m r l N m m I r l u u m

A A d N

..

h h h h v v v v C J U U U

u u u u u u u u \DLD\D \D

1 1 1 1

l.r.r.r- N N N N

m m m m

n n n m . . . . " N O

A A A A

m m m r l N

V

cl

m m I m

m

m U N A

rl rl m

N

0

A

rl

"

Y u o .rl u m u u .rl m a 0 .rl Y U u m U Y U P . rl W

urn

; 0 .rl 4.l m Y m a 0

c .rl

..w m o

Table 4 . 3 i l l u s t r a t e s t h a t on ly three types of devices can achieve high

c o l l e c t i o n e f f i c i e n c y (approaching 99 percent ) on very f i n e p a r t i c u l a t e s ;

these a r e t h e bag f i l t e r , t h e w e t v e n t u r i scrubber , and t h e ESP. The dry

cyclone o r mul t ic lone can approach 9 0 percent e f f i c i e n c y but only on

p a r t i c u l a t e s i n t h e 5 t o 25 pm (197-984 micro-inch) range.

contained i n Table 4.3 a l s o i n d i c a t e s t h a t o t h e r types of w e t sc rubbers

perform much poorer clrari t h e v e n t u r i scrubber , al though i t should be

pointed out t h a t combination scrubbers are not adequately covered by

t h e s e d a t a and probably have e f f i c i e n c i e s i n t h e 95 t o 99 percent range

on p a r t i c u l a t e s of 1 t o 5 u m ( 4 0 t o 197 micro-inch).

The information

Fur ther information on c o l l e c t i o n e f f i c i e n c y can b e a s c e r t a i n e d

from performance guarantees of fe red by many companies who manufacture

t h e s e c o n t r o l devices . Vendor guarantees t y p i c a l l y s p e c i f y an o u t l e t dus t

loading t o b e m e t based on assumed p a r t i c l e s i z e s and i n l e t dus t

concent ra t ions . Severa l such guarantees a r e included i n Table 4.4. It

should be noted t h a t t h i s information w a s obtained from proposed modif icat ion

o r expansion p r o j e c t s of s e v e r a l i r o n o r e companies and thus should b e

d i r e c t l y a p p l i c a b l e t o t h e c o n t r o l of i r o n oxide or b e n t o n i t e dus t s .

4.2.2 F i e l d T e s t Data

I n a d d i t i o n t o t h e b a s i c c o n s i d e r a t i o n s presented i n t h e previous

sec t ion , s i g n i f i c a n t d a t a a l s o are a v a i l a b l e through f i e l d t e s t i n g of

a c t u a l e x i s t i n g sources and c o n t r o l devices ,

two types.

submit any a v a i l a b l e emission source test d a t a through Sect ion 1 1 4 of

t h e Clean A i r Act. m e bulk of these d a t a a r e summarized and presented i n

Appendix C of t h i s document. Secondly, three p l a n t s were s e l e c t e d f o r

a d d i t i o n a l f i e l d t e s t i n g under EPA c o n t r a c t a s s o c i a t e d with t h i s program.

These d a t a are b a s i c a l l y of

F i r s t , most i r o n o r e p l a n t s w e r e contacted and requested t o

4-29

1 I 1 1 0 8 I 1 I I I I ! II I I 1 I I 1 I 1

I I I I I I I I I I I I I I 1 I I I I I I

E C

e K C

C C

.r

r r

Q

1

r , C

U

E

3 5\

h

1 1 I.!.

m . h

N O N 'rl

I I Z

m N

m m m M

m U m e Y 5 w U m m

Y

m

-5

U C H

w m

2 . e 0 $4 Y m m

m C 0 rl U

.rl U rl

2

m r.

h I 1 I.!.

h urn m r l

1 1

N d

. .

. . OZ

m m m 3 m U

5 m U m Y W

2 H

Lo m .rl Y U m 7 V e H

c $4 5 N

..

m

rl U .rl U rl a

I I

h m u ? ? OZ

h I 1 I.!d

d 0 Y U C 0 U

m U .rl e 0 U C a, m

9 rd a

U

$4 m ,d rl 7 F*

Y m U rl .rl 1u

M m m

h - D r.

m m

h h m m - V h

?: OZ

h N m r.r. A -

. .

M e .rl V

rl

m U .rl c 0 U C a

$ e

m

Y m U d .rl w 0 Y a h Jz

rl m .rl U m z

.. g

Y m e % $4 U m -u m D I a m m PI 5

4-30

m e ln m m

h m r.0 . . OZ

h

t? m a d -

m U a

2 m Y U

01 U

$4 1 k

2

h

v U

U I

5 m a h c

g U 1 e

$4 m P

Y U m U m

9

3

g .rl U m e .rl e !z U

h

v e r.

r. m

h r . m 0 0 . . OZ

h

? ? m r l -

m m m m M

m U m

m U

2 W.

0

% a, a h c .. 8 U 3 e

$4 GI D

Y U 0

.rl Y U

9

a

5 +

r. m m

h rnN 00 . . OZ

h

I 1 I.!.

m m m m M

m U ro

m U m Y W

4 ' rl m Y U U 0 U

-5 3 Y

10 m d

Ei W

This t e s t i n g w a s done a t t h e Hanna Mining Company, Groveland p l a n t ,

t h e Eveleth Taconi te Company, and a t Cleveland C l i f f ' s , Empire Mine.

Although much of t h e d a t a r e l a t e t o t h e t o t a l mass rate of

emissions, source information a l s o w a s obtained on c o l l e c t o r e f f i c i e n c i e s .

For purposes of d i scuss ion , t h i s w i l l be ca tegor ized as major sources or

minor sources .

4.2.2.1 Pffjor Scurces. Test d a t a i n t h i s category are pr imar i ly

from c o n t r o l devices opera t ing on t h e main process gases from t h e p e l l e t i z a -

t i o n machines. The most cornon c o l l e c t o r s used f o r t h i s purpose are

t h e dry mechanical c o l l e c t o r s , such as t h e mul t ic lone o r simply a drop-out

chamber. A summary of the da ta a v a i l a b l e on t h e s e devices i s contained i n

Table 4 . 5 . These measured e f f i c i e n c y va lues , i n genera l , s u b s t a n t i a t e t h e

t y p i c a l va lues discussed i n the previous s e c t i o n .

of tests were obtained on iarge-diameter cyclolies and t h e e f f k i e n c j j of

t h e s e devices t y p i c a l l y averaged about 80 percent .

e f f i c i e n c y was from 48 t o 88 percent . On t h e o t h e r hand, a much g r e a t e r

v a r i a t i o n in opera t ing performance was noted wi th mul t ic lone i n s t a l l a t i o n s .

These devices had opera t ing e f f i c i e n c i e s ranging from 7 .5 up t o Y11.8 percent .

This wide v a r i a t i o n might be a t t r i b u t e d t o e r o s i o n and h o l e formation

al lowing some u n i t s t o bypass much of t h e dus t emissions. I f t h e u n i t

is w e l l maintained, however, i t appears t h a t mul t ic lone c o l l e c t o r s can

perform a t 90 percent o v e r a l l c o l l e c t i o n e f f i c i e n c y .

For example, a number

The range in opera t ing

The remaining f i e l d test d a t a on w e t sc rubbers and ESP u n i t s

again point o u t t h a t t h e s e c o l l e c t o r s a r e much s u p e r i o r t o the dry

cyc lonic devices .

f i l t e r a b l e p a r t i c u l a t e s with a 97.3 percent removal for t o t a l p a r t i c u l a t e s .

The w e t v e n t u r i scrubber w a s very c l o s e t o t h e s e performance f i g u r e s i n

The ESP f o r i n s t a n c e showed 99.2 percent removal of

4-31

1 1 1 I P I I 1 I 1 I I I 1 I I 1 1 I I I I '

I I I I I I I I I I I I I I I I I I I I I

v m U rn m U

U

$ rl PI k m d U 1 m I

z 2 2 !i

4 e

3:

0 m

I I

rn m

3 0 >I 0

m 3 a .rl U d

g

3

: rn

m M

U QJ

2 $4

a

.: W

4-32

5

$ al d

w $4 0

W

U e m U M m e rl

0 m

___

I I I I 0 I I I I I i I I I I I I I I I I I

t o t a l p a r t i c u l a t e removal bu t repor ted ly w a s no t o p e r a t i n g a t i ts b e s t

dur ing t h e test per iod.

4.2.2.2 Minor Sources. Only l i m i t e d da ta were obtained i n

t h i s s tudy on t h e performance of smaller c o l l e c t i o n devices which a r e

used f o r c o n t r o l of c r u s h e r s , conveyors, t r a n s f e r po in t s , e t c . The

bulk of t h e s e da ta per ta ined pr imar i ly t o t h r e e types of wet scrubbers

a s summrized i n Table 4 .6 Typice l ly , t h e wet scruhhers t e s t e d a l l

showed c o l l e c t i o n e f f i c i e n c i e s g r e a t e r than 99 percent during some

per iod of t e s t i n g .

b e t t e r performance from one device over t h e o t h e r two t h a t were t e s t e d .

From these da ta , it would b e d i f f i c u l t t o a s s i g n

4-33

I I I I I 1

2 e: I I m

2 W

U

I I I I I I

\D

.j

W 4 !a

I I 8

I I I I I 'I

4-34

rn W 01 c 0

01' W $4

U rl rl

n

References f o r Chapter 4

1. SO2 Abatement f o r S t a t i o n a r y Sources i n Japan, EPA-600/2-76-013a, January, 1976.

2. "Sulfur Removal and Recovery", Symposium a t t h e 167th Meeting of t h e American Chemical Soc ie ty , Los Angeles, C a l i f o r n i a , Apr i l 4-5, 1374.

3. "Sulfur Emission Control For I n d u s t r i a l Boi lers" , Proceedings of t h e American Power Conference, Volume 36, 1974.

4. R. D. Ross, " A i r P o l l u t i o n and Industry" , 1972.

4- 35

I I I I 0 l I I 1 I 0 I I I I I I I 1 1 I 1

I I I I I I I I I I I I I 1 I I

I I I 'I

5. MODIFICATION AND RECONSTRUCTION

In accordance with s e c t i o n 111 of t h e Clean A i r a c t , as amended

i n 1970 and 1974, s tandards of performance s h a l l be e s t a b l i s h e d f o r new

sources w i t h i n a s t a t i o n a r y source category which " . . . m y c o n t r i b u t e

s i g n i f i c a n t l y t o a i r p o l l u t i o n ..." apparatus ( f a c i 1 i t i e s ) w i t h i n a s t a t i o n a r y source, s e l e c t e d as "af fec ted

Standards apply t o opera t ions o r

f a c i l i t i e s , " t h a t i s f a c i l i t i e s f o r which a p p l i c a b l e s tandards of performance

have been promulgated and the c o n s t r u c t i o n o r modif icat ion of which commenced

a f t e r t h e proposal of s a i d s tandards.

It i s important t o note t h a t an " e x i s t i n g f a c i l i t y " may become

subjec t t o s tandards of performance if deemed modified o r reconstructed a s

defined i n t h e general provis ions of 40 CFR P a r t 60.

5.1 40 CFR PART 60 PROVISIONS FOR MODIFICATION AM) RECONSTRUCTION

5.1.1 Modification.

S e c t i o n 60.14 d e f i n e s modi f ica t ion as follows:

"Except as provided under paragraphs ( a ) , ( e ) , and (f) of

t h i s s ec t ion , any physical o r o p e r a t i o n a l changes t o an e x i s t i n g

f a c i l i t y which r e s u l t i n an i n c r e a s e i n the emission rate t o t h e

atmosphere of any p o l l u t a n t t o which a s tandard a p p l i e s s h a l l be

considered a modif icat ion w i t h i n t h e meaning of s e c t i o n 111 of

t h e Act. Upon modif icat ion, a n e x i s t i n g f a c i l i t y shall become an

a f f e c t e d f a c i l i t y f o r each p o l l u t a n t t o which a s tandard a p p l i e s

and f o r which t h e r e i s an i n c r e a s e i n t h e emission rate t o t h e

atmosphere." 5-1

-1 I I I I I I I I I I I I I I I I I I I I I

The exception in paragraph (d) allows for an existing facility to

undergo a physical or operational change which results in an increase in

the emission rate of any pollutant to which a standard applies, but not be

deemed a modification, provided the owner or operator can demonstrate to

the Administrator's satisfaction (by any of the procedures prescribed under

paragraph [b] of this section) that the total emission rate of that pollutant

from all facilities within the stationary source has not increased. This

may be accomplished by decreasing the emission rate from other facilities

within the stationary source, to which reference, equivalent or alternative

methods of sampling and analysis can be applied, to compensate for emission

rate increases resulting from physical or operational changes to an existing

facility.

installation or improvement of control systems or through physical or

operational changes, including reducing a facility's production rate. In

addition, an owner or operator may completely and permanently close any

facility within the stationary source to prevent an increase in the total

emission rate from occuring regardless of whether reference, equivalent or

alternative test methods can be applied, if it can be clearly demonstrated

(by any of the procedures prescribed under paragraph [b] of this section)

that the emission rate reduction resulting from such closure offsets any

increase.

The required emission reduction may be effected through the

Paragraph (e) lists certain physical or operational changes which

will not be considered as modifications, irrespective of any change in the

emission rate. These changes include:

a . Routine maintenance, repair and replacement.

b. An increase in the production rate not requiring a capital

expenditure as defined' in section 60.2(bh).

5-2

c. An increase in the hours of operation.

d.

standard, the existing facility was designed to accommodate that alternate

fuel or raw material.

Use of an alternative fuel or raw material if prior to the

e. The addition or use of any system or device whose primary

function is the reduction of air pollutants, except when an emission control

s y s t e ~ ! is reuwrer! or replaced hy R system considered to be less efficient.

f. The relocation or change in ownership of an existing facility.

Paragraph (b) clarifies what constitutes an increase in emissions

in kilograms per hour and the procedures for determining the increase including

the use of emission factors, material balances, continuous monitoring systems,

and manual emission tests. Paragraph (c) affirms that the addition of an

affected facility to a stationary source does not make any other facility

wickin that source subject tu standards of performance. Paragraph <f) simply

provides for superseding any conflicting provisions.

5.1.2 Reconstruction.

Section 60.15 regarding reconstruction states:

"An existing facility shall be considered an affected faciiicy

by the Administrator upon reconstruction through the replacement

of a substantial majority of the existing facility's components

irrespective of any change of emission rate.

may request the Administrator to determine whether the proposed

reconstruction involves replacement of a substantial portion of

the existing facility's components based on the capital cost of

all new construction and other technical and economic consider-

at ions. "

The owner or operator

I I I I P 1 I I I I 1 I I I I I I I I I I I

5- 3

I I I I I I I I I

I c I I I 1 I I I I I

The purpose of t h i s provis ion i s t o ensure t h a t an Owner o r

opera tor does not perpetuate an e x i s t i n g f a c i l i t y by rep lac ing a l l but

v e s t i g i a l components, support s t r u c t u r e s , frames, housings, etc., r a t h e r than

t o t a l l y rep lac ing it i n order t o avoid subjugat ion t o appl icable standards

of performance. A s noted, upon reques t EPA w i l l determine i f t h e proposed

replacement of an e x i s t i n g f a c i l i t y ' s components c o n s t i t u t e s reconstruct ion.

5.2 APPLICABILITY TO THE I R O N ORE BENEFICIATION INDUSTRY

The i r o n o re i n d u s t r y t y p i c a l l y undergoes modif icat ion, recon-

s t r u c t i o n , o r a d d i t i o n of capac i ty by t h e a d d i t i o n of new equipment i n t e g r a t e d

i n t o the e x i s t i n g p lan t . The except ions, of course, are the c l e a r l y new

source p l a n t s t h a t would be cons t ruc ted t o mine a new depos i t . A s such, t h e

a p p l i c a b i l i t y of s e c t i o n 111 standards t o t h e i r o n o r e b e n e f i c i a t i o n indus t ry

would be twofold.

F i r s t l y , new source p l a n t s c l e a r l y would be "af fec ted f a c i l i t i e s "

i f cons t ruc t ion commenced a f t e r the da t e o f proposal of these s tandards.

Secondly, e x i s t i n g p l a n t s would a l s o become "af fec ted f a c i l i t i e s " i f t h e p lan t

undergoes expansion by a d d i t i o n of capac i ty and t h e expansion commenced after

t h e da t e of proposal of t h e s e s tandards. It should be noted, however, t h a t

t h e expansion f a c i l i t i e s which, f o r t h e most p a r t , are constructed as new

and separa te production l i n e s , would be the only f a c i l i t i e s termed "affected

f a c i l i t i e s " . This means, of course, t h a t t h e e x i s t i n g production l i n e s , even

i f i n t h e same physical l o c a t i o n , would not be covered under t h e s tandards.

One a d d i t i o n a l cons idera t ion arises concerning t h e a p p l i c a b i l i t y

of these s tandards and t h i s i s descr ibed in paragraph (e) concerning the use

of a l t e r n a t i v e f u e l s .

a f fec ted by t h i s aspec t because of t h e a n t i c i p a t e d change over t o coa l f i r i n g

of indura t ion systems i n s t e a d of n a t u r a l gas f i r i n g .

I n a l l p r o b a b i l i t y t h e i r o n o r e indus t ry w i l l be

An i n c r e a s e i n emissions

5-4

w i l l r e s u l t as p e r t a i n i n g t o s u l f u r oxides from combustion of t h e coal .

Current ly , many p l a n t s a r e being redesigned t o accomodate t h i s a l ternat ive

f u e l and the a p p l i c a b i l i t y of t h e s tandard w i l l be i n ques t ion u n t i l such

redes ign i s complete.

The major problem i n the i r o n ore indus t ry of implementing any

s tandards per ta in ing t o e x i s t i n g p l a n t s w i l l be a problem of r e t r o f i t t i n g

the c o n t r o i device t o tile r q u i p r e n t iised and w i t h i n t h e physical 1 i F z t a t i o n s

of the bui ldings. A t y p i c a l example would be t h e r e t r o f i t t i n g of a specific

c o n t r o l device t o each source of emission i n a p lan t us ing s h a f t furnaces. A

t y p i c a l s h a f t furnace w i l l exhaust some 12 m 3 / s (25,000 cfm) of ho t gases and

handle approximately 15.5 kg/s (55 tons per hour) of p e l l e t s . If a baghouse

is the c o n t r o l device [ each 1 2 m 3 / s (25,000 cfm) baghouse would r e q u i r e ap-

ioximately 23 m 2 (250 f t 2 ) ] , then t o r e t r o f i t t o a t y p i c a l s i t u a t i o n , say 27

furnaces , the p lan t

gas cool ing and temperature c o n t r o l device.

r e t r o f i t i n t o e x i s t i n g p l a n t s .

o r e p l a n t s around the furnace a rea i n t h a t t h e furnace f l o o r where the gases

w i l l be coming o f f a r e genera l ly from 1 5 t o 30 m (50 t o 100 f e e t ) o f f t h e

grolmd, t h e r e f o r e i r e q u i r i n g support o r suspension. Typica l ly , t h e p l a n t s

a r e designed with minimum a v a i l a b l e space w i t h i n the covered s t r u c t u r e ,

t h e r e f o r e , always posing a space requirement problem.

r e q u i r e s some 627 m' (6,750 f t 2 ) of a r e a p l u s space f o r

This poses a r e a l problem t o

Addi t iona l problems a r e encountered i n i r o n

The r e t r o f i t t i n g of dry cyclone and wet scrubbers would appear t o

pose t h e least problem of r e t r o f i t ; whereas the baghouse would pose t h e

l a r g e s t problem and e l e c t r o s t a t i c p r e c i p i t a t o r s an in te rmedia te problem

based pr imari ly on space requirements.

5-5

I P I c I I I. I I I I 1 I 1 I I I I 1 1 I

I I I I 1 I it 1 I E I t

b I' I I .I IJ I I I I I

-6. MODEL EMISSION CONTROL SYSTEMS

The emission c o n t r o l system, a s def ined , cons is ' t s of t h e combina-

t i o n of a process and c o n t r o l technique. This s e c t i o n t h e r e f o r e w i l l

o u t l i n e several example emission c o n t r o l systems - t h e purpose being t o

provide opt ions f o r t h e s e l e c t i o n of a "best system of emission reduction".

These s e l e c t i o n s then would be t h e b a s i s f o r p o t e n t i a l s tandards under

Sect ion 111 of the A c t which apply t o new and modified sources o r f o r

s tandards under Sec t ion 1 1 2 which, i n a d d i t i o n a p l l y t o e x i s t i n g sources .

This d iscuss ion of c o n t r o l systems is divided i n t o var ious sub-

s e c t i o n s corresponding t o t h e s e p a r a t e process opera t ions wi th in an i r o n

o r e p l a n t .

6 .1 M I N I N G , BLASTING, AND HAULING

There a r e few c o n t r o l system a l t e r n a t i v e s f o r t h e mining,

b l a s t i n g , and haul ing of i r o n o res . The process opera t ions involve

pr imar i ly open p i t mining but some underground mining i s prac t iced . For

the few underground opera t ions , emissions have not been measured but a r e

expected t o be very low and the re fo re , no c o n t r o l devices are s p e c i f i e d .

For t h e open p i t o p e r a t i o n s , the f u g i t i v e d u s t emissions are b e s t con-

t r o l l e d by t h e use of water and/or chemical sprays .

haulage loads and haul roads should a l s o be p r a c t i c e d t o reduce f u g i t i v e

emissions from these sources .

Wetting of the

6.2 PRIMARY CRUSHING

A l l open p i t i r o n o r e p l a n t s u t i l i z e t h e gyratory-type c rusher

f o r primary crushing of t h e o r e , underground mines use j a w c rushers ; thus,

t he re are no process a l t e r n a t i v e s considered f o r t h i s opera t ion . The

c o n t r o l system however, can have a number of v a r i a t i o n s as discussed below.

6-1

-1- 1 I I 1 I r 1 I z E I1 I I u I I 1 I I I I

Case 1 (a ) - This c o n t r o l opt ion would c o n s i s t of t h e u s u a l

p r a c t i c e of employing water s p r a y s a t t h e c rusher top where o r e is dumped

i n from trucks. The c rusher d i scharge (pan feeder and conveyor) would

be hooded and exhausted t o a dry cyclonic-type c o l l e c t o r .

d u s t s would be recovered and u s e d in subsequent processing. This c o n t r o l

system i s r a t e d a t about 80 percent e f f i c i e n c y and w i l l r e s u l t i n emissions

of about 8.9 kg/1000 Mg (20 pounds p e r 1000 tons) of o r e processed.

Tables C - 1 and C-12).

Col lec ted

(See

Case I ( b ) - E s s e n t i a l l y t h e same as Case I ( a ) except t h i s

a l t e r n a t i v e would incorpora te a wet scrubber f o r c o n t r o l of t h e c rusher

discharge emissions. Water sprays again would be used a t t h e c rusher top.

Case I ( c ) - This c o n t r o l op t ion would involve hood c o l l e c t i o n of

both t h e top and bottom crusher emissions and t h e use of a baghouse c o l l e c t o r

f o r both sources . This c o n t r o l a l t e r n a t i v e would r e s u l t i n emissions of

about 1.1 kg/1000 Mg (2.5 pounds p e r 1000 tons) of ore processed.

Tables C-17 and C-19).

(See

6 . 3 SECONDARY CRUSHING, SCREENING, CONVEYOR TRANSFER, AND ORE STORAGE

These process opera t ions a r e conducted b a s i c a l l y the same from

plan t t o p l a n t w i t h i n t h e indus t ry . A s m a l l segment of t h e i n d u s t r y ,

however, employs e n t i r e l y d i f f e r e n t processing f o r f i n e gr inding of t h e

ore . One process v a r i a t i o n i s t h e u s e of t h e dry autogenous gr inding and

a i r c l a s s i f i c a t i o n system and t h i s is u t i l i z e d a t two of the Hanna-

operated p l a n t s . Reportedly, t h i s process h a s no p a r t i c u l a r advantages

and a change w i l l be made t o t h e w e t g r ind ing system. The two p l a n t s

p r e s e n t l y using t h e dry system have s i g n i f i c a n t l y higher emissions f o r t h e

f i n e gr inding opera t ions a s i n d i c a t e d i n Appendix C .

The o t h e r main process v a r i a t i o n is t h e use of w e t autogenous

gr inding of o r e feed from t h e primary c rushers . This op t ion , of course,

would e l i m i n a t e most of t h e p a r t i c u l a t e emission sources a s s o c i a t e d wi th

t h e f i n e gr inding s t eps .

successfu l ly us ing t h i s approach.

Curren t ly only one p l a n t i n t h e i n d u s t r y i s

6-2

Considering the above aspects, only three control system

alternatives are selected as outlined below.

Case II(a) - This control option comprises the conventional secondary and tertiary crushing process with the use o f hooding and wet scrubbers to control particulate emissions from all sources. The

particular scrubber employed may be any one of the several discussed in

Chapter 4 , but must have collection efficiencies equal to or greater than 99 percent of entering particulates.

available and demonstrated technology. This level of performance is considered

Case II(b) - Essentially the same as Case II(a) except baghouse collectors would be used in place of wet scrubbers. This option could

involve combining some sources into one collector.

Case II(c) - This control option would involve the use of wet autogenous grinding mills as a process variation over conventional crushing equipment. by this option, there is no need to specify a control device.

dust emissions may be generated however around conveyors feeding the autogenous mills and

Because particulate emissions would be essentially eliminated

Some minor

these emissions are estimated at about i.8 kgii000 iyig

( 4 pounds per 1000 tons) of ore processed.

6 . 4 PELLET INDURATION

The r c n t r c l systems nannciated with pellet induration are perhaps

the most complex part of the current study. Basically, there are three types

of process variations currently in use by the industry, the straight grate,

the grate-kiln, and the vertical shaft systems. There presently is a fourth

furnace configuration referred to as the circular grate which is reported to

incorporate all the best features of both the grate-kiln and straight-grate

systems. For purposes of discussing control device alterations, only the

grate-kiln and the straight-grate systems are discussed below, since these

two systems process the majority of iron ore in the U . S .

6-3 I I I

-I- I 1 f I I I 1 I 1 1 I I 1 I 1 I I I 1 1 1

6 . 4 . 1 Grate-Kiln System

The grate-kiln system, its emission points, and the various control

system options are presented in Figure 6 . 1 .

is characterized by selecting different combinations of control devices for

each source of emissions.

the cooler process air exhaust, and the smaller emission points commonly

called the grate feed, grate discharge, and cooler discharge.

Each control system alternative

The sources shown are the main waste gas exhaust,

Case III(a) - This control system option consists of the common practice of employing a dry multiclone collector for the main waste gases and wet scrubbers such as the Rotoclone or Ducon units for the minor emission

points. No coUector is utilized for the cooler exhaust. It is estimated that this alternative will result in emissions in the range of 446 to 892 kg/1000

Mg (1000 to 2000 pounds per 1000 tons) of pellets produced.* Case III(b), (c), and (d) - These control system options are

identical to Case III(a), except for the use of a different control device

f o r the main waste gas emissions. is selected and emissions are estimated at about 89 kg/1000 Mg (200 pounds per

1000 tons)* of pellets produced. is used with emissions as low as 6 3 kg/1000 Mg (140 pounds per 1000 tons)* of pellets and in Case III(d), a baghouse collector is selected. tests of the baghouse have been made but it is expected to have emissions

close to that of the ESP option. Case III(e) - This control system option is considered to provide

In Case III(b), a wet Venturi scrubber

In Case III(c), an electrostatic precipitator

No full-scale

an alternative to the use of wet scrubbers for the minor point emissions of the indurating machine. A baghouse could be utilized for this purpose although no present plant is considering such a system. With a baghouse,

emissions would be slightly reduced over that anticipated from wet scrubbers

and the improvement would be in the finer particle sizes. Case III(f) and (g) - These options are considered to provide

alternatives for the control of the cooler exhaust emissions. Very little data is available on these emissions but they typically range from 13 to 6 3 kg/1000 Mg ( 3 0 to 1 4 0 pounds per 1000 tons) of pellets produced.

*For detailed emission data, see Table 3 . 9 .

6-4

( a ) Case 111 (d) Case IIi (C) Case IIi

1. Mult ic lone 1. Ventur i sc rubber 1. ESP 1. Baghouse 2. Wet scrubber 2. Wet scrubber 2. Wet scrubber 2. Wet scrubber 3. Wet scrubber 3. Wet scrubber 3. Wet scrubber 3. Wet scrubber 4. Wet scrubber 4. Wet scrubber 4. Wet scrubber 4. Wet scrubber r .,.-. 2. c ?.T̂ nn .,-..- 5 , None 5. None , . L I V L L r

Case iii (E)

Figure 6.1. Model Pellet Indurat ion-Grate Ki ln Options

6-5

I .3 I P 9 CI I I 1 I I' I* I tl I I I P I 3 I I

a 1 1 I 1 I' P I 2 1 I II E

1 I 1 1 1 I I

11

6 . 4 . 2 Straight Grate System

The straight grate system, its emission points, and the various

control system options are presented in Figure 6 . 2 .

simplification, only the Dravo-Lurgi configuration is considered; a similar

diagram would also apply to the McKee type machine. The sources shown are

the windbox exhaust, the hood exhaust, and the smaller emission points

commonly called the machine discharge and the hearth-side layout exhaust.

For reasons of

Case IV(a) - This control system option consists of the usual practice of employing a dry multiclone collector for the windbox exhaust and wet scrubbers such as the Rotoclone o r Ducon units f o r the minor emission points. No collector is utilized f o r the cooler exhaust. It is estimated that this alternative will result in emissions of about 536 kg/1000 Mg (1200 pounds per 1000 tons) of pellets produced.*

Case IV(b), (c), and (d) - These control system options are identical, except f o r the use of a different primary control device for the .

main emission points. In either case, the hood and windbox exhaust streams are fitted with a separate control device or combined into a single source

of emissions. It should be noted however that sulfur oxides will appear predominately in the windbox exhaust and the combining of sources may not be practical from this standpoint. In Case IV(b), a wet venturi scrubber

is utilized. No straight grate plants presently employ such a system but emissions.most likely would be similar to Case III(b) or 89 kg/lOOO Mg (200 pounds per 1000 tons) of pellets produced.* static precipitator and Case IV(d) with a baghouse again would have emissions

similar to the respective grate-kiln options.

Case IV(c) with an electro-

Case IV(e) - This control system option is considered to provide an alternative to the use of wet scrubbers for the minor point emissions

of the indurating machine. With a baghouse, overall emissions would be

slightly reduced over that anticipated from wet scrubbers.

*For detailed emission data, see Table 3 . 9 .

6 - 6

Control Device Legend

Case IV(a) Case IV(b) Case IV(c)

1. Multiclone 2 . None

’. 2 . (Venturi Scrubber1 )* 2 . kSP]* 3 . !.Jc: Scrubber 3. Wet Scrubher 3. Wet Scrubber 4. Wet Scrubber 4. Wet Scrubber 4. Wet Scrubber

Case IV(d1 Case IV(e)

(8aghouse) * 2 . j. Wac s,.u.u7uei.

4. Wet Scrubber .) D-^L^..”^ 2. Y”~.L”....C

4. Baghouse

* These sources may be f i t t e d w i t h separate u n i t s o r combined i n t o a s ing le

source.

F igure 6 . 2 . Model P e l l e t Indura t ion - S t r a i g h t Grate Options.

6-7

7-

I c 4 1 I’ f 3‘ t I t 9’ I. I 11 I I I P I 1 I 1 -

APPENDIX C

Iron Ore Plant

Emission Data

1 1 I I 1 2' I 1 1 I 1 1 s I 1 I z T I 1 I \

-I: 1 I. I I I I 1 s 1 I I I I 1 I I 11 I’ 1 8 1

- a E h 0

v l w r. V U .A

r . m m 0

I d d

h a0 3 h I -E

rl W PI v

-4 PI 3 m U 0 U

$ 3 00000 a a o m r . m N 3

0 0 0 0 0 0 0 p1 r.P-r.P-r.r.

m h W W vl

1 1 1

222 ddrl

CQCQW

000 ? ? ?

m a l e C d o o m d d E 0 0 0 0 O d U U U o o m e ? d Z

e e e N N N m m m

“I-

m m 7.i 444

. . .

m w u l m m u l m O d d O O O \ D

O O O O O O m . . . . . .

x 4

I I I I I 112

\D 0 0

. .

I

m r.

N e d N

m

4 0 d U

g

2

~ -

I

m r.

m 00

0

m c 0 2

m N I I I d 0 I m e

r.LD00 m u.3.?/? o o o m 0: \D

N N

..

d e e c c w 0 0 0 : s : c n n n rl

U

&

m p l r . m m m r . m . . . . . .) . . mu-u-? - lm+.+ c -$Ik

h v)

0 U d d

c-2

. . . m e n

2 n 4 .. W N U m

$ 4

g 2 : X x P

a a, d + a a 1 m

.d

5 I4 0 w e H

h

W m

- __

I I 1 I I c f I 1 I c 1 I I 1 I 1 .p I I I 1

ii 1 I 1 I I 1 I 8 1 I I d I I IE I I I' t 1 1

8 - E d L i C m o c v) u. .d 0 F

W h e m O r

- 5

v C .r c " I. c C

.r

a

? Q

.c c

c a

: E v c F c P ..

rl

0

M m e 0 0

3 n

0 I.

0 0 0

N ..

ro 0

M m n 0 0

Ll z n

0 r.

O 0 0

.3 L

3

3

o o o m o o o m o 0 m I . l . r . m m . 3

0000000 0 0 0 0 0 0 0 0 0

rDm*I.ulnmrr Ip)

0 0 0 0- o,o,o 0,

3 0 im ..I..

3 N m 3 3

. .. c- 3

.. v) 3 m U 0 H

m

m r. m d

m d

3 m .f

r v e a

N '

E - x

L

i w \ o m o 1 r ) \ o \ o m o 3 1 r ) J ( 1 0 0 O c o 0 0

0 0 m a o o o o o 1 n 3

. . . . . . .I .

M M m m a e n e 0 3 3 m

0 0 U C e c o c v u .rl

v u u m m 0 0'4 0 m a r l c e 0 u u u L i L i 3 0 0 2 3 m 3 r a n ~ : z z c a o z c a

U L i o

4.l m o r m M h C

m m 3 x u a m m u o m U > m s m n c m e U C X 3 P 0 X O U o m m c m m u m

.A c 4 4 3 u x LiD ( u ( u Y 3 3 3 Q a m U U Q Q v c o i m m 0 0

m c 4 0 m Li m Li Li u Y Z X k U X n 4 &

m o m x 3 V s $ Z

1 11 1 E 1 1 f 1

v, I. I c t ' i a,

m

,. d

m rl

Li

u a m rn C 0

m fi

X x D P m .rl rl a a 2 ul

.rl

5 I4 0

W G Y

h

v m

c-4

1 1 1 I 1 1' 1 I 1 I 1 8 11 1 S I I I;' I 1 1

T

D ./ 11 c I c Y .r I.

c

I.

a

: t

I E

a c

W

L E C .r

n

? 0

h

N W a $ . m 2

.A .d .A

m 3 0 0 . .

W

Y $ 2 U M 3 m n m

0 0 0 0

m * m! m-

c-5

o m 3 3 . .

d m 0 0 m \D\Doo3 l n r . P - 3 m a N N e

. . . .

m w w g g g

3

m m N

3 0000000 0 PI 0000000 0

m o m m e l n m u ~ N

0~0~0"0~0~ m- 0 '" 3

N 3

..

VI r. 3 m

.. U rl

u W D

U 0

C 0

m C

m x D

'0 W .rl 7.4 a a 3 m C 0 d U

2

kl

z 0 w C H

h

W m

h

v m

v1 u .d U rn .d Y m U u m Y m c V

a U Y a a cc U E .i C a

rn m .rl

4

4

m k

.d c

C a m

a a =, rn

%

rn ,. 'a ' a

U ' v )

VI c 0 4 VI rn .d E

W

w 0

m 0 Y 3 0 v)

U Y a

A X .d u z . o

u p c m

0 . . U 3 N

m ? Z

r o m 3 3 . . 30

a m c c 0 0 4 3 u u .d d u u d 4

2 2

mr. . . m e

m M I4 m a Srn 0 3 V I 0 4 S a

m m

h a 3 $ 4 - O N v

.r( .d .rl Y Y Y

c 3 3 3 c o u u u o u c c c u 3 a J w m 3 n + + + n

roo er. e a

h m m VI Y 4.l

a, ri U m 0 U

u c

UNO\ m cm m rl

C L 0

v

m r . * m m r.3 r.0003

* N O 0 0 m

. . . . . . .

.. m c m a r VI 0 c c c 4 0 0 0 0 3 3 .d 4 C C C U U rn ~ m O O O O O rn ?I c 0 0 u U u 'd 1 0 3 3 3 0 0 6 ~ z n n n & d w

m m d ro? . . . .

m h

ri

U rl

$4 m 0 U u 0

m

I

e

m m z h

a a d ri a a 3 VI

2

e

d 4J

?? 0 'y e H

h

v m

-1 I I I I 1 I I 1 1 1 1 1 1 1 0 I P I a I I

~m . . N m rl

2 a l o 6 3 0 0 3 4 u u

.rl 3 u s 3 E 1

2; r a m

00 00 0 0

3 3

...%

m o

m m *

c- 7

N N

0 0 . .

rl m .rl U m z

:

0 0 0

m I

I

\' \' '"1 Ql

3 Fu

N 3

m r.

rl m

.. U rl

U al D 0 U U 0

g

5 m C

rc x

V al .rl rl a a 3 m C 0 d U m

0 Lu C H

e

E

h

v m

c n N mr. r.0

- 3 W U P m v

m m

u L U G c o 0 r

U G

0 U

w m m C L C

v

h w o w e O N v

m e r . o u e 3 N 0 0 4 e

x x * x 3 3 s '"."r m m .t

UOI m u 3 0 . . m m

0 0 . . m ~ e m ~ m e m 3 e e 0 0 0 m N . . . . . . I . .

0 0 m m o o o o c n u m Im m

h U e

4 3 8 m n &

.. ,"

3 4 m .a d .a m C $ 4 ! 4 $ 4 C 0 3 1 1 0 .rl u u u .rl u c c c u m w w w m z > > > z

3 m c 0 .d iJ

z" ul r. cn 4

U 4

$4 W D 0 4.8 U 0

m 0 c 2 h D

P W d d a a 3 0)

!2 d

2 $4

0 'u c H

h

v m

3 N m r. 4.l D O c

mr. COU . . -3

4

m M

C- 8

j TABLE C - k . IRON ORE I'LANT EMISSION DATA

(Picknnds Mather and Company - Er ie Mine)

%

Poin t ~ o u r c e ~ h a r n c t e r i s t i c s @) P a r t i c u l a t e Product ion Emission

1 Gas Flow, Temp, Emissions, Rate , Fac to r ,

Source of Emissions scfm F C o l l e c t o r Used I b f h r tans/hr lb / ton

2 x 97,200 2 . 36-in. gy ra to r s ( 4 u n i t s ) 4 x 15,000 3. Pan feeders (2 u n i t s ) 2 x 20,000 4. Drive house (2 u n i t s ) 2 x 10,000

1. Ore s to rage (2 u n i t s ) 2 x 8,000

4. Feeders and b e l t s (2 u n i t s ) 2 x 20,000

i n e Crushing

2. Ore s to rage (2 u n i t s ) 2 x 9,600 3. Feeders , sc reens , and b e l t s (7 u n i t s ) 7 x 33,000

a 1

Oncent ra tor e- Fine are s to rage (6 u n i t s ) 2. Rod m i l l feeders (9 units) 3. Transfer po in t s (2 u n i t s ) I Tota l Benef ic ia t ion :

S i l o s and f eede r s (11 u n i t s )

3. Coal s torage 4. Screw conveyor

e l l e t P lan t (27 shaft furnaces1

1. TOD R ~ S (24 u n i t s ) 2

. _ 2. Top gas (2 u n i t s ) 3. Tap gas (1 u n i t ) 4. Bottom gas (25 u n i t s )

1 Bottom gas (1 u n i t ) P e l l e t handl ing (2 u n i t s ) E leva to r s (2 u n i t s ) Chips c i r c u i t (3 u n i t s ) Loading pocket (4 u n i t s )

To ta l P e l l e t i z a t i o n

6 x 12,000 9 x 16,800

860,800

2 x 8 , 5 0 0

11 x 1,500 9 x 2,000

15,200 300

24 x 38,640 2 x 39,400

57,960 2 5 x 12,000

39,400 2 x 26,000 2 x 4,500

33,200 63.000

1,560,000 I

_ - 77 71 --

_ - _ _ 75

--

Wheelabrator bag AAF Rotoclone AAF Rotoclane AAF Rotoclone

AAF Rotoclone Wheelabrator bag AAF Rotoclone AAF Rotoclone

_ _ AAF Rotoclone -_ AAF Rotoclone _- AAF Rotoclone

_ _ Wheelabrator bag _- Wheelabrator bag -- Wheelabrator bag _- Wheelabrator bag

315 Am. Std. Mult ic lone -- Am. S td . Mul t ic lone _ _ Am. S t d . Mul t ic lone 375 AAF Rotoclone 190 Am. Std. Mult ic lone _ _ AAF Rotoclone _ - AAF Rotoclone _ _ AAF Rotoclone 270 AAF Rotoclane

' T o t a l P l a n t Emissions:

(a)

c ) d )

Emissions es t imated a t 0.03 g l s c f .

Emissions est imated a t 0.05 g l s c f . Emissions est imated a t 0.01 g/Scf . Emissions based on MPCA tests a t Erie.

Information suppl ied by Pickands Mathcr and Company on September 26, 1975.

c- 9

2 x 25(a) 4 x 4.5 2 x 35.6(b)

(b)

2 x 4,3(c)

2 x 3.4(c) 2 x 2.5") 7 x 3.3 2 x 8.6"'

(b)

6 x 5.1"' 9 x 7 .2(=) 2 x*@) - -

11 x O.l(d)

302.5 3544 0.085 (Ore) 112. L

(b) 1.3 (d )

9 x 0.2

-- .

(b ) 2 x 67.8(e)

67.8(e) 25 x 0 .6 (b )

24 x 28.1

45.7(b) 2 x 11.1@) 2 x 1.9")

14.2") 4 x 1 7 . 8 ( b ) J J , J - - - -

1054.1 . 1176 0.9

1356.6 1176 1.15 .. ( P e l l e t s )

1 I I a 1 15 1 t I 1. Y I

.- m * 1,

hh

a n - w n m \De 0 0-

o o m I x x o

. .r.

- 0 x x x x N N h N

x x x x N e N N

m a l m m c c c c 0 0 0 0 4 4 4 3 u u o 0 .d .A .d .d u u u m u m a m a 4 3 d c 3 c c c c 1 1 9 0 1 0 0 0 0

. . . O . o o o o m a l : u l : u u u u u u u o u 0 0 0 0 r n c n r n d c n d d d d

2zz;2;:$$

rl P-

3 m

" .n N

LI m P

U a m 0

C 0

2. C

z

!i 0

U

a C m

M m D

M m P

M M M M m m m m D O S P

a m m 3 LI 0 u U QJ 3 d 0 U

.. ? % I

: m )-.

:"E

12 > a

m C 0 .d

m .d E

W W 0 QJ 0 LI 1 0 cn

.. m C 0 .d m m rl 6

W

m m m c c c 0 0 0

u o o 0 0 0 u u u

3 3 3

2 2 2

L I Q U L I 0 0 0 0 u u u u m m m m L I u u L I 0 0 0 0 D D D D m a m m 3 3 3 3 m m m m m m m m c c c c 3 3 3 3

$ 4 m m m o c c c u o o o m 3 3 3 Q U O U 0 0 0 0

m o o 0 m

D U U U

3 d d d

3 3 3 3 d

m r l o m m I I " I

r. I # m i I I N ,

m - d i t ?

d - r n i t I n . .

x x x x N i t "

u3 W I n .it . .In . m d d m x x x x N N P - N

. . N 3 0 0 . .

PI0 x x LI I

m c

hh m m h u u m .d .d u c c .d 9 1 c

1 o m V V N ..

P- V h

m m u

h m U .d C 3 3 3 h v m

c-10

I 1 TABLE C-&. IRON ORE PLANT EMISSION DATA

(Reserve Minine Company)

Gas Flow, Temp, h1ission5, Rate, Fac tor . Source of Emissions scfm F C o l l e c t o r Used l b l h r t m s l h r l b / t o n

d-+- --&f*Xc&+==&p, . .- 9,:: 0 6 d

N ,'. b o

ininK and Ore Transport Coarse Crushing

1. Primary 2. Secondary 3. Feeders , conveyors, and b i n s

"Operations a t Babbi t t Mine, no information on p a r t i c u l a t e emissions"

ine Crushing

1. Dump pocket 47,000 60 NI NI 2. Pan f e e d e r 14,700 60 NI NI

4. Storage b i n (2 u n i t s ) 2 x 73,400 60 NI NI 5. Crusher feed (2 u n i t s ) 2 x 75,000 70 NI NI 6. Conveyor t r a n s f e r 62,800 70 NI NI 1 7. Conveyor d ischarge (2 u n i t s ) 2 x 36,000 70 NI NI

a 1

i: I 1 I, 1 1 1

3. Conveyor t r a n s f e r 24,200 60 NI NI

Concentrator

Transfer b i n (2 u n i t s ) 2 x 18,800 60 FAA D r y cyclone NI Red M i l l f eeders (22 u n i t s ) 22 x 30,000 60 FAA D r y cyclone 2 2 x 1.2")

NI 3. Lab p u l v e r i z e r 3.500 60 None - - - Tota l Benef ic ia t ion : 1,220,000 NI 3436 _ _

(Ore) Bentoni te F a c i l i t i e s

1. Storage (2 u n i t s ) 2 x 1,300 70 Sly bag NI . . 2. Mixers (3 u n i t s ) 3 x 4,800 70 Dracco bag NI 3. Mixers (4 u n i t s ) 4 x 1,800 70 Sly bag NI 4. Mixers (3 u n i t s ) 3 x 1,300 70 Sly bag NI 5. Unloading (1 u n i t ) 4,900 70 AAF Bag NI

1. Windbox exhaust (6 u n i t s ) 6 x 110,800 3 7 5 , None 6 x 183(n'b) 2. Hood exhaust (6 u n i t s ) 6 x 88,500 215 None 6 x 50.6(a'b) 3. Windbox exhaust (2 u n i t s ) 2 x 115,000 460 None 2 x 376.6('") 4. Hood exhaust (2 u n i t s ) 2 x 226,000 220 None 2 x 635.4(a'c)

6. Grate discharge (6 u n i t s ) 6 x 32,000 150 AAF Rotoclone 6 x 22.6") 7. Grate discharge (4 u n i t s ) 4 x 32,000 150 AAF Rotoclone 4 x 16.3") 8. P e l l e t t es t l a b 5,500 60 Wheelahrator bag N I 9. Conveyor hoods (27 u n i t s ) 27 x 10.000 70 None NI

1 0 x 10.000 70 None NI

. e l l e t P l a n t (Einht StraiKht-Grate Lines1

5. Grate feed (3 u n i t s ) 3 x 25,000 170 AAF R o t a l o n e 3 x 5.1(=4

- - 10. S i l o exhaust (10 u n i t s ) Total P e l l e t i z a t i o n 2,580,000 -7 1221 3.0

7 L TC . 7 (Pe l1 e t s )

J@@ ,64/ 6 1 J-d a) b) Based on Machine No. 6 which has r o l l e r f e e d e r and second s t a g e c o o l i n g recycled.

Emiesion d a t a suppl ied by Reserve Mining Company.

icj Baaed on Machine NO. 12.

I I 1 1 I

1 i

- - m c 0 .d 10 m

.A E W

W U m d 1 u d U $4 a a c 0

e 0 .d U m

0 w C .d

0 C

W C

E

”

2 U

.d D e m m U .n m C 0 4 U m , W

8 -

Y) C .d e

Y H Y ~ z z z m x x x x x x x

m u 0 h W

e H H H Y H H H z z z z z z z

H H H Y Y H H z z z z z z z

m m m m e e e m m m m m m m N N N N N N N

F. rn

.d C 3

h A h e - u u

m

h - m V I 1 d I

Y Y Y Y Y z z z z z

M m

h

m u

c-12

.Tee** m m m m m N N N N N

.d c o . . . . . u - 4 N m . T Y ) C m m

M a D

w a l w b l c c c o o o o u 3 - 3 m u u u u

m w w w u u u e m 0 0 0 0

z z z z 0 0 0 O d r n d d 0 0 w c c c c o o o m c c

h m U d C 1

m v

-3 W W w

01 LI m u W

. . . . . . . . . . 3

W PI

I 1 It I I I 1 1 J 1 I I 1 1 I I: ii

t r' I

0:". m m G

0 d M

. . 0 0

C- 13

e rl

0

N

M

3

m e

Q m 2 Y 0 U 0 m 3 4 0 U

- L

1 is

- m :-. 1 % I Q I U Im

m c 0 .r( m m .r( E w w 0

m 0 CI 2 0 m

- - c : ..I M

c 0

.r( U m E !+ 0 w c .r(

0 z - -

m m m m m 0 0 !+ & c 0 4 U m .r(

U .r( W W c 0) m

A M

. . P , & M m m w w c

0 .r( U

3 N . . m o

,$=

C- 14

m r.

3 m

., 0 m !+ W D 0 LI

c s

c 0

h C m a

U

c 0 !+ H

m W W .A 3

5

Y

$

Q C m A

m v r?

h e P m .a 3 a 1 m m U m Q

c 0

.A m m .r( E

W

a

h

v m

I I 1 I 1 0 I f I 1 I' I a

b' I € I I I I 1

m'

I 1 il: I t I I I 3 1 I I I 1 8 I I I I 1 I

.rl U

0 00 W c 00

.rl

0 -0 ror.

8 O,

-

C-15

m m

0 3 3

3 m

m I:

a m mr. mr. r.*

. .

C- 16

Y) l. cn 3

* 0 N

!4 m e E W

z c 0

h c m

0 U

c 0 Y Y

m w w .rl 4 U

1 V c m 3 m 3

0

h

IJ m .rl -I

a 1 m m U m a c 0 ..l m m rl E

W

'u .-.

e

a

h

v m

I I 1 I I c 1 1 I 11 I 1

1 I I I I 11 I I 1

1 .,

I 1 It 1 I I 1 I 1 1 I I I t I I I I I 1 I C-17

0

&

.rl U m .rl 0 .rl

c

m r. m rl

m p1

Y W D

U a W m

*

2

g 2

7z

h

F U

Y H

m u.4 'u .rl rl V I

,e C m 4 a,

rl U

h P P W .rl rl a a

2

2 m LI m P

a 0 .d m m rl

W B

h

v m

.d 0

rl o m 3 .d w m o c o m m

o m u h c a l u e u w w r l m s u % m u .rl 3 0 c u

w o w w u r l . . c d r l N w w w

: : 2 u

m a %

I 1 1 1 t P 1 1 1. 1, I I

4 1 I t 1 t I I

a m1

I I '1 1 I I I 8 1 1 I 1 1 11 I I I I I 1 I 4-

- -5 2

c

4 c) "XI 0 3 3 3 0

4

N N

0

La 0 La

"! 3 m 3

G 0 ! a & & w m m m c w w w Y

O N 0

"N m r - 4

0 0 0

?I m La

.I

.. G 0 .rl U m N .d U al 3 3 0)

P4

3 rd U 0 H

rD r.

rl m

.. m N

C 0

x e

5 Ir 0 w C H

c-19

co m

c-20

r l N r n

I I 1 t t 1 I 8 1 1 I I a

1 1 I I I I I 1

.'

c-21

IA r.

3

0 (?

M m e

U al

m

I

5 n

VI w w .rl d U I

V

rl al 2 01 rl U

2.

V m .A rl a a 7 10

C 0 .rl U

8

e

2 0 w C H

m v

h U rl

U v1 rl

a r m N

41

0 0 z z ,

c-22

v1 P-

.1

0 m

G 0

v) u. u.

h P P m rl rl a a a e

h

v m

\ I

I 1 I 1 P 1 1 I 9 1 I m I! I I 1 1 I I I

(16

~-

I I b 1 I I I I b l1 I I I e I I I I' I 1 I

TABLE C-12a. IRON ORE PLANT EMISSION DATA

(Eveleth Taconi te Company)

Po in t Source C h a r a c t e r i s t i c s (a) P a r t i c u l a t e Product ion Emission Gas Flow, Temp, Emissions Rate, Fac to r ,

Source of Emissions scfm F C o l l e c t o r Used l b / h r ( a j tons/hrCa) Ib / ton

/--

BAA Cyc??ne .

y 7 f MininC and Ore Transport 1. Truck Dump 61,000 -- 2 . Loading P x k e t 52 3'4!060 -- 3 . Ore Unloadina Zr./ --

Tota l Mining and Ore Transport : 119,000

Coarse Crushing

1. Crusher Discharge 17,000 -- Fine Crushing

1. Secondary (2 u n i t s ) 2 x 24,000 - - 2 . Tertiary (3 units) 3 x 20,000 --

1. Conveyor 12,000 -- Concentrator

2 . si10 4,000 -- 3. Rod M i l l Feeders (2 u n i t s ) 2 x 12.000 --

Total Bene f i c i a t ion : 165-000 33haao

Bentoni te F a c i l i t i e s

1. si10 9.000 -- 2. Transfer S t a t i o n s 4,000 --

P e l l e t P l an t ( h e Grate-Kiln Line)

1. Waste Process Gas 260,000 -- 2. Cooler Exhaust 119,000 -- 3. Grate Feed 19.000 -- 4. Grate Discharge 19.000 -- 5. Cooler Discharge 20,000 -- 6. P e l l e t Loadout 8 , 0 0 0 --

Total P e l l e t i z a t i o n : 458,000

Tota l P l a n t Emissions:

FAA Cyclone

AAF Scrubber AAF Scrubber

AAF Scrubber FAA Cyclone AAF Scrubber

Ducon Scrubber Buel l Baghouse

Ducon Ventur i "None" Ducon Scrubber Ducon Scrubber DuCOn Scrubber AAF Scrubber

6.3 1.6

0.3 0.03

53.5 9.2 0.2 0.5 0.5 0.1

64.3 3 03 0.21

274.5 288 0.95

(concent ra te )

( p e l l e t s )

(e) Information suppl ied by Evele th Taconi te Company on September 2 , 1975.

C-23

f .

rr) b Ln 3

.. N

$4 m n E m &I a m VI

C 0

2 e m a 0 U

01 U .r( C 0 0 m w c 4.l m e 5 w h D

V m .r( 3 a 4 m

C 0 4 U m E $4 0 W C Y

h

v m

I I 1 1 1 0 1 1 i 'I I 1

1 I I I I I I I

,r m

U m W

m y l r . m . . 4 3

J J O 0 0

0 0 . . u r D m \ D \ D 3 0

h 3 0 0 0 0 3

~ 3 o o o o m . . . . . .I . 2

od m yllm 3

0 N

N

m VI

2

V m m 3 L, 0 U 0 m 3 3 0 U

" L

1

,. r m >. rm

> a 1 u 1 m

. E

LI C 0 .rl m m 4 E w 'u 0

m 0 $4

0 m a

Y W m m D 1 D O 1s $ 4 M o m m e

U U L , .r( m w m $4 D D D h 1 D D D m U 3 2 1 D C w L , $ 4 $ 4 D 0 0 0 1

3 m m m L I 0

c c c c m o m 0 0 0 u c u o o 1 0 1 1 1 n z n n n

L,$4 m m D D

1 1 L,$4 0 0 m m

D P

$ 4 $ 4 m a l m D C D D O D 3 3 1 U V L , u h U m u m

m a l c c 0 0 3 3 o o h h v v

3 h k Z h

c 3 0 3 o m 11 n m

4J C m 3 & 3 m U 0 w

m 3

. m D > N W

U

3 -

m i-? 3 m x x N m

0

m m m . . e 3

Nl LI !! 0 a m C m

h .̂ _. U .4 C 3

h m n u m .a U c 4 3 c

a N -c h . . l4h $4 3 0

0 3 c m u

C w C 0 V

. . m . . .

C-24

I I I I I I I I i I I I I 11 I I I I I 1 I

g I F .rl h c W O L a u. d o s 6 d - w r 4

F2

W

0

m a.

; 6

I I

0 0 N

3 I

v)

W .rl U 4 3 d

r4

W U .rl

:

U

a. !3

3

m

r (I L

o a 2:

P L

m m I

C-25

U I w w U M W U e m m 3 .2

% a

~n

3

I O w o M 7

m 3 0

3 u

- A h

4 w v m n o

V W 4 3 a a 2 m U m

U

.rl 0 .rl w 4-(

n

5

2 a .rl

U 0

0 0 .rl U

8 0 w E: .rl

0 E: VI d

z .. W U 0 z

a W rn 9 $4 0 U u W 3 2

-.

? % : " 3 r n 1. 3m 4 E

0 - 0 J U 1 0 7

rn C 0

.rl rn rn .rl E W

w 0

W u $4 1 0 cn

u

3 W &

~

H z

W rn 1 0 r: M m m

I

a 0

.! U .rl 3 .rl U m F*

W U 3 C 0 U C W m

w . 3 4 N m . 3 m a

co N

.3

h - n

m m 0

x IA

A

W C 0 3 u .rl U 3

3 a,

i cn

<

3 m .3

3

2 X m

~~

0 r. m

h W v I

W N In

m m

~

N a .3

X v)

W C 0 4 U .rl U 3

3 U 0 U

v1

2

r. m m

m 0

X m

3

h 3

-

H z

W C 0 d 0 0 u 2 3

2 M C 3 3

h m U m

I" a v

a, rn

3 m N m

-1: .. r I

U O rn .rl 1 U a m

S N x .rl . m u l . r n h C h w U

M Z M U S U M a 3 rn r n - .A .rl C U 3 m r n E U E C U C . r l O W

U M . d M U o + 0 1 w 1 a H & C .rl u c U 3 3

m a r a c u r uv) 3 m .rl i m

g - m o a m 3 w

E $ - $ 1 2- 2- w - 3

C-26

m w ! + c w

- 7 2 w u M 3

m 3 0

3 u

u n

3

3 x o n u

.s U ul 3 4 - 0 u m ' u 3 3 1

W E .3 0 3 N 3 3

U Q $4 .rl u w u u e - l u E 1 0 W E U u a * S w a U m u u

v l m C W 0 - m

E W E 4 : d W S C C w o o 3 .d 4

W C C

" C

S U Y m .A .rl

n o 0

- L" ." h% -2

v u a w m m

.A 3 r n r n a .rl .rl a 3 u u

C U U o w w 0

" 4 3 4 . e u 3 r l a o o w r n m E 0 u c 4 $4 0 0 r n 3 u w .rl .rl U z c c c x H H H U

" S S .i

I I

I 1 I I 1 P 1 1 .I a

W .d 4 a a 1 rn

m m -0

U C

I I

W 4 0 .rl W I 0

C 0 4 U m E u 0 'u c

: I

.. 1 1 I I

m hhh U m D U 0 v v v z

I . I I. I1 I I I I i I I I I I I I I I I t I

- I .~

00 0 0 00 0 0

0- \D *. '", l n ~ ~ l n a m N Z N x x

H z

m 1 0

m

v1

% m

I I

H z

v1 m .rl U .rl rl .rl o m b m U .d

3 5 U

a

0 0 0

2 . . ,

m

rl

r.

lnv) I

0 0 1 I I o m 1 I I * v )

mv) I

C-27

B B m a 55

wl \D

I wlm

C-28

I .

I I I I t

I I I I It P I I I P I 1 I I I 1 I

h H z

0 0 0

U 0 rl

..

ln 0

N

0 ‘ o r m:

O Y H O O O lnzzoo ln m N d d

0 0

H lnz d N

c-29

“ u r l m m m‘E) u m r n d d

w a m a m 1 d m m

x m D P

*2

Y .. m

mu m o -2

m rl m

Nr.\D m m m . . . H Y N N \ D Y H H z z - 3 U z z z H z

c Lc L: a

N 7 O r r l a

C L

U

N o,

m

W Y k Y w w m 4 U 1 3 3 .rl U Y Y U u u u rl m m m 1 c c c

w w o o o c c u u u

Y W

W P e 0

3 Y U o r m U)M

0 U 1

~ D D n e e

g

c ",-, 2 2 2

z

% a 2 0 0 3 1 3 ~ r z z n n n m r l m m n

C-30

...

I I 1 1 1 P 1 1 1 1 I I m

1 I I I I I I I I

m

~

- - ~-~

I I I If I I I I I, D I I I I1 I I I I I 1 I

?2". m m r . O N - N 4 H H r D

x x z z

m 4 d

H U H z z z H z

m m N

rn u m a * rlr. 4 4 Q J N a v

a . u r n o r . v m

90: 4 0

;1 H H

z z x x N N I N N

a a a a o )

d d r ( 3 4 0 0 0 0 0 0 0 0 0 0 u u u u u 0 0 0 0 0 & & & & a

g g g g s

h 4 rn

H H z z

00000 00000 00000~ -1.1..

\ ~ m m n \ ~ N

0 0 L o

N ..

o o o o c o o o o c

n o m o o m m m m

0 0 0 0-c ...I..)

4 N N d

x x x x N N N N

x x x N N N

h fn a

0 N

rn

.. s d

2. U

4 m U 0 U

0 rl .A rn

4 . . . . .

r l N m d m . . 4 N

. . . 4 N m

C-31

. .LD n o .

U

x x !+z N N

0

LD rl

U

m N 0 0 0 0 . .

HUH1 z z z H z h M G d

3" * x U .d U U d U G m rl U 4 I

G 0 d U rd Y 0 a h 0 U

rl m m U VI

VI

3 v

H H z z H z

m m m m G G G C 0 0 0 0 rlrlrlrl u u u u 0 0 0 0 U U U U 0 0 0 0 d d d d

m 0 1

3 3 rd

19

u u 0 0 U U 0 0 d d m a l m

G G C b b 0 0 0 Z Z Z 3 3

h rl VI

H H z z

I VIVI u r n . .

m

N

4

x x x N N N

.. ," . . m U d C 1 N v

- m U

m .. d U rd

0 .rl w m $ m rl rd LI 0 H

C-32

_-

I I I I I I I I 1 I I I I I I I I I I I 1

e e e. e. m m. N m dd00c;N m m m m u z

. r n r . . m ;'e

3

u w rl m

o d m 3

e

m e . . N O 3

x m

hh m m u u .d .d

5 5 N m v v

2N.N. 000

x x x e h 3 3 3

u u h m m m a n a a n a 2 2 2 0 0 0 m r n r n

h m U

8 8 8 u u u rnrnrn

. . . 3 N m

m 0 0 0

x m

.. 8 4 U m 4 0 d w m

m d rd U 0 U

5

3 3

00 . .

x x * e

00 00 O. e-

. . 3 N

N

.,- I.....,..

m m z x x x x x x x x N

m N m N m N - N I " . .

hh m n m m u m u u 4

. . . . . . . . . d ~ m e m a r - m r n

.. ii 3 PI

U m 3 3

2

8 d

U m

. . .. m

a 0 h U

-2

c 0 - d U O Y O M m u * : .rl u \ w f 4

C 0 .rl U u a l m 1 u 1 O d * Y a

am^

h

d? u - m m r l c Y O O d u ) d m \ U m M

F 4 w 2 2

h

v m U L e U

c

c n c 9 L c

c

C U

e E C !l

r

r

I :

a

i

r

rl a rl

rl ..

N

.. .. rlrl

h (0

h m

2 3 mrl

a! n u

vl 0

0 rl a x

m m m 0 0 0

0 0 0 . . . rlrl

0 0

0 0

x x u u

. . r. m 0

x a

0 0 U 1 n

rl

r.

x a

H H

a m U m

Ln 0

0

x N

h rl m

a a x N

H H

a m U m

r. m . a 0 0

x a 0

N Q

rl 0

0 r.

x ' 4 m N

x x x -3-4 r l r l m

GI x 0

c u o 1 4 0 U H I .rlz c o r l U h U u 1 3 4 5

a m

a u 0 E! n x n m n

Y m D D 1

a I Y m u Y r n 0 srl M U m m a z

Y m D D 3 Y U rn

4 4 4 u u u m m m z z z

z r l o m g a l H U

rn 0 0 . . N O \ 4-4 mr. . . . r l N bar. x x z x x x

H

. . r. . m u .

m x

D r n r. ? $ u -

t?? u m . . 4 4 arl

01 r. 011 s

h h h m m m U U U .rl .rl .rl c c c 3 3 1 U

h

m Y m -u m m w

. . U m .rl U

.A w

m

rl m U 0 E+

2 a

c-34

I I I I I I I I I I I I I I 1 I I I I 1 1

2

cl a)

E L

E! Y n

0 0 0

e e x

"

N

2

a)

0

m a

; 5

c-35

.I

I

U 0 u v u a l c I L 0 -43 rl 0 V

H z

rl al a x

E 4

C 0

,. $ n

m 0 N .. n

N

h in U .rl C a N v

-4

m m \D m

O m H H H Pl -4 z z z rl ? ?

C-36

0

2 -4

I I 1 I I 0 I I I I I' I

1 I I I I I I I

I

I 1

P-

x Ln

I ,I I I

+ a 3

0 e

000000

o,O,?. 0-0. O, O ~ O O ~ P -

..

0

O. h P- O ..

h 0 0

0

U

0 0 0 0

x 1; ro

.. , g

2 2 0 0

r. -3

0

h m U

.j

P- 0 m

I ? x x x x x “ N N N

c-37

Ln m 0

“NN I

00000 0 0 0 0 0 0 0 0 0 0 0-0- 0 -..... m . j m . j V I I, VI & m o d N m x x x x “ N N I

m P-

rl

m N

$4 m

U CI 0 C 0

0 U

u m

m

.,

eo

5 2

h D

“2

2 8

d 3 a a

4

i 0

VI fi H

h

v m

C-38

m

I

December - US EPAE. J ,' 'i AP-42 Section Number: 1 1.23 Reference Number: 3 Title: Standard Support...

Documents

Transcript of December - US EPAE. J ,' 'i AP-42 Section Number: 1 1.23 Reference Number: 3 Title: Standard Support...