Teknik MetalurgiTeknik Metalurgi 05. Carbo - Metalothermic

Zulfiadi Zulhan/Taufiq Hidayat/Imam Santoso 2021 MG-3111 Pyrometallurgy

05. Carbo - Metalothermic

Zulfiadi Zulhan

Taufiq Hidayat

Imam Santoso

Department of Metallurgical Engineering

Faculty of Mining and Petroleum Engineering

Institut Teknologi Bandung

INDONESIA

Pyrometallurgy (MG-3111)

5th Semester – 2021/2022

Teknik MetalurgiTeknik MetalurgiTeknik Metalurgi


NO TALKING

NO SLEEPING

NO MOBILE PHONE

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Course Content

1. Introduction

2. Refractory

3. Slag

4. Material Preparation: Aglomeration, Drying, Calcination, Roasting

5. Carbo- / Aluminothermic (Metalothermic)

6. Smelting, Refining

7. Pyrometallurgy of Copper Production I

8. Pyrometallurgy of Copper Production II

9. Mid Exam

10. Pyrometallurgy of Tin Production

11. Pyrometallurgy of Nickel Production(Nickel Matte, FeNi)

12. Pyrometallurgy of Zinc and Lead Productions

13. Production of Ferro Alloy I (FeMn)

14. Production of Ferro Alloy II (FeCr, FeSi)

15. Group Presentation (FeNb, FeMo, FeTi, FeV, FeTa, FeW, CaSi, CaC2 etc.)

16. Final Exam


Reduction of Metal Oxides

A large number of metals are produced from oxide raw materials, for

example iron, manganese, chromium, tin, nickel. In case of lead and zinc,

sulfide ores are first roasted to give oxides which are subsequently reduced

to metal. Sulfide ores can be converted directly to matte or to metal using

“flash smelting technology”

Other oxides are decomposed by means of a reducing agent (carbon,

carbon monoxide, hydrogen, and metals which has higher affinity for

oxygen (metallothermic). C, CO and H2 are industrial importance and

economic reducing agent

Only oxide of more noble metals can be converted to metal by simple

thermal decomposition:

Silver oxide decomposes at T>200oC → 2Ag2O = 4 Ag + O2

PtO decompose at T>500oC → 2PtO = 2 Pt + O2

PdO decompose at T>900oC → 2PdO = 2 Pd + O2


Metal Oxide Reduction by C and CO

Reaction of metal oxides with carbon monoxide:

MeO + CO = Me + CO2 (indirect reaction)

If solid carbon is present in the reaction mixture:

MeO + CO = Me + CO2

CO2 + C = 2 CO (Boudouard reaction)

+

MeO + C = Me + CO (direct reaction)


Lo

g p

CO

2/ p

CO

Indirect Reaction:

MeO + CO = Me + CO2

For reduction of metal oxide with

CO (absence of solid carbon), the

curve for Boudouard reaction can

be disregarded.

Cu2O, PbO and NiO can be

reduced at CO2/CO ratio between

102 and 105 (very small

concentration of CO in the gas).

If pure CO is used, practically all

CO will be converted into CO2

before the reaction stops.

For reduction of MnO and SiO2,

requires pure CO gas (free of

CO2). Reaction will stop as soon

as CO2 is formed. In other word,

these reduction is impossible in

practice.


Lo

g p

CO

2/ p

CO

In the presence of solid carbon

(Direct Reduction), carbon reacts

with CO2. Boudouard line is

considered.

SnO2 is reduced by C at T > 610oC

Fe3O4 can be reduced to FeO at

T > 650oC

FeO to Fe at T > 700oC

MnO is reduced by C: T> 1400oC

SiO2 is reduced by C: T> 1600oC

At higher temperature Al2O3 and

MgO can be reduced by carbon.

Reduction of metal oxides by solid

carbon is called Carbothermic


Ellingham Diagram


Thermodynamic of Iron Oxide Reduction (CO-CO2)

0

10

20

30

40

50

60

70

80

90

100

0 200 400 600 800 1000 1200 1400

Temperature [°C]

CO

/ (

CO

+ C

O2)

[%]

Fe3O4

FeO

Fe

Ptot = 0.2 atm

Ptot = 1.0 atm

Ptot = 5.0 atm


Blast Furnace


SiO2 can be reduced by carbon

at temperature more than

~1750oC.

SiO2 + 2C = Si + 2CO


Al2O3 can be reduced by

carbon at temperature more

than 2000oC.

This temperature can be

achieved in electric arc furnace.


Aluminum Carbothermic Technology (ACT)

(in development phase)

Advantage of ACT:

- Energy consumption of 10 kWh/kg Al (versus over 13 kWh/kg Al for Hall-

Heroult)

- capital costs as low as $1250 per MTY (versus 4,000 per MTY for Hall-

Heroult)

- operating cost reductions of over 10 %,and

- up to 37 % reduction in CO2 emissions for fossil-fuel power plants.

Crbothermic Advanced Reactor Process is a multi-stage system in which a

molten slag bath containing alumina and carbon is reacted to produce

aluminum carbide in a low temperature stage. The resulting alumina –

aluminum carbide slag then flows into a high temperature stage where the

aluminum carbide is reacted with the alumina to produce aluminum metal.

The aluminum is less dense than the slag and accumulates as a layer

floating on the slag.


Aluminium Carbothermic Technology

The overall reaction for carbothermic aluminum production can be written

Al2O3 + 3 C = 2 Al + 3 CO

25 25 2000 600 °C

Al2O3 3 C

Al2O3 + 3 C = 2 Al + 3 CO, H298 = ... T ref.= 298 K

2 Al

2273 K

3 CO

873 K

Energy consumption ~ 7.9 kWh/kg Al

Energy efficiency around 80%


Aluminium Carbothermic Technology

If Al2O3 and C is heated at atmospheric pressure, a complex product is

formed.

Al2O3 and Al4C3 can occur as separate phases, or they can combine to

make a liquid Al2O3-Al4C3 slag.

Al4C3 is stable only up to 2150°C; above it decomposes to Al and C. The

Al phase always contains some C.

Stage 1: 2 Al2O3 + 9C = Al4C3 + 6 CO

Stage 2: Al4C3 + Al2O3 = 6 Al + 3 CO


Flow chart of ACT concept

Stage 1: 2 Al2O3 + 9C = Al4C3 + 6 CO

Stage 2: Al4C3 + Al2O3 = 6 Al + 3 CO


Metal Oxide Reduction

with Hydrogen

Pure hydrogen is less industrial

importance reduction than

carbon and carbon monoxide

(may be used under special

condition).

Very often the reduction is

carried out with mixtures of CO

and H2.

Natural gas is used as source of

this reduction gas.

Product of reduction with hydrogen

is metals.

By reduction with carbon, carbide

might be formed


Thermodynamic of Iron Oxide Reduction (H2-H2O)

0

10

20

30

40

50

60

70

80

90

100

0 200 400 600 800 1000 1200 1400

Temperature [°C]

H2 / (

H2 +

H2O

) [%

]

Fe3O4

FeO

Fe


Thermodynamic of Iron Oxide Reduction

(CO-CO2-H2-H2O)

0

10

20

30

40

50

60

70

80

90

100

0 200 400 600 800 1000 1200 1400

Temperature [°C]

CO

/ (

CO

+ C

O2)

[%]

or

H2 / (

H2 +

H2O

) [%

]

Ptot = 0.2 atm

Ptot = 1.0 atm

Ptot = 5.0 atm

Fe3O4

FeO

Fe


Metallothermic

Metal which has higher oxygen affinity is used as reducing agents.

Silicon, aluminium and also magnesium can be used as reduction agents

in order to produce metals of low carbon content.

Metallothermic reactions are usually carried out between solid or molten

reactants to give molten products.

Example:

2 Cr2O3 + 3Si = 4 Cr + 3SiO2 (silicothermic)

Cr2O3 +2 Al = 2Cr + Al2O3 (aluminothermic)


Silicothermic Ferrochromium Production


Aluminothermic

FeTi, FeV, FeNb and Cr(99%)

can be produced by

aluminothermic.

Reaction can be done

autogeneously, i.e. by igniting

a mixture of cold oxide with

aluminium powder.

Compare to carbothermic:

- Slag volume of metallothermic

is large, high loss of valuable

metal in slag.

- Not possible to produce metal

completely free of silicon and

aluminum


Aluminothermic


Terima kasih!Program Studi Teknik Metalurgi

Fakultas Teknik Pertambangan dan Perminyakan

Institut Teknologi Bandung

Jl. Ganesa No. 10

Bandung 40132

INDONESIA

www.metallurgy.itb.ac.id

Dr.-Ing. Zulfiadi Zulhan, ST., MT.

[email protected]

Taufiq Hidayat, ST., M.Phil., Ph.D.

[email protected]

D.Sc. (Tech.) Imam Santoso, ST., M.Phil

[email protected]

Teknik MetalurgiTeknik Metalurgi 05. Carbo - Metalothermic

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