No. 7 Riddhika Jain Iron Ore Tailings Reprocessing to ... · Iron Ore Tailings Reprocessing to...

Iron Ore Tailings Reprocessing to Maximize Ore Production

Iron Ore Conference 2015Riddhika Jain

© Outotec – All rights reserved

Overview

Why the need for tailing

processing?

Decreasing Fe grade of Iron ore reserves

Need for sophistication of processing plants due to

inter-grown ore bodies

Increase in demand of iron

ore incoherence

with increase in steel demand

Valuable mineral in

tailings dumps due to lack of

suitable processing

The Fe content of the tailings

varies and reaches more than 55% Fe in

some Asian regions

7/20/20152 Iron Ore 2015 | Riddhika Jain


Testing’s Focus

Optimizing Existing Operations• Minimize tailing production• Proper tailing disposal and water recovery management.Tailing Reprocessing • Flowsheet designing for re-processing tailings resulting from former

operations.• Beneficiation using modular units consisting of SLon in series with

desliming, WLIMS or gravity separation

7/20/2015 Iron Ore 2015 | Riddhika Jain3


Working Principle of Outotec SLon High Gradient Magnetic SeparatorVertical carousel• Mag flushing in opposite direction of feed • Reduced matrix pluggingPulsation Bath• Reduce particle momentum• Minimize entrapmentRod Matrix• Ensure all particles see high gradient zones • High magnetic force while minimizing entrapment of particles



Working Principle of Outotec SLon High Gradient Magnetic Separator



PROCESS DEVELOPMENT TESTING ON TAILING SAMPLES FROM OPERATIONS

WORLDWIDE



CUSTOMER 1 - BRAZIL

• Client is the second majorsteel-maker company inBrazil

• Flotation rejects andthickener underflow testedusing SLon lab unit for plantoptimization

• Slon recovered upto 66.6%Fe from flotation rejects andupto 59.9% Fe fromthickener underflow

• Increase in magnetic fieldintensity increased in ironrecovery but also increase inSiO2, Al2O3 and Mn whichreduced Fe grade


0

10

20

30

40

50

60

70

62

62.5

63

63.5

64

64.5

65

65.5

66

66.5

0 0.2 0.4 0.6 0.8 1 1.2

Fe R

ecov

ery

(%)

Fe G

rade

(%)

Magnetic Intensity (Tesla)

Fe Grade (%)Flotation RejectsFe Grade (%) Slimes

Fe Recovery (%)Flotation RejectsFe Recovery (%)Slimes


CUSTOMER 2 – BRAZILSLON 100 TESTING

• Feasibility testing was doneon flotation tailing samplewith 6 to 7 % iron.

• Test showed the increasein recovery of Fe content inmagnetic fraction withincrease in magnetic fieldfrom 0.15 to 0.5 T

• Screening of feed beforethe SLon feed showing abig improvement removingthe coarse silica.

Test # Products Test Conditions

Mass % Fe Assay Fe Recovery

1Mag 0.5 Tesla

Pulsation 240

21.82 33.81 78.46

N-mag 78.18 2.59 21.54

2Mag 0.3 Tesla

Pulsation 240

17.80 36.40 67.00

N-mag 82.20 3.88 33.00

3Mag 0.15 Tesla

Pulsation 240

10.54 40.78 44.45

N-mag 89.45 6.00 55.55

The coarse particle (+150 mesh) were removed by screening. 47.73% by weight -150 mesh.

4Mag 0.5 Tesla

Pulsation 240

27.14 47.68 79.70

N-mag 72.86 4.52 20.30

The coarse particle (+200 mesh) were removed by screening. 32.02% by weight -200 mesh.

5Mag 0.5 Tesla

Pulsation 240

34.12 55.27 82.35

N-mag 65.88 6.13 17.65



CUSTOMER 2– BRAZILPILOT SCALE TESTING WITH SLON 500


• Increase in Fe recovery with increase in magnetic field.

• Fe grades increases till 0.48 T and results indicated 84.50% Fe recovery with Fe grade of 28.16%.

• Silica recovery increases with the magnetic field too but the rate of increase is very low from 0.29T to 0.48T


CUSTOMER 3 - AFRICA SLON 100 TESTING

•Tailing sample with 48.9% Fe.•Screened at 250um to remove oversize resulting in minor iron losses of 0.8%•Pre-treated using LIMS to remove magnetite form the sample•Operating variables

magnetic intensity (0.1 – 1.0T) pulsating frequency (0-300 ppm)matrix size (1, 1.5, 2, 3 and 4mm).

•A combined concentrate grading 66% iron could be achieved at recoveries of 60% to 75%.



CUSTOMER 3 - AFRICA SLON 100 TESTING

•Tailing sample with 47% Fe.•Screened at 250um ( minor iron losses of 1.4%)•Pre-treated using LIMS to remove magnetite form the sample•Operating variables

magnetic intensity (0.1 – 1.0T) pulsating frequency (0-300 ppm)matrix size (1, 1.5, 2, 3 and 4mm).

•A combined concentrate grading 63% to 64% iron at a recovery of 50% to 66%



CUSTOMER 3– AFRICASLON 750 TESTING

•The two composites were combined and screened at 250 micron and pre-treated using LIMS•Operating variables

magnetic intensity (1.0T) pulsating frequency (200 - 300 ppm)matrix size (1.5 mm). % Solids ( 12% & 21%)

•Lower solids content in feed and 250 ppm of pulsating frequency were chosen with Fe grade of 65.5 % at a recovery of 77.7 %



CUSTOMER 3– AFRICA SLON 750 TESTING MASS BALANCING



CUSTOMER 4 – RUSSIASLON 100 TESTING

Test # Products Test Conditions

Mass % Fe Grade % Fe Recovery

1

LIMS Mags

0.5 TeslaPulsation

220

21.52 57.78 30.58

SLon Mags41.82 50.01 51.43

LIMS+SLon Mags 63.34 52.65 82.01

Nonmags36.66 19.96 17.99

Feed 100.00 40.67 100.00

2

LIMS Mags

0.3 TeslaPulsation

220

20.72 57.78 29.66

SLon Mags32.70 51.84 42.00

LIMS+SLon Mags 53.42 54.14 71.66

Nonmags46.58 24.55 28.34

Feed 100.00 40.36 100.00

3

LIMS Mags

0.3 TeslaPulsation

250

22.03 57.78 31.51

SLon Mags 29.34 52.69 38.27

LIMS+SLon Mags 51.37 54.88 69.78

Nonmags 48.63 25.13 30.22

Feed 100.00 40.40 100.00

• Testing of Russian iron ore sample containing 40.36% iron using SLon 100 and 900 Gauss LIMS.

• Magnetic separation effectively produced maximum grade of 54.88% Fe with 69.78% recovery



TESTING 4 – RUSSIASLON 500 TESTING

• Testing of sample with 40.3% Fe and 39.6% SiO2 using SLon 500 in series with 1000 Gauss LIMS

• Pre-treatment : Grinding using rod mill to reduce the sample size from 100% of -5mm to P80% of 82 microns (labeled as Sample II) for downstream flotation testing.

• A combined concentrate grading 53.2% Fe with 85.2% recovery from the magnetic circuit.

Test Products Test Conditions

Mass % Fe Grade %

Fe Recovery

%

Sample II

LIMS+SLon Mags

0.5T

Pulsationstroke: 20mm,

Pulsation:250,

Ring speed:2.5 rpm.

64.62 53.2 85.2

Non-mags 35.38 16.7 14.8

Feed 100.0 40.3 100



TESTING 4 – RUSSIASLON 500 TESTING

•The magnetic separation feed of the sample-I have a coarser grinding fineness than the test feed of sample II.

•Finer grinding enabled much higher recovery along with comparable grade.

•Magnetic concentrate was then tested for flotation circuit for further upgradation.



CUSTOMER 5 – AFRICASLON 100 TESTING

•Flowsheet designing for Phase 1a,1.8 Mt/a tailing processing plant using a two stage SLon magnetic separation circuit

Testing for Rougher Circuit

• Operating conditions : -Matrix – 2mm, 3mm - Pulsation frequency (200, 250 or 300 ppm) -Magnetic field (0.5, 0.6, 0.7 and 0.8 Tesla)

• Optimum conditions were 0.6 Tesla utilizing 3 mm rod matrix at 300ppm

Testing for Cleaner Circuit

• Same operating conditions as rougher

• Optimum conditions were 0.35 T, 3 mm matrix at 300ppm

• Cleaner tailings at 12.1% of head feed with 47% Fe were used for Scavenger testing

Testing for Scavenger Circuit

• Optimum conditions produced concentrate weighing 7 to 8% of the head feed at 63.7% Fe grade and 76.5% Fe recovery.

Conc. Tails



CUSTOMER 5 – AFRICASLON 100 TESTING

Sample Fe Fe2O3 SiO2 Al2O3 MgO CaO Na2O K2O TiO2 MnO P2O5 Cr2O3

Rougher SLon Feed

22.0 31.4 54.1 8.46 0.64 0.09 0.02 0.2 0.17 0.88 0.09 0.03

Cleaner SLon

Concentrate

66.1 94.4 1.74 1.09 0.15 0.07 0.02 0.14 0.35 1.37 0.05 0.03

Scavenger SLon

Concentrate

63.7 91.0 3.05 1.86 0.26 0.11 0.04 0.30 0.34 1.73 0.06 0.03

Final Estimated

Concentrate

65.5 93.5 2.08 1.29 0.18 0.08 0.03 0.18 0.35 1.46 0.05 0.03



CUSTOMER 5 – AFRICA SLON 750 PILOT TESTING

•100 kg (-1mm) subsample was subjected to rougher – cleaner circuit lock cycle testing (seven cycles)•Rougher conditions were 0.6 T, 3 mm matrix, 300 ppm & 169 kg/h feed rate.•Cleaner conditions were 0.35 T, 3 mm matrix, 300 ppm & 87 kg/h feed rate.•The cleaner stage tailings from previous cycle were proportionally added to the next cycle’s rougher feed.• The results showed the process stability.

London Mining - Marampa Tailings Lock Cycle Testing

0

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30

35

40

45

50

55

60

65

70

Cycle 1 Cycle 2 Cycle 3 Cycle 4 Cycle 5 Cycle 6 Cycle 7

%

RO wt%

CL wt%

RO Fe

CL Fe

RO SiO2+Al2O3

CL SiO2+Al2O3



CUSTOMER 5 – AFRICA PLANT

• Customer 5 currently has two processing plants which operate a total of 22 SLon 2500 units.

• Both plants are identical and have a rougher/cleaner WHIMS circuit. • Feed which is a mixture of old tailings and weathered ore (20 – 25 %

Fe) is screened at 1mm prior to SLon processing.• The Rougher Stage design throughput capacity is 875 T/Hr/Plant (7

SLon 2500 units) at 40% solids.• The Cleaner Stage design throughput capacity is 360 T/Hr/Plant (4

Slon 2500 units) at 21% solids.• Product grade produced – 65.0% Fe



CUSTOMER 6 – USASLON 100 TESTING

• The testing was done for facility that extracts and processes iron-bearing tailings leftover from previous iron mining operations

• Slon 100 testing parametersfeed charge (200g and 270g)matrix rod size (1.5, 2 and 3mm)pulsation frequency (200 or 300 ppm) magnetic intensity (0.6, 0.8 and 1T)

• At the conditions evaluated, the SLon recovered from 54 to 81% of the iron from tails at grades ranging from 61% to 52% Fe.

• SLon 2500 and SLon 2000 has been installed in Rougher – Cleaner circuit respectively for downstream processing of mined leftover tailings in 1.1 million tonne per year iron ore beneficiation facility



CONCLUSION• Enhanced iron recoveries from a tailing stream containing hematite

using gravity, magnetic and flotation separation techniques• Designed and implimented circuits with magnetic separation as a

process stage that are proven to be efficient in recovering iron from tailing streams and dumps at the desired Fe grade and an acceptable recovery.

• Outotec’s SLon VPHIMS proved to be effective in recovering Iron from various tailing samples around the world with Iron grade ranging from 6% all way to 48%

• Desired product grades were achieved for each testing with Fe recoveries up to 85% in the magnetic separation stage.


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