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7/25/2019 GHD Iron Ore Beneficiation
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Magnetite and Hematite
Beneficiation
Kristine (Kris) Edwards
Principal Process Engineer
GHD Energy & Resources
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Table of Contents
About GHD
Different forms of iron ore
Whats it for?
Main types of separationSome familiar flowsheets
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At a glance
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Basic Types of Iron Oxides
HematiteFe2O3 ,Pure hematite is 69.94% Fe Martite - Fe2O3, crystal structure different to hematite and weakly magnetic
GoethiteFeO(OH) or Fe2O3.H2O , combined water,contained in the
crystal structure of the mineral. It is not surface or free water. When heated
above 350 C this comes off as water vapour reducing the overall mass of
the sample which increases the percentage of the other remaining elements.
Loss on Ignition (LOI)
Theoretically Goethite is 62.85%Fe, 10.14 H2O, 89.86 Fe2O3
LimoniteFeO(OH).nH2O
MagnetiteFe3O4or Fe2O3.FeO is 72.36%Fe
MagHemitemixture of magnetite and hematite
http://localhost/var/www/apps/conversion/tmp/scratch_7/backup%20links.pptx#2.%20Loss%20On%20Ignitionhttp://localhost/var/www/apps/conversion/tmp/scratch_7/backup%20links.pptx#2.%20Loss%20On%20Ignitionhttp://localhost/var/www/apps/conversion/tmp/scratch_7/backup%20links.pptx#2.%20Loss%20On%20Ignitionhttp://localhost/var/www/apps/conversion/tmp/scratch_7/backup%20links.pptx#2.%20Loss%20On%20Ignition7/25/2019 GHD Iron Ore Beneficiation
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Old Quality and possible Future Quality
Until 1999 iron ore quality needed to meet very specific targets.
World markets dictated
%Fe > 60%
%SiO2
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Lump definition
Lump is -32mm + 8mm (6.3mm for some)
The specifications include:
Maximum amount of -8mm (6.3mm)
Maximum amount +32mm
Tumble and abrasion (levels that indicate its tolerance to shipping and to
survival into the blast furnace)
Reduction, swelling and Low temperature Breakdown All for how it goes through the Blast Furnace
All for how it goes through the Blast Furnace
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Fines definition
Fines are -8mm (-6.3mm for some)
The specifications include:
Maximum amount of +8mm (6.3mm)
Maximum amount -150 micron
Reducibility, sinter testing
All for how it goes through the sinter plant and then into the Blast Furnace
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Pellet definition
Pellets use concentrate as feed, the size is ore dependent but is generally
in the range of 45 micron down to 27 micron. Material finer than that oftengives pellet with lower strength.
Pellets are balls around 8mm in size
The specifications include:
Tumble and abrasion (levels that indicate its tolerance to shipping and to
survival into the blast furnace) Reduction, swelling and Low temperature Breakdown
All for how it goes through the sinter plant and then into the Blast Furnace
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Blast Furnace Hot Metal vs Slag
Effect
Fe Reports to hot metal (95-97%)
P Reports to hot metal (90-95%)
Mn Reports to hot metal and slag
SiO2 Reports primarily to slag but some contribution as Si in hot metal
Al2O3 Reports to slag
CaO Reports to slag
MgO Reports to slag
S Reports mainly to slag but parts go to the hot metal
Na2O, K2O Report primarily to slag but have bad effects physically on thefurnace
Zn Reports to flue dust can penetrate the furnace lining and
recirculate in the system
TiO2 Reports primarily to slag affecting viscosity
As, Cu, Sn, Ni Report to hot metal
Cr Reports primarily to hot metal
H2O Reports to off gas
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Typical Australian DSO Sinter
Fines Chemical Compositions
Name Fe SiO2 Al2O3 CaO MgO P S H2O LOI
BHPB Mac 61.70 3.35 2.00 0.01 0.06 0.067 0.038 8.5 5.8
BHPB Mt Newman63.00 4.15 2.10 0.06 0.09 0.079 0.010 6.1 3.1
BHPB Yandi 57.70 5.40 1.40 0.04 0.05 0.040 0.011 8.0 10.2
HI Pilbara Blend 61.84 4.28 2.23 0.10 0.08 0.081 0.016 7.0 5.2
HI Yandi 58.80 4.50 1.51 0.04 0.09 0.048 0.008 8.0 9.7
Robe River 57.10 4.70 2.50 0.51 0.16 0.027 0.015 8.5 10.0
FMG Rocket 59.50 3.90 1.90 0.05 0.07 0.054 0.030 8.0 8.0
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Brazilian Itabirite Concentrate
Typical Traded Ore Specifications
Name Fe SiO2 Al2O3 P S H2O LOI
Carajas 67.40 0.80 0.80 0.023 0.006 8.0 1.2
Vale SSF 66.00 3.65 0.70 0.026 0.005 4.7 0.9
Samarco Sinter Feed 67.10 1.85 0.50 0.045 0.010 8.3 0.8
Samarco Low Silica Pellet feed 67.17 1.10 0.30 0.040 0.003 9.6 2.4
Samarco Medium Silica Pellet feed 66.79 1.54 0.32 0.045 0.003 9.5 2.43
Carajas Pellet Feed 65.80 1.20 1.50 0.040 0.600 11.4 2.2
Vale Southern System Pellet Feed 67.80 1.40 0.40 0.035 0.150 7.7 0.9
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BENEFICIATION (ben-uh-fish-ee-eh-shun)
Whether an iron deposit can be upgrades to a suitable grade is ORE
DEPENDENT
Each deposit has to be tested
Although for DSO simple descriptions, such as Marra Mamba and
Brockman can tell quite a lot about how it will crush
When it comes to processing there is no guarantee that a given ore type will
ever get to grade profitably.
There is often no correlation between head grade and ability to separate.
Testing is really the only way to tell.
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How do we separate iron from gangue?
Four main methods around the world:
Magnetic Separation
Sizing (common in WA)
Gravity Separation
Flotation (mainly used in Brazil)
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Magnetic separation as a primary process
Low intensity magnetic separation (
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Typical Magnetite Plant
ROM
Stockpile
Primary Crusher
primary crusher product
Finisher Tails
Plant Feed
finisher water
Tails Thickener
Cobber Conc
Ball Mill
Cyc Feed water
Mag Stockpile
SAG Mill Feed
SAG Mill
Cyclone
Finisher MS
Sieve Bend
Rougher Feed
Rougher MS
Tailings PumpTSF
Paste Thickener
Process Water TankFresh Water Tank
Cobber MS
Cyclone Feed Sump
sag mill water
Primary Screen
Screen US
SAG Discharge
Screen OS
mag concentrate
Filter
Rougher Conc
Sieve US
DSM OS
BM Feed
Cyclone Feed
BM Discharge
Paste
Tails Thickener UF
Filtrate
Cobber Tails
Paste Slimes
TThickener Feed
Thickener OF
Fresh Water
Rougher Tails
Conc Thickener
Finisher Conc
Conc Thickener UF
Thickener OF_2
Conc Thickener OF
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Example of Sizing for Upgrade
Given this Drop Test Results
Overall grade is quite good at 60.7, but if you
could remove the -0.150mm fraction, it would
increase to 63.4%Fe at 80% of the mass and
the SiO2would drop from 9.3 to 5.5% Screening at 0.15mm requires wet screening,
pumps and tailings. There are other options
(such as screen at 1mm and then cyclone to
make the cut size)
Screen w t% %Fe %SiO2
+25.0 3.5 56.8 10.1
-25.0 +20.0 3.8 62.3 6.1
-20.0 +15.0 5.2 62.6 6.2
-15.0 +10.0 5.7 62.2 6.4
-10.0 +8.0 2.7 62.1 6.5
-8.0 +3.150 12.8 62.8 6.2
-3.150 +1.180 8.5 62.2 6.3
-1.180 +0.600 5.7 63.4 5.1
-0.600 +0.300 13.9 65.8 3.2
-0.300 +0.150 18.2 65.0 4.8
-0.150 +0.075 13.0 51.7 23.0
-0.075+0.045 4.2 43.4 33.1
-0.045 2.8 51.1 18.1
100.0 60.7 9.3
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Upgrading by fines removal
Lump Stockpile
ROM Stockpile
Cone CrusherRolls Crusher
Truck
Scrubber and Trommel
Fines Stockpile
Cyclopak
Thickener
Wet Screen
To Tailings
scrubber water
may not have trommel
May feed directly to Scrubber
may have dewatering/sizing cyclones
may only produce fines
Process Water
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Gravity Separation
The higher the iron in a particle the heavier it tends to be.
This is represented in the specific gravity of the particles
Hematite 4.8 - 5.1
Magnetite 5.3
Goethite 3.3 - 4.3
Limonite 2.94.3
Silica 2.65
Clays 1.8 - 3
Because you are trying to separate the heavier particles from the light
particles, size has an affect. A 1mm particle of pure silica will weigh
approximately the same as a pure hematite particle of 0.55 mm
The feed requires tight sizes to accomplish separation.
Each size fraction is best suited to particular types of equipment.
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Gravity Separation - Types
JigsCoarse jigs 32 x 8 mm
Fine Jigs 8 x 4mm, 8 x 2mm, 4 x 1mm
Up Flow classifiers
-2mm
Heavy media separation
Drum separator -32mm x 8mm
Cyclone -8mm x 1mm
Spirals
Reflux Classifier
-1mm +45 micron
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Jigs versus Heavy media
Generally each type of machine requires the screening and general layout for
either jigs or heavy media separators.
The main deciders in this would be the SG cut point for the given ore.
Heavy media will only reach about 3.6 maximum density. Some iron ores need
4 or 4.1 SG to upgrade and this is really only achievable in the jigs.
On the other hand at lower SG, the heavy media circuit will always get better
recoveries and sometimes better grades than the jigging circuit. But it has to
be enough of a difference in order to justify the costs of the ferro silicon
loss.
The best way to determine the correct choice is to pilot side by side.
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Upgrading by Fines Gravity treatment
ROM Stockpile
Cone CrusherRolls Crusher
Truck
Scrubber and Trommel
scrubber water
May feed directly to Scrubber
Fines Stockpile
Wet Screen
Thickener
Belt Filter
Up Current Classifier
Spirals
To Tailings Dam
Process Water
Reflux Classifier
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Upgrading by Heavy Media
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Less than 45 micron
Once below 45 micron there are only a few options for upgrading -
magnetic separation or flotation
Low Intensity Magnetic Separation
For magnetites
Wet High Intensity Magnetic separation (or Medium Intensity)
Gaustec, Slon, Jones WHIMS, Readings, Eriez WHIMS, Metso HGMSvariations on a theme.
Flotation
Reverse flotation of gangue
Direct flotation of the iron oxide
Many WA ores do not contain liberated iron particles in these fine sizes.
The exception would be blue dust, but it would have to be treated without
any contamination fine iron silicates.
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