GHD Iron Ore Beneficiation

7/25/2019 GHD Iron Ore Beneficiation

1/25

Magnetite and Hematite

Beneficiation

Kristine (Kris) Edwards

Principal Process Engineer

GHD Energy & Resources


2/25

Table of Contents

About GHD

Different forms of iron ore

Whats it for?

Main types of separationSome familiar flowsheets


3/25

At a glance


4/25

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%20Ignition


5/25

Old Quality and possible Future Quality

Until 1999 iron ore quality needed to meet very specific targets.

World markets dictated

%Fe > 60%

%SiO2


6/25


7/25

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


8/25

Fines definition

Fines are -8mm (-6.3mm for some)


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


9/25

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


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


10/25

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


11/25

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


12/25

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


13/25

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.


14/25

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)


15/25

Magnetic separation as a primary process

Low intensity magnetic separation (


16/25

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


17/25

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


18/25

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


19/25

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.


20/25

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


21/25

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.


22/25

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


23/25

Upgrading by Heavy Media


24/25

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.


25/25

www.ghd.com

Documents

GHD Iron Ore Beneficiation