hpgr and iron ore processing

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Insights Session

HPGR in the Iron Ore Industry

Presented by Karri Dorrington,

Process Engineer

j ENVIRONMENTAL PROCESSING DESIGN & VERIFICATION PRODUCT INNOVATION PROJECT MANAGEMENT OPERATIONS TRAINING SKILLS HIRE

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Outline

• What is HPGR?

• Benefits of HPGRs

• Iron ore types around the globe

• HPGR use in the iron ore industry

• HPGR in iron ore plant design

• Testwork


What is HPGR

• High Pressure Grinding Rolls (HPGR)

• Similar to the typical fixed roll crusher

• Force applied to push one roll towards the fixed roll

and raise pressure between the rolls

• Force on the material mainly compressive

• Introduces micro cracking – favourable for further comminution

• Higher reduction ratios than fixed rolls

Source: Mine Engineer Website (2012)


HPGR

• Reduced power consumption hard ores – 10 to 15%

• Requires secondary crushed feed

• Reduced BWI

• Replaces SAG mill-smaller ball mill

• CAPEX similar

• 10% moisture in feed

Source: Technomine Website (2012)


HPGR

Source: Weir Minerals Website (2012)

Source: World of Mining Professionals Website (2012)


HPGR vs Cone Crusher

• HPGR and Cone Crusher Product


Benefits to Magnetic Separation

0

10

20

30

40

50

60

70

80

Wt.FeSiO2Al2O3MgO

Mag

ne

tic R

eco

vere

y,

%

HPGR Coarse Cob

Cone Coarse Cob

0

10

20

30

40

50

60

70

80

90

100

Wt.FeSiO2Al2O3MgO

Assa

y,

%

HPGR Coarse Cob

Cone Coarse Cob


HPGR vs Cone Crusher

• More even size distribution

• Finer size distribution

• Lower magnetic recovery of gangue minerals such as MgO, Al2O3 and

SiO2

• Lower mass recovery

• Typically a higher iron grade (and other metallics)


Iron Ore Types Around the World

Brazil:

Itabirite, Hematite Australia:

Hematite, Magnetite South Africa:

Hematite, Magnetite

China:

LG Hematite

East Africa:

Itabirite, Hematite India:

LG Itabirite

Canada:

Hematite, Magnetite

USA:

Hematite, Magnetite

Russia:

Hematite


HPGR in Iron Ore Processing

• Applied to iron ore industry mainly for regrinding of pellet feed to

improve properties in the pelletising process

• Over time has been applied to other iron ore processes to improve

concentrates

• Australia − Magnetite (Karara)

− Vanadiferous, Titaniferous Magnetite (Future: Mount Peake)

• South Africa − Hematite (Khumani)

• Brazil − Itabirite (Samarco)


Karara Project

• JV project

• Long life magnetite concentrate operation (30+ years)

• Low-grade magnetite to produce a high-grade premium concentrate

• Have issues getting the power efficiency to the SAGs and therefore

optimum operating

• 2011 installation of HPGR

• Installed downstream of the secondary crusher

• HPGR significantly lifted feed rates


Karara Project


Mount Peake Project – FS Underway

• Polymetallic ore body

• Two stage HPGR installed after the secondary crusher

• Lower operating cost

• Efficient in producing the required feed size (two stages required)

• Micro-cracking

• Reduced mass recovery on coarse cobbing

• Changes to the process – HPGR still beneficial


Mount Peake Project (Scoping Study)


Khumani Mine

• High grade hematite deposit in South Africa

• Formally BKM Project (Bruce, King and Mokaning)

• 10 Mt export quality iron ore per annum increasing to 16 Mt

• Civil construction began in 2006

• December 2007 first delivery to Bruce primary crusher

• Late 2007 construction of jigs and HPGR

• HPGR utilised to reduce middlings particle size


Khumani Mine


Khumani Mine

• Single HPGR located after Jigging of the Lump

• Size reduction from -32.0 +6.0 mm to -6.0 mm

• More efficient than cone crusher

Source: International Mining (2008)


Samarco Project

• JV between BHP Billiton and Vale

• Low grade itabiritic ore

• Ore Reserve = 451 Mt (wet) as of 2008

• Conveyor belts transport the ore to the beneficiation plant, whilst a

396 km slurry pipeline transports the pellet feed to the pellet plant on

the coast

• HPGR prior to grinding, de-sliming and flotation


Samarco Project


HPGR Plant Design

• Normally HPGR is located after the primary/secondary crushing

• Can replace tertiary crushing with SAG mill, where a ball mill is still

required

• Can replace secondary/tertiary/quaternary crushing

• Not suitable for all ore types − High fines/clays lead to impaired comminution

− High ore competency and abrasiveness will lead to increased wear rates

− High moisture (>10%) will cause washout of the autogenous layer


HPGR vs. SAG Mill Design

1. Original circuit design SAG/AG mills

and ball mills (Huckleberry SABC

circuit), however very energy

intensive and also energy inefficient

accounting for ~80% of the overall

process plant energy (depending on

the overall process)

2. Changes to design lead to HPGR

and ball mill circuits, thus lowering

the energy consumption costs

slightly

3. Further examination, HPGR and

stirred mills circuits demonstrated it

is technically feasible and showed

promising benefits over traditional

options

1

2

3

Source: E&MJ News (2013)


Why Choose HPGR? What are the

Drivers?

• Benefits to downstream processing – magnetic separation, flotation,

leaching

• Better energy efficiency – lowering costs

• Replacement of equipment to increase grinding efficiency

• Willing to investigate with testwork to see if ore is amenable


Testwork

• Prior to selection of HPGR testwork is required

• Testwork involves: − Pressure tests

− Roll speed tests

− Roll gap tests

• Testwork reveals if the ore is amenable to HPGR

• HPGR settings influence throughput, product size distribution and

micro-cracking


References

• Karara Mining Ltd (2013) Energy Efficiency Opportunities KML Expansion Project

• TNG Limited (2012) Executive Summary Mount Peake Project Pre-Feasibility Study

• Moore, P (2011) Samarco – An Iron Ore Pioneer, International Mining, Dec 2011

• Burchardt, E (2013) HPGRs in Hard Rock Mining, Mining Magazine

• Wang, C., Nadolski, S., Mejia, O., Drozdiak, J., Klein, B (2013) Energy and Cost Comparisons of HPGR-Based

Circuits, E&MJ News

• Morley, C (2010) HPGR-FAQ, Journal of the Southern African Institute of Mining and Metallurgy


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