modelo de prueba con m20 isamill

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ENERGY EFFICIENCIES FROM CONCENTRATEREGRIND in an ISAMILL™

Anglo Base Metals

Procemin Mineral Processing Conference

October 2008

Cecilia Arrué and Leonardo Soto



Las Tórtolas Cu and Mo Concentrator

• Part of the Los Bronces Division and wholly owned by AngloAmerican Chile

• During 2007, the entire Los Bronces Division produced231,216 tons of Cu, 182,894 ton as concentrates, 46,420 tonas cathodes and 1 903 ton as sul hates lus 2 582 ton fine

Anglo Base Metals

Mo.



Flowsheet

Rougher and ScavengerConcentrate Regrind

Anglo Base Metals



Test Objectives

• Evaluate the energy savings and enhanced flotationcharacteristics from regrinding in an IsaMill.

• Of particular interest was regrinding the concentrate whenthe plant was treating a higher amount of a harder orecalled Donoso Este. – Chalcopyrite finely dissimilated. Increased liberation is needed.

Anglo Base Metals

– This ore is expected to constitute a greater portion of the plant’sfeed in the near future. Extra grinding capacity is required.

• Earlier studies: Donoso Este ore, theconcentrate would need to be ground

to a P80 of 30 µm at a minimumenergy requirement of 42.9 kWh/t.



IsaMill™

Impeller pumps liquid back into

chamber to retain media

Shaft rotating at highspeeds generating disc tip

speeds ~ 20 m/s

DisplacementBody

Multiple stages of grinding

GrindingDisks

GRINDING MECHANISM & MEDIA RETENTION

Impeller pumps liquid back into

chamber to retain media

Shaft rotating at highspeeds generating disc tip

speeds ~ 20 m/s

DisplacementBody

Multiple stages of grinding

GrindingDisks

GRINDING MECHANISM & MEDIA RETENTION

Anglo Base Metals

Recirculating grinding patterns of mediaoccur between disks due to variation invelocity profile across disks

Media centrifuged to outside of grindingchamber by high centrifugal forcegenerated inside mill

Rotor

Productexit

GrindingChamberShaft

PATENTEDPRODUCT

SEPARATOR

CLASSIFICATION ZONE

Recirculating grinding patterns of mediaoccur between disks due to variation invelocity profile across disks

Media centrifuged to outside of grindingchamber by high centrifugal forcegenerated inside mill

Rotor

Productexit

GrindingChamberShaft

PATENTEDPRODUCT

SEPARATOR

CLASSIFICATION ZONE



Methodology

• The tests were conducted using a M20 IsaMill pilot unit in accordancewith Xstrata Technology’s standard signature plot procedures.

• These proven procedures allow for direct scale up data for large scaleinstallations.

• Signature plot tests areessentially a batch type testwhere slurr is assed throu h

Anglo Base Metals

the mill in 4 to 5 successivestages.

• Used 3.5 mm MT1 ceramicmedia. Fine media key toIsaMill™’s energy efficiency.



Results

Gross Specific Energy vs Product Size

100

g y ( k W h / t )

Upper Range Limit

Lower Range Limit

29 kWh/t

Ball Mill (Minimum) = 42.9 kWh/t

Anglo Base Metals

1

10

10 100

Product Size (µm)

G r o s s S p e c i f i c E n

e r

Test 5

Test 8

Test 12

Test 9

Test 10

Ball Mill - minimum

30

17 kWh/t



Effect on Flotation

20,0

25,0

30,0

35,0

40,0

r a d e ,

%

Anglo Base Metals

0,0

5,0

10,0

15,0

0% 10% 20% 30% 40% 50% 60% 70% 80%

Cu Rec, %

C u

Standard

Isamill - T8

Isamill - T9

• Samples were floated several weeks after grinding and therefore the particlesurface may have been oxidized



Operating Cost Estimates

Anglo Base Metals

Operating Expenses for Forecasted Energy Prices



Conclusions

• Testwork results demonstrate that the IsaMill can processthe rougher-scavenger concentrate achieving the desiredP80.

• The IsaMill was found to offer advantages in energyefficiency even when:

Anglo Base Metals

– Assuming the higher energy requirements found in the measuredrange. – Preliminary estimates for the alternatives is significantly

underestimated.

• When using the IsaMill to regrind down to a P80 of 25 µm,an increase in final concentrate grade was observed (from18% to 31% Cu) in the preliminary flotation tests, with nomajor impact on Cu or Mo recovery.



Conclusions

• An IsaMill at Las Tórtolas would be operated in opencircuit thus eliminating the recirculating load and simplifythe flowsheet. Pre-cyclones or thickeners would beconsidered only to increase the IsaMill feed density.

• Despite the higher purchase price for ceramic media than

Anglo Base Metals

that of steel, IsaMills offer reduced total operating costsbecause of more efficient milling and lower mediaconsumption.

• Not the complete picture – more work should be carriedout to further demonstrate the benefits of regrinding in anIsaMill.



Advancements in the field of ConcentrateRegrind in an IsaMill™

• Continuous operation.- Confirm grinding media consumption and/or optimal type and size.

- Test different ore types (to have a complete idea of energy savings)

• Analysis of energy requirements for different plant feed.

Anglo Base Metals

• Further analysis of a narrow size distribution and inertgrinding media on cleaner flotation.

• A more detailed comparison of the IsaMill™ performance toother technology types. – High confidence head-to-head tests?



ISAMILL™

Anglo Base Metals

modelo de prueba con m20 isamill

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