The Right Tools in the Right Place:

How Xstrata Nickel Australasia Increased

Ni Throughput at its Cosmos Plant

Dan Curry, Michael Cooper, Tom Shouldice, Josh

Rubenstein, and Michael Young

7th International Mineral Processing Seminar

PROCEMIN 2010

Santiago, Chile

December 2010

Presentation Outline

• Background

• The De-Bottlenecking Challenge

• Where We Started

• The Opportunities

• Final Flow Sheet

• Does It Work?

XNA’s Cosmos Concentrator in Western Australia

Background on Cosmos

• Started in 1999 by Jubilee Mines NL

• Concentrator built from used equipment with three year LOM

• High grade (7% Ni), coarse pentlandite, low impurities (exhausted)

• In February 2008, Xstrata assumed management control of Jubilee

mines and established XNA

• Current feed 4% Ni, stringer sulphides, significant Mg and As, and

harder ore

• Mine could easily out-produce mill

• Debottlenecking of mill required to improve NPV

The De-bottlenecking Challenge

• As part of XNA’s growth strategy, the following targets were set:

– Increase Ni feed capacity from 1.3 tph to 2.8 tph (115%)

– Increase mass flow capacity through the SAG mill from 25 to 45

tph (80%)

– Add capability to treat ores with impurities

• Project developed and managed in-house.

• A$ 3.4 M budget

Original Flowsheet

Capacity:

25 t/h SAG feed

1.3 t/h Ni flotation feed

Note:

Unusual recirculation of

cleaner tail and concentrate

Opportunity - Comminution

• Jaw crusher and CV’s could easily cope with tonnage increase

• SAG mill had spare capacity based on float feed characteristics

– Opportunity to increase SAG throughput and coarsen grind

without reducing rougher /scavenger recovery

Very high Pe and Gn liberation from SAG

More like a cleaner feed than a rougher feed

Opportunity – Flotation & Filtration Capacity

• 1.3 – 2.8 t/h Ni required additional float and filter capacity

• Flotation technologies selected on delivery time and characteristics. Self

aspirating devices minimised capital.

– Jameson : 14 weeks, froth washing, fine particle collection

– Wemco : 20 weeks, coarse particle collection

• Existing 24 m2 filter replaced with new 32 m2 Larox

Opportunity – Skim Cell as Rougher 1

• As the SAG throughput increased, the grind coarsened

• This meant less liberated Pe in SAG cyclone U/F (Skim feed)

• Skim Cell performance deteriorated in SAG recirc load

• Skim Cell re-piped to take SAG cyclone O/F (first rougher)

Opportunity – Primary Cleaning

• Significant (22% w/w) liberated NSG in rougher concentrate

• A single cleaning stage could reject NSG and increase Ni grade

• Supported by limiting grade recovery curve

Opportunity – Regrinding

• Coarser SAG grind increased composites in final concentrate

• Test work supported regrinding prior to secondary cleaning

Opportunity – Regrinding

• M500 IsaMill installed using low wear inert ceramic media

• IsaMill is industry standard for regrinding in this size range

• Sized from data base information – no test work

• Target grind P80 = 20 m achieved

New Flow Sheet

IsaMill

Rghr Rghr Scavs

Prim Clnr

Regrind

Sec Clnr

Clnr Scav

ReClnr

Nickel Recovery

MgO Rejection

Tail

Conc

• Each stage has a specific role

– Skim, Wemco and Jameson as rghr/scav - for Ni recovery

– Old rougher cells used as cleaners – for MgO rejection

– Old cleaner cells used as recleaner – for As rejection

Rougher/

Scavenger

Cleaners

Re-Cleaners

Arsenic Rejection

Results – SAG and Ni Throughput

0

5

10

15

20

25

30

35

40

45

50

2008 Jan-09 Feb-09 Mar-09 Apr-09 May-09 Jun-09 Jul-09 Aug-09 Sep-09 Oct-09 Nov-09 Dec-09

Mill T

hro

ug

hp

ut

(tp

h)

Budget Actual

0

200

400

600

800

1000

1200

1400

1600

1800

2000

2008 Jan-09 Feb-09 Mar-09 Apr-09 May-09 Jun-09 Jul-09 Aug-09 Sep-09 Oct-09 Nov-09 Dec-09

Co

nc

en

tra

tor

Ni F

ee

d t

pm

Budget Actual

95% of budgeted tonnes milled in 2009

87% of design t/h achieved

Further improvement in t/h needed

Priority challenge for 2010

Planned mined grades not achieved

New circuit not pushed on Ni t/h

Residence time seems adequate

Results – Flotation

Pentlandite recovery improved in each size fraction

Results – Overall (to 12 Dec 2009)

10

12

14

16

18

20

22

24

26

28

30

70 75 80 85 90 95 100

Recovery (%Ni)

Fin

al C

on

cen

trat

e G

rad

e (

%N

i) 2009 2010 2010 Budget

Concentrator availability in 2009 (despite major changes) = 96.8 %

Acknowledgments

XNA For permission to publish

XT For assistance with commissioning and optimisation

Vendors For (almost) doing what was promised

Cosmos Site For managing and supervising the project (and living

with the result…)

Thank You