greg rasmussen
TRANSCRIPT
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