Process Plant Manager Greg Moore

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Process Plant Manager Greg Moore Powered By Docstoc
					Process Plant Manager Greg Moore




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Process Plant Background



 • Process Plant commissioned 1997 (capacity 2.8 Mt pa)
 • Sherritt Gordon whole ore pressure oxidation technology
 • Elevated cut off grade strategy
     • High grade ore processed
     • Lower grade ore stockpiled
 • Original plant design allowed for expansion
 • Flotation circuit commissioned 2007




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  Design Philosophy


                • Gold is locked within pyrite mineral
                • Direct cyanidation only 30% gold recovered
                • Greater than 90% contained pyrite needs to be oxidised
                • Pyrite (sulphide’s) oxidised in the Autoclaves
                • Ore feed to autoclave 6.5% S
                • 205oC, 2 t oxygen for every tonne S, 2650 kPa
                • Pyrite oxidizes to ferrous sulphate
                • Exothermic reaction (generates heat)
                • 54 minutes to achieve > 90% S oxidation



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  Flow Sheet

                                         So f t O r e
                                          Si z er
                                                                          4 .4 M t p a
                                                                                                                  HF O Gr ind ing C ir cui t
                    HG O St o ckp il e



                                                                                                                                                                                                           Gr ind T hickeni ng
                                                        Pr imar y
                                                        C r usher
                                                                                                                                       B all M i ll
                                                                              3 .0 M t p a       SA G M ill
                    F GO St o ckp ile
                                                                                                                 F GO Gr ind ing C ir cui t




                                                                                                                                                                B yp ass li ne
                                         Seco nd ar y
                                          C r usher                                                                                     B all M ill
                                                                                                  SA G M ill

                                                                                                                                                                                                           Pr e- o xid at i o n
                                                                                                                                                                                                               st o r ag e

             10 t / h Oxyg en




                                                                                                 F GO F l o t at io n C ir cuit
                                                                                                                                                                                       F lo t at io n
      72 t / h O xyg en                                                                                                                                                             C o ncent r at io n
                                                                                                                                                                                        St o r ag e


                                                                                                                                               F lo t at io n
                                                                                                                                                  C o nc
                                                                                                                                               T hickener




 Go ld                                                                                                                                                                                                             >5. 0 M t p a
B ull io n
                         Go l d
                   Elect r o wi nning                                                                                                                                            Pr essur e Oxid at io n
                                                                                         C I L C ir cuit                                         C C D W ash
                                                                                                                                                                                      A ut o cl aves
                                              C ar b o n St r ip p ing


                                                                         D eep Sea T ailing s
                                                                              D isp o sal
                                                                                                                                                                                                                                   23
Continued processing improvements


                         5,000                                                                                                                  100.0%

                                                                                                                                                90.0%
                         4,500
                                                                                                                                                80.0%
                         4,000




                                                                                                                                                         Autoclave Operating Tim e (% )
                                                                                                                                                70.0%
   Tonnes Milled (000)




                         3,500
                                                                                                                            Flotation Circuit   60.0%

                         3,000                                                                                                                  50.0%
                                                       Pilot                              Pebble
                                                    flotation                            crushing
                                                                                          circuit                                               40.0%
                         2,500                        plant
                                                                                                            Additional
                                                                  Autoclave heat                            autoclave                           30.0%
                         2,000                                    recovery circuit                         feed pumps
                                  Additional
                                 oxygen plant                                                                                                   20.0%

                         1,500
                                                                                                                                                10.0%

                         1,000                                                                                                                  0.0%
                                 1998      1999         2000      2001         2002      2003       2004         2005     2006       2007

                                                                         Tonnes Milled   AC Op Time




                                                                                                                                                                                          24




 Autoclave throughputs rising

                                                  Autoclave Throughput (t/op hr)
                                                                                                                                                       198
                                                                                                                                      185
                                                                                                           175           176
                                                                               169         170
                                                                160
                                   146            148

       126




   1998                           1999          2000            2001          2002        2003             2004          2005        2006        2007 YTD



                                                                                                                                                                                          25
Flotation Operating Strategy


     •     Maximise autoclave Sulphur production & oxygen utilisation

     •     Maximise gold to Sulphur ratio

     •     Autoclaves operate best in the 6%-6.5%S range

     •     Maximise HGO throughput – Highest recovery

     •     Utilise FGO flotation circuit to produce a concentrate:

            •       Optimise sulphur content

            •       Improve the economics of marginal ore

     •     Utilize excess FGO grinding capacity to supplement AC feed




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Indicative Processing Costs


 •       Total Processing Cost typically US$15 -17/tonne milled

 •       Power                                       36%
                •   HFO 65%


 •       Maintenance                                 30%
                •   Pressure oxidation 29%


 •       Operations                                   34%
                •  Lime 33%
                • Other 34%
                  (grinding media/flocculant, mill liners, cyanide)


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Key Initiatives

•          Third CCD Thickener online – Saving approx $2m/annum
•          Oxygen bottling & CIL injection – Saving $250k/annum
•          Crushing circuit debottlenecked
•          Soft ore circuit upgrade underway
•          Automated oxygen backup system underway
•          Two Autoclave overhaul in TPS
•          Heat recovery bypass Q1 2008
•          Enlarge heat recovery drains Q1 2008
•          CV4 Radial stacker upgrade Q1 2008
•          Quench water system upgrade


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Gold Production


                          800                                                                             10

                                                     648                                    651
                                       625    606               607           599    596                  8
                          600                                           551
    Gold Production koz




                                520                                                                532
                                                                                                               Head Grade g/t




                                                                                                          6
                          400
                                                                                                          4

                          200
                                                                                                          2


                            0                                                                             0
                                1998   1999   2000   2001   2002       2003   2004   2005   2006    Q3
                                                                                                   2007
                                                                                                   YTD
                                              Gold Production         Head Grade

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