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									 KNELSON GRAVITY SOLUTIONS


   The global gravity
  perspective, recent
  developments, new
applications and future
possibilities for gravity
   Global Gravity Summit 2006
        Kevin Peacocke
                                 1978            25th
                                              2003
                                    Anniversary
                                Knelson Concentrators, a corporate partnership dba Knelson
So,
      what’s so special about
        centrifugal gravity
       Separation anyway?
It is fast!
  It is clean




• Water and power only!
      It is energy efficient



Knelson specific separation energy   0.2kwh/t



Water and associated energy          0.4kwh/t



TOTAL                                0.6 kwh/t
       It is low cost



• Example:      KNELSON XD 70 @ 600 tph

• Capital                      0.02 $/t

• Power                        0.021 $/t

• Maintenance                  0.007 $/t

• TOTAL                        0.048 $/t
Yes, yes,


but is it ……..   effective?
• Typical South African Wits ore, centrifugal gravity
  recovers around 45% of the gold in seconds........




• And the other 45% takes another 40 hours to dissolve,
  adsorb, elute, electrowin, smelt!
The gravity advantage
                 Classical Flotation

Large
installations!
Conventional Flotation
Gravity in flotation
           Advantageous comminution


HPG cake
  Advantageous comminution


Disintegration
In water
      Advantageous comminution

Breakage at grain
boundaries
      Advantageous comminution


Even the gold,

so

No overgrinding
Gravity on Cleaner Tails
     (Middlings)
Gravity Scavenge Flotation
            Gravity Flotation Equivalent

     Feed                       * NO REAGENTS
                                * LOW POWER
                                * RES TIME - SECONDS
                                * SMALL FOOTPRINT
                                * IMMEDIATELY VARIABLE




                                  FinalTails




  Rougher -
Scavenger CVD
                                     Final
                                  Concentrate
                  Cleaner CVD
        Pre-Concentration


•   Recovery into small mass:

    • Improve process economics

    • Allow more intensive treatment of concentrates

    • Eliminate a troublesome contaminant –
    eg pre robbers
   Knelson CVD       pre-concentrating gold ore


Pre-concentration allows more economic treatment
         Ultra-grind / gravity

Concentrate




Tower
mill




                       High grade
                       concentrate
    Intensive Cyanidation –
“Extreme Processing”
                   Heap Leach

High inventory
Long return time
Classical Heap Leach



                                   CN


                  Leach Pad




                              %         Days

                              66         90
Gravity Heap Leach - CIL
Environmentally sensitive or
challenging locations

                    At the top of the fjord




                         On Arctic Circle
  Space constraints

Hemmed in by river and steep valleys
Gravity only flowsheet

                      Mozley cyclone
                 2

                                                      20000 litre
                                                      header tank




        Double spirals                                                                                       Rod mill


                                                                      Shaking table
                                                                                                                  Krebbs cyclone
                                                                                                                                     1
                                                                                          C


                                                      T                                                      Ball mill



  1                                2                      6                           4             3




                                                                                                                               From river
                                                                                  Knelson     Knelson                                F
                                                                                  CVD20       CD20

      Tailings pond                                                                                          Settling tank




                                                                                              CD20
                                                                                              Concentrates
                                                     Au concentrate


                                                                                                                              Knelson Gravity Solutions

                                                                                                                                       GEXCO AB
                                                                                                                                      Bindal Gruver

                                                                                                                                   Conceptual Flowsheet
                            Sulphide concentrate 2            Sulphide concentrate 1
                                                                                                                     Date:    12/5/06     Drawn:      K. Peacocke
Containerised simple construction
Gravity only module – free and sulphide gold
  Appropriate processing



• Africa has:

• 30% of the globes remaining mineral wealth
 comprising        40% of the gold
                   60% of the cobalt
                   90% of the platinum
        Alluvial gold modules


•Simple

•Cost effective

•Fast
                  Tailings Scavenging

•   Low capital
•   Low opex
Tailings scavenging – value proposition




• Its not about percent…..



                  ………..Its about dollars

10% recovery of a 0.3g/t tailing at 600tph
  is over $3 million per annum!
Knelson XD70 Tailings Module
      Cyanide destruction



• Passage of cyanide slurry through the Knelson results in free
  CYANIDE DESTRUCTION

• This is enhanced by using various fluidisation additives

• There is also evidence of WAD Cyanide destruction too
Knelson CD30 SS on BIOX
           Summary


• Gravity processing can enhance and sometimes
  replace conventional processing methods with major
  advantages



• New applications abound




• Constrained by conventional thinking!


                       Thank you

								
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