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The Latest Developments in Iron Ore Processing

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  • pg 1
									       Council for Mineral Technology




The Latest Developments in Iron Ore
            Processing
                    5 June

                  Isabel King
Iron ore Processing
   Introduction: Iron Ore Processing
• Overview
  – Suppliers, sources early days


• Crushing Techniques

• Processing Options
  – Coarse processing
  – Fines processing


• Conclusions
               Overview
         Largest Iron Suppliers

• Vale

• BHP

• Rio Tinto

• Kumba Iron ore
                 Overview
              Iron Ore Sources
• Hematite
 (Fe2O3)


• Magnetite
 (Fe3O4)


• Titaniferous Magnetite
 (Fe2+ (Fe3+ ,Ti)2O4)
              Overview
             Occurrence
• Massive

• Banded Iron Formation
  (BIF)

• Limonite

• Taconite
                     Overview
• Main Use of Iron Ore
  – Steel Industry

• Iron Ore Processing in the Early Days
  –   Mine
  –   Crush
  –   Screen
  –   Sell

• Present
  – Need Upgrading
                 Overview
        Objective of Processing
• Preparation for smelting
  – SiO2 <3%
  – Fe>63%
  – Al2O3 <3.5%
  – S and P content minimise


• Maximise recovery and yield
Iron Ore Mine -Thabazimbi
Iron Ore Crushing
          Crushing Techniques
• Primary/Secondary Crushing
  – Jaw
  – Gyratory
  – Kawasaki


• Tertiary Crushing
  – Cone
  – High Pressure Grinding Roll
    (HPGR)
            Crushing Techniques
        Cone Crushing vs. HPGR
• Cone Crushing
  – Minimise flakiness
  – Shape factor influences Jig/DMS
    performance

• HPGR
  – Better liberation in tertiary capacity
Iron Ore Screening
            Processing Options

              Hematite                     Magnetite
• Coarse (-32+8mm)
                         DMS/Jigging

• Medium (-8+1mm)

• Fine (-1mm+212 / 75mm)
                            Spirals/TBS/     LIMS/
                            WHIMS/           Flotation
• Slimes (-212mm)
                            Flotation
Jigging on Iron Ore
                 Jigging on Iron Ore
• Narrow size classes
   – -32+8mm
   – -8+3mm
   – -3+1mm

• Size and Density Separator
• Fines Jigs hard to control
• ‘Over the bed’ Jigs
• ‘Through the bed’ Jigs
   – Ragging

• Capacity
   – 85t/h per meter width of jig to max of 4m wide jig
Dense Media Separation on Iron Ore




 DMS Drum               DMS Cyclone
       Dense Media Separation on Iron Ore
                               Floats sieve bend




Feed



                   Sinks
                           Overflow
Dense Media Separation on Iron Ore




 DMS Drum Sinks         DMS Drum Floats
 Dense Media Separation on Iron Ore
• DMS Drum
  – Up to 4.6m diameter
  – Process 600t/h lumpy iron ore
• DMS Cyclone
  – Only -6mm material for iron ore
  – 360mm diameter cyclone
  – Process 40t/h per cyclone
• Larcodems
  – -90+6mm stones
  – 1.2m diameter
  – Operating capacity of 600-800t/h
  – Efficient separation at SG’s as high as 4.1g/cm3
 Dense Media Separation on Iron Ore

• Cut SG of 3.6-3.8 g/cm3
• Not considered at 4g/cm3
  – Viscosity of FeSi

• Ferrosilicon
  – Water atomised
  – Gas atomised

• Maximise recovery and yield
Dense Media Separation on Iron Ore
                    DMS vs. Jigging

             DMS                              Jigging
• High operating cost               • Low operating cost
• Efficient separation              • Less efficient separation
   –   Depends on bottom size          – Narrow size classes
   –   Near density material           – Recovery losses
   –   Optimse yield and recovery      – Higher tailings grades
   –   Lower tailings grades


• Density Separation                • Size and density
   – Small effect on size             separation
                                                                                           DMS vs. Jigging
                                                                        DMS simulation                                                                                                                                 Jig simulation

                  100.0                                                                                                                                       100.0
                              20-15mm        15-12mm
                                                                                                                                                                            20-15mm            15-12mm
                   90.0       12-9mm         9-6mm                                                                                                             90.0
                                                                                                                                                                            12-9mm             9-6mm
                              6-4mm          4-2mm
                                                                                                                                                                            6-4mm              4-2mm
                              2-1mm          1-0.5mm
                   80.0                                                                                                                                        80.0         2-1mm              1-0.5mm


                   70.0                                                                                                                                        70.0




                                                                                                                                          mass % to product
                   60.0                                                                                                                                        60.0
discrete mass %




                   50.0                                                                                                                                        50.0


                   40.0                                                                                                                                        40.0


                   30.0                                                                                                                                        30.0


                   20.0                                                                                                                                        20.0


                   10.0                                                                                                                                        10.0


                    0.0                                                                                                                                         0.0
                       2.50   2.60   2.70   2.80   2.90   3.00   3.10    3.20   3.30     3.40   3.50   3.60   3.70   3.80   3.90   4.00                            2.50   2.60   2.70   2.80      2.90   3.00   3.10    3.20   3.30     3.40   3.50   3.60   3.70   3.80   3.90   4.00
                                                                           mean sg                                                                                                                                       mean sg




                          Results for the same product grade
                                                                        DMS                  Jig
                                                                                                                                   NB: Very dependent on feed size distribution
                                        Ep                              0.07               0.144
                                        D50                             3.16                3.19
                                        Yield                           77%                70%
                      Fines Processing

                 Hematite                            Magnetite
• -1mm + 212 / 75mm                           • -1mm + 212 / 75mm
   – Spirals and Teeter Bed Separator (TBS)      – Wet Low Intensity
   – Wet High Intensity Magnetic Separation        Magnetic Separation
     (WHIMS)                                       (LIMS)
   – SLon Magnetic Separation                    – TBS


• -212 / 75mm                                 • -212 / 75mm
   – WHIMS                                       – LIMS
   – SLon                                        – TBS
   – Flotation                                   – Flotation
Spirals
                         Spirals
• Mostly water flushed spirals
  – SC20FE
  – 1.5t/h


• High capacity spirals
  –   Reduce footprint of plant
  –   Deeper troughs
  –   Wider
  –   4-7t/h
Teeter Bed Separation (TBS)
      Teeter Bed Separation (TBS)
• Fluidised bed

• Part of spiral circuit
  – Final cleaning of concentrates


• Feed preparation for spiral circuit on
  coarse material
  – -3mm particles are too coarse for spirals


• BIF as a two pass system
Wet High Intensity Magnetic Separation
              (WHIMS)
                   WHIMS
• Magnetic susceptibility
  – Difference has to be large

• Not recommended
  – Paramagnetic gangue minerals are
    present

• Effective on slimes
  – Much finer sizes than 212mm

• Capacity of 120t/h
SLon
                       SLon
• High gradient magnetic separator (HGMS)

• Combined force field
  – Magnetism
  – Pulsating fluid
  – Gravity

• China and Peru

• Separating fine hematite and magnetite

• Capacity of 120t/h
                   Flotation
• Main purpose to add additional
  recovery

• Reverse/Direct flotation

• Taconite
  – Part of magnetic separation circuit
  – Selective flocculation
  – Fine grinding, pellitisation
            Typical Magnetite Processing Circuit
            1


 Crushing                                           "75" micron



                                                                  Fine LIMS
                                                                  max 5 passes
HPGR


                                                                                 4

                                                                    5
                  "212" micron

                                                2                                    7
                                 Coarse LIMS                       Fine TBS
                                 max 5 passes


                                                                                 6

                                       3
LIMS Plant
Wet Low Intensity Magnetic Separator
              (LIMS)
 Processing of Titaniferous Magnetite
• Mostly magnetic separation

• Performance of gravity
  separation affected by grind

• Possibility of producing a
  secondary ilmenite product???
Conclusions
          Acknowledgements

Jeremy Bosman – University of Pretoria/ Pesco
           Carl Bergmann - Mintek
          Thank you




www.mintek.co.za

								
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