Council for Mineral Technology Developments in Ore Sorting Technologies 5 June 2009 Carl Bergmann Specialist: Research
Contents Current status and description of electronic sorting Modern sensor types Latest developments and improvements X- ray transmission : Commodas Ultrasort X-ray fluorescence : Rados
Some history Both conductivity and photometric sorters 1970 s Remnants of old radiometric sorters at some Witwatersrand gold mines Optical sorters with line scan cameras since 1990 s Estimated ±300* sorters in ore and minerals sorting worldwide (excluding diamond fluorescence sorters) * Source: Commodas/Ultrasort and Rados
Sensor based sorting applications Industrial Minerals Base Metals Precious Metals Diamonds & Gems Fuel Calcite Feldspar Dolomite Talc Quartz Magnesite Salt Iron Manganese Copper Zinc Nickel Tungsten Slag Gold Platinum Diamonds Tanzanite Emeralds Uranium Coal
Sensor based sorting principles 1 Material feed 2 Vibratory feeder 3 Free fall acceleration 4 Sensor - Line scan camera(s) 5 Data processing 6 Air pressure valves 7 Accept stream Reject stream 8 Network interface for central control 5
Available Sensors within the Electro Magnetic Spectrum Range of sensors Gammaradiation X-ray Ultraviolett (UV) Visible light (VIS) NearInfrared (NIR) Infrared (IR) Microwaves [m] 10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 Sensor/ Technology Material Property Mineral Application RM (Radiometric) Natural Gamma Radiation Uranium, Precious Metals XRT (X-ray transmission) XRF COL (CCD Color Camera) PM (Photometric) NIR (Near Infrared Spectrometry)* IR (Infrared cam)* MW-IR (heating in conjunction with IR)* Atomic Density Visible Fluorescence under X-rays Reflection, Brightness, Transparency Monochromatic Reflection/Absorption Reflection, Absorption Heat conductivity, heat dissipation Sulfides & Metals heat faster than other minerals Base/Precious Metals Coal, Diamonds Diamonds Base/Precious Metals Ind. Minerals, Diamonds Ind. Minerals, Diamonds Base metals Industrial Minerals Base Metals Industrial Minerals Base/Precious Metals Radio waves 10 1 10 2 Alternating current (AC) 10 3 10 4 EM (Electro- Magnetic sensor) Conductivity Base Metals» * Under development
Lessons learnt - General Feed Preparation! Defined size class ranges Clean surfaces Monolayer of particles Predictable trajectory Interparticle crushing may give better liberation leading to a lower percentage of composite stones Rock type ROM distribution Crusher A Crusher B Chromitite 42.89 38.39 37.58 Pyroxenite 1.08 0.89 0.99 Pegmatoid 5.37 5.08 4.55 Anorthosite 1.9 1.76 1.78 Light Contacts 6.97 5.14 0.76 Dark Contacts 4.4 2.79 0.96 <20mm fines 37.39 45.95 53.38
Lessons learnt Optical Sorting Wide range of ambient temperatures in South Africa: affects the illuminating light colour which changes the way the particles are seen so: Fluorescent lights Water cooled fluorescent LED lights Also: Clean, dry, oil-free, rust free air compressed air for the valves Needs relevant skills level to operate and maintain
Some improvements General Developing technology Faster computer speed More robust construction (Commodas/Ultrasort merger) Run of Mine (ROM) Series Industrial Processing (PRO) Series Gem Stone (GEM) Series
Image improvement new lenses New lenses (2009) Old lenses
Image improvement new lenses Old lenses Blue Shadow New lenses (2009) Better texture recognition 11
Slow motion video Optical Sorting Latest Pro Series Sorter at Mintek
XRT Sorter at Mintek Throughput 16 40 tph Size Range -40mm +10mm Compressed air 55 kw ;pressure 8 bar 13
XRT Images Low-Grade Sulfide Ore Medium- Grade Sulfide ore Massive - Sulfide ore 14
Rados Introduction Developed in Russia Direct XRF assay of particle surfaces Mechanical ejectors no compressed air Extremely robust Modular units RADOS clip
Rados Sorter Internal view Ore Feed Chutes XRF Sensors Mechanical Actuators
Rados XRF Sorting RADOS Model Particle Size Range Throughput (tph) SRF4-050M 60mm +10mm 3 5 SRF4-150M -150mm +30mm 10 20 SRF3-300M -300mm +150mm 25 35 49 plants in Russia and neighbouring countries 2-5 elements measured simultaneously per particle Sorting rules are easily set, product and waste grades are measured Due to be installed at Mintek later this year
Bank of 6 Rados Sorters
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Conclusions Sensor Based Sorting is still a developing technology that is rapidly evolving. Improvements are continually being made in terms of sorter robustness and measurement sensitivity. A very wide range of sensors are now available and in development and is predominantly represented by Commodas Ultrasort X-Ray transmission sorting has particular promise in the field of dry coal sorting. For other silicate minerals, the current top size that the X- rays can pass through is around 40mm The Rados X-Ray fluorescence sorting technology, developed and operated in Russia, will soon be available for local testing.
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