Council for Mineral Technology
Developments in Ore Sorting Technologies
5 June 2009
Carl Bergmann
Specialist: Research
Contents
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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
Calcite
Feldspar
Dolomite
Talc
Quartz
Magnesite
Salt
Base Metals
Iron
Manganese
Copper
Zinc
Nickel
Tungsten
Slag
Precious
Metals
Gold
Platinum
Diamonds
& Gems
Diamonds
Tanzanite
Emeralds
Fuel
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
[m]
10-12
Gamma-
10-11
radiation
10-10
X-ray
10-9
10-8
Ultraviolett (UV)
10-7
Visible light (VIS)
10-6
Near Infrared (NIR)
10-5
10-4
Infrared (IR)
10-3
Microwaves
10-2
10-1
Radio waves
Sensor/
Technology
Material Property
Mineral Application
RM (Radiometric)
Natural Gamma Radiation
Uranium, Precious Metals
XRT (X-ray
transmission)
Atomic Density
Base/Precious Metals
Coal, Diamonds
XRF
Visible Fluorescence under
X-rays
Diamonds
COL (CCD Color
Camera)
Reflection, Brightness,
Transparency
Base/Precious Metals
Ind. Minerals, Diamonds
PM (Photometric)
Monochromatic
Reflection/Absorption
Ind. Minerals,
Diamonds
NIR (Near Infrared
Spectrometry)*
Reflection, Absorption
Base metals
Industrial Minerals
IR (Infrared cam)*
Heat conductivity, heat
dissipation
Base Metals
Industrial Minerals
MW-IR (heating in
conjunction with IR)*
Sulfides & Metals heat
faster than other minerals
Base/Precious Metals
EM (ElectroMagnetic sensor)
Conductivity
Base Metals
101
102
Alternating current
(AC)
103
104
* Under development
»
Lessons learnt - General
Feed Preparation!
Interparticle
crushing may
give better
liberation leading
to a lower
percentage of
composite
stones
• Defined size class ranges
• Clean surfaces
• Monolayer of particles
• Predictable trajectory
Rock type
Chromitite
Pyroxenite
Pegmatoid
Anorthosite
Light Contacts
Dark Contacts
<20mm fines
ROM distribution
Crusher A
Crusher B
42.89
1.08
5.37
1.9
6.97
4.4
37.39
38.39
0.89
5.08
1.76
5.14
2.79
45.95
37.58
0.99
4.55
1.78
0.76
0.96
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
New lenses
(2009)
Old lenses
Image improvement – new lenses
Old lenses
Image improvement – new lenses
New lenses
(2009)
Blue Shadow
Better texture recognition
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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
MediumGrade
Sulfide ore
Massive Sulfide ore
14
Rados Introduction
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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)
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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
Heading
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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 Xrays 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.
Thank you
www.mintek.co.za