Lecture 11 – MINE 292

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Tramp Metal Removal
 To protect crushers (electromagnets as well as metal detectors)
Magnetite Recovery
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Primary iron ore processing (taconite ores)
Pyrrhotite Recovery or Removal
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Nickel recovery
Gangue removal (zinc ores, gold ores, nickel ores)
Magnetic minerals removal
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Scheelite, talc, quartz, kaolinite,, industrial minerals
DMS Magnetite Recovery
 Media recovery and upgrading (purification)
Cleaning hematite concentrates (high-intensity)
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Final stage upgrading

 Diamagnetic
 Repulsion by magnetic forces
 Paramagnetic
 Attraction to magnetic forces
 Rutile, ilmenite, chromite
 Ferro-Magnetic
 Very-highly attracted to magnetic forces
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1,000,000 times effect of paramagnetism
Effect disappears above Curie temperature (~620 °C)
Iron, nickel, magnetite, pyrrhotite

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Magnetic Induction (flux) = B in Tesla
Field Intensity induced through particle = H (A/m)
Permeability = µ o
(T·m/A)
Magnetization Intensity = M (4π x 10 -7 T) - ignored
B = µ o
(H + M)
B = µ o
H
 For ferromagnetic materials, must consider magnetic susceptibility (S = M/H)
B = µ o
H (1 + S)

Magnetization vs. Field Intensity
 Slope = S (magnetic susceptibility)

Magnetization vs. Field Intensity for Fe
3
O
4
 Slope = S (magnetic susceptibility)
 For H = 1 T, S = 0.35
 Full saturation at 1.5 T
 Iron saturates at ~ 2.3 T

Magnetic Field Gradient
 Capacity depends on field gradient as well as field intensity
 Rate at which intensity increases as surface of magnet is approached
 F is proportional to
H x dH/dl
 Introduction of magnetic particles has the same effect but agglomeration of particles will block the separator

Magnetic Induction Required for Different Minerals

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Low-intensity (LIMS)
 600 – 700 gauss (0.6-0.7 Tesla)
High-intensity (HIMS)
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WHIMS (wet)
10,000 gauss (10 T)
High-gradient (HGMS)
 Fine magnetic matrix
 15,000 gauss (15 T)
Permanent Rare-Earth Magnetic Separators (PREMS)
 500-1,000 gauss (0.5-1.0 T)
Super-Conducting Magnetic Separation (SCMS)
 50,000 gauss (50 T)
Eddy-Current Magnetic Separation (ECMS)
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Application of current to mixture of substances
Separation of metals in electronic waste

CBM (cross-belt magnetic separator)
 Magnets (5-6) located above belt
 Operating variables
 Field strength (up to 15 T)
 Pole gap typically 2 mm
 Belt speed (fixed)
 Splitter position (manually adjusted)
 Feed rate ~1.5 tph

Cross-belt Self-cleaning Separator

IRM (induced roll magnetic separator)
 Operating variables
 Field strength (up to 15 T)
 Pole gap typically 2 mm
 Roll speed (fixed)
 Splitter position (manually adjusted)
 Feed rate ~2.5 tph

Suspended Magnets – tramp metal

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Applied to coarse sized particles that are strongly magnetic
Drum-type separators
Dry for sizes > 0.5 cm
Wet for sizes < 0.5 cm
Called Cobbing
Applied to DMS media recovery and upgrading
Typical field strength = 0.6-0.7 T
Gap for Magnetite = 50-75 mm
Gap for pyrrhotite = 10-15 mm down to 2 mm uses permanent ceramic or rare-earth magnets

Drum Cylinder Rotation Capacity Feed Power
Diameter Length Speed Top Size
(mm)
600
(mm)
1200-1800
(rpm)
35
(tph)
10-30
(mm)
2
(kW)
1.5-2.2
900
1200
1500
1800-2400 28-35 40-70
1800-3000 18
3000 16
80-180
150-260
3
3
3
3.0-4.0
5.5-7.5
11.0

Counter-current Magnetic Separator

High-Intensity Magnetic Separation
 Dry High Gradient Magnetic Separator

 Must remove highly-magnetic material to prevent blocking
 Feed size > 1mm
 Constant supply of clean, high-pressure water
 Steady feed rate and density
 Generally applied for fine particle removal
 Final stage cleaning or upgrading
 Field Strength up to 15 T (electromagnetic)
 Feed rate = 25-30 tph for 16-pole unit
 Gap typically 2 mm
 Splitter position varied to control process

Superconducting Cryogenic Mag Sep

Eddy-Current Magnetic Separation
 Applied in recycling industry
 Diamagnetic materials can be separated
 Spinning magnets cause an eddy-current in Aluminum such that a magnetic field is created that repels Al particles

Beach Sand Processing for R-E and Zr

Beach Sand Processing for Zircon

EDS applied to copper wire/glass/PVC

 Sensors
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Cameras & Video cameras
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X-ray tubes lasers
 Types
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Photometric - colour/reflectance optical properties
Radiometric - gamma radiation - Uranium
UV - scheelite
Conductivity - sulfides
Magnetic - iron minerals
X-rays luminescence- diamonds microwave attenuation hyper-spectral neutron absorption - boron

Principles of Photometric Sorting