Magnetic separation

In mineral processing plant, By creating an environment comprimising a magnetic force (Fm), a gravitional force (Fg) and a drag force (Fd) magnetic particles can be separated from nonmagnetic particles by Magnetic Separation.

Competing forces

• Gravitational force (Fg) determined by particle size and particle density.

• Hydraulic force (Fd) for wet magnetic separators, determined by particle diameter, shape, liquid viscosity and velocity (see wet LIMS and wet HGMS below.)

• Centrifugal force (Fc) for rotating dry magnetic separators, determined by particle size, density and drum speed. (see dry LIMS below.)

• Air drag force (Fa) for dry magnetic separators, determined by particle size, density and air velocity. (see dry HGMS below).

Separator Types

Wet LIMS = Low Intensity Magnetic Separator

• Wet separation of ferromagnetic particles

• Magnetic field in separation zone * = 1-3 kGauss

* approx. 50 mm (2 inches) from drum surface

Wet HGMS = High Gradient Magnetic Separators

• Wet separation of paramagnetic particles

• Magnetic field in separation zone* = 2-20 kGauss

* on matrix surface

Dry LIMS = Low Intensity Magnetic Separators

• Dry separation of ferromagnetic particles

• Magnetic field gradient in* separation zone = 1-3 kGauss

* approx. 50 mm (2 inches) from drum surface

Dry HGMS = High Gradient Magnetic Separators

• Dry separation of paramagnetic particles

• Magnetic field in separation zone* = 2-20 kGauss

* on matrix surface

Wet LIMS - Concurrent (CC)

• Short pickup zone

• Coarse particle tolerant up to 6 mm - 0.2 inch (up to 20 mm - 0.8 inch with special tank)

• High capacities for low grade feeds

CC is normally used as primary separation (cobber), "working horse" for large

capacities and coarse feeds, mainly in iron ore industry.

Wet LIMS - Countercurrent (CTC)

• Long pickup zone = improved recovery

• Many pole passages = improved grade

• Self adjusting level control

• Coarse particle intolerant max 0.8 mm, due to sedimentation risk.

CTC used as: Rougher and finisher for multistage concentration of magnetic iron ore.

Wet LIMS - Counter Rotation (CR)

• Very long pickup zone

• Good separation with high recoveries

• For both low and high grade feeds

• Unsensitive for sedimentation, particles up to 3 mm can be separated

• Self adjusting level control

CR used as: same as CTC above when sedimentation is at risk, mainly in the iron ore industry.

Wet LIMS - Dense Media Recovery (DM)

• Very long pickup zone

• For extremely high recoveries of very fine particles

• HG (high gradient) version available for high recovery from very dilute pulp

Dry LIMS – Drum Separator (DS)

• Alternating polarity with different pole pitches giving good recovery and grade

• Variation of drum speed 1-8 m/s (3 – 26 ft/s) gives metallurgical flexibility

• Not sensitive to particle size 0.01 - 20 mm (150 mesh - 3/4")

DS can be used for separation of all types of dry ferromagnetic separation processes:

• Iron and steel slag treatment

• Reduced pyrite ash separation

• Calcined ilmenite production

• Iron metal powder production

• Magnetite or supergrade magnetite production

Dry LIMS – Belt Separator (BSA)

• For coarse particles minus 200 mm

• Alternating polarity with different pole pitches giving good selectivity

• Rubber belt for protection of separator drum and even distribution of the feed

• Variable speed for optimal separation

BSA and BSS mainly used for separation of coarse ferromagnetic ores and slags

sinonine can also provide sand washing plant EPC.

Sinonine technology team