1. Wet Drum Magnetic Separators
These separators are used for the continuous separation of magnetic particles from slurries. They are mostly employed in the mining industry for the separation of iron ore. Wet drum design is especially suitable for large volumes of slurry making it efficient. The structure usually consists of a rotating drum with a magnetic media shell; the latter is usually made of stainless steel. The magnetic field can be produced by permanent magnets or an electromagnet.
Wet drum magnetic separators are very effective in the separation of fine magnetic particles from the non-magnetic material. They have some benefits like easy to maintain and does not require much water and this is very important in areas where there is a shortage of water. But they need to be maintained often to avoid problems such as clogging and wear, which may reduce efficiency. The drums are often made of materials that can handle the abrasive environment of mineral processing such as stainless steel or rubber.
Three disc dry magnetic separators are useful in the separation of fine magnetic particles from dry materials. These separators use three rotating magnetic discs, each of which produces different levels of magnetic fields. This makes it easy to sort materials depending on their magnetic characteristics as they are easily separated. The equipment is used in mineral processing to separate non-magnetic minerals from magnetic ones, for instance in the processing of tin, tungsten and other related minerals. The major parts are the feed hopper, magnetic discs and the conveyors, which are mostly made of stainless steel for strength.
These separators are especially useful for small scale operations because they can handle small particles at low rates of throughput. The feature of multiple discs enables a high selectivity and accuracy in the separation process which is very important when dealing with valuable minerals. However, they have lower capacities and hence are not ideal for large scale industrial uses. Some of the factors that may affect the performance of the equipment include feed particle size and the moisture content of the material being fed to the equipment.
Electrostatic separators use an electric field to sort particles according to their electrical conductivity. They are especially applied in the process of separating non-magnetic materials from magnetic ones and are normally used in combination with magnetic separators. These separators are very effective particularly in the separation of fine particles and materials that have close physical characteristics. The main parts are the corona electrode, the grounded electrode, and a high voltage power supply. The materials used are usually able to withstand the tough working environment due to their corrosion resistance.
The efficiency of electrostatic separators depends on the working conditions such as humidity, temperature, and size of the particles. They provide high efficiency in the separation of conductive and non-conductive materials, so they are used in recycling, mineral processing, and even in the food industry. However, the level of control needed for the best performance can be somewhat difficult to achieve and the equipment is not recommended for use with moist materials. Also, safety measures must be put in place to cater for the high voltage that is needed for the operation of the equipment.
High intensity magnetic separators are used to create very strong magnetic fields which are suitable for the separation of weakly magnetic materials. These separators are useful in industries where there is need to separate particles of small size such as in the recovery of hematite and other weakly magnetic particles. The equipment commonly includes a magnetic drum or roll, which is constructed from rare earth magnets, which are much more powerful than ordinary magnets. The construction may also incorporate stainless steel parts due to the high levels of stress that mineral processing entails.
These separators are very efficient in the classification of fine particles to enable the recovery of valuable minerals. But they are energy consuming and need a sound infrastructure to sustain the high magnetic fields. This makes them more appropriate for bigger and more industrial type of businesses. The high cost of rare earth magnets and the energy consumption are the main drawbacks but their ability to separate even weakly magnetic materials often makes the investment worthwhile.
5. High Gradient Magnetic Separators
High gradient magnetic separators (HGMS) employ a matrix of very fine, magnetisable wires to produce a high gradient magnetic field. This kind of setup is especially suitable for the classification of fine and ultrafine particles, which is widely applied in the processes of purifying kaolin, extracting rare earth elements, and eliminating impurities in minerals. The components usually consist of a solenoid coil that produces the magnetic field and a matrix, which is usually made of steel wool or expanded metal to increase the gradient of the magnetic field.
HGMS are characterized by high efficiency and selectivity in the separation of fine particles and are used in mining and paper industries. They are especially useful when it is necessary to separate very fine magnetic particles which cannot be separated otherwise. But they are not easy to manage and control, and need constant supervision and tuning up to ensure their efficiency. The efficiency of the equipment is also influenced by the feed’s magnetic characteristics and particle size.
