The magnetic separator uses the magnetic difference between minerals for separation, plays the role of improving ore grade, purifying solid and liquid materials, and recycling waste. It is one of the most widely used and highly versatile models in the industry. one.

Magnetic separators are widely used in mining, wood industry, ceramics, chemical, food and other industries. For the mining industry, the magnetic separator is suitable for wet or dry magnetic separation of manganese ore, magnetite, pyrrhotite, roasted ore, ilmenite, hematite and other materials with a particle size of less than 50mm. It is also used for coal , Iron removal operations and waste disposal operations of non-metallic minerals, building materials and other materials.

Structure and working principle of magnetic separator

The magnetic separator (take the wet permanent magnetic drum magnetic separator as an example) is mainly composed of 6 parts: cylinder, roller, brush roller, magnetic system, trough, and transmission part. The cylinder is coiled and welded from 2-3mm stainless steel plate into a cylinder, and the end cover is a cast aluminum piece or workpiece, which is connected to the cylinder with stainless steel screws. The motor drives the cylinder, magnetic roller and brush roller to rotate through a reducer or directly using a stepless speed-regulating motor.

After the slurry flows into the tank through the ore box, under the action of the water flow from the ore spray pipe, the ore particles enter the ore supply area of the tank in a loose state. Under the action of the magnetic field, the magnetic mineral particles are magnetically aggregated to form "magnet clusters" or "magnet chains". The "magnet clusters" or "magnet chains" move toward the magnetic poles in the pulp under the action of magnetic force and are adsorbed on the cylinder. . Since the polarities of the magnetic poles are alternately arranged along the rotation direction of the cylinder, and are fixed during operation, the "magnet cluster" or "magnetic chain" will generate magnetic stirring phenomenon due to the alternating magnetic poles when the cylinder rotates, and become mixed The gangue and other non-magnetic minerals in the "magnet cluster" or "magnet chain" fall off during turning, and the "magnet cluster" or "magnet chain" that is finally attracted to the surface of the cylinder is the concentrate. The concentrate goes with the cylinder to the weakest part of the magnetic system edge, and is discharged into the concentrate tank under the action of the flushing water jet from the discharge pipe. The non-magnetic or weakly magnetic minerals are left in the pulp and discharged out of the tank with the pulp. , That is, tailings.

Magnetic Circuit Design and Magnet of Magnetic Separator

The closed loop through which the magnetic flux intensively passes is called the magnetic circuit. The magnetic system of the magnetic separator needs to generate a certain strength magnetic field, and most of the magnetic flux in the magnetic field is required to concentrate through the separation space. The height, width, radius and number of poles of the magnetic system, the magnetic potential difference between adjacent magnetic poles, the pole pitch, the ratio of the pole face width to the pole gap width, the shape of the magnetic pole and the magnetic end face, and the distance from the magnetic end face to the center of the arrangement Distance, etc. have no small influence on the magnetic field characteristics.

The magnetic separator shown in the following figure is taken as an example. The magnetic circuit part adopts a five-pole magnetic system. Each magnetic pole is made of ferrite and neodymium iron boron permanent magnet. On the upper side, the magnetic guide plate is fixed on the shaft of the cylinder through the bracket, the magnetic system is fixed, and the cylinder can rotate. The polarities of the magnetic poles are arranged alternately along the circumference, and the polarities are the same along the axial direction. The outside of the magnetic system is a roller made of stainless steel non-magnetic material. The non-magnetic material is used to prevent the magnetic field lines from entering the selected area through the cylinder and forming a magnetic short circuit with the cylinder. Non-magnetic materials should also be used for the part of the tank close to the magnetic system, and the rest should be made of ordinary steel plates or hard plastic plates.

For the permanent magnet separator, the permanent magnet is the most important component, and the quality of the permanent magnet determines its performance characteristics. Permanent magnets of magnetic separators are generally made of a certain size (for example, length × width × height = 85 × 65 × 21 mm), so it is customary to call permanent magnet block or abbreviated as magnetic block. The permanent magnet materials that can be used as the magnetic system of the magnetic separator include permanent magnet ferrite, alnico, iron chromium cobalt and manganese aluminum iron, samarium cobalt permanent magnet materials, and neodymium iron boron permanent magnet materials. At present, the mainstream permanent magnet materials used in domestic magnetic separation equipment are mainly permanent magnet ferrites, followed by neodymium iron boron permanent magnet materials.

In the design of the magnetic circuit, it is necessary to choose which permanent magnet material to use according to the specific conditions of various aspects. The influencing factors can be summarized into the following aspects:

◾Magnetic field strength: A constant magnetic field is to be generated in the designated working space. The strength of this magnetic field determines which permanent magnetic material needs to be used. The magnetic properties of neodymium iron boron permanent magnets are much higher than ferrites.

◾Requirements for the stability of the magnetic field, that is, the influence and adaptability of permanent magnet materials to environmental temperature, humidity, vibration and shock

◾Mechanical properties, such as the toughness, flexibility and compressive strength of the magnet;

◾Price factor