Introduction of magnetic circuit design and magnet of magnetic separator
The closed loop through which the flux concentrates is called the magnetic circuit. The magnetic system of a magnetic separator needs to produce a certain intensity of magnetic field, and most of the magnetic flux in the magnetic field is required to concentrate through the sorting space. The height, width, radius and number of poles of the magnetic system, the magnetic potential difference between adjacent poles, the pole distance, the ratio of pole width to pole gap width, the shape of poles and magnetic extreme surfaces, and the distance between the magnetic extreme surface and its alignment center all have a great influence on the magnetic field characteristics.
As an example, the magnetic circuit of the magnetic separator shown in the figure below is composed of five-pole magnetic system, each pole is bonded by ferrite and Nd-Fe-B permanent magnet blocks, and is fixed on the permeable plate by screw through the central hole of the magnetic block. The permeable plate is fixed on the axis 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 same along the axis. Outside the magnetic system is a drum made of stainless steel non-magnetic material. The non-magnetic material is used to avoid magnetic lines from entering the selected area through the drum and forming a magnetic short circuit with the drum. Non-magnetic material should also be used near the magnetic system of the groove body, and common steel plate or rigid plastic plate should be used for the rest.
Permanent magnet is the most important component of permanent magnet separator, and its performance characteristics are determined by the quality of permanent magnet. Permanent magnets of magnetic separators are usually made of a certain size (e.g. length x width x height = 85 x 65 x 21 mm), so they are customarily called permanent magnet blocks or magnetic blocks for short. Permanent magnetic materials used as magnetic system of magnetic separator include permanent magnet ferrite, Al-Ni-Co, Fe-Cr-Co, Mn-Al-Fe, Sm-Co, Nd-Fe-B and so on. At present, the mainstream permanent magnet materials used in domestic magnetic separation equipment are mainly permanent magnet ferrite (strontium ferrite, barium ferrite), followed by Nd-Fe-B permanent magnet.
In the design of magnetic system, 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 as follows.
1. Magnetic field intensity: A constant magnetic field is generated in a specified workspace, and the intensity of the magnetic field determines what kind of permanent magnet material is needed. The magnetic properties of Nd-Fe-B permanent magnets are much higher than that of ferrites.
2. Requirements for magnetic field stability, i.e. the influence of permanent magnet materials on environmental temperature, humidity, vibration and impact and their adaptability
3. Mechanical properties, such as toughness, flexibility and compressive strength of magnets
4. Price factor
The above is about the magnetic circuit design of magnetic separator and the introduction of magnet size and material. I hope it will be helpful to you!