Because of the different magnetism of different minerals, when they enter into the magnetic field of magnetic separation equipment, they bear different magnetic force and move in different trajectories. Finally the minerals are divided into magnetic and non-magnetic materials, or weak and strong magnetic products, realizing magnetic separation.
The magnetic difference of minerals is the basis of magnetic separation. Minerals' magnetic force can be measured, and according to its magnetic force degree they can be divided into three categories: (1) Strong magnetic minerals. Such as magnetite and pyrrhotite, with a small amount. (2) The weak magnetic minerals. Such as hematite, limonite, ilmenite, psilomelane, pyrolusite, garnet, etc., with plenty of reserves. (3) Non-magnetic minerals. Most of the non-metallic minerals and nonferrous metal minerals belong to this category. In the magnetic field of magnetic drum separator, strong magnetic minerals suffer the largest magnetic force, the weak magnetic minerals bear a small magnetic force, and the non-magnetic minerals are not affected by magnetic force or only bear a slight magnetic force.
The magnetic field of magnetic drum separator is a necessary condition for magnetic separation. Magnetic fields can be divided into even magnetic field and uneven magnetic field. The degree of uneven magnetic field can be reflected by magnetic field gradient----the change rate of magnetic field force along with the space moving. The bigger the magnetic field gradient is, the greater is the degree of uneven magnetic field. The magnetic force suffered by magnetic particles is in direct proportional to magnetic field intensity and magnetic field gradient. If the magnetic field gradient is zero, the magnetic particles will be not affected by magnetic force, thereupon, the magnetic separation will break down. Therefore, the even magnetic field is not suitable for magnetic drum separator.
In the process of magnetic separation, the ore particles are affected by a variety of forces, gravity, centrifugal force, water flow force, friction force, etc. in addition to magnetic force. When the magnetic force is greater than the sum of the rest forces, the magnetic particles will be sucked out or deviate from the material flow, classified into magnetic products, and the rest into non-magnetic products, realizing the separation of different magnetic minerals.