Magnetic separation is one of the most important separation methods in mineral processing engineering. At present, magnetic separation technology is generally recognized by strong magnetic separation, weak magnetic separation and multi-stage separation, so as to select the final concentrate.
Magnetic separation is divided into dry separation and wet separation. Different mineral processing methods are selected for different mineral compositions. The main problems facing dry selection are the problem of dust diffusion, how to prevent the diffusion of mineral dust effectively, not to pollute the environment, and to ensure the health of the workers. The better effect of wet separation is downstream magnetic separator, which has good taste of concentrate and high recovery rate. Of course, the magnetic separator used in the coal preparation plant is recommended to use the counter current type magnetic separator, the countercurrent is a kind of magnetic separator to ensure the recovery rate. The coal preparation plant is required to recover the heavy medium, so the recovery rate and countercurrent are more suitable.
Magnetic separation process is a dry and wet magnetic separation process method for magnetite. The magnetic separation process is mainly a three-level magnetic separation process for ore powder. After wet material magnetic separation, the magnetic field strength selected for magnetic separation is 400 ~ 1200 GS, The magnetic drum rotation speed is 60 to 320 revolutions per minute. The wet material is dehydrated into finished iron concentrate powder. Generally, the iron content is 35 % of the ore. After the magnetic selection of this method, the iron concentrate powder iron content can reach 68 to 70 %. The combined process method, The utilization rate of ore can reach 90 %, and the water consumption in the process is low, water saving, cost reduction, and pollution reduction. The dust selected by the magnetic dust is captured by the dust removal device and will not cause air pollution. This method is a production efficiency and product quality. Creative process methods that are free from environmental pollution.
The magnetic selection process is mainly carried out in the magnetic separator. The process is that when the slurry enters the sorting space, the magnetic ore is magnetized under the action of a non-uniform magnetic field, which is affected by the magnetic field attraction, so that it is sucked on the cylinder and then carried by the rotating cylinder to the discharge end. Discharge into magnetic products. Non-magnetic ore particles, due to the small magnetic field force they receive, remain in the slurry and are discharged into non-magnetic products. This is the magnetic separation process.
When the mineral particles pass through the magnetic field of the magnetic separator, they are simultaneously affected by magnetic force and mechanical force(gravity, centrifugal force, dielectric resistance, friction, etc.). The magnetic force of a more magnetic ore is greater than the mechanical force it receives, and the magnetic force of a non-magnetic ore is small, and the mechanical force dominates. Due to the different combined forces of magnetic and mechanical forces acting on various ore grains, their trajectories are also different, so that the final separation of minerals can be achieved.
Application of magnetic separation process: black metal ore separation-iron ore magnetic separation; Selection of colored and rare metals-tungsten tin separation, copper Molybdenum separation, copper lead separation; Magnetic separation recovery of magnetic heavy intermediates in heavy medium ore dressing; Removal of iron-containing impurities in the ore dressing of non-metallic mineral raw materials-Kaolin iron removal; Wastewater treatment.
1. Weak magnetic separation of magnetite
The ore treated by daguoshan iron ore of anshan iron and steel company in China is anshan type poor magnetite. The original iron content is 30 % ~ 40 %, and the sio2 content is 42 % ~ 46 %. The principle process adopted is the phase grinding phase selection process, and the separation equipment is the permanent magnetic dehumidification groove and the permanent magnetic tube type magnetic separator.
2. Reduction roasting of hematite, mirror iron ore, siderite-weak magnetic selection, strong magnetic selection for manganese iron ore, wolframite coarse concentrate and zirconite coarse concentrate, ilmenite, high territory and coal.