Magnetic separation is an effective beneficiation method. According to the difference in specific magnetic susceptibility of various minerals, magnetic separation is carried out with magnetic separators with different magnetic field strengths, which are generally divided into three categories.
1. Strong magnetic minerals, with a specific magnetic susceptibility greater than 3000*10-6 cm3/g, such as magnetite, pyrrhotite, etc., can be effectively separated from gangue minerals by weak magnetic separation equipment.
2. Medium magnetic minerals, the specific magnetic susceptibility coefficient is 500-3000*10-6 cm/g, such as semi-phantom hematite and some ilmenite, chromite, etc., use medium magnetic field magnetic separation equipment for separation.
3. Weak magnetic minerals, with a specific magnetic susceptibility of 15~500*6 cm3/g, such as hematite, limonite, iron carbonate, ferromanganese, drusenite, rhodochrosite, rutile and some ilmenite, etc. , It is recovered by strong magnetic separation and other methods, and the specific magnetic susceptibility is less than 15*10-6 cm3/g. It is a non-magnetic mineral, such as quartz, feldspar, fluorite, etc.
The magnetic separation process should be selected through tests. For magnetite ore, in general large and medium-sized magnetic separation plants, when the grinding particle size is greater than 0.2 mm, one-stage grinding and magnetic separation are commonly used; when it is less than 0.2 mm, two-stage grinding is used. Magnetic separation, if some qualified concentrates can be selected under rough grinding conditions, the staged grinding section separation process is adopted. If the tailings can be discarded after roughing under rough grinding conditions, the process of rough grinding and roughing and regrinding of the rough concentrate can be used. When the ore contains weak magnetic minerals and strong magnetic minerals, the weak magnetic-strong magnetic combined process can be used. . When the ore can be discarded under the condition of large lumps, magnetic pulleys can be used to pre-separate and discard part of the waste tailings. In water-deficient areas, dry grinding and dry magnetic separation can be used.
Magnetization Roasting Magnetic separation is mainly to deal with weak magnetic iron ore. The ore is heated during roasting and the weak magnetic iron ore is changed into strong magnetic iron ore in a suitable post-atmosphere, and then magnetic separation can be carried out to obtain better separation. index. There has been a long-term production practice for reduction and roasting of 75-20 mm lump ore in my country.