Several methods of processing magnesite

In addition to the main component magnesium oxide, magnesite ore often contains impurities such as calcium oxide, FeCO3, MnCO3, Al2O3 and SiO2. In order to remove harmful impurities and improve the grade of ore, the current industrial beneficiation methods of magnesite mainly include flotation, roasting and chemical treatment.

1. Flotation method—using differences in physical and chemical properties to sort minerals

Flotation is one of the main processes for magnesite beneficiation. By alternately using reverse flotation and forward flotation, effective separation of target minerals and gangue minerals can be achieved. During the positive flotation process, it should be carried out under alkaline conditions. By adding inhibitors such as water glass, sodium hexametaphosphate or Aspergillus, calcium-containing minerals such as dolomite can be selectively inhibited to improve the purity of magnesite.

2. Magnetic separation method - efficient removal of iron impurities

The presence of iron impurities has a serious impact on the quality and refractory properties of magnesite. Magnetic separation is a common method for removing iron impurities. It uses strong magnetic force to separate iron minerals from magnesite. For different forms of iron, the magnetic separation method can effectively remove iron that exists in the form of homogeneous particles and iron-containing minerals such as magnetite, limonite, and chlorite embedded in magnesite.

3. Gravity separation method—optimizing the processing of ores with lower raw ore grades

The gravity separation method is suitable for processing magnesite lumps with lower raw ore grade and coarser particle size. Through the heavy media beneficiation method, the difference in density between different minerals is used for sorting. Commonly used gravity separation equipment includes conical resuspension separators, drum resuspension separators and heavy medium cyclones. This method can improve the recovery rate of magnesite and reduce production costs.

4. Roasting method - using thermodynamic properties to achieve mineral separation

The roasting method utilizes the differences in thermodynamic properties between different minerals to roast magnesite at high temperatures. By controlling the roasting temperature and time, the magnesite is decomposed and carbon dioxide is released. The resulting light-burnt magnesium is brittle and easy to crush and screen; while the gangue mineral talc becomes hard, thereby achieving effective separation of the two minerals. The roasting method has the advantages of low cost and simple process, but its effect is limited when dealing with complex ores, and it is generally used as a pretreatment or preenrichment operation.

5. Chemical treatment method—preparation of high-purity magnesite products

For magnesite ores with finer mineral embedded particle size and homogeneous impurities, chemical treatment has become an effective treatment method. After increasing the surface activity and solubility of the ore through high-temperature calcination, it is leached using hydrochloric acid, nitric acid, sulfuric acid, ammonium salt or bicarbonate, etc., and the impurities are separated according to the degree of leaching, and finally a high-purity magnesium oxide product is obtained. Chemical treatment method has high treatment effect, but the operation is complicated and the cost is high.

6. Photoelectric beneficiation and electrostatic beneficiation—innovative technology improves separation effect

In addition to the traditional methods mentioned above, innovative technologies such as photoelectric beneficiation and electrostatic beneficiation have also shown certain application potential in magnesite sorting. Photoelectric beneficiation uses the difference in surface color of minerals for sorting; electrostatic beneficiation uses the rectification and critical potential differences of minerals to achieve mineral separation in a high-voltage electric field.