Methods for purifying and reducing impurities in magnesite

Magnesite is a key raw material for the production of magnesium materials and is widely used in the fields of magnesium metal, refractory materials and chemical building materials. Its main component is magnesium carbonate, but impurities such as silicon dioxide, calcium oxide and iron oxide will affect the quality and use of the product. High-purity magnesite raw materials can improve the performance and value of end products.

Magnesite is a trigonal carbonate mineral with magnesium as the main component and contains trace impurities such as silicon, calcium, aluminum and iron. These impurities exist in different forms. For example, calcium mostly exists in the form of inclusions or interstitial fillings between crystals, while silicon mainly affects hardness and acid solubility.

In order to purify magnesite, the commonly used flotation method can effectively remove silicon and calcium impurities. Reverse flotation is used for desiliconization, and positive flotation is used for decalcification. In addition, electrostatic separation, thermal separation and gravity separation can also desiliconize and reduce calcium to a certain extent. Magnetic separation is the main method for removing iron impurities and is often used in combination with other processes.

For magnesite with finely embedded and isomorphous impurities, traditional beneficiation methods have limited effects and produce a large amount of waste tailings. Therefore, chemical removal methods such as ammonium salt method, hydration method, acid leaching method and carbonization method are adopted. These methods roast magnesite, add reagents to separate magnesium ions, and then treat them by pyrolysis, calcination, etc. to obtain high-purity magnesium oxide.

In summary, there are various purification technologies for magnesite, including physical and chemical methods, which aim to improve the quality and application range of magnesium products.