What is the function of cryolite?

Cryolite is a term that people often hear, but not many people know about it. In fact, the essence of cryolite is a mineral, which includes many chemical components, such as sodium hexafluoroaluminate. Cryolite has many characteristics, such as being slightly soluble in water, especially able to dissolve alumina. These properties make cryolite widely used in industry.

The role of cryolite:

It is rare in nature and is usually artificially produced. It is mainly used as a flux for aluminum electrolysis; it is also used as a wear-resistant additive for abrasive products, which can effectively improve the wear resistance and cutting force of the grinding wheel, and extend the service life and storage time of the grinding wheel; it is a flux for ferroalloys and boiling steel, a flux for non-ferrous metals, a deoxidizer for casting, a catalyst for olefin polymerization, and is used in glass anti-reflective coatings, emulsifiers for enamel, opacifiers for glass, flux for welding materials, fillers in the ceramic industry, pesticides and other industries.

Industrial quality requirements

Cryolite is used most in the aluminum industry, with annual global consumption of about 700,000 tons. In 1999, the market sales volume of cryolite in China was about 130,000 tons. As a flux for electrolytic aluminum smelting, cryolite must meet certain requirements in terms of sodium-aluminum molecular ratio, impurity content, water content, etc.

First of all, the ratio of sodium to aluminum in cryolite should be as high as possible. The higher the molecular ratio, the higher the current efficiency of electrolytic aluminum smelting, the less fluorine loss, and the less environmental pollution caused. In addition, high molecular ratio cryolite is more suitable for use in industries other than the aluminum industry.

Secondly, the content of impurities such as silicon oxide, iron oxide and phosphorus pentoxide in cryolite should be low. The presence of these impurities directly affects the quality of aluminum ingots and the current efficiency of aluminum smelting.

Third, the water content of cryolite should be as low as possible, as the presence of water will increase the consumption of cryolite.

Status of Cryolite in China

The production and application of high molecular weight cryolite have been studied and discussed in the United States and Japan. The production of high molecular weight cryolite using sodium fluorosilicate as raw material has been realized in industrial production. China's cryolite products comply with the GB/T4291-2007 standard, but each manufacturer will formulate corresponding corporate technical indicators based on the purpose and user requirements. The supply of cryolite in the market is relatively tight, which has a lot to do with the immature production technology of manufacturers. The products cannot meet user requirements. In addition, some of the raw materials used are also relatively tight and the cost of raw materials is too high, such as fluorite. In August 2008, the price of cryolite in China's domestic market was around 5,000 yuan/t.