Calcium fluoride introduction: characteristics and application fields

Calcium fluoride is an inorganic compound with the chemical formula CaF2. It is colorless crystal or white powder. Calcium fluoride is insoluble in water, slightly soluble in inorganic acids, and reacts with hot concentrated sulfuric acid to generate hydrofluoric acid. Calcium fluoride is generally prepared by the action of calcium carbonate and hydrofluoric acid or repeated treatment of fluorite powder with concentrated hydrochloric acid or hydrofluoric acid. Calcium fluoride minerals in nature are fluorspar or fluorspar, often in gray, yellow, green, purple and other colors, sometimes colorless, transparent, glassy, brittle, and have significant fluorescence.

Physical and chemical properties of calcium fluoride

Density: 3.18g/cm3

Melting point: 1402°C

Boiling point: 2500°C

Refractive index: 1.434

Crystal structure: It belongs to the equiaxed crystal system, in the form of cube, octahedron or dodecahedron.

Colorless crystal or white powder, natural ore contains impurities, slightly green or purple. Glows when heated.

Calcium fluoride is extremely insoluble in water, soluble in hydrochloric acid, hydrofluoric acid, sulfuric acid, nitric acid and ammonium salt solution, insoluble in acetone. It forms a complex when dissolved in aluminum salt and iron salt solutions, and reacts with hot concentrated sulfuric acid to generate hydrofluoric acid. Calcium fluoride reacts with concentrated sulfuric acid in a lead vessel to produce hydrogen fluoride. It can form eutectics with various metal oxides.

Application fields of calcium fluoride

Calcium fluoride has a wide range of uses, and with the advancement of science and technology, its application prospects are becoming more and more broad. It is mainly used in the three major industries of metallurgy, chemical industry and building materials, followed by light industry, optics, engraving and national defense industry. Therefore, according to the application requirements, my country's fluorite mineral products mainly include four series of varieties, namely fluorite lump ore, fluorite concentrate, fluorite powder ore, and optical and engraved fluorite.

Metallurgical Industry

Fluorite has the characteristics of lowering the melting point of refractory substances, promoting the flow of slag, separating slag and metal well, desulfurizing and dephosphorizing during the smelting process, and enhancing the forgeability and tensile strength of metals. Therefore, it is widely used as a flux in iron and steel smelting and ferroalloy production, ferrochemical process and non-ferrous metal smelting.

Chemical industry

Another important use of fluorspar is the production of hydrofluoric acid. Hydrofluoric acid is produced by reacting acid-grade fluorspar (fluorspar concentrate) with sulfuric acid in a heating furnace or tank. It is divided into anhydrous hydrofluoric acid and hydrofluoric acid with water. They are both a colorless liquid. , volatile, has a strong pungent smell and strong corrosiveness. It is a key raw material for the production of various organic and inorganic fluorides and fluorine elements.

Building materials industry

Fluorite is also widely used in building materials industries such as glass, ceramics, and cement, and its consumption ranks second in China.

In the glass industry, fluorite is added as a flux and opacifying agent, which can promote the melting of glass raw materials; in cement production, fluorite is added as a mineralizer. Fluorite can lower the sintering temperature of the charge, reduce fuel consumption, and at the same time enhance the liquid phase viscosity of the clinker during sintering and promote the formation of tricalcium silicate; in the ceramic industry, fluorite is mainly used as enamel, and it can be used in the production of enamel It plays the role of color aid and flux in the process; fluorite is also used in the enamel industry and cast stone production.

Other uses

With the improvement of people's living standards, the demand for jewelry and handicrafts continues to increase. Fluorite has a dense structure, bright and diverse colors, and is valued as a raw material for craft carving.