Molten cryolite is a mineral. Monoclinic crystal system. Columnar crystal or block. Mohs hardness of 2.5. The density is 2.97 to 3.00 g/cm. The refractive index is 1.38-1.339. Birefringence 0.001, positive light. The dispersion value is 0.024. Glass luster to grease luster. Transparent. Colorless, white, brown or red. Produced in granite and pegmatite veins that invade gneiss. It is used as a flux in the electrolytic aluminum industry to produce opacifiers for opalescent glass and enamel. No other compound has been found to replace molten cryolite. This is because molten cryolite has other indispensable properties besides being able to dissolve alumina, such as elements that do not contain more positive electrical properties than aluminum, have good stability, do not decompose under normal conditions, are non-decomposable, do not deliquesce, and have a high melting point. In aluminum, it has good electrical conductivity and saves electricity. It can be said that if there is no molten cryolite, there may not be such a large-scale aluminum industry in the world, the price will not be so low, and the application will not be so extensive. Molten cryolite can be made from hydrofluoric acid, sodium carbonate and aluminum. The main producing area is Greenland.
Improve grinding wheel wear, cutting, cutting force, flux, aluminum electrolysis
The dissolution of alumina in molten cryolite is divided into two steps, namely the rapid dissolution of alumina and the shedding and dissolution of the agglomerated alumina on the surface of the electrolyte. The dissolution of alumina in molten cryolite is slowed down due to the decrease of electrolyte temperature due to the addition of alumina, and the formation of alumina/electrolyte agglomeration on the surface of the electrolyte, causing the surface area of alumina to contact with molten cryolite to decrease. The dissolution rate of alumina is related to the stirring speed, the preheating temperature of alumina, the temperature of the system and the type of alumina.
It is mainly used as a flux for aluminum electrolysis; it is also used as an anti-wear additive for grinding products, which can effectively improve the wear resistance, cutting and cutting force of the grinding wheel, prolong the service life and storage time of the grinding wheel; flux of ferroalloy and boiling steel, non-ferrous metal flux, casting deoxidizer, olefin polymerization catalyst, as well as glass anti-reflective coating, enamel emulsifier, glass emulsifier, welding material flux, ceramic filler, pesticide pesticides, etc. .