Cryolite, also known as sodium fluoroaluminate or sodium aluminum fluoride, has a molecular formula of Na3AlF6. It is a small white crystal with no smell. Its solubility is greater than that of natural cryolite. Its specific gravity is 3, hardness is 2 ~ 3, melting point is 1000 ℃, and it is easy to absorb water and moisture. Cryolite is mainly used as flux for aluminum electrolysis, wear-resistant filler for rubber and grinding wheel, enamel opal, glass shading agent and metal flux, pesticide for crops, etc. Hall heroult process uses cryolite based fluoride melt as solvent to produce metal aluminum. So far, no other compound has been found to replace cryolite.
Electrolytic aluminum carbon slag is a kind of solid hazardous waste material. Its main components are carbon, fluoride, alumina, iron compounds and other trace elements. Once there is a large amount of carbon slag in the electrolytic cell, it will seriously endanger the power production, such as increasing the electrolyte voltage, increasing the power consumption and shortening the service life of the electrolytic cell, resulting in the decline of the comprehensive economic index of electrolytic production. Therefore, the carbon slag in the electrolytic cell must be salvaged in time.
The sluggish development of recycled cryolite and electrolytic aluminum industry is caused by many reasons. Behind this phenomenon, there is a huge realistic gap and the negative impact of overcapacity. The deep-seated reform of the chemical industry is the inevitable road of development. Cryolite manufacturers should deeply analyze their own shortcomings, develop new industrial technologies and produce cryolite in combination with production methods at home and abroad, so that their production and development can be on the right track.
Why this phenomenon? There are many reasons. In many non-ferrous metal industries, the contradiction of aluminum industry is prominent, or the problem of oversupply left by overcapacity makes the development of aluminum industry difficult. As the name suggests, electrolytic aluminum needs a lot of electricity. The excessive consumption of electricity will inevitably lead to the bad development of the industry. Such a production mode is facing the risk of being eliminated.
It is mainly used as flux for aluminum electrolysis; It is also used as a wear-resistant additive for grinding products, which can effectively improve the wear-resistant, cutting and cutting force of the grinding wheel, and prolong the service life and storage time of the grinding wheel; Ferroalloy and boiling steel flux, nonferrous metal flux, casting deoxidizer, alkene polymerization catalyst, as well as anti reflective coating for glass, emulsifier for enamel, opacifier for glass, flux for welding materials, filler for ceramic industry, pesticide, pesticide and other industries and enterprises. This is because cryolite not only can dissolve alumina, but also has some other indispensable properties, such as no elements with higher electrical properties than aluminum, good stability, no decomposition, volatilization and deliquescence under general conditions, higher melting point than aluminum, good conductivity, saving electricity, etc. It can be said that without cryolite, there might not be such a large-scale aluminum industry in the world, the price would not be so low and the application would not be so extensive.
