What is cryolite

Cryolite raw materials and finished products

Cryolite is a mineral, also known as sodium hexafluoroaluminate (Na3AlF6), which is a small white crystal with no odor. It has a higher solubility than natural ice crystals, a specific gravity of 3, a hardness of 2-3, a melting point of 1000 ℃, and is prone to water absorption and moisture.

The use and function of cryolite

Cryolite is rarely produced in nature and is usually artificially manufactured. Mainly used as a flux for aluminum electrolysis; Also used as a wear-resistant additive for grinding products, it can effectively improve the wear resistance, cutting force, and extend the service life and storage time of grinding wheels; Iron alloy and boiling steel fluxes, non-ferrous metal fluxes, casting deoxidizers, olefin polymerization catalysts, as well as emulsifiers for glass anti reflective coatings, enamel, glass opalescent agents, welding flux for ceramics, fillers for pesticides, insecticides and other industries.
In addition to being able to dissolve alumina, cryolite also has other essential properties, such as not containing elements with higher electrical conductivity than aluminum, good stability, no decomposition, volatilization, or deliquescence under general conditions, a melting point higher than aluminum, good conductivity, and energy savings. It can be said that without cryolite, the world may not have such a large-scale aluminum industry, prices would not be so low, and applications would not be so widespread.

Cryolite beneficiation process flow

1. Take out the carbon residue from the electrolytic cell, cool it down and crush it, then use a crusher or sand making machine to finely crush it to 3mm, and then use a ball mill to grind it to the most suitable particle size for flotation, which is 0. 45 to 0. 76mm size.
2. There are flotation reagents in the mixing drum, and the ground carbon slag and reagents are thoroughly stirred in the mixing drum.
3. The carbonaceous solid waste in aluminum electrolysis production, including anode waste residue and waste anode carbon blocks, is crushed using crushers, sand making machines, and ball mills. The grinding machine powder is then sent into flotation cells according to different categories and flotation agents and clean water are added. The amount of flotation agent used per ton of material is 50-200g, and the slurry concentration is controlled at 30% -50%. The pH value of the slurry system is adjusted to 2-5 using inorganic acids. The single flotation time in the flotation cell is 5-10 minutes. After multiple flotation cycles, electrolytes and carbon powder are obtained.
The equipment used by Jihong Machinery undergoes processes such as crushing, screening, and purification. The equipment is simple and highly automated, and the produced cryolite fully meets national standards. The profit margin of cryolite is huge, the price advantage is obvious, and the product does not have to worry about sales.

Ice crystal crusher equipment

The four roll crusher is a medium and fine crusher with a simple structure and reliable performance. The four roll crusher is suitable for the fine crushing operation of solid materials with compressive strength less than 300Mpa and moisture content less than 30%, such as crushing various ores, coke, coal, ceramic raw materials, water slag, gypsum, salt, clay, chemical raw materials, etc. or solid materials with hardness equivalent to the above. It has the characteristics of low maintenance cost, large crushing ratio, reliable performance, low over crushing rate, less dust, and low noise. （Click to view more information about the four roll crusher）

Ice crystal grinding equipment

Energy saving ball mill is a key equipment for crushing materials after they have been crushed. It is widely used in the production industries of cement, silicate products, new building materials, refractory materials, fertilizers, black and non-ferrous metal beneficiation, and glass ceramics, for dry or wet grinding of various ores and other grindable materials. （Click to view more information about cryolite grinding equipment）

Select ice crystal stone supporting equipment

The mining mixing bucket is suitable for various metal ores, mainly used for mixing before flotation to fully mix the reagents with the slurry, and can also be used for mixing other non-metallic minerals. （Click to view more selection of cryolite supporting equipment）

The Six Major Functions of Cryolite in Aluminum Smelting Process
1. Pure cryolite does not contain metal impurities with a higher precipitation potential (discharge potential) than aluminum. As long as impurities are not introduced from the outside, electrolytic production can obtain relatively pure aluminum.
2. Cryolite can dissolve alumina well, and the solubility of alumina in cryolite solution is about 10% at an electrolysis temperature of 950 ℃ -970 ℃.
3. At the electrolysis temperature, the density of the cryolite alumina solution is lower than that of the aluminum liquid at the same temperature. It floats on the aluminum liquid to prevent aluminum oxidation and facilitate better separation between the electrolyte and aluminum.
4. Cryolite has a certain conductivity, which prevents the voltage drop of the electrolyte layer from being too high.
5. Cryolite melt has a certain fluidity at the electrolysis temperature, and the anode gas can be discharged from the electrolyte, which is beneficial for the circulation of the electrolyte.
6. In the molten state, cryolite does not absorb water and has low volatility, reducing material consumption and ensuring electrolyte stability.

At present, there are several main processes for producing cryolite both domestically and internationally
Hydrofluoric acid method: can be divided into dry and wet methods. Dry method is to react gaseous hydrofluoric acid with aluminum hydroxide at 400-700 ℃ to produce fluoroaluminate (H3AlF6), which is then reacted with soda ash at high temperature to produce. Wet method is produced by reacting 40-60% hydrofluoric acid with aluminum hydroxide and then adding soda ash.
Fluorosilicic acid method: It can be divided into ammonium fluoride intermediate product method and sodium fluorosilicate intermediate product method. The former is generated by reacting fluorosilicic acid with ammonia water after ammonification and then with sodium aluminate. The latter is produced by recovering sodium fluorosilicate from fluorine-containing waste gas in phosphate fertilizer production, and then undergoing processes such as ammonification synthesis.
Carbonation method: Cryolite can also be produced by adding carbon dioxide to sodium aluminate and sodium fluoride solutions.
Aluminum industry recycling method: Dilute hydrofluoric acid recovered from the waste gas of aluminum refining can react with sodium aluminate to recover cryolite.
Alkali method: It is obtained by roasting, crushing, and leaching soda ash, fluorite, and silica sand, and then reacting them with aluminum sulfate. It is rarely used in industry.