ã€China Aluminum Network】 Aluminum electrolyte is the core part of aluminum electrolysis. It is a high-temperature melt that connects the anode and the cathode. The electrolyte uses cryolite as the solvent and alumina as the solute. Because cryolite and alumina contain a certain amount of impurities, and in order to improve the physicochemical properties of the electrolyte in the electrolysis production, some additives are also added to the electrolyte, so the electrolyte for industrial production is composed of various components. Industrial aluminum electrolytes usually contain cryolite (about 80%), aluminum fluoride (9%~13%) and alumina (1.5%~3.5%) and additives calcium fluoride, magnesium fluoride, and lithium fluoride (5%~ 7%). The use of cryolite as a solvent for molten alumina is because it can basically meet the needs of aluminum electrolysis. It has the following features: (1) The molten cryolite can dissolve alumina, dissociate the alumina into ions and electrochemical reaction, and the primary crystal temperature of the electrolyte is lower than the melting point of the cryolite, thereby reducing the electrolytic reduction temperature of the alumina. . (2) At the electrolysis temperature, the density of molten electrolyte is lower than the density of aluminum liquid by about 10%. It can float well on the electrolyzed aluminum liquid, which simplifies the structure of the electrolyzer and reduces the oxidation loss of aluminum. , conducive to the electrolysis process. (3) The molten electrolyte has good fluidity. Under normal production conditions, it is beneficial to the separation of aluminum and electrolyte, and the discharge of gas, so that the electrolyte temperature and composition are relatively uniform in all parts of the tank. (4) The molten electrolyte has good electrical conductivity and thermal conductivity. (5) Cryolitic and solid electrolytes are essentially non-absorbent and have low volatility, which reduces electrolyte consumption and ensures relatively stable electrolyte composition. The above characteristics of the cryolite-alumina melt are not possessed by other substances. Therefore, it is appropriate to use cryolite-alumina fluoride molten salt system as an electrolyte in aluminum electrolysis production.
