First, aluminum fluoride is produced by a wet process. The gas generated after the high-temperature reaction of sulfuric acid and fluorite is directly absorbed into 30% to 35% hydrofluoric acid, and then it is synthesized with aluminum hydroxide at about 90°C. AlF33H2O is filtered and dehydrated and dried at high temperature to obtain aluminum fluoride AlF3 finished product.
As the water vapor generated during dehydration decomposes AlF3, the wet aluminum fluoride content is low, impurities are high, water content is high, bulk density is low, and fluidity is poor. Basically, it is not suitable for modern electrolytic cells and belongs to the elimination process. Nowadays, the dry production process is more commonly used, that is, the crude acid dry method.
The gas produced by the high temperature reaction of sulfuric acid and fluorite enters the fluidized bed after rough washing, and reacts with dry aluminum hydroxide to form fluoride under high temperature aluminum. Since the hydrogen fluoride content after rough washing is about 96%, The impurities are higher, and the impurities of aluminum fluoride products are also higher. Especially without desiliconization, the silicon dioxide content of aluminum fluoride manufacturers' products reaches 0.25%. These impurities will affect the quality of electrolytic aluminum and increase the power consumption during the electrolysis process.