Aluminum Electrolyte Liquidus Temperature Determination And Applied Research

Bath temperature, liquidus temperature and cryolite ratio are important parameters in Hall-Heroult for aluminum electrolysis. Low liquidus temperature enables low bath temperature. The current efficiency increases with the decreasing of bath temperature. It is difficult to determine the temperature parameters of the aluminum electrolyte because of its corrosive nature and high temperature. It has become an important task to exactly measure bath temperature, liquidus temperature and cryolite ratio quickly.Direct method for measuring the temperature parameters of aluminum electrolyte was studied in present paper, and a suitable thermocouple and a sampling implement for this method were obtained through lots of experiments. On the basis of this method and the characteristics of the bath, a instrument named CQ- II molten salts liquidus temperature analyzer was developed. The results of spot experiments show that it is very convenient and fast to obtain accurate temperature parameters of aluminum electrolyte with this instrument.An uniform design is adopted to test the relationship of cryolite ratio, additives and liquidus temperature of the system Na₃AlF₆-Al₂O₃-MgF₂-CaF₂-LiF, a mathematical model was obtained and proved by experiments of actual aluminum electrolyte. The results show the deviation between the predicted value of liquidus temperature gained from the model and the measured is within ±5℃. The deviation between of predicted value of liquidus temperature gained from the model and the measured is within ±0.09.