Dissolution and Agglomeration Behavior of Alumina in Aluminum Electrolysis

The agglomerating behavior and heat transfer process upon the addition of smelting grade alumina into cryolite electrolyte were studied using the see-through cell platform, especially the formation and dissolution of the agglomerate. The dissolution rate of the alumina agglomerate was measured, and physicochemical properties of the alumina agglomerate was analyzed. The influence factors, such as the electrolyte temperature, alumina feeding amount, alumina preheating temperature and superheat during the dissolution and formation of the agglomerate were investigated through heat balance calculation. The results show that during the re-establishment of a new heat balance after alumina feeding, the absorbed heat for alumina dissolution is firstly supplied by electrolyte cooling. When the temperature drop is above the liquidus temperature of the electrolyte, which cannot provide enough heat for the dissolution, electrolyte condensation would take place and release more heat. In contrast to a relatively high electrolyte temperature and high superheat, a high frequent and small amount of alumina feeding would benefit the electrolysis process. © 2021, Editorial Department of Journal of Northeastern University. All right reserved.