Recycling of spent refractory materials to produce Al–Si master alloys via the aluminum reduction cell

Abstract

Abstract This paper explored a process for preparing Al–Si master alloys by recycling spent refractory material via aluminum electrolytic cells. The feasibility of spent refractory material electrolysis in the electrolytic cell was evaluated through thermodynamic analysis. The dissolution rates of alumina and spent refractory material were compared to obtain the appropriate mixing ratio. The effect of the addition of spent refractory material on the process was studied. The results show that the cryolite ratio, cathode voltage drop, and bath level were generally stable and had little negative effect on electrolysis. The current efficiency for the production of Al–Si master alloys was about 4% lower than that for the production of primary aluminum, which increased power consumption. However, the alumina consumption per ton of metal produced was reduced by 100 kg, which reduced the consumption of smelter grade alumina. Adding spent refractory material as a raw material to the aluminum electrolytic cell, fluorides were recycled to the electrolyte, whereas alumina and silica were electrolytically reduced to form liquid aluminum and silicon at the cathode. The process proposed shows immense advantage of generating no waste as slag, water or gas, and achieving cleaner production.