How the Chemistry of Raw Materials Affects Aluminum Produced in Cells with Prebaked Anodes

Abstract

This paper analyzes how major impurities found in raw materials affect the chemistry of primary aluminum. Alumina and prebaked anodes tend towards lower quality due to the depletion of natural sources of high-quality bauxites and using low-quality carbon to make prebaked anodes (PA). The authors analyzed the chemistry of raw materials supplied for electrolysis. The paper shows the investigated upward trends in the presence of Fe and Si impurities in alumina and prebaked anodes, which jeopardizes the aluminum production process. The increased presence of such materials worsens the chemical composition of the resulting liquid aluminum. If the finished product is to be of high quality, alumina and PA mast contain, respectively (wt.%): 0.010 and 0.024 Fe, 0.013 and 0.022 Si. The proposed idea is to categorize the alumina in storage. Alumina from different manufacturers must then be batched in such a way as to have consistent, ‘averaged’ chemistry before going to electrolysis cells.