METHOD OF TREATING SPENT POTLINER MATERIAL FROM ALUMINUM REDUCTION CELLS

摘要

A process of treating spent potliner material from aluminum reduction cellsand recovering useful products. In the process of thepresent invention, spent potliner material is introduced into an acid digestercontaining, for example, sulfuric acid. As a result of thisstep, a gas component is produced which includes hydrogen fluoride, silicontetrafluoride and hydrogen cyanide. Also, a slurry componentis produced which includes carbon, a refractory material including silica,alumina, sodium compounds such as sodium sulfate, aluminumcompounds such as aluminum sulfate, iron compounds such as iron sulfate,magnesium and calcium compounds such as magnesium andcalcium sulfate. The slurry component remains in the digester after the gascomponent is removed. The gas component is recoveredand heated to an effective amount to convert or decompose the silicontetrafluoride to fumed silica, hydrogen cyanide to a remaining gascomponent.