A method for the elimination of cyanide into spent cathodes linings of aluminum electrolysis cells under particular into consideration the fluoride recuperation

摘要

The process is used to destroy or detoxify the cyanide present in old furnace bottoms. This process overcomes the problems which result from the presence of cyanides in the used bottom carbon when this is leached or tipped. To solve the problem, the bottom carbon containing the cyanide, after appropriate size reduction is subjected to a thermal treatment in which both free and complex cyanide is destroyed. The carbon is preferably heated to a temperature in the range of 300-500 DEG C. Under these conditions, hydrogen fluoride or other fluorine compounds are not yet released.