Use of leaching cake from refractory lining of dismantled electrolysers in cement production

Abstract

A hydrometallurgical technology has been proposed for processing the refractory part of the lining of aluminum production electrolysers dismantled and disabled for overhaul. Fluorine-containing compounds are transferred to the solution, which allows obtaining cryolite for being used in the electrolysis process. It is recommended to use solid residue from leaching (cake) with a minimum content of alkalis and fluorine as an additive to the mixture for cement production. According to the results of experiments on obtaining portland cement by traditional firing technology, the limiting content of alkali metal oxides (not higher than 4.5% by weight, calculated as Na2O) in the leaching cake was determined, the optimum content of this additive in the charge is from 5 to 12% depending on chemical composition of lime used.