Pyrohydrolysis system for processing fluorine- containing spent and waste materials

Abstract From the Canadian patent

A pyrohydrolysis system is provided for the recovery of valuable components from waste and spent materials generated in electrolytic aluminum reduction facilities. The pyrohydrolysis system employs a dense phase fluidized bed reaction zone for the pyrohydrolysis of coarse feed, a dilute phase fluidized reaction zone for pyrohydrolyzing fine feed, this zone being superimposed and interconnected with the dense phase zone. The offgases after removal of the solids, are contacted in a dilute phase fluidized zone, with a source of Al2O3 to remove residual Na values and to produce Na-free HF. The solids from the first dilute zone, having a desired high Na:Al atom ratio, can be combined with the …