PROCESS FOR OBTAINING TREATED COAL AND SILICA FROM COAL CONTAINING FLY ASH

摘要

A process for treating mixtures of solid coal and fly ash containing metallic oxides, silicon dioxide and sulfur compounds in order to produce treated coal and substantially pure silicon dioxide comprising (1) reacting a mixture of the coal and fly ash with hydrogen fluoride in water to produce a liquid stream comprising silicon fluoride and metal fluorides and a solids stream comprising unreacted coal and sulfur compounds; (2) reacting the sulfur compounds with metallic nitrates dissolved in water to form an aqueous solution of nitrate, metallic and sulfur ions; (3) separating the aqueous solution of nitrate, sulfur and metallic ions from the solid coal; (4) washing the previously treated solid coal with water; (5) reacting the silicon fluorides and metal fluorides with metallic nitrates in an aqueous mixture to form solid silicon dioxide; and separating the solid silicon dioxide from the aqueous mixture.