Silica recovery from waste obtained in hydrofluoric acid and aluminum fluoride production from fluosilicic acid

A procedure is presented for utilization of waste silicas from hydrogen fluoride synthesis and aluminum fluoride production. A method of purifying silica from fluorine impurities is given. Results of studies on application of by-product silicas from the fluorine processing as fillers for rubber mixtures and urethan elastomers is given. Conditions are presented for preparing chemically pure solutions of sodium and potassium metasilicates of average modules. The surface of the refined silica is modified by using methanol solutions of various silane coupling agents or titanate coupling agent solution in carbon tetrachloride. Effects of the type of the modifier used and of its amount on the strength of butadiene-styrene rubber vulcanizates and urethane elastomers are determined.