Process for preparing phosphorus acid from industrial waste materials

Abstract

An improved process is provided for preparing highly purified phosphorus acid from industrial waste materials which are produced as by-products from the manufacture of sodium hypophosphite. Such industrial waste materials contain substantial quantities of calcium phosphite, and appreciable quantities of various metals such as iron, magnesium, aluminum and arsenic. The process of the present invention comprises, in a preferred embodiment thereof, reacting a slurry of said waste materials with sodium carbonate to produce calcium carbonate as a precipitate and a solution of sodium phosphite. The sodium phosphite solution is then passed through a cation ion exchange resin in the hydrogen form to produce a highly purified phosphorus acid product having significantly reduced quantities of metallic impurities.

Dependencies are inferred from the claim text.