Process for removing phosphorus and heavy metals from phosphorus trichloride still bottoms residue

摘要

Unreacted phosphorus and heavy metals, such as arsenic and antimony, are removed in environmentally acceptable form from the non-aqueous still bottoms residue resulting from the production of PCl3, by reacting the residue with an excess of calcium hydroxide in the form of an aqueous lime slurry and separating the reaction product into a precipitate and a filtrate. The reaction with lime slurry may be preceded by hydrolysis with water. The precipitate passes the Toxicity Characteristic Leaching Procedure (TCLP) test and the filtrate contains less than 5 ppm of the heavy metals, thus permitting disposal by landfill and sewering, respectively, under EPA regulations.