Abstract: The specification discloses a method for the treatment of particulate materials such as soils and sludges containing arsenic compounds which comprises contacting the material with a source of iron (III) ions and a source of magnesium (II) ions to stabilize the material against leaching of arsenic. A preferred source of iron (III) ions is iron (III) sulfate and a preferred source of magnesium (II) ions is magnesium oxide.

Abstract: A process in which spent catalyst from chlorofluorocarbon production is treated to detoxify the catalyst for safe disposal or reprocessing. The spent catalyst includes antimony and arsenic halides, halogenated organic liquids, and has an upper liquid portion and a lower sludge or semisolid portion. The processing of both the liquid and sludge portions includes hydrolyzing the catalyst in an aqueous solution of ferric chloride resulting in formation of a ferric ion/fluoride ion complex in addition to insoluble compounds, and neutralizing the reaction mass following hydrolysis with an aqueous suspension of calcium hydroxide. The volatile organics are stripped from the neutralized reaction mass and collected for reuse or disposal. The reaction mass is dried to yield the insoluble compounds in a solid form for subsequent reprocessing or disposal.