CONVERSION OF HAZARDOUS CHROMIUM PLATING SLUDGE INTO ALUMINOTHERMIC CHROMIUM METAL

Chromium plating sludge waste from hard and decorative chromium platingoperations is classified as a hazardous waste and its disposal is a majorenvironmental concern. Climax Research Services (CRS) will develop techniquesto recycle the chromium metal values in the sludge back into the domesticmetallurgical industry as purified aluminothermic chromium metal. This proposaladdresses initially the hydrometallurgical treatment of chromium plating sludgeto remove unacceptable impurity elements. Using fractional crystallization ofchromium sulfate followed by calcination, a purified chromic oxide will beproduced from the sludge. Pre-proposal work by CRS has demonstrated thetechnical validity of this approach. The chromic oxide will then be transformedby aluminothermic reaction into commercially-viable pure aluminothermic chromiummetal, using procedures developed in a previous EPA research contract.Aluminothermic chromium metal sales will be directed at the national non-ferrousfoundry industry. This transformation of an environmentally harmful, hazardous,sludge into an environmentally acceptable industrial product is technicallyfeasible and commercially attractive. It responds directly to EPA concerns forhazardous waste disposal.