Oxidation of cyanide in a hydrocyclone reactor by chlorine dioxide

The greatest amounts of cyanide-containing wastes are produced by precious metals milling operations, the electroplating industry and coal processing or coking effluents processes. Because of high toxicity and to comply with federal and state regulations, the treatment of wastewater is required befo re safe discharge of cyanide wastes. In this regard, the gas-sparged hydroc yclone (GSH) has been tested as a reactor for the treatment of cyanide solu tions for cyanide destruction by oxidation with the use of chlorine dioxide gas (ClO2). The results show oxidation efficiencies of free cyanide approa ched 99% at all pH values in 5 min. The use of NaCl was also considered for the generation of chlorine dioxide. Excellent performance appears to offer operational and cost advantages over conventional processes.