Removal of heavy metals and cyanide from gold mine waste-water by adsorption and electric adsorption

BACKGROUNDCyanide leaching is the most widely used technology in the gold industry and this process produces large amounts of waste-water requiring treatment before returning to the environment. There are several established techniques available to treat such toxic waste but all have some disadvantages. This study considers the use of electrical adsorption treatment of a gold mine waste-water containing cyanide, high copper, iron, and thiocyanate content, as well as the precipitating liquid without iron. RESULTSA cell fitted with carbon electrodes made from low grade coal was used in this study and using an applied voltage of 2.0V, plate spacing of 1cm, and adsorption time of 24h, the electric adsorption process provided good results on the raw cyanide waste-water, with observed percentage removal of total cyanide (71.14), zinc (99.52) and iron (83.28). The liquid waste, following precipitation of the raw solution with zinc sulfate, was also studied and after 5h the percentage removals of cupric ion were 90.63, 71.49 and 90.63, respectively. Analysis showed that in the process of electric adsorption, the ions in solution interacted by directional migration, enrichment precipitation and adsorption processes. CONCLUSIONSElectrical adsorption provides a suitable process for the treatment of waste-waters from the cyanide leaching of gold. (c) 2015 Society of Chemical Industry