Abstract: The present invention, relates to the recovery of zinc values from an acidic solution containing hydrocyanic acid. The zinc is recovered as complex zinc cyanide anions which may, if desired, be recycled for the (selective) preliminary removal or separation of adsorbed copper values from an (strong or weak base) anion exchange material, the anion exchange material additionally being loaded with adsorbed cyanide complexes of precious metal values such as gold and silver. The invention, further relates to the recovery of cyanide values associated with copper cyanide complexes which are adsorbed on or taken up by an (strong or weak base) anion exchange material; the recovered cyanide values, for example, being available for recycling to a cyanide leach stage for leaching additional metal values from an ore or the like.

Abstract: The present invention relates to the decontamination of soil and the like and, in particular, soils which are contaminated with metal as a result of the activities of human beings. The invention provides a physical and a chemical means for treating soil aggregate so as to obtain a product aggregate having a relatively low metal content. The physical means is characterized by the classification of a soil aggregate into portions of differing size and metal content. The chemical means is characterized by contacting a soil aggregate with an aqueous lixiviant comprising an organic acid component to lift metal from the aggregate. The physical and chemical means may be used in a combined process for decontaminating soil aggregate.