Hydrometallurgical recovery of zinc from hot dip galvanizing ash

In this laboratory study a process has been developed for zinc recovery from chloride-containing zinc ash formed during hot dip galvanizing. The ash is leached with diluted H 2SO 4 and the main impurities, such as iron, copper, cadmium, and organic compounds are removed from leach liquors by pH-controlled precipitation using ZnO as a neutralizing agent. The process is finished by active carbon and cementation precipitation. Chloride-free zinc hydroxy-carbonate is precipitated from purified leach solutions. Metallic zinc is obtained by the electrowinning process performed with zinc sulphate solution originating from dissolution of zinc hydroxy-carbonate prepared in diluted H 2SO 4.