Leaching behavior of zinc from crude zinc oxide dust in ammonia leaching

Zinc extraction from crude zinc oxide (CZO) is beneficial to the full utilization of secondary resources and environmental protection. In this paper, a systematic investigation was carried out to study the leaching behavior of CZO by using ammonia-ammonium carbonate solution. It was found that the maximum leaching rate of zinc from CZO dust was 95.7% under the conditions of [Zn]T: [NH3]T: [CO32−] =1: 7.00: 1.75, liquid to solid ratio 5: 1, leaching temperature 30 °C and leaching time 60 min. Compared with pure zinc oxide (PZO) leaching, the CZO leaching required longer time and more leaching agents, which is caused by the Cd2+, Pb2+ and other metal cationic impurities in CZO. The metal cationic impurities dissolved in the leaching solution and combined with ammonium to form complexes, consuming leaching agents and affecting zinc leaching.