Research On The Leaching Process Of Zinc-bearing Ash In The System Of Ammonia-ammonium Bicarbonate

The behavior of zinc and main impurities in three kinds of typical zinc-bearing ashes was analyzed. The effects of pH, total ammonia concentration, ratio of solid to liquid (L/S), temperature and leaching time on the leaching behavior of zinc and main impurities in three kinds of pretreatmented zinc-bearing ashes were investigated.Zinc in three kinds of typical zinc-bearing ashes was primarily presented as the form of insoluble zinc oxide, and the grades of which were over50%. The impurity elements containing Cu, Fe, Mn, Pb and Cd were presented as the form of insoluble compounds, and the contents of Fe and Pb were evident higher than that of others. The impurity element Cl in ashes could be completely removaled after washed with water.In the ammonia-ammonium bicarbonate system, the leaching of zinc and parts of impurities such as Fe, Mn and Pb could be promoted with the increase of pH, whereas depressed when pH was higher than10.50. And the leaching of Cu and Cd could be promoted with the increase of pH. The leaching yield of zinc and main impurities could be increased by raising the L/S and leaching temperature. The effects of total ammonia concentration and leaching time on the leaching yield of zinc and main impurities were faint. The leaching yield of zinc was over80%for three zinc-bearing ashes under the conditions including total ammonia concentration of9mol/L, pH of10.00, L/S of5, temperature of50℃and the reaction time of60min. The mian impurities in the leachate could be effectively removed by oxidation and cementation.