Removal of zinc from blast furnace dust by chemical leaching

Chemical leaching zinc from blast furnace dust concentrate(BFDC) treated by physical separation was investigated in order to reduce the content of zinc,and all common operating factors,such as leaching duration,temperature,ratio of liquid to solid and stirring rate,have tested.The results show that among the three leaching chemicals tested(sulfuric acid,ferric chloride and amine) sulfuric acid is the best one for leaching zinc.A zinc leaching rate of 73.9% is achieved and resultantly the content of zinc in the product is reduced from 1.46% to 0.38% under the following proper leaching conditions: ratio of liquid to solid 8?1,room temperature(about 20 ℃),acid concentration of 125 g/L,leaching time 35 min and stirring rate 150 r/min.The kinetics and reaction mechanism of zinc acid leaching indicate that the leaching reaction conforms to the equation: 1?2α/3?(1?α)2/3=kt,the activation energy for the sulfuric acid leaching is 8.89 kJ/mol,and the leaching process is controlled by diffusion.