Study On Sulfur - Arsenic Copper Leaching In Alkaline Sulfide System

On the basis of the review on the enargite treatment, the central disposal of As of enargite is focussed and further studied in this dissertation. The alkaline leaching by sulphide sodium is proposed for the removal of As from enargite. Furhtermore, the phase changes in the leach are analyzed, through which the existence of Cu is changed and so that the recovery of Cu from the pretreated ore could be processed by more alternatives. The main research contents are as follows:The enargite concentrate for the experiments contains 12% of As, 0.5% of Sb and 38% of Cu approximately. Based on the exploratory tests, the removal of As from enargite is proved effective in alkaline sodium sulphide system. The selectivity of alkaline sodium sulphide leaching to As and Sb is also proved.The effects of leaching temperature, concentration of lixivant, particle size of concentrate and agitation speed on the leaching of As, Sb and Cu are studied and the alkali sodium sulphide leaching process is further determined as follow: T=95 ℃, [Na OH]ini.=2.5 M, [Na2S]ini.=1.0 M, S/L=1:20 g/m L, particle size(P80)of-30 μm, rotation time of 2.0 h and agitation speed of 500 r·min-1. Under these conditions stated above, the leaching of As and Sb can be achieved as higher as more than 95%, through which As and Sb are successfully removed from enargite.The leaching residues are analyzed by the mineralogical means, such as QXRD, SEM as well as EDS. The results show that As and Sb can be effectively removed from engartite and apparent phase changes have taken place in the alkaline leach. Several copper-sulphur compounds such as digenite, bornite and sodium copper sulphide(Na Cu5S3) are produced. Furthermore, the behavior of chalcopyrite and pyrite in atmospheric and pressure leaching in alkaline solutions are also discussed.