SEMICONDUCTOR ENERGY-BAND THEORY OF SODIUM HUMATE INTERACTING WITH SULPHIDE MINERALS AND ITS APPLICATION IN FLOTATION SEPARATION

摘要

This paper presents the results of research based on a semiconductor energy-band theory developed to investigate the mechanisms of the interaction of the organic depressant (sodium humate) with sulfides. Results of tests indicate that desorption of dixanthogen on pyrite is an electrochemical process in the presence of sodium humate. Sodium humate can influence the electron level of pyrite, which can affect the stability of xanthate film on the mineral surface, but sodium humate can not affect the energy-band structure of chalcopyrite. The edge level of the conduction band of pyrite can be lowered greatly by sodium humate. This causes the density of the electrons of the pyrite surface and of the areas of the unoccupied level of xanthate (dixanthogen) overlap the edge level of the conduction band. Therefore, electrons are easily transferred into the unoccupied level (dixanthogen) from the occupied level (edge of the conduction band). As a result, dixanthogen on the mineral surface is reduced. It can be predicted from the difference of sodium humate interacting with chalcopyrite and pyrite that the dixanthogen on the pyrite surface will be reduced, but dixanthogen on the chalcopyrite will remain stable. Therefore, chalcopyrite will maintain good floatability, but pyrite will be depressed in flotation in the presence of sodium humate. Results of the separation of CuS by means of sodium humate in a laboratory and in industrial tests verify the above research.