The Research on the Effect of Grinding on the Flotation of Pyrite and Chalcopyrite
|School||Central South University|
|Course||Mineral Processing Engineering|
|Keywords||pyrite chalcopyrite grinding atmosphere grinding media mechanical electrochemistry|
Grinding is an important necessary section in minerals process. The surface of sulphide minerals would occur redox reactions and the surface properties would be changed. Therefore, it is significative to study the grinding process and its effect on the flotation.In this paper, the effect of grinding time, pH value of the pulp, dosage of the collectors on the flotation of pyrite and chalcopyrite which were ground with different grinding medium and different grinding atmosphere are studied, the paper also uses electrochemical testing method to study interactions between grinding media and minerals as well as the effect of electrochemical on those interactions.The results of flotation test show that grinding media and atmosphere has a great effect on the flotation of sulphide minerals. In flotation of pyrite, The flotation recoveries of pyrite grinding with ceramic balls are highest. The flotation recoveries grinding with fericc balls is lowest, The flotation recoveries grinding with stainless steel balls is intervenient. In nitrogen atmosphere, the flotation recoveries of pyrite grinding with ceramic balls are much higher than that in air atmosphere. The flotation recoveries grinding with stainless steel balls is rise in nitrogen atmosphere. There is litter change grinding with ceramics balls in nitrogen atmosphere. The method of pyrite recoveries in nitrogen atmosphere is same as that in air atmosphere. In flotation of chalcopyrite, The flotation recoveries of chalcopyrite grinding with ceramic balls are highest. The flotation recoveries grinding with fericc balls is lowest, The flotation recoveries grinding with stainless steel balls is intervenient. In nitrogen atmosphere, the flotation recoveries of chalcopyrite grinding with ceramic balls are much higher than that in air atmosphere under vacuum condition. The flotation recoveries of pyrite grinding with stainless steel balls in nitrogen atmosphere is rise too. There is litter change grinding with ceramics balls in nitrogen atmosphere. But the influence of atmosphere and grinding medium on the flotation of chalcopyrite is under acidic conditions. The calculations of thermodynamics show that, S0 would be created in the surface of pyrite and chalcopyrite when the surface of pyrite and chalcopyrite are oxidized appropriately. When oxidative atmosphere strengthen, S0 or polysulfide would be oxidized to SO42-. In high Eh or under under vacuum condition, the product is hydroxo complex of ferric in flotation system. The hydroxo complex of ferric would be producted in flotation systems.The results of mechanism electrochemical testing show that, the pyrite and chalcopyrite electrode act as cathode when using the ferric medium or stainless steel medium as abrading agent and anode current generates on the grinding medium surface. The surfaces of grinding medium occur oxidation reactions. The product is hydroxo complex of ferric, which would covering on the surfaces of mineral, This substance can weaken the sorption of mineral and collector. The mineral flotation is prevented. However, the pyrite and chalcopyrite electrode act as anode and oxidation reaction occurs on the mineral surface and anodic current generates on the mineral surface when using ceramic medium as abrading agent, which will improve the sorption of the mineral and collector and promote the flotation of the mineral. The larger the abrading force between themediums and mineral electrode is, the larger current are in the system. The minerals or grinding medium woule be oxidized completely, and the flotability of the mineral will be decrease in the flotation system.In nitrogen atmosphere, the current is lower than that in air atmosphere.The corrosion electrochemistry tests show that, compare with in air atmosphere, corrosion potential of iron medium is much higher in nitrogen atmosphere, and corrosion potential of iron medium is rise a litter. The influence of atmosphere is obviously on flotation with fericc medium grinding. But the influence is minor with ceramics medium grinding.