To investigate effect of metallic ion activation on different particle sizes of quartz in butyl xanthate solution,six common ions(Pb^(2+),Cu^(2+),Fe^(3+),Fe^(2+),Mg^(2+) and Ca^(2+)) were introduced as activators.The approaches of micro-flotation,adsorption test and zeta potential measurement were adopted to reveal the mechanism of ion activation.The results show that Pb^(2+),Cu^(2+) and Fe^(3+) are effective activators for the flotation of quartz in butyl xanthate solution because of their absorption on activated quartz surface.Average recoveries of fine particles(<37 μm) are greater than those of coarser particles(37-74 μm),suggesting that the former is easier to be activated and more likely to be floated and thus entrained in sulphide concentrate.From another perspective,addition of metallic ions(Pb^(2+),Cu^(2+) and Fe^(3+)) renders zeta potentials move positively,and addition of the same metallic ions and butyl xanthate makes zeta potential drop apparently,which support a mechanism where they adsorb onto quartz surface,resulting in an expected increase in butyl xanthate collector adsorption with a concomitant increase in the flotation recoveries.
Interaction mechanism of the collector,2-mercaptobenzothiazole（MBT）,with chalcopyrite and sphalerite surfaces were investigated by Fourier transform infrared（FTIR） and density functional theory,Results of FTIR showed that some characteristic peaks of MBT were observed on the chalcopyrite surface,including C=N,C=N-S and C-S stretching vibration peaks,and the adsorption product was CuMBT.But there were no characteristic peaks of MBT on the sphalerite surface.The thione molecular form of MBT was the most efficient and stable,N and exocyclic S were the more favourable reactive sites for nucleophilic attacked by metal atoms.Compared with ZnS（110）,MBT is more readily adsorbed on CuFeS2（112）.Attachment of MBT occurs due to strong bonding through exocyclic S p and s orbits with Cu d orbit on CuFeS2（112） and electron transfer from Cu atom to S atom.Under the vacuum condition,MBT in the form of thione molecular cannot be adsorbed on ZnS（110） spontaneously.
The hydrophobic flocculation of marmatite fines in aqueous suspensions induced by butyl xanthate （KBX） and ammonium dibutyl dithiophosphate （ADD） was investigated using laser particle size analysis, microscopy analysis, electrophoretic light scattering, contact angle measurement and infrared spectroscopy. The studies were performed on single minerals with size 〈20 μm by varying several parameters, including pH, collector concentration and kerosene addition. The results show that the floc fotation closely correlated with the size of flocs and the particle hydrophobicity, but was not lowered with increasing the particle surface charges due to collector adsorption. Under good operating conditions, the floc flotation of marmatite fines as a function of KBX and ADD can all reach floatability over 90%, in comparison with conventional flotation obtaining floatability of about 60%. It also has been found that a small addition of kerosene greatly improved the floc flotation because of the formation of oil films on marmatite particles. The results of FTIR spectra indicate that adsorption of the two collectors onto marmatite were chemical adsorption.
The composition of passive layer of chalcopyrite was investigated by X-ray photoelectron spectroscopy（XPS）, accompanied with cyclic voltammetry（CV）. The leaching experiment shows that the extraction rates of Cu with leaching for 30 d by sterile control and microorganisms are 4.0% and 21.5%, respectively. In comparison, 3.8% and 10.5% Fe are leached by sterile control and microorganisms, respectively. The results of XPS studies suggest that Fe atoms dissolve preferentially from the chalcopyrite lattice, and disulfide（S22-）, polysulfide（Sn2-） and elemental sulfur（S0） are identified on the chalcopyrite surfaces leached by sterile control and microorganisms. Additionally, sulfate（SO42-） is detected on the chalcopyrite surfaces leached by microorganisms, and most of it probably originates from jarosite. The analysis of CV results reveals that metal-deficient sulfide（Cu1-xFe1-yS2-z, yx） and elemental sulfur（S0） passivate the surface of chalcopyrite electrode. The elemental sulfur and/or jarosite coating on the chalcopyrite surface may have impact on the leaching process; however, the disulfide, polysulfide or metal-deficient sulfide plays a more key role in the chalcopyrite leaching.
Effects of collectors(butyl xanthate(BX), O-isopropyl-N-sulfur ethyl carbamate(Z-200) and emulsified kerosene), dereagent(sodium sulfide) and depressant thioglycollic acid(TGA) on the flotation of chalcocite and molybdenite were investigated through flotation. The first principle theory was adopted to understand the difference of their surfaces and reaction between minerals and reagents. Results of flotation tests revealed that selectivity of emulsified kerosene is the best of three collectors in separation of chalcocite and molybdenite, though the others also display excellent collecting properties. Sodium sulfide can effectively remove collectors adsorbed on chalcocite surface, and TGA is an effective depressant of chalcocite at pH 8-9. Through first principle study, molybdenite displays relatively stronger covalence property while bonding interaction between copper atoms in chalcocite enhanced its ionicity. Bonding interaction is weaker in reaction of TGA and molybdenite, so it shows higher hydrophobicity and better flotability. Therefore, TGA is an effective inhibitor in the separation.
The effects of galvanic interaction between galena and pyrite on their flotation and electrochemical characters were studied by electrochemical,adsorption,flotation and FTIR techniques,respectively.Electrochemical tests indicate that galena is electrochemically more active than pyrite and serves as an anode in galvanic combination with pyrite.The galvanic current density from a mixture of galena and pyrite is 4 times as high as the self corrosion current density of galena,which indicates that the corrosion rate of galena is accelerated.Adsorption tests show that the adsorption of butyl xanthate on galena surface is enhanced,and affected by a combination of pyrite-galena mixtures and conditioning time.Compared with individual mineral particles,galvanic interaction reduces the floatability difference between galena and pyrite.The flotation recovery of galena decreases while that of pyrite increases when two minerals are mixed together due to the influence of galvanic interaction on the formation of hydrophilic/hydrophobic product.The FTIR results show that the formation of dixanthogen on pyrite surface is depressed due to the galvanic interaction.
