Electrochemical mechanism and flotation of chalcopyrite and galena in the presence of sodium silicate and sodium sulfite

The electrochemical mechanism involved in the selective separation of chalcopyrite from galena was investigated by flotation and electrochemical methods in the presence of sodium sulfite and sodium silicate,respectively,as a single depressant and their mixture as a combined depressant.Flotation tests revealed that the floatability of chalcopyrite was unaffected by depressants and its recovery remained constant(>80%)within the studied dosage range.Galena flotation was severely depressed with descending depressing order as follows:combined depressant﹥sodium silicate﹥sodium sulfite.Electrochemical analysis confirmed the high affinity of depressants on the galena surface,resulting in the formation of hydrophilic species,such as lead sulfite,lead sulfate,and lead orthosilicate.The oxidation of chalcopyrite surface and depressants did not exhibit any signals;conversely,the self-oxidation of chalcopyrite was depressed.The results of cyclic voltammograms well agreed with flotation results,demonstrating that chalcopyrite primarily reacted with the collector O-isopropyl-N-ethyl thionocarbamate and that galena mostly reacted with depressants.

Electrochemical and spectroscopic study of interfacial interactions between chalcopyrite and typical flotation process reagents

Comparative voltammetry and differential double-layer capacitance studies were performed to evaluate interfacial interactions between cnalcopyrite（CuFeS2） and n-isopropyl xanthate（X） in the presence of ammonium bisulfite/39wt%SO2 and caustic starch at different pH values.Raman spectroscopy,Fourier transform infrared（FTIR） spectroscopy,contact angle measurements,and microflotation tests were used to establish the type and extent of xanthate adsorption as well as the species involved under different mineral surface conditions in this study.The results demonstrate that the species that favor a greater hydrophobicity of chalcopyrite are primarily CuX and S^0,whereas oxides and hydroxides of Cu and Fe as well as an excess of starch decrease the hydrophobicity.A conditioning of the mineral surface with ammonium bisulfite/39wt%SO2 at pH 6 promotes the activation of surface and enhances the xanthate adsorption.However,this effect is diminished at pH ≥ 8,when an excess of starch is added during the preconditioning step.

Dynamics of electrodeposition of tetraethylthioram disulphide(TETD) on pyrite surface

The electrode process of pyrite in diethyldithiocarbamate (DDTC) solution pH 11.4 was investigated by using cyclic voltammetry, potentiost atic and chronopotentiometry. Tetraethylthioram disulphide(TETD) was electrodepo sited on pyrite electrode surface as the electrode potential is higher than 0.2 V. The relationship of the current density caused by diffusion and reaction time can be ascertained as i =1/(9.08×10 -5 +4.77×10 -3 t 0.5 ) , and the diffusion coefficient of DDTC on pyrite surface is about 3.72×10 - 6 cm 2/s. At pH 11.4, the thickness of TETD adsorbed on pyr ite surface is about 1.63 molecule layer. The electrochemical dynamics equation of the reduction of TETD on pyrite surface is given as η =0.116-0.064log[1- ( t/τ ) 0.5 ]. The kinetic parameters were determined as follows: the ex change current density ( i 0) is 3.08 μA/cm 2; the transmission coeffi cient( α ) is 0.462.

Kinetics of electrochemical process of galena electrode in diethyldithiocarbamate solution

The electrode process of galena in diethyldithiocarbamate (DDTC) solution at pH 11.4 has been investigated using cyclic voltammetry, potentiostatic and chronopotentiometry. Electrodeposit of PbD 2 on galena electrode surface can occur while the electrode potential is higher than -0.05?V. The relationship between the current density caused by diffusion and reaction time has been ascertained, and the diffusion coefficient of DDTC on galena surface in DDTC solution is about 1.12×10 -6 cm 2/s. A passive PbD 2 film covers the surface of galena electrode.