| The electrowining copper process has been investigated to extract copper from low-grade copper ores by glutamine complexing leaching.According to the complex chemistry,equilibrium distribution of the species in the system of glutamine was calculated and plotted using MATLAB.It is presented that the predominant species of copper are Cu(Glu)22- with few Cu2+ and Cu(Glu),Carbonate are CO32-and HCO3-,glutamine are Glu2-,HGlu-,Cu(Glu)22- with few Cu(Glu),H2(Glu) and H3(Glu)+. The relationship between the equilibrium concentration of each species with pH,[Cu2+]T and [Glu2-]T are derived.Copper electrodeposition mechanism in the glutamine complex system was Studied by electrochemical methods. Anode reaction was oxygen precipitation of water electrolysis, copper complexed with glutamic acid discharged for the precipitation of copper in cathode. Apparent activation energy was calculated to be 34.065KJ·mol-1 by linear sweep voltammetry in different temperatures, (an, j0) was (0.36, 0.105A·m-2) at (0.07V～0.24V) and (0.35,0.024A·m-2) at (0.43V～0.54V) by tafel relationship linear fitting.Then,the influence of the concentration of [Cu2+]T,[Glu2-]T,pH and temperature on the current of copper discharge were studied.Nucleation mechanism of copper deposition was discussed by cyclic voltammetry and chronoamperometry.A cross-closed ring appeared in cyclic voltammograms indicated that the electrical deposition of copper may had experienced the nucleation process.Compared with the standard nucleation curve,that in the glutamine system fitted in with three dimensional continuous nucleation,and converted from instant nucleation to continuous as the concentration of copper increased.Then, process conditions of copper deposition were investigated in the glutamine system,and the influence of copper concentration,glutamine concentration,pH,current dencity,polar distance and temperature on current efficience,cell voltage and energy consumption were also studied for determination of process conditions. |
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