This paper elaborated on the sustainability of the copper extraction process. In fact, an alternative copper extraction route from mixed sulphide ores, chalcopyrite and chalcocite using mesophilic biomass consortium a...This paper elaborated on the sustainability of the copper extraction process. In fact, an alternative copper extraction route from mixed sulphide ores, chalcopyrite and chalcocite using mesophilic biomass consortium at 33.3 °C and ferric leaching process were attempted. Bioleaching experiments were settled with a fraction size of-75+53 μm. Bacteria were used as the catalyst. A copper yield of 65.50% was obtained. On the other hand, in ferric leaching process, with a fraction size of-53+38 μm, when the temperature was increased to 70 °C, the copper leaching rate increased to 78.52%. Thus, comparatively, the mesophilic bioleaching process showed a more obvious advantage in copper extraction than leaching process with a high temperature. However, it has been resolved from the characterization performed using SEM-EDS, FTIR and XRD observations coupled with different thermodynamic approaches that, the indirect mechanism is the main leaching mechanism, with three transitory mechanisms(polysulphide, thiosulphate and elemental sulphur mechanisms) for the mixed chalcopyrite-chalcocite ore. Meanwhile, the speciation turns into Cu2 S-Cu S-Cu5 Fe S4-Cu2 S before turning into Cu SO4. While ferrous oxidation and the formation of ferric sulphate occur, and there is a formation of strong acid as bacteria digest sulphide minerals into copper sulphate at low temperature, which is why this copper production scenario requires a redox potential more than 550 m V at room temperature for high copper leaching rate.展开更多
Nanostructured zinc-copper mixed ferrite was synthesized using sol-gel method. Different compositions of ferrite, Zn_((1-x))Cu_xFe_2O_4(x=0.0, 0.25, 0.50, 0.75), characterized by XRD, reveal single phase inverse spine...Nanostructured zinc-copper mixed ferrite was synthesized using sol-gel method. Different compositions of ferrite, Zn_((1-x))Cu_xFe_2O_4(x=0.0, 0.25, 0.50, 0.75), characterized by XRD, reveal single phase inverse spinel in all the samples. With increasing copper content, the crystallite size increases. The surface morphology of all the samples, studied by SEM, shows porous structure of particles. The prepared samples were also analyzed by FT-IR and TEM. Catalytic activity of the samples was studied on lanthanum oxalate decomposition by thermogravimety.The rate constant k has the highest value with x=0.75 and 5%(mole fraction) of the catalyst and is attributed to high copper content, the mixed sites Cu^(2+)-Fe^+ and/or Cu^+-Fe^(2+) ion pairs besides the one component sites Cu^(2+)-Cu^+, Fe^(3+)-Fe^(2+), as a result of mutual charge interaction. In other words, the increasing activity of mixed oxides is attributed to increase in the content of active sites via creation of new ion pairs. With increasing Zn content, particle size increases. Variation of catalytic activity of ferrite powders is due to the changes of the valence state of catalytically active components of the ferrites, which oxidizes the carbon monoxide released from lanthanum oxalate.展开更多
文摘This paper elaborated on the sustainability of the copper extraction process. In fact, an alternative copper extraction route from mixed sulphide ores, chalcopyrite and chalcocite using mesophilic biomass consortium at 33.3 °C and ferric leaching process were attempted. Bioleaching experiments were settled with a fraction size of-75+53 μm. Bacteria were used as the catalyst. A copper yield of 65.50% was obtained. On the other hand, in ferric leaching process, with a fraction size of-53+38 μm, when the temperature was increased to 70 °C, the copper leaching rate increased to 78.52%. Thus, comparatively, the mesophilic bioleaching process showed a more obvious advantage in copper extraction than leaching process with a high temperature. However, it has been resolved from the characterization performed using SEM-EDS, FTIR and XRD observations coupled with different thermodynamic approaches that, the indirect mechanism is the main leaching mechanism, with three transitory mechanisms(polysulphide, thiosulphate and elemental sulphur mechanisms) for the mixed chalcopyrite-chalcocite ore. Meanwhile, the speciation turns into Cu2 S-Cu S-Cu5 Fe S4-Cu2 S before turning into Cu SO4. While ferrous oxidation and the formation of ferric sulphate occur, and there is a formation of strong acid as bacteria digest sulphide minerals into copper sulphate at low temperature, which is why this copper production scenario requires a redox potential more than 550 m V at room temperature for high copper leaching rate.
文摘Nanostructured zinc-copper mixed ferrite was synthesized using sol-gel method. Different compositions of ferrite, Zn_((1-x))Cu_xFe_2O_4(x=0.0, 0.25, 0.50, 0.75), characterized by XRD, reveal single phase inverse spinel in all the samples. With increasing copper content, the crystallite size increases. The surface morphology of all the samples, studied by SEM, shows porous structure of particles. The prepared samples were also analyzed by FT-IR and TEM. Catalytic activity of the samples was studied on lanthanum oxalate decomposition by thermogravimety.The rate constant k has the highest value with x=0.75 and 5%(mole fraction) of the catalyst and is attributed to high copper content, the mixed sites Cu^(2+)-Fe^+ and/or Cu^+-Fe^(2+) ion pairs besides the one component sites Cu^(2+)-Cu^+, Fe^(3+)-Fe^(2+), as a result of mutual charge interaction. In other words, the increasing activity of mixed oxides is attributed to increase in the content of active sites via creation of new ion pairs. With increasing Zn content, particle size increases. Variation of catalytic activity of ferrite powders is due to the changes of the valence state of catalytically active components of the ferrites, which oxidizes the carbon monoxide released from lanthanum oxalate.
