A comparative study of the dissolution kinetics of galena ore in binary solutions of FeCl3/HCl and H2O2/HCl has been undertaken.The dissolution kinetics of the galena was found to depend on leachant concentration,reac...A comparative study of the dissolution kinetics of galena ore in binary solutions of FeCl3/HCl and H2O2/HCl has been undertaken.The dissolution kinetics of the galena was found to depend on leachant concentration,reaction temperature,stirring speed,solid-to-liquid ratio,and particle diameter.The dissolution rate of galena ore increases with the increase of leachant concentration,reaction temperature,and stirring speed,while it decreases with the increase of solid-to-liquid ratio and particle diameter.The activation energy （Ea） of 26.5 kJ/mol was obtained for galena ore dissolution in 0.3 M FeCl3 /8.06 M HCl,and it suggests the surface diffusion model for the leaching reaction,while the Ea value of 40.6 kJ/mol was obtained for its dissolution in 8.06 M H2O2 /8.06 M HCl,which suggests the surface chemical reaction model for the leaching reaction.Furthermore,the linear relationship between rate constants and the reciprocal of particle radius supports the fact that dissolution is controlled by the surface reaction in the two cases.Finally,the rate of reaction based on the reaction-controlled process has been described by a semiempirical mathematical model.The Arrhenius and reaction constants of 11.023 s^-1,1.25×10^-4 and 3.65×10^2 s^-1,8.02×10^ 6 were calculated for the 0.3 M FeCl3/8.06 M HCl and 8.06 M H2O2/8.06 M HCl binary solutions,respectively.展开更多
The dissolution kinetics and mechanisms of reaction of Batagbon Kaolin in sulphuric and fluosilicic acids were studied. Leaching temperature, acid concentration, particle size, solid-to-liquid ratio, and stirring spee...The dissolution kinetics and mechanisms of reaction of Batagbon Kaolin in sulphuric and fluosilicic acids were studied. Leaching temperature, acid concentration, particle size, solid-to-liquid ratio, and stirring speed were selected as process parameters. It is observed that the dissolution rate increases with decreasing particle size and solid-to-liquid ratio, and increases with stirring speed, acid concentration, and leaching temperature. The experimental results indicate that the dissolution rate is of mixed control via hydrogen ion [H＋] action, with reaction order of 0.813 and the reaction kinetics can be expressed as gmt=[1-（1-x）l/3＋y/6[（l-x）l/3＋ 1-2（1-x）2/3]. The activation energy of the process is determined to be 21.6 k J/mol. The level of the product quality is also evaluated.展开更多
The dissolution kinetics of a Nigerian chalcopyrite ore in hydrochloric acid was studied in this article. Acid concentration, reaction temperature, and ore particle size were chosen as experimental parameters. The che...The dissolution kinetics of a Nigerian chalcopyrite ore in hydrochloric acid was studied in this article. Acid concentration, reaction temperature, and ore particle size were chosen as experimental parameters. The chemical and morphological studies of the ore before and after leaching at optimal conditions were carried out by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. It is revealed that increasing the acid concentration and system temperature and decreasing the ore particle size greatly enhances the dissolution rate. The dissolution kinetics was found to follow the shrinking core model for the diffusion control mechanism where the activation energy （Ea） of 32.92 kJ.mo1-1 was obtained for the process and supported by morphological changes at a higher dissolution of 91.33%.展开更多
Zn（Ⅱ） and Pb（Ⅱ） from Nigerian sphalerite and galena ores were bioleached by a mixed culture of acidophilic bacteria.The influences of pH and ferric ion on the bioleaching rates of sphalerite and galena were exam...Zn（Ⅱ） and Pb（Ⅱ） from Nigerian sphalerite and galena ores were bioleached by a mixed culture of acidophilic bacteria.The influences of pH and ferric ion on the bioleaching rates of sphalerite and galena were examined.The result shows that pH 2.1 and 2.7 are favourable for the leaching of Zn（Ⅱ） and Pb（Ⅱ） from sphalerite and galena,respectively.It was observed that the use of agarose-simulated media caused cells to excrete exopolymers containing ferric ions which enhanced oxidation.The oxidation equilibrium for sphalerite and galena took 3 and 4 d,respectively.About 38.3% sphalerite and 34.2% galena were leached within 1 d and approximately 92.0% Zn（Ⅱ） and 89.0% Pb（Ⅱ） were recovered in 5 d,respectively.The unleached residual products were examined by X-ray diffraction for sphalerite,revealing the presence of elemental sulphur（S）,zinc sulphate（ZnSO4） and few traces of calcium aluminate（Ca3Al2O6）.The XRD pattern also indicates the presence of elemental sulphur（S）,lead sulphate（PbSO4） and few traces of itoite [Pb（S,Ge）（O,OH）4] and cobalt lead silicate [Pb8Co（Si2O7）3] in the unleached galena ore.展开更多
文摘A comparative study of the dissolution kinetics of galena ore in binary solutions of FeCl3/HCl and H2O2/HCl has been undertaken.The dissolution kinetics of the galena was found to depend on leachant concentration,reaction temperature,stirring speed,solid-to-liquid ratio,and particle diameter.The dissolution rate of galena ore increases with the increase of leachant concentration,reaction temperature,and stirring speed,while it decreases with the increase of solid-to-liquid ratio and particle diameter.The activation energy （Ea） of 26.5 kJ/mol was obtained for galena ore dissolution in 0.3 M FeCl3 /8.06 M HCl,and it suggests the surface diffusion model for the leaching reaction,while the Ea value of 40.6 kJ/mol was obtained for its dissolution in 8.06 M H2O2 /8.06 M HCl,which suggests the surface chemical reaction model for the leaching reaction.Furthermore,the linear relationship between rate constants and the reciprocal of particle radius supports the fact that dissolution is controlled by the surface reaction in the two cases.Finally,the rate of reaction based on the reaction-controlled process has been described by a semiempirical mathematical model.The Arrhenius and reaction constants of 11.023 s^-1,1.25×10^-4 and 3.65×10^2 s^-1,8.02×10^ 6 were calculated for the 0.3 M FeCl3/8.06 M HCl and 8.06 M H2O2/8.06 M HCl binary solutions,respectively.
文摘The dissolution kinetics and mechanisms of reaction of Batagbon Kaolin in sulphuric and fluosilicic acids were studied. Leaching temperature, acid concentration, particle size, solid-to-liquid ratio, and stirring speed were selected as process parameters. It is observed that the dissolution rate increases with decreasing particle size and solid-to-liquid ratio, and increases with stirring speed, acid concentration, and leaching temperature. The experimental results indicate that the dissolution rate is of mixed control via hydrogen ion [H＋] action, with reaction order of 0.813 and the reaction kinetics can be expressed as gmt=[1-（1-x）l/3＋y/6[（l-x）l/3＋ 1-2（1-x）2/3]. The activation energy of the process is determined to be 21.6 k J/mol. The level of the product quality is also evaluated.
文摘The dissolution kinetics of a Nigerian chalcopyrite ore in hydrochloric acid was studied in this article. Acid concentration, reaction temperature, and ore particle size were chosen as experimental parameters. The chemical and morphological studies of the ore before and after leaching at optimal conditions were carried out by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. It is revealed that increasing the acid concentration and system temperature and decreasing the ore particle size greatly enhances the dissolution rate. The dissolution kinetics was found to follow the shrinking core model for the diffusion control mechanism where the activation energy （Ea） of 32.92 kJ.mo1-1 was obtained for the process and supported by morphological changes at a higher dissolution of 91.33%.
文摘Zn（Ⅱ） and Pb（Ⅱ） from Nigerian sphalerite and galena ores were bioleached by a mixed culture of acidophilic bacteria.The influences of pH and ferric ion on the bioleaching rates of sphalerite and galena were examined.The result shows that pH 2.1 and 2.7 are favourable for the leaching of Zn（Ⅱ） and Pb（Ⅱ） from sphalerite and galena,respectively.It was observed that the use of agarose-simulated media caused cells to excrete exopolymers containing ferric ions which enhanced oxidation.The oxidation equilibrium for sphalerite and galena took 3 and 4 d,respectively.About 38.3% sphalerite and 34.2% galena were leached within 1 d and approximately 92.0% Zn（Ⅱ） and 89.0% Pb（Ⅱ） were recovered in 5 d,respectively.The unleached residual products were examined by X-ray diffraction for sphalerite,revealing the presence of elemental sulphur（S）,zinc sulphate（ZnSO4） and few traces of calcium aluminate（Ca3Al2O6）.The XRD pattern also indicates the presence of elemental sulphur（S）,lead sulphate（PbSO4） and few traces of itoite [Pb（S,Ge）（O,OH）4] and cobalt lead silicate [Pb8Co（Si2O7）3] in the unleached galena ore.
