A batch of column experiments was carried out to investigate the change of Cr（Ⅵ） concentration leached out from chromium-containing slag with HCI as leaching agent, and to study influences of pH, ratio of solid mas...A batch of column experiments was carried out to investigate the change of Cr（Ⅵ） concentration leached out from chromium-containing slag with HCI as leaching agent, and to study influences of pH, ratio of solid mass to solution volume, flow velocity and temperature on Cr（Ⅵ） leaching. The optimal parameters were obtained for Cr（Ⅵ） leaching and a fitting model was established to describe the procedure of Cr（Ⅵ） leaching. The results show that Cr（Ⅵ） concentration in leachate increases with decreasing pH and increasing flow velocity and temperature. Moreover, Cr（Ⅵ） leaching percentage increases with increasing ratio of solid mass to solution volume. The optimal parameters for Cr（Ⅵ） selective leaching are as follows： pH=3.0, 1：5 of ratio of solid mass to solution volume, 180 mL/min of flow velocity and 40 ℃ of temperature. The procedure of Cr（Ⅵ） leaching fits well with the model： v= 1.87t^-0.54, indicating that the leaching rate of Cr（Ⅵ） declines in an exponential order of-0.54.展开更多
Sulfur speciation transformation during bioleaching of pyrite-containing sphalerite concentrate by thermophile Sulfolobus metallicus （S. metallicus） at 65 ℃ was investigated by X-ray diffraction （XRD）, diffuse re...Sulfur speciation transformation during bioleaching of pyrite-containing sphalerite concentrate by thermophile Sulfolobus metallicus （S. metallicus） at 65 ℃ was investigated by X-ray diffraction （XRD）, diffuse reflectance Fourier transform infrared spectroscopy （FT-IR） and sulfur K-edge X-ray absorption near edge structure spectroscopy （XANES）. The results show that the presence of S. metallicus effectively enhances the dissolution of the mineral. The yield of zinc increases from 0.5 g/L in sterile control to 2.7 g/L in bioleaching. The pyrite in the concentrate facilitates zinc dissolution in the early stage, but has hindrance role in the late stage for the formation of jarosite. Sulfur speciation analyses show that jarosite and elemental sulfur are main products in bioleaching process, and the accumulation ofjarosite is mainly responsible for the decline of leaching efficiency.展开更多
Based on the existing form of Zn2 Si O4 in willemite, the chemical precipitation method was used to synthesize Zn2 Si O4.Through the orthogonal experimentation, the reaction conditions of melten Na OH decomposing Zn2 ...Based on the existing form of Zn2 Si O4 in willemite, the chemical precipitation method was used to synthesize Zn2 Si O4.Through the orthogonal experimentation, the reaction conditions of melten Na OH decomposing Zn2 Si O4 were optimized, and the optimal experimental conditions include reaction temperature of 400 °C, reaction time of 4 h, and alkaline-to-ore molar ratio of 20:1.Based on the optimized experiment, on-line detection for the alkali leaching was made by using Raman spectroscopy; XRD was used to analyze the structure of water leaching residue, to explore the reaction mechanism of Na OH decomposing Zn2 Si O4. The results show that during the reaction process, the Si — O bond in Si O4 is destroyed, and the Na OH inserts itself into the silicate lattice,producing an immediate Na2 Zn Si O4 product. After the alkali leaching process, Zn2+ can be separated from the Si O4 array, which can be released out of the silicate in the form of ZnO.展开更多
基金Projects(2006AA06Z374 2007AA021304) supported by the National High-Tech Research and Development Program of China
文摘A batch of column experiments was carried out to investigate the change of Cr（Ⅵ） concentration leached out from chromium-containing slag with HCI as leaching agent, and to study influences of pH, ratio of solid mass to solution volume, flow velocity and temperature on Cr（Ⅵ） leaching. The optimal parameters were obtained for Cr（Ⅵ） leaching and a fitting model was established to describe the procedure of Cr（Ⅵ） leaching. The results show that Cr（Ⅵ） concentration in leachate increases with decreasing pH and increasing flow velocity and temperature. Moreover, Cr（Ⅵ） leaching percentage increases with increasing ratio of solid mass to solution volume. The optimal parameters for Cr（Ⅵ） selective leaching are as follows： pH=3.0, 1：5 of ratio of solid mass to solution volume, 180 mL/min of flow velocity and 40 ℃ of temperature. The procedure of Cr（Ⅵ） leaching fits well with the model： v= 1.87t^-0.54, indicating that the leaching rate of Cr（Ⅵ） declines in an exponential order of-0.54.
基金Project(50974140) supported by the National Natural Science Foundation of ChinaProject(VR-09157) supported by Beijing Synchrotron Radiation Facility (BSRF) Public User Program,China
文摘Sulfur speciation transformation during bioleaching of pyrite-containing sphalerite concentrate by thermophile Sulfolobus metallicus （S. metallicus） at 65 ℃ was investigated by X-ray diffraction （XRD）, diffuse reflectance Fourier transform infrared spectroscopy （FT-IR） and sulfur K-edge X-ray absorption near edge structure spectroscopy （XANES）. The results show that the presence of S. metallicus effectively enhances the dissolution of the mineral. The yield of zinc increases from 0.5 g/L in sterile control to 2.7 g/L in bioleaching. The pyrite in the concentrate facilitates zinc dissolution in the early stage, but has hindrance role in the late stage for the formation of jarosite. Sulfur speciation analyses show that jarosite and elemental sulfur are main products in bioleaching process, and the accumulation ofjarosite is mainly responsible for the decline of leaching efficiency.
基金Project(2007CB613603)supported by the National Basic Research Program of ChinaProject(51204037)supported by the National Natural Science Foundation of China
文摘Based on the existing form of Zn2 Si O4 in willemite, the chemical precipitation method was used to synthesize Zn2 Si O4.Through the orthogonal experimentation, the reaction conditions of melten Na OH decomposing Zn2 Si O4 were optimized, and the optimal experimental conditions include reaction temperature of 400 °C, reaction time of 4 h, and alkaline-to-ore molar ratio of 20:1.Based on the optimized experiment, on-line detection for the alkali leaching was made by using Raman spectroscopy; XRD was used to analyze the structure of water leaching residue, to explore the reaction mechanism of Na OH decomposing Zn2 Si O4. The results show that during the reaction process, the Si — O bond in Si O4 is destroyed, and the Na OH inserts itself into the silicate lattice,producing an immediate Na2 Zn Si O4 product. After the alkali leaching process, Zn2+ can be separated from the Si O4 array, which can be released out of the silicate in the form of ZnO.
