This research aimed to enhance the column bioleaching recovery of uranium ore by Acidithiobacillus ferrooxidans.Seven factors were examined for their significance on bioleaching using a Plackett-Burman factorial desig...This research aimed to enhance the column bioleaching recovery of uranium ore by Acidithiobacillus ferrooxidans.Seven factors were examined for their significance on bioleaching using a Plackett-Burman factorial design.Four significant variables([Fe2+]initial,pH,aeration rate and inoculation percent)were selected for the optimization studies.The effect of these variables on uranium bioleaching was studied using a central composite design(CCD).The optimal values of the variables for the maximum uranium bioleaching recovery(90.27±0.98)%were as follows:[Fe2+]initial=2.89g/L,aeration rate420mL/min,pH1.45and inoculation6%(v/v).[Fe2+]initial was found to be the most effective parameter.The maximum uranium recovery from the predicted models was92.01%.This value was in agreement with the actual experimental value.The analysis of bioleaching residue of uranium ore under optimum conditions confirmed the formation of K-jarosite on the surface of minerals.By using optimal conditions,uranium bioleaching recovery is increased at column and jarosite precipitation is minimized.The kinetic model showed that uranium recovery has a direct relation with ferric ion concentration.展开更多
The column bioleaching of copper flotation tailings was comparatively investigated using layered heap construction method(LM),agglomerate heap construction method(AM),and pellets-sintering heap construction method(PM)...The column bioleaching of copper flotation tailings was comparatively investigated using layered heap construction method(LM),agglomerate heap construction method(AM),and pellets-sintering heap construction method(PM).The bacterial communities of free,attached,weakly-attached,and strongly-attached microbes in the later bioleaching stage were investigated.In AM group,the addition of lump sulphide ore resulted in the low leachate pH,high ferric iron concentration,and rapid microbial adsorption,which obtained the maximum copper extraction(60.1%)compared with LM(54.6%)and PM(43.9%)groups.The relative abundance of dominant genera and microbial communities of different microbiota underwent changes in three heap construction methods.The alpha-diversity indexes of attached,weakly-attached,and strongly-attached microbes were different,while no significant change was observed in free bacteria.The variation of whole bacterial community was significantly associated with solution pH,total iron,and ferric iron concentrations.Pearson correlation analysis and partial least square path model both indicated that attached bacteria made larger contribution to the copper extraction of tailings.展开更多
This study is to assess the effect of magnesiumrich gangue dissolution on the ore containing chalcopyrite and carrollite from Democratic Republic of the Congo （DRC）. The ore contains 11.0 wt% magnesium and 2.4 wt% c...This study is to assess the effect of magnesiumrich gangue dissolution on the ore containing chalcopyrite and carrollite from Democratic Republic of the Congo （DRC）. The ore contains 11.0 wt% magnesium and 2.4 wt% copper. When Mg^2＋ concentration is over 20 g·L^-1 after 2 months in column bioleaching, the redox potential of leachate keeps stable, much less than that when Mg2＋ concentration is below 20 g·L^-1. Meanwhile, the extractions of Cu^2＋ and Co^2＋ from chalcopyrite with carrollite obviously inhibited by Mg^2＋ concentration of over 20 g·L^-1 were investigated. The extraction of cobalt depends on chalcopyrite dissolved in column reactor. The growth and oxidation activity of bacteria are affected by high Mg^2＋ concentration （〉20 g·L^-1） in leachate of column reactor. As the rate of gangue dissolution depends on the amount of sulfuric acid, the decrease of the particle size relates to the increase of the total particle surface area and acid consumption. Therefore, the operation of pre-leaching for magnesium removal is not the most effective and economical way to solve the problem of magnesium-rich gangue minerals dissolution.展开更多
A high temperature-tolerating thermoacidophilic archae （TA） was isolated from water samples collected from a hot sulfur-containing spring in the Yunnan Province, China, and was used in bioleaching experiments of a l...A high temperature-tolerating thermoacidophilic archae （TA） was isolated from water samples collected from a hot sulfur-containing spring in the Yunnan Province, China, and was used in bioleaching experiments of a low-grade chalcopyrite ore. The TA grow at temperatures ranging from 40 to 80℃, with 65℃ being the optimum temperature, and at pH values of l.5 to 4.0, with an optimum pH value of 2.0. The bioleaching experiments of the chalcvpyrite ore were conducted in both laboratory batch bioreactors and leaching columns. The results obtained from the bioreactor experiments showed that the TA bioleaching rate of copper reached 97% for a 12-day leaching period, while the bioleaching rate was 32.43% for thiobacillus ferrooxidans （Tf） leaching for the same leaching time. In the case of column leaching, tests of a two-phase leaching （196 days）, that is, a two-month （56 days） Tf leaching in the first phase, followed by a 140-day TA leaching in the second phase were performed. The average leaching rate of copper achieved for the 140-day TA leaching was 195mg/（L.d）, while for the control experiments, it was as low as 78mg/（L .d） for the Tf leaching, indicating that the TA possesses a more powerful oxidizing ability to the chalcopyrite than Tf Therefore, it is suggested that the two-phase leaching process be applied to .for the heap leaching operations, whereas, the TA can be used in the second phase when the temperature inside the heap has increased, and the primary copper sulfide minerals have already been partially oxidized with Tf beforehand in the first phase.展开更多
基金the Tarbiat Modares University & Nuclear Science and Technology Research Institute for their financial support
文摘This research aimed to enhance the column bioleaching recovery of uranium ore by Acidithiobacillus ferrooxidans.Seven factors were examined for their significance on bioleaching using a Plackett-Burman factorial design.Four significant variables([Fe2+]initial,pH,aeration rate and inoculation percent)were selected for the optimization studies.The effect of these variables on uranium bioleaching was studied using a central composite design(CCD).The optimal values of the variables for the maximum uranium bioleaching recovery(90.27±0.98)%were as follows:[Fe2+]initial=2.89g/L,aeration rate420mL/min,pH1.45and inoculation6%(v/v).[Fe2+]initial was found to be the most effective parameter.The maximum uranium recovery from the predicted models was92.01%.This value was in agreement with the actual experimental value.The analysis of bioleaching residue of uranium ore under optimum conditions confirmed the formation of K-jarosite on the surface of minerals.By using optimal conditions,uranium bioleaching recovery is increased at column and jarosite precipitation is minimized.The kinetic model showed that uranium recovery has a direct relation with ferric ion concentration.
基金financial supports from the National Key R&D Program of China(No.2018YFC1801804)the Shandong Provincial Natural Science Foundation,China(Nos.ZR2020QD120 and ZR2018LD001)Project of Introducing and Cultivating Young Talent in the Universities of Shandong Province,China(No.QC2019YY144)。
文摘The column bioleaching of copper flotation tailings was comparatively investigated using layered heap construction method(LM),agglomerate heap construction method(AM),and pellets-sintering heap construction method(PM).The bacterial communities of free,attached,weakly-attached,and strongly-attached microbes in the later bioleaching stage were investigated.In AM group,the addition of lump sulphide ore resulted in the low leachate pH,high ferric iron concentration,and rapid microbial adsorption,which obtained the maximum copper extraction(60.1%)compared with LM(54.6%)and PM(43.9%)groups.The relative abundance of dominant genera and microbial communities of different microbiota underwent changes in three heap construction methods.The alpha-diversity indexes of attached,weakly-attached,and strongly-attached microbes were different,while no significant change was observed in free bacteria.The variation of whole bacterial community was significantly associated with solution pH,total iron,and ferric iron concentrations.Pearson correlation analysis and partial least square path model both indicated that attached bacteria made larger contribution to the copper extraction of tailings.
基金financially supported by the National High Technology Research and Development Program of China(No.2012AA061502)the National Basic Research Program of China(No.2010CB630906)
文摘This study is to assess the effect of magnesiumrich gangue dissolution on the ore containing chalcopyrite and carrollite from Democratic Republic of the Congo （DRC）. The ore contains 11.0 wt% magnesium and 2.4 wt% copper. When Mg^2＋ concentration is over 20 g·L^-1 after 2 months in column bioleaching, the redox potential of leachate keeps stable, much less than that when Mg2＋ concentration is below 20 g·L^-1. Meanwhile, the extractions of Cu^2＋ and Co^2＋ from chalcopyrite with carrollite obviously inhibited by Mg^2＋ concentration of over 20 g·L^-1 were investigated. The extraction of cobalt depends on chalcopyrite dissolved in column reactor. The growth and oxidation activity of bacteria are affected by high Mg^2＋ concentration （〉20 g·L^-1） in leachate of column reactor. As the rate of gangue dissolution depends on the amount of sulfuric acid, the decrease of the particle size relates to the increase of the total particle surface area and acid consumption. Therefore, the operation of pre-leaching for magnesium removal is not the most effective and economical way to solve the problem of magnesium-rich gangue minerals dissolution.
基金This work was supported by the Yunnan Provincial Natural Science Foundation of China （No. 2000E0101M）.
文摘A high temperature-tolerating thermoacidophilic archae （TA） was isolated from water samples collected from a hot sulfur-containing spring in the Yunnan Province, China, and was used in bioleaching experiments of a low-grade chalcopyrite ore. The TA grow at temperatures ranging from 40 to 80℃, with 65℃ being the optimum temperature, and at pH values of l.5 to 4.0, with an optimum pH value of 2.0. The bioleaching experiments of the chalcvpyrite ore were conducted in both laboratory batch bioreactors and leaching columns. The results obtained from the bioreactor experiments showed that the TA bioleaching rate of copper reached 97% for a 12-day leaching period, while the bioleaching rate was 32.43% for thiobacillus ferrooxidans （Tf） leaching for the same leaching time. In the case of column leaching, tests of a two-phase leaching （196 days）, that is, a two-month （56 days） Tf leaching in the first phase, followed by a 140-day TA leaching in the second phase were performed. The average leaching rate of copper achieved for the 140-day TA leaching was 195mg/（L.d）, while for the control experiments, it was as low as 78mg/（L .d） for the Tf leaching, indicating that the TA possesses a more powerful oxidizing ability to the chalcopyrite than Tf Therefore, it is suggested that the two-phase leaching process be applied to .for the heap leaching operations, whereas, the TA can be used in the second phase when the temperature inside the heap has increased, and the primary copper sulfide minerals have already been partially oxidized with Tf beforehand in the first phase.
