The effect of pH values on the extracellular protein and polysaccharide secretions of Acidithiobacillus ferrooxidans was comparatively investigated in different phases of bacterial growth during chalcopyrite bioleachi...The effect of pH values on the extracellular protein and polysaccharide secretions of Acidithiobacillus ferrooxidans was comparatively investigated in different phases of bacterial growth during chalcopyrite bioleaching. The results indicate that the extracellular protein is always more than the extracellular polysaccharide secreted by attached cells on the chalcopyrite, on the contrary, and is always less than the extracellular polysaccharide secreted by free cells in the solution at bacterial adaptive phase, logarithmic phase and stationary phase whenever pH value is at 1.0, 1.5, 2.0 or 2.5; free cells are mainly through the secretion of extracellular polysaccharide rather than the extracellular protein to fight against disadvantageous solution environment, such as high concentration of metal ions and unsuitable pH solution; both amounts of polysaccharide and protein secreted by attached cells are mainly positively related to the solution acidity rather than the total concentration of soluble metal ions. The experimental results imply that bacteria are mainly through secreting more extracellular polysaccharide to fight against disadvantageous environment and the extracellular protein perhaps plays an important role in oxidation？reduction reactions in the bioleaching system.展开更多
The effects of silver sulfide (Ag 2S) on the bioleaching of chalcopyrite and pyrite were investigated in this paper. It has been shown that Ag 2S enhanced the yields of bioleaching of chalcopyrite but inhibited the bi...The effects of silver sulfide (Ag 2S) on the bioleaching of chalcopyrite and pyrite were investigated in this paper. It has been shown that Ag 2S enhanced the yields of bioleaching of chalcopyrite but inhibited the bio oxidation of pyrite. The addition of Ag 2S selectively increased the copper dissolution from the chalcopyrite containing ores in shake flasks with a recovery of 85.3% compared with 24.3% without Ag 2S, while slightly decreased the iron yields from 51% to 41.8%. The copper extraction of the chalcoopyrite containing waste rock in column leaching charged with 18 kg mass increased up to 21.7% in the presence of Ag 2S, while only 3.4% in the absence of the catalyst. The mechanism of Ag 2S catalysis could be explained well by the "Mixed potential model".展开更多
基金Project(31200382)supported by the National Natural Science Foundation of China
文摘The effect of pH values on the extracellular protein and polysaccharide secretions of Acidithiobacillus ferrooxidans was comparatively investigated in different phases of bacterial growth during chalcopyrite bioleaching. The results indicate that the extracellular protein is always more than the extracellular polysaccharide secreted by attached cells on the chalcopyrite, on the contrary, and is always less than the extracellular polysaccharide secreted by free cells in the solution at bacterial adaptive phase, logarithmic phase and stationary phase whenever pH value is at 1.0, 1.5, 2.0 or 2.5; free cells are mainly through the secretion of extracellular polysaccharide rather than the extracellular protein to fight against disadvantageous solution environment, such as high concentration of metal ions and unsuitable pH solution; both amounts of polysaccharide and protein secreted by attached cells are mainly positively related to the solution acidity rather than the total concentration of soluble metal ions. The experimental results imply that bacteria are mainly through secreting more extracellular polysaccharide to fight against disadvantageous environment and the extracellular protein perhaps plays an important role in oxidation？reduction reactions in the bioleaching system.
文摘The effects of silver sulfide (Ag 2S) on the bioleaching of chalcopyrite and pyrite were investigated in this paper. It has been shown that Ag 2S enhanced the yields of bioleaching of chalcopyrite but inhibited the bio oxidation of pyrite. The addition of Ag 2S selectively increased the copper dissolution from the chalcopyrite containing ores in shake flasks with a recovery of 85.3% compared with 24.3% without Ag 2S, while slightly decreased the iron yields from 51% to 41.8%. The copper extraction of the chalcoopyrite containing waste rock in column leaching charged with 18 kg mass increased up to 21.7% in the presence of Ag 2S, while only 3.4% in the absence of the catalyst. The mechanism of Ag 2S catalysis could be explained well by the "Mixed potential model".
