The Effect And Mechanism Of Different Nutrition On Bioleaching Pyrite By Community

The mobilization of metal cations from almost sulfide ores by biological iron and sulfur oxidation of acidophilic microbes is referred to as bioleaching.Bioleaching technology attracts more attention for its low cost and environmental protection.At the same time,the process of leaching tailings and sulfide ores by application of microorganisms is considered to the main reason caused acid mine drainage(AMD)and environmental pollution.It has significance for the treatment of heavy metals wastewater and development of bioleaching technology to thoroughly understand the metabolic characteristics and mechanism.The acidophilic microbial community(named 5Biol)applied in this study mainly consist of autotrophic Acidithiobacillus caldus oxidized inorganic sulfur compounds and mixotrophic Sulfobacillus thermotolerans that is able to oxidize either inorganic sulfur compounds and/or iron(?)ions.Lixiviant from pyrite bioleaching conducted to leach pyrolusite showed a good performance in manganese extraction.And the efficiency of pyrolusite bioleaching was improved in low pH?high ORP and high concentration of Fe(?)environment.It indicated the process of pyrite bioleaching played a key role at the whole reaction.In order to further improve efficiency and understand mechanism of pyrite bioleaching,sulfur and yeast extract were used to enhance A.caldus and S.thermotolerans respectively.Under the effect of low concentration of yeast extract,the proportion of S.thermotolerans was increased in initial period.And the period of bioleaching was decreased by 2 days.The fluorescent quantitative analyses showed that low concentration of yeast extract caused the expressions of sulfocyanin rubisco and oxoglutarate involved in iron oxidation.autotrophic and heterotrophic carbon metabolism respectively,indicating that the efficiency of pyrite bioleaching was improved by enhance growth and iron oxidation of S,thermotolerans.It also indicated that high concentration of yeast extract had significant effects on the growth of S.thermotolerans.However,it resulted in its metabolic way trended to be heterotrophic in the whole bioleaching process.Combined with community dynamics,it can be found that the proportion of A.caldus was increased with adding 0.5%elemental sulfur,and the rate of acidization was accelerated.However,the efficiency of bioleaching was inhibited.Taken together,these results indicate that the main impetus of pyrite bioleaching was iron oxidation from S.thermotolerans.And the key role of A.caldus in the community was to ensure selectivity of iron oxidation developed by S.thermotolerans and more stable existence of ferrous iron.