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Screening Of Acidithiobacillus Ferrooxidans With High Activity And Resistance And Its Application On The Bioleaching Of Copper Ore

Posted on:2010-01-31Degree:MasterType:Thesis
Country:ChinaCandidate:G Z FengFull Text:PDF
GTID:2191360302955211Subject:Soil science
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Acidithiobacillus ferrooxidans can oxidize ferrous ions and reductive sulfur and results in metal ions leached, it is considered to be the major bacterium in the course of leaching. In this dissertation, firstly, acid mine drainage from tonglv mountain and shitouzui ancient mine area were collected for the isolation and purification of high active Acidithiobacillus ferrooxidans and the 16S rDNA of the isolate was analyzed. Secondly, we study the physiological property and determine the decree of resistance of strain SY to Cu2+, Cd2+, Ni2+, Zn2+. Lastly, bioleaching experiments with strain SY to the low-grade oxide - sulphide mixed copper ore collected from yunnan,anhui and daye were studied and discussed.In the initial enrichment experiment, eight strains of iron-oxidizing bacteria were isolated. Ferrous iron oxidation activity was measured as the second screening for these isolates. Strain SY was the most active on ferrous iron oxidation among the Acidithiobacillus ferrooxidans strains tested and selected for further study.The 16S rDNA fragments of strain SY was amplified, cloned, sequenced and homologous analysis. It revealed that the strain SY was closely related to Acidithiobacillus ferrooxidans (DQ 062116.1). Therefore it is accepted that strain SY is Acidithiobacillus ferrooxidans.The physiological and biochemical characteristics analysis showed that the optimal growth pH and growth temperature was about 2.0 and 30°C respectively. But the whole time of ferrous ions complete oxidation was not heavily affected by the inoculation.Experiments about heavy metal resistance of strain SY show that the MTC values were: 300, 350, 700, 800 (mmol/L) to Cu2+, Cd2+, Ni2+, Zn2+ and it demonstrate a high resistance. In addition, after the domestication about a month, the copper-adapted strain was able to complete oxidation ferrous ions at 400 mmol/L Cu2+ with 20% (v/v) inoculation amount in two days.Bioleaching experiments with strain SY to the low-grade oxide - sulphide mixed copper ores collected from Yunnan,Anhui and Daye in Hubei reveal that bacterial leaching with a high recovery rates nearly 30% than acid leaching after leaching about 20 days. It indicates that the strain has good application prospects in the leaching of sulfide minerals. In addition, the extraction rate were 84.28%.. 74.38%,33.31% from Yunnan,Anhui and Daye core sample in bio-leaching process respectively.Compared with the relevant literature about strains of Acidithiobacillus ferrooxidans, we can see that strains SY with a relatively high resistance to some heavy metal is able to meet the leaching requirements of complex multi-metal ore. It indicates that the strain has a good application prospect. The leaching result of mixed copper ore in Daye region by strain SY showed that indigenous strains can show a lot of advantages in the bioleaching of ores.
Keywords/Search Tags:Acidithiobacillus ferrooxidans, Physiological properties, Biooxidation, Heavy metal tolerance, Bioleaching
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