| With the human exploitation of mineral resources, gold resources are depleted, easy to handle ore is declining, refractory gold ores has become the focus of research and development. The gold concentrates from Guizhou Nibao, containing gold16.78g/t, arsenic4.45%, sulfur35.85%,2.42%of carbon, and the gold particle size extremely small(most less than2μm). Flotation concentrate has a low grade of gold and sulfur and arsenic are inseparable.It is a typical refractory metallurgical gold ore. According to the characteristics of this sample, efficient strain breeding, biological pre-oxidation process and cyanide leaching were carried out. The community of micro-organisms in the pre-oxidation system is studied by building16SrDNA clone library conduction and Real-time PCR.From the five species which were collected from Nibao Gold mine(NB), Zijinshan Copper mine(ZJ), Baishan Nickel and Cobalt Copper mine(BS), Mojiang Nickel and Cobalt mine(MJ), Dexing Copper mine(DX), we chose NB strains in test and we get the final NB strains through constantly adapter and domestication. It is a group composited by bacillus, coccus and spirillum. This group growth well at45℃,10%of the quantity, concentrate and0.1g/L yeast extract energy as material.After constant transfer of domestication, we got a high efficient group, the ability of oxidation were greatly improved. Compared with the starting strian, domestication strian sulfur oxidation increased by15.40times,arsenic oxidation increased by3.12times, and the gold leaching rate increased by7.63times.At45℃,10%of the quantity and10%pulp density, biological pre-oxidation of15days the sulfur oxidation rate is49.21%, the arsenic oxidation rate is68.03%and the gold leaching rate is77.91%. About22%of the gold is still remain in leaching residue, the reason is extremely slight gold was the gangue package and pyrite oxidation not completely and carbon absorption.After biological pre-oxidation,the main material of the generation of slag are jarosite and ferric arsenate, the organic carbon content dropped27.88%, and the inorganic carbon content down70.59%, explain the strains of carbonaceous NB has certain degradation function.The result of16SrDNA clone library conduction show that bacteria mainly composition by the Sulfobacillus sp.(52%), Sulfobacillus thermotolerans (25%), Leptospirillum ferriphilum (23%), and the archaea is Ferroplasma acidiphilum.Through the five kinds of design has specific primer Acidithiobacillus sp., Leptospirillum sp., Sulfobacillus sp., Ferroplasma sp., Universal:Bacteria and Archaea, of the sample for DNA amplification, fluorescent quantitatiVe Real-time monitoring results show that only three successful primer amplification, respectively Leptospirillum sp., Sulfobacillus sp., Ferroplasma sp., three kinds of bacteria is the percentage0.0049%,1.64%,98.37%.The diversity of domestication strian was significantly lower than the start strian, and NB strain is different from the strain of other organisms used in the pre-oxidation process.The dominant strain is archaea Ferroplasma acidiphilum, play a major role in the process of pre-oxidation, Leptospirillum ferriphilum for arsenic trioxide strains, Sulfobacillus sp.、Sulfobacillus thermotolerans are oxidation sulfur bacteria, both of them and Ferroplasma acidiphilum can use organic carbon source for energy to grow, might be in carbon quality haVe certain degradation function.Compared with other biological pre-oxidized species, NB has wide growth temperature range, has acid resistance ability and more strong, especially suitable for the oxidation process for arsenic carbonaceous refractory gold ores. |
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