Characterization Of Serratia Sp. From Electrolytic Manganese Residue And The Study On Its Leaching Ability Of Manganese

Manganese is a kind of important mineral resource for our national economy. Manganese ore resources are rich in China, yet with fewer rich ores but more low-grade ores, complex ores and fine refractory ores. rich ore resources are in critical shortage presently. Microbiohydromtallurgy is a sort of economic method that utilizing microbe to extract valuable metals from minerals, which is particularly suitable for disposing low-grade ores, sub-marginal ores and spent ores and featuring merits like low cost, little investment, low energy consumption and little environmental pollution. Wherefore, it is of momentous practical significance for studying the bioleaching of manganese. In this study, a bacterium screened by Peng Xiaowei with strong manganese resistance was further studied, as well as the bioleaching of manganese in electrolytic manganese residue applying the bacterium. The characteristic of the bacterium was further identified by observing its phenotype with scanning electron microscope, extracting its DNA and PCR amplification of 16S rDNA; And the effect of different metal ions on manganese leaching rate was researched, as well as the optimized condition of bioleaching. Besides, the effect of chemistry extraction and bioleaching was contrasted as well as the variation in the binding forms of manganese before and after leaching. A bacterium of strong manganese resistance was screened from electrolytic manganese residue. The small round transparent colony is wet, thin, a little ridgy with regular edge and without flagellum or luster. Based on 16S rDNA, the sequencing result indicated that the bacteria strain is a species of Serratia sp., named as Serratia sp. A1.The shake-flask leaching experiments of manganese residue with serratia sp. Al indicated that the optimized condition of bioleaching was at initial pH value 6.0, solids concentration 10% and cultivated temperature 37℃,and when the leaching rate was up to 80.8%. To investigate the effect of metal ions on the bioleaching of serratia sp. A1, different concentrations of Fe2+, Fe3+, Mg2+ and Hg2+were put in the solution separately. The results showed that a given mass of metal ions were all in favor of the bioleaching, while superfluous metal ions would be inhibitory. It was economic and appropriate to add 15g/L of Fe2+, and the highest leaching rate of manganese was reached with 6g/L of Fe3+, 10g/L of Mg2+or 0.15g/L of Hg2+,up to 82.7%,65.1% and 51.2% respectively.The partitioning of manganese into different fractions was investigated before and after leaching by applying the sequential extraction procedures of the optimized European Community Bureau of Reference (BCR). Three kinds of extractant (EDTA, HN03 and CaCl2) were researched for manganese extraction, and compared with bioleaching, it was known that serratia sp.Al bacteria had a more prominent leaching ability with a manganese-leaching rate up to 79.7% after 3 days, while the rates of three chemistry extractants were 54.4%(EDTA), 34.1%(HNO3) and 23.1%(CaCl2) respectively, which indicated that bioleaching had a more extensive potential application. Before and after chemistry extraction, the proportion of manganese in acid-extraction fraction decreased prominently while the residual fraction increased. Before and after bioleaching, the proportion of manganese in acid-extraction and sulfide and organic matter/sulfide-bound fractions changed prominently, varied from 34.2% and 18.9% to 16.1% and 36.9% respectively, which showed that manganese in electrolytic manganese residue would stay in stable and nonbioavailable forms with low environmental hazard after leaching.