Acid-producing Acitivity Of Acidithiobacillus Thiooxidans And Microbioleaching Of Low-grade Phosphate Ores

Microbiohydro-metallurgy or micro-bioleaching, which can save energy, reduce pollutant emission and treat complicated low-grade refractory ores, has become one of the most important dressing techniques. For its good bioleaching ability, Acidithiobacillus have been widely researched and used in micro-bioleaching. Acidithiobacillus thiooxidans (At. t) is one of the bioleaching bacteria, which can oxidize sulfur and reductive-state sulfides to produce sulfuric acid and play vital role in micro-bioleaching and desulphation of coal.A strain of At. t isolated from a sulfur-containing hot spring in Guangxi was used to leach low-grade phosphate ore after being purified and cultivated. It is indicated that the strain shows good growing activity and acid-producing ability while the initial pH of the culture medium was 2.4. The pH of the culture medium declines to 1.8 in a cultivated period. The strain performs well in the bioleaching of phosphate ore, and the leaching rate reaches 23.13%.Microwave mutagenesis study, ultraviolet mutagenesis study and microwaveultraviolet mutagenesis study were carried out with the strain in order to do some further research on acid-producing activity and leaching capability of At. t. The results indicate that acid-producing activity and leaching capability of phosphate of At. t are changed notably for different mutagenesis agents and different mutagenesis time.The pH of the culture medium of At. t strain after microwave mutagenesis is lower than that of the original strain, which indicates that acid-producing activity of At. t enhanced after microwave mutagenesis. The leaching capability of At. t changed effectively after microwave mutagenesis. The leaching-rate of the strain mutagenized with microwave for 10s is the highest and is enhanced by 41.55% compared to the original strain.Acid-producing activity and leaching capability of At. t changed markedly after ultraviolet mutagenesis. The leaching-rate of the strain mutagenized with ultraviolet for 15min is the highest and is enhanced by 30.44% compared to the original strain.After microwave- ultraviolet mutagenesis, acid-producing activity of At. t strain is enhanced. Leaching rates of phosphate of several strains are higher than that of the original strain. The leaching-rate of the strain mutagenized with microwave for 15s and with ultraviolet for 15min is the highest and is enhanced by 31.22% compared to the original strain.