Bioleaching Of Low-grade Phosphate Ore With The Mixed Acidophilic Bacteria And Pseudomonas Aeruginosa

The mixed bacteria of Acidithiobacillus ferrooxidans ( At.f ) and Acidithiobacillus thiooxidans(At. t), which were for phosphorus leached of low-grade phosphate rock, were isolated from acidic drainage from a mine in Hui Bei Province. Results showed that the mixed bacteria had higher rate of phosphorus leached, which increased 32%, faster leaching rate and lower consumption of energy sources , compared with Acidithiobacillus ferrooxidans. Ferrous and pyrite played a significant role in promoting the leaching of the ore and the optimal dosages were 7 g/100 mL and 0.5 g/100 mL. Appropriate amount of tween 40, 60 and 80 all could promote the interaction between the mixed bacteria and the ore and increase the rate of phosphate leached. The leaching conditions were defined as follows: initial pH was 1.5; inoculum concentration was 15% (v/v); phosphate concentration was 1.5 g per 100 mL;the phosphorus leached was up to 51.07%.The optimal technological parameters of bioleaching soluble phosphorus by mutated mixed bacteria were: radiating with 595 W microwave for 20 s, increased 65%; irradiating with 30 W ultraviolet ray lamp for 3 min, increased 67%; treating with 400 W ultrasound for 30 times(a time: cavitation time 3 s, interval time 7 s), increased one time ; mixing with 0.6 mL of 0.2 mol/L sodium nitrite for 20 min, increased 17%; treating with 400 W ultrasound for 30 times on the positive mutated strains by microwave, increased one time; irradiating with 30 W ultraviolet ray lamp for 3 min on the positive mutated strains by microwave, increased 78%. Organic acids including malic acid, citric acid and oxalic acid, which were released by the mixed bacteria, soluted the rock phosphate together with sulphuric acid.The strain LLJQ-1 was isolated from the low-grade rock phosphate leached Solution. It was characterized by the morphological observation, the physiological and biochemical analysis, the studies of nitrate and alcohol Utilization, 16S rDNA sequencing analysis and the morphological analysis. The result showed that the strain LLJQ-1 was identified as Pseudomonas Aeruginosa. It was the first time to report the strain as the phosphate solubilizing microorganism in this study. In the conditions that initial pH was 2.5, phosphate concentration was 1.0 g per 100 mL and inoculum concentration was 10% (v/v), the phosphorus leached of the strain LLJQ-1 was 83.90%. Under the same condition (pH was 2.5), the phosphorus leached of the strain LLJQ-1 increased 45% compared with the sulfuric acid leaching. The main organic acids which were released by the strain LLJQ-1 were citric acid, malic acid and tartaric acid, and the content of citric acid was up to 74.82 g/L.