Experimental Study on Leaching of a Low-grade Phosphate Ore with Thiobacillus Ferrooxidans

Thiobacillus ferrooxidans was used to leach a low-grade phosphate ore. The optimal growth conditions of Thiobacillus ferrooxidans was investigated, and the bacteria that could resistant to high slurry concentrations was obtained by step-by-step transfer of domestication. Domesticated bacteria was used to leach phosphate ore to achieve the purpose of improving the leaching rate. A phosphate mine in Guizhou with a grade of 13.17% P₂O₅ was used as the research object. The results showed that the activity of Thiobacillus ferrooxidans oxide was strong under the conditions of temperature of 33 ℃ and initial pH of 1.6, and the higher concentration was 1.63×10⁸ mL⁻¹. The P₂O₅ leaching rate of thiobacillus ferrooxidans after domestication was 76.6%, and the corresponding thiobacillus ferrooxidans without domestication was only 60.3%. When the mass concentration of slurry was 1%, 3%, 5%, 7% and 9%, the leaching rates of phosphate ore were 56.4%, 70.4%, 75.2%, 64% and 44.7%, respectively. The leaching rate of phosphate ore with pyrite as nutrient was 78.6%, which was 17.1 percentage points higher than the leaching rate with sulfur as a nutrient. The study improves the leaching rate of low-grade phosphate ore, and it shortens the phosphate leaching time.