Effect of ore solid concentration on the bioleaching of phosphorus from high-phosphorus iron ores using indigenous sulfur-oxidizing bacteria from municipal wastewater

Dephosphorization of high-phosphorus iron ore is an unsolved problem worldwide so far. Biotechnology could be a cost-effective and environment-friendly way to solve this problem. A novel method for bioleaching of phosphorus from high-phosphorus iron ores using indigenous sulfur-oxidizing bacteria from municipal wastewaters was first reported in this work. Before bioleaching, the contents of phosphorus and iron from the high-phosphorus iron ore used were 1.04 and 47.89% (w/w), respectively. The effects of ore solid concentration on the phosphorus bioleaching were investigated. It was found most of phosphorus existed in the form of apatite in the iron ore. After bioleaching for 41 days, the final ore slurry pHs at all solid concentrations 10–300 g/L were between 0.09 and 0.63. The average contents of phosphorus and iron in the bioleaching solid residues were 0.21 and 51.7% (w/w), respectively. The average removal percentage of phosphorus and percentage of iron lost were 82.3 and 1.7%, respectively. After bioleaching, the high-phosphorus iron ore was suitable to be used in the manufacture of iron and steel. The optimal ore solid concentration for bioleaching of phosphorus was 250 g/L under the bioleaching conditions. Thus, this bioleaching process seems to be economic and effective.