Study On Bioleaching Conditions Of Vanadium From Vanadium-bearing Stone Coal

The bioleaching of vanadium from vanadium-bearing stone coal has been studied by using Acidthiobacillus ferrooxidans and mixed bacteria of Acidthiobacillus ferrooxidans, in order to determine the feasibility and optimal technological conditions. The influence of parameters such as pulp density, leaching temperature, initial pH and rotation speed on vanadium leaching efficiency was investigated. Moreover, the effect of parameters such as p H, Eh, the concentration of Fe2+, total iron and V of leaching liquid was measured in the process of leaching to detect its variation. On the basis of single-factor experiments, the conditions including leaching temperature, initial pH and rotation speed for the bioleaching were optimized by using Box–Behnken Design(BBD) and Response Surface Methodology(RSM) during the bioleaching process. Under the optimum condition, aerobic and anaerobic techniques were alternately used to strengthen the leaching of vanadium from vanadium-bearing stone coal. Finally, the residue was analyzed by scanning electron microscope(SEM) in order to observe the change in the sample according to its composition before and after the leaching process. The main results of the investigation are summarized below.The experiments of bioleaching vanadium-bearing stone coal were respectively carried out with Acidthiobacillus ferrooxidans, mixed bacteria of Acidthiobacillus ferrooxidans, and another one without culture of bacteria in the media. The results showed that the leaching efficiency of Acidthiobacillus ferrooxidans, mixed bacteria of Acidthiobacillus ferrooxidans were superior to the leaching efficiency of the culture medium without bacteria.The bioleaching of vanadium from vanadium-bearing stone coal has been studied by using Acidthiobacillus ferrooxidans. The results showed that the best condition of the experiment was 3% for pulp density, 30 ℃ for leaching temperature, initial pH value of 2.0 and rotation speed of 150 r/min on single-factor experiments. When the best condition was satisfied, the leaching efficiency of vanadium reached 67.8%. The optimized results showed that the predicted leaching efficiency of vanadium could reach 70.38%, when the optimum condition of the experiment was 30 g/L for pulp density, 32 ℃ for leaching temperature, initial pH value of 2.1 and rotation speed of 147 r/min.Under the optimum condition, validation experiments were carried out. The measured vanadium leaching efficiency were an average of 69.2% and fit the predicted values. It indicated that the model is accurate. In the course of keeping alternate aerobic and anaerobic condition, the results showed that the leaching efficiency of vanadium reached 65.0%, when the condition of the experiment was 30 g/L for pulp density, 32 ℃ for leaching temperature, initial pH value of 2.1 and rotation speed of 147 r/min. The scanning results showed Acidthiobacillus ferrooxidans adsorbed on the surface of mineral the stone coal and the adsorption was beneficial for the oxidation and decomposition.The bioleaching of vanadium from vanadium-bearing stone coal has been studied by using mixed bacteria of Acidthiobacillus ferrooxidans. The results showed the best condition of the experiment was 30 g/L for pulp density, 35 ℃ for leaching temperature, initial pH value of 1.8 and rotation speed of 150 r/min on single-factor experiments. When the best condition was satisfied, the leaching efficiency of vanadium reached 68.5%. The optimized results showed that the leaching efficiency of vanadium could reach 69.2%, when the optimum condition of the experiment was 3% for pulp density, 32 ℃ for leaching temperature, initial pH value of 1.82 and rotation speed of 161 r/min.Under the optimum condition, validation experiments were carried out. The measured vanadium leaching efficiency were an average of 68.5% and fit the predicted values. It indicated that the model is accurate. In the course of keeping alternate aerobic and anaerobic condition, the results showed that the leaching efficiency of vanadium reached 67.0%, when the condition of the experiment was 30 g/L for pulp density, 32 ℃ for leaching temperature, initial pH value of 2.1 and rotation speed of 147 r/min.The scanning results showed mixed bacteria of Acidthiobacillus ferrooxidans adsorbed on the surface of mineral the stone coal and the adsorption was beneficial for the oxidation and decomposition.