Study On Recovery Of Iron From Tailings Using Microbial Fuel Cell

In recent years, the technology of MFC could recycled chemical energy from sewage or the solid waste, and transform it into clean electricity directly, which has become the current hot research topic in the field of environmental biotechnology. Studies of MFC technology changes with each passing day, its application field expanding rapidly, MFC has become the technology of the pollution control and biomass conversion, which has great potential application value. At present, along with the exploitation of mineral resources, high quality and easy to choose mineral resources has been decreasing, the rest of the minerals are some tailings and low grade minerals, they not only take up a lot of land, but also cause pollution to the ecological environment, therefore, recycling of the tailings resources have a certain economic benefits, and microbial leaching technology has certain advantage in recycling low grade mineral, but at present the traditional microbial leaching rate is relatively low, how to further improve the leaching rate of metal ions in the tailings becomes a big problem.In microbiological leaching technology, involving the biochemical reaction, in the above reaction if add the electrochemical process, may accelerate the process of leaching reaction, would be conducive to microbial leaching. This study with pyrrhotite tailings as an example, this article use the FeS simulation on anode of the MFC and at the same time inoculate bioleaching microorganisms to the MFC anode, construct the MFC biological anode. MFC technology and microbial leaching technology, build the FeS-MFC system, make full use of the advantage of the MFC technology in microbial electrochemical, so the system not only has innovation on the microbial leaching technology, but also has certain innovation on microbial fuel cells, expand the function and application of microbial fuel cell anode area, and also has a certain academic value and commercial value. In this paper, the main research contents and results were as follows:（1） Studied for sulfur oxidizing bacteria domestication method of mother liquor, FeS-MFC device startup method, and the feasibility of using MFC technology leaching ore, and through the study of FeS concentration and in influence on the voltage and iron ions leaching rate, seek the suitable concentration of FeS. Results show that use the FeS as energy to domesticated sulfur oxidizing bacteria, its concentration of 25 g/L, which is advantage to the domestication of leaching microorganism, anode chamber FeS concentration of 25 g/L, the maximum output voltage of 654.3 mV, maximum power density for 1082 mW/m2, corresponding ion leaching rate was 36.2%. This suggests that the use of MFC technology leaching FeS model is feasible.（2） Comparative studied the control group, inoculated microbe mother liquor FeS- MFC group and traditional microbial leaching on the change of the voltage and power density, studied characteristics of FeS-MFC device. The results showed that the inoculated microbe mother liquor FeS –MFC, the stability of the output voltage is 690.4 mV, MFC reactor power density for 1343 mW/m2, compared with the control, raised more than three times, the anode CV curve presents obvious REDOX peaks. Domesticated microbes in the process of leaching liquor（oxidation sulfur bacteria） can be further oxidized the intermediate element sulfur from FeS transformation process, alleviate the sedimentation caused by electrode and FeS surface passivation phenomenon, in promoting the MFC electricity production at the same time, improve the efficiency of the leaching of iron ion, also found that microbial catalysis and channel state is not only beneficial to the system voltage output and iron leaching, but also can accelerate the leaching rate of iron ions. Develop basic research in MFC leaching mining technology, to further explore the leaching mechanism and process, improve the energy recovery, has important theoretical and practical significance.（3） Studied the traditional biological leaching and vaccination FeS- MFC group electron micrograph and EDX analysis of ferrous sulfide slag, anodic microbial activity analysis, and the oxidation mechanism of microbial fuel cells leaching FeS were analyzed, and the research results showed that the inoculated microbe mother liquor FeS- MFC microbial activity in reactor is more intense, which is the important reason for the power and leaching rate with high, in the traditional biological leaching and vaccination FeS- MFC group, thiobacillus microbes oxidate elemental sulfur into sulfate, effective prevent ferrous sulfide mineral sulfur membrane formation on the surface passivation, for leaching of ferrous sulfide minerals have a positive effect, in the FeS-MFC system, oxidation leaching of FeS is given priority to the direct mechanism.（4） Examined the use of MFC single chamber technology processing research of lixiviant, discussed under the condition of different pH, producing different and the change of power density curve, and according to the optimal treatment leachate pH conditions, studied the potential of cathode and anode, the change of the voltage, at the same time analyze the leaching of iron ion change before and after running, using electron microscope extreme precipitation and electrode surface morphology of cathode and anode, and elements of precipitation XPS analysis. Results show that the pH value of 4.5 is suitable using single-chamber MFC recycling leaching liquid of iron ions, and can produce high power, analyze the distribution of precipitation is produced by the anode precipitation accounts for over 80% of the total amount of precipitation, surface of the cathode and bottom of the reactor has less precipitation, deposits on the surface of the anode is mainly Fe₂O₃, cathode surface sediments mainly Fe₂O₃ and FeO.