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Although the country is rich in iron ore resources, but with the rapid development of the steel industry and the consumption of large quantities of steel, domestic iron ore supply gap is growing, the availability of iron ore resources are increasingly tend to lean, fine, mixed, which oolitic hematite abroad recognized as the most difficult election of iron ore, and its reserves of iron ore accounted for about 9% of total reserves, it is difficult by conventional processing methods for phosphorus removal. Therefore, in recent decades developed low-cost, environmentally friendly microbes such hydrometallurgical technology is expected to be applied phosphorus iron ore technology. The main subject by studying three kinds of strains (Aspergillus niger (Aspergillus niger), eosinophilic ferrooxidans (At.f bacteria) and eosinophilic thiooxidans (At.t bacteria)) for high phosphorus iron ore Stone phosphorus removal capacity, optimize the test conditions, the test were discussed on the basis of these three kinds of bacteria step, two leaching mechanism of action, for industrial applications provide a scientific basis. By Strains and ore leaching tests, you can get the following conclusions: (1) magnetic roasting temperature indicator concentrates the greatest impact on the optimal roasting conditions: temperature 850 ℃, time 25min, reducing weight accounts for ore 5%, the magnetic field strength 1500Oe, resulting concentrate indicators: iron grade of 54.92%, the recovery rate 86.78%, P content of 0.83%, concentrate mainly composed of magnetite, magnetic hematite (γ-Fe2O3) and quartz ; (2) use of 0.1mol / L in 5 different acids on ore and roasting - magnetic separation of iron ore leaching tests, the combined effect of phosphorus and Iron sulfate is best; worst effect of citric acid and phosphorus removal, but improve iron grade have a certain effect; oxalic acid and phosphorus removal works best, but the maximum rate of iron loss; mixture of citric acid and oxalic acid has some mention iron phosphate lowering effect; single sulfuric acid can handle slurry of ore concentration of 5% and 6% roasting - magnetic iron ore, and phosphorus indicators meet industry standards; (3) in the pulp concentration of less than 2%, Aspergillus niger and direct leaching ore roasting - magnetic separation of iron ore effect is ideal; in two steps leaching process, cultivating Aspergillus optimum conditions: PKO medium, inoculum 4%, initial pH 4.0, nitrogen as ammonium chloride, carbon source is sucrose, the filtration solution on phosphorus ore is better than right alum [NH4Fe3 (SO4) 2 (OH) 6]. Direct leaching process, the lowest rate on standing phosphorus; shaker agitation, speed of 140r/min best, pulp density exceeds 3% phosphorus removal rate can not be achieved; join pyrite to a certain extent, improve At.f phosphorus removal bacteria, but can also lead to high sulfur content; magnetic stirrer and electric mixing conditions, can handle no more than 4% pulp density and sulfur content exceeded. Two-step leaching process, energy source for the S powder, the liquid on the slurry concentration of 6% or less of the ore and roasting - magnetic concentrate phosphorus removal are fine, but after leaching ore, the sulfur content of the ore more than 1%, processing ore, its phosphorus, sulfur content can compliance; With the pulp density increases, the phosphorus removal rate decreased; (5) At.t bacteria directly after dipping ore phosphorus removal rate standards, but leaching After the solid sulfur content exceeded. Two-step leaching test, after filtration bacteria bacteria bacteria containing liquid leaching was no significant difference in the effect of leaching time 18h best final solids are reduced to a phosphorus content of 0.15% or less, but after phosphorus ore , the S content in the ore will reach more than 1%, while the treatment of concentrates containing less than 0.2% Phosphorus; (6) culture pH after mixing Thiobacillus achieve 0.8, the filtered broth extraction of iron ore, able to handle slurry concentration of 6% of roasting - magnetic iron ore, after leaching solids content of 0.25% phosphorus, sulfur content of less than 0.27%; (7) under the action of ultrasound enhanced bacterial filtrate sulfuric acid and At.t leaching process, with the increase of ultrasonic time (60min or less), solid phosphorus content decreased, iron grade has increased, there is a certain recovery rate decreased; With the pulp density increases, the effect of variation phosphorus, iron lower grades, recoveries increased. In sulfur content, the leaching of concentrates solids generally less than 0.25% sulfur content, there is no At.t At.t fungi and bacteria leaching effect less.
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