With the steel industry, the available resources are increasingly tend to lean ore, fine, heteroaryl. China's high- phosphorus iron ore reserves accounted for 14.86% of the total reserves, reaching 7.45 billion yuan. At present, due to the high phosphorus content, it cannot be fully utilized. In the high-concentration iron ore mine in western Hubei, the main mineral-hematite has a very fine grain size and is often symbiotic, cemented or intertwined with other minerals. It is currently recognized as the most difficult type of iron ore selected at home and abroad. Therefore, research on iron ore phosphorus removal technology is very important. In recent years, domestic and foreign research on different ore properties has carried out a more in-depth study on iron ore dephosphorization process, while acid leaching and microbial leaching methods, such as iron ore leaching and dephosphorization experiments, are considered to be An effective method. In this test, the ore is treated by acid leaching and microbial leaching to achieve the effect of iron and phosphorus removal. The microscopic identification, XRD and scanning electron microscopy studies show that the ore composition of the ore is relatively simple, the iron mineral is mainly hematite, followed by limonite, occasionally magnetite; the gangue mineral is mostly quartz . The second is chlorite, collophanite, dolomite, calcite and kaolinite. First, the test materials and methods (1) Test materials Oxalic acid (C 2 H 2 O 4 ), citric acid (C 6 H 8 O 7 ), H 2 SO 4 , HN0 3 , HC1 are analytically pure, formulated to 0.1 mol / L; Species. In the bioleaching test, the strain used Thiobacillus ferrooxidans (At. f) and Aspergillus niger. Among them, At.f was collected from a hot spring water in Guangxi and was identified by purification. The Aspergillus niger was collected from the soil of a vegetable field in Wuhan and identified by purification. Medium. At.f strain was selected from 9K medium: (NH 4 ) 2 S0 4 3g, KCl 0.1g, MgS0 4 ·7H 2 O 0.5g, K 2 HP0 4 0.5g, Ca(N0 3 ) 2 0.Olg, distilled water 700mL , pH=3.0, sterilized at 121 °C for 20 min, 300 mL of pre-formulated 14.78% FeS0 4 ·7H 2 0 solution and filter sterilization; Aspergillus niger used inorganic phosphorus medium: glucose lOg, (NH 4 ) 2 S0 4 0.5 g, NaCl 0.3g, KCl O.3g, MgS0 4 ·7H 2 O 0.3g, FeS0 4 ·7H 2 0 0.03g, MnSO 4 ·4H 2 0 0.03g, of which 3g Ca 3 (P0 4 ) 2 is changed to K 2 HP0 4 lg, 1 L of distilled water, natural pH, sterilized at 121 ° C for 20 min. (2) Test methods The acid pickling acid leaching test uses a 250ml Erlenmeyer flask, respectively containing 100ml of the corresponding acid solution, adding the ore, and stirring and stirring in an air bath oscillator for 40h. The bioleaching test used a 250 ml Erlenmeyer flask, and the At.f strain filtrate cultured in a shaker for 7 days and the 100 ml Aspergillus niger filter solution (medium speed filter paper filtration) were respectively selected, and the slurry concentration was 2%. Unless otherwise specified, when the culture liquid is cultured, the volume of the conical flask is 250 mL, the volume of the medium is 100 mL, the inoculum of At. f is 10%, and the fungus is selected with 1 ml of Aspergillus spore solution at a concentration of 10 8 cpu. /ml, oscillated in a shaker, wherein the speed of the shaker used by At.f was 140r/min, the temperature was 30°C, the speed of the shaker used by Aspergillus was 180r/min, and the temperature was 32°C. Second, the results and discussion (1) Acid leaching and phosphorus removal The effect of acid species on the effect of phosphorus leaching. The experimental study on the effect of leaching and dephosphorization of the ore by 0.1 mol/L oxalic acid (C 2 H 2 O 4 ), citric acid (C 6 H 8 O 7 ), H 2 SO 4 , HNO 3 and HCL, respectively. The concentration of the slurry is 2%, and the results are shown in Fig. 1. Figure 1 Effect of five kinds of acid on iron and phosphorus reduction of ore It can be seen from Fig. 1(a) that the removal efficiency of citric acid (C 6 H 8 O 7 ) is the worst, only 77.84%, and the phosphorus removal rate of the other four acids is above 80%, of which oxalic acid ( C 2 H 2 0 4 ) The best phosphorus removal effect was 95.52%, followed by sulfuric acid (93.91%), and the effect of nitric acid and hydrochloric acid was close. It can be seen from Fig. 1(b) that after the oxalic acid leaching, the iron grade is close to the ore (43.73%), and the other four acids have improved the work position. Among them, the sulfuric acid effect is the best in improving the iron grade, and the iron grade after treatment is 49.08%. The effect of nitric acid and hydrochloric acid is close, but both are higher than citric acid. In addition, in terms of iron loss rate, the iron loss rate was 8.83% except for oxalic acid, and the iron loss rate was less than 2% after the other four kinds of acid treatment. The effect of inorganic acid is better than that of organic acid, and the recovery rate of iron after sulfuric acid treatment is 99.57%. It can be seen from the above analysis that the comprehensive effect of single inorganic acid for iron and phosphorus removal is better than that of single organic acid, and the sulfuric acid has the best effect. However, many fungi in nature can produce a variety of organic acids at the same time, and Aspergillus can produce a large amount of oxalic acid, citric acid and the like at the same time. Considering the poor effect of citrate dephosphorization, but with the effect of iron extraction, good acid removal effect of oxalic acid, poor phosphorus removal effect, etc., oxalic acid and citric acid are mixed in different proportions for leaching and dephosphorization. The effect of mixed organic acids on the effect of phosphorus removal by leaching. Different ratios of oxalic acid and citric acid were mixed and leached, and the mixing ratios were 100:0, 80:20, 60:40, 20:80, 0:100, and the pulp concentration was 2%. The result is shown in Fig. 2. Show. Figure 2 Effect of mixed oxalic acid and citric acid on iron and phosphorus reduction of ore (100:0, 80:20, 60:40, 40:60, 20:80, 0:100) As can be seen from Fig. 2(a), as the mixing ratio of oxalic acid to citric acid decreases, the phosphorus removal rate tends to decrease. In the ratio of 100:0 to 20:80, the phosphorus removal rate is above 92%; but when there is only citric acid in the acid solution, the phosphorus removal rate is significantly reduced, only 75.29%. It is indicated that the phosphorus removal effect is significant in the presence of oxalic acid in the acid solution. It can be seen from Fig. 2(10) that the iron grade varies little with respect to the ore in the mixing ratio of 100:0 to 20:80, which is about 44%; and when only citric acid is present, the iron grade after treatment For 46.87%, the effect of iron extraction is better; and with the decrease of the ratio of oxalic acid to citric acid, the recovery rate of iron is gradually increasing. From the above analysis, it can be further determined that the phosphic acid dephosphorization effect is better than citric acid, but the citric acid iron extraction effect is superior to oxalic acid. The mixture of the two acids can achieve better iron and phosphorus removal effects, which can play a certain role in the future determination of the acidogenic acid species. The effect of slurry concentration on the phosphorus removal effect of sulfuric acid leaching. When the slurry concentration is 2%, the single sulfuric acid leaching effect is the best, and the pH value of the leaching solution after leaching is still low, so the acidity can still treat some iron ore. The effect of slurry concentration on the phosphorus removal effect of sulfuric acid leaching was investigated. The results are shown in Fig. 3. Fig.3 Effect of iron and phosphorus reduction on ore in sulfuric acid under different pulp concentration conditions It can be seen from Fig. 3(a) that as the concentration of the slurry increases, the phosphorus removal rate gradually decreases. When the pulp concentration is 2%, the phosphorus removal rate reaches 93.06%; when the pulp concentration reaches 5%, the phosphorus content in the ore after treatment is 0.18%; the phosphorus removal rate is 78.82%; when the pulp concentration reaches 6%, the ore is in the ore. The phosphorus content was 0.25% and the phosphorus removal rate was 70.59%. It can be seen from Fig. 3(a) that when the slurry concentration is lower than 6%, the iron recovery rate is greater than 97.89%, and the relative change is not large. As for the iron grade, as the concentration of pulp increases, the iron grade tends to decrease. When the slurry concentration is 6%, the iron grade is 46.54%. It can be seen from the above analysis that when the slurry concentration is ≤ 5%, the phosphorus removal effect can meet the industrial requirements. (3) Biological leaching and phosphorus removal test The At.f strain was used for the leaching test, and the At.f strain after 7 days of growth was filtered with a slow filter paper, and the filtered bacterial solution was immersed in the ore concentration. The concentration of the pulp was 2%, and the pH value during the growth of At. Figure 4. After 24d, the slurry is filtered and dried, and the phosphorus content in the solid is 0.25%. Separation of phosphorus by Aspergillus niger. The spores of the 2 ring of A. niger were inoculated into 100 ml of inorganic phosphorus medium. The change of PH value during the growth of Aspergillus niger was shown in Fig. 5. Figure 4 Changes in pH during At.f leaching Figure 5 pH change during the growth of Aspergillus niger As a result of one-step leaching, the Aspergillus niger will enclose the mineral, which makes it difficult to separate the bacterium after leaching. Therefore, the two-step leaching method is used for leaching. The filtrate (without mycelium and spores) was directly leached with a concentration of 2%. After 40 hours of reaction, the ore was filtered and dried. The test results showed that the residual phosphorus content was 0.2 2%, which achieved better phosphorus removal. effect. Third, the conclusion (1) In the phosphorus leaching test, 100 ml of 0.1 mol/L oxalic acid (C 2 H 2 O 4 ), citric acid (C 6 H 8 O 7 ), H 2 SO 4 , HNO 3 and HCL are used, and the pulp concentration is 2 %, a single inorganic acid iron extract is better than organic acid. Among them, sulfuric acid has the best effect; citric acid has the worst effect on phosphorus removal, but it has certain effect on improving iron grade; oxalic acid has the best phosphorus removal effect, but the iron loss rate is the largest. (2) In terms of organic mixed acid leaching, with the decrease of the ratio of oxalic acid to citric acid, the phosphorus removal rate is gradually reduced, the recovery rate is gradually increased, and the iron grade is relatively stable after treatment. When the mixing ratio is between 100:0 and 20:80, the phosphorus removal effect is ideal. (3) With the increase of slurry concentration, the phosphorus removal rate of single sulfuric acid leaching is gradually reduced, and the ore iron grade after treatment is gradually reduced, and the iron recovery rate does not change much. When the concentration of pulp is 5%, the phosphorus removal rate can reach 78.82%; when it is higher than 6%, the phosphorus removal effect can not meet the relevant requirements. (4) The phosphorus content in the solids after leaching and dephosphorization by At.f and Aspergillus niger was 0.25% and 0.22%, respectively, which achieved a good phosphorus removal effect. Ring Die Pellet Machine is an efficient centrifugal Biomass Pellet Making Machine which absorbs the quintessence of various pellet mills both at home and abroad, the heart part adopts "double-layer die" as the unique structure. The rollers are made by abrasion-proof alloy steel. Ring Die Pellet Machine Pellet Making Machine,Ring Die Pellet Machine,Ring Die Pellet Mill,Napier Grass Pellet Machine Jinan Shanghangda Machinery Co., Ltd. , https://www.jinanshdmachine.com