Bacterial leaching of uranium can take different forms depending on the size of the leaching. The laboratory generally uses a shake flask leaching method, an air lift percolator leaching method and a column leaching method, and industrial production often employs a heap leaching method, a pool immersion method, and an in situ leaching method. This study combines the characteristics of a mine uranium ore and the actual production of the industry, using laboratory bacterial column leaching to simulate the industrial production of bacterial heap leaching, using laboratory bacterial pool immersion to simulate the industrial production of bacterial pool leaching, by comparing the relevant parameters in the leaching process Change the law to explore the preferred bacterial leaching method for the uranium ore. First, the test materials and methods (1) Test ore sample The test ore samples were taken from a uranium mine and the chemical multi-element analysis results are shown in Table 1. Before the test, all ores were thoroughly mixed and sieved, and the uranium content of each grade ore obtained by screening was sampled and analyzed. The results are shown in Table 2. Table 1 Results of multi-element analysis of mineral samples Table 2 Analysis results of ore sample size and uranium content It can be seen from Table 1 that FC 2 O 3 and FeO in the ore account for 0.565% and 0.750%, respectively, and the Fe content is high, which can provide energy for the growth and reproduction of bacteria, and is beneficial to bacterial leaching. At the same time, the high content of fluorine in the ore (0.77%) requires that the leaching bacteria have strong adaptability to the high fluorine environment to ensure the efficiency of leaching. It can be seen from Table 2 that uranium is mainly distributed in ore of 5~8mm size; the ore particle size is less than 8mm, and the particle size distribution is reasonable, which makes the ore have good permeability, which is beneficial to the leaching solution and the ore. The contact area ensures the growth, reproduction and leaching efficiency of the leaching bacteria in the ore. (2) Source and cultivation of strains Bioleaching strains used in the tests was separated from uranium ore mine site and acid waste water, purification, mutagenesis of acclimation, alkylene iron ferrooxidans (Acidthiobacillus ferrooxidans) and thiooxidans (Acidthiobacillus thiooxidans) mixed bacteria. The strain has the physiological characteristics of strong activity, good adaptability, high salinity resistance, strong anti-fluorine ability, and can grow rapidly under the condition of pH=1.2, and can even grow slowly under the condition of pH=0.6. In order to improve the adaptability of bacteria to fluorine in the ore, the diluted ore acidified tail liquid is used as the medium, and the strain is gradually domesticated to have better adaptability to the target ore. (3) Test equipment and test parameters The column immersion device uses a special plexiglass column with a column diameter of 150 mm and a column height of 2 m. The pool dip unit is made of plastic barrel. The top of the barrel is 60cm in diameter, the bottom diameter is 45cm, and the height is 80cm. The bottom is provided with a vent hole to provide oxygen for bacteria to survive. The test device is shown in Figure 1. Figure 1 Test device The test parameters are as follows: 1. The ore amount is 20kg; 2. The initial pH of the acid prepreg is 0.9~1.3 (sulfuric acid concentration 10g/L); 3, the initial pH of the immersion liquid work is 1.5~1.9, and the pH of the control liquid is 1.8~2.0; 4. The concentration of ferric iron in the infusion solution is about 5 g/L; 5. The pool is immersed under aerated conditions. Second, test results and analysis (1) pH change and acid consumption rate The pH value is an important parameter in the leaching process. It is not only related to whether the leaching bacteria can adapt to the environment of the ore sample and the leaching agent, but also to the dissolution and precipitation of iron and uranium. The pH value and acid consumption rate during column immersion and pool leaching tests are shown in Fig. 2. China Mineral Processing Technology Network Figure 2 pH change and acid consumption rate curve △ - pH value of the immersion liquid; ○ - pH value of the leachate; □ - acid consumption rate It can be seen from Fig. 2 that during the acid leaching process, the pH values ​​of the column leaching and the pool leaching leaching are relatively large, mainly because the acid in the acidizing stage contains a large amount of acid-consuming substances to consume the acid in the leaching solution, which causes the pH of the leaching solution to fluctuate up and down. . The pH value of the column leachate is higher than that of the pool, and the acidification time of the pool is less than that of the column, indicating that the acid-consuming substance in the ore reacts well with the acid in the solution when the tank is immersed under aeration conditions, resulting in most acid-consuming substances. Can be consumed in a shorter period of time. Therefore, in the initial stage of acidification, the column pickling time can be shortened by increasing the amount of spray and the spray time. The test was carried out until the end of the 48th day. The acid consumption rates of the two leaching methods were 3.38% and 2.16%, respectively, which were relatively low, but the column leaching was greater than the pool leaching. It can be seen that good aeration conditions are beneficial for the leaching bacteria to convert the sulfur element in the leaching system into sulfuric acid, and the pool leaching method is advantageous for reducing acid consumption. (II) Change law of Eh value and iron concentration in leachate In order to accelerate the oxidation rate of UO 2 , it is necessary to ensure that the Eh value of the leaching system is sufficiently high. The changes of the concentration of Fe 3 + and Fe 2 + in the leachate affect the bacterial leaching effect, and indirectly reflect the state characteristics of the uranium leaching bacteria. The variation of Eh value and iron concentration in the column leaching and pool immersion test leaching solution is shown in Fig. 3. Figure 3 Change in Eh value and iron concentration of leachate △-concentration Fe 2 + concentration; ○-lead Fe 3 + concentration; ■-leaching Eh value It can be seen from Fig. 3 that in the leaching stage, due to the oxidation of bacteria, the Eh values ​​of the leaching solutions of the two leaching modes are in a high state, which is 700-900 mV, which promotes the immersion uranium process. After the start of the leaching, the total iron concentration of the leaching solution was about 5 g/L, which was basically balanced with the total iron content of the leaching agent, indicating that no iron precipitation occurred during the immersion. The low Fe 2 + content in the leachate indicates that the leaching bacteria grow well in the leaching system and have higher activity, which can promote the leaching of uranium. (III) Change law of uranium concentration and fluorine concentration in leachate Leachate uranium concentration is an important parameter to characterize the effect of uranium leaching. The test ore has a high fluorine content, and the fluoride ion eluted during the leaching process has an inhibitory effect on the activity of the bacteria, which may affect the leaching of the uranium. For this reason, the strains used are resistant to fluorine and domesticated, so that they are better adapted to the ore. Sex. The uranium concentration and fluorine concentration of the leachate during the leaching process are shown in Figure 4. Figure 4 Changes in uranium concentration and fluoride concentration in leachate ◇-uranium concentration; ■-fluorine concentration It can be seen from Fig. 4 that the uranium concentration of the leachate has the following change rule: the concentration of the column leaching uranium fluctuates in the acidification stage, and the uranium concentration decreases after the addition. The reason may be that the acid-consuming substances in the ore at the initial stage of leaching consume a large amount of acid. As the acid-consuming substances in the ore gradually decrease, the acid gradually dissolves the hexavalent uranium in the ore, and the uranium concentration of the leachate gradually increases; As the leaching proceeds, the easily soluble hexavalent uranium in the ore is slowly reduced, and the uranium concentration in the leachate is gradually decreased. Because the ore in the pool immersion is more fully contacted with the acid solution, the uranium concentration in the leachate reaches a maximum. As the leaching progresses, the uranium concentration in the leachate also decreases due to the decrease of hexavalent uranium in the ore. After the addition of bacteria, the leaching bacteria and Fe 3 + oxidant played a certain role in column leaching and pool leaching, and gradually leached the uranium which was difficult to leach, so that the uranium concentration of the leaching solution was maintained in a certain concentration range for a long time. The concentration of column leaching uranium can be maintained for 16 days at around 100mg/L, and the concentration of immersion uranium in the pool can be maintained at around 100mg/L for 14d. When the pool was immersed until the 25th day, the ore was turned over, and the uranium concentration of the leaching solution increased from 81mg/L to 182.3mg/L. After the 37th and 45th tumbling, the uranium concentration of the leaching solution also increased, indicating that the leaching is beneficial to the leaching agent. Fully function with ore to improve leaching efficiency. During the leaching process, the concentration of fluorine in the column leaching and pool leaching leaching was 800-1000 mg/L, and the change increased with the increase of uranium concentration, indicating that the uranium was leached and the fluorine encapsulated in the ore was also leached. The pool leaching solution is more fully contacted with uranium ore, and the change of fluorine content in the leaching solution is small, which is beneficial to the growth of leaching bacteria. It can be seen that the combined strains after fluoride-tolerant acclimation can better adapt to the leaching system, and have good activity in both column leaching and pond leaching, so that the uranium leaching effect is improved. (4) Comprehensive test results The test took a total of 48 days, and the uranium leaching rate of the liquid meter was changed as shown in Figure 5. The comprehensive test results are shown in Table 3. Figure 5 Uranium leaching rate curve □-column dip; ○-pool dip Table 3 Comprehensive test results index Column dip Pool dip Ore grade uranium /% 0.1027 0.1027 Mineral sample quality / kg 20 20 Mineral sample size / mm <8 <8 Total acid consumption rate /% 3.38 2.16 Leaching cycle /d 48 48 Liquid meter leaching rate /% 88.35 88.18 Slag uranium grade /% 0.0104 0.0133 Slag meter leaching rate /% 89.85 87.05 It can be seen from Fig. 5 that the uranium leaching rate increases rapidly in the early stage of the test, and the hexavalent uranium in the ore and the tetravalent uranium which is easily leached and leached are quickly leached by the sulfuric acid solution, and then the tetravalent uranium which is difficult to be oxidized in the ore is gradually oxidized by the bacteria. The catch rate has increased more slowly. The leaching rates of the column immersion pool were 88.35% and 88.18%, respectively, and the leaching effect was better. It can be seen from Table 3 that the leaching rates of column leaching and pool leaching are 89.85% and 87.05%, the slag uranium grades are 0.0104% and 0.013%, respectively, the acid consumption is 3.38% and 2.16%, respectively, and the leaching period is 48d. It indicates that the bacterial column leaching and the pool leaching method have a good effect on the test uranium ore. Comprehensive leaching period, acid consumption, slag meter leaching rate and other indicators and industrial conditions, it is considered that the bacterial column leaching method can be used as a priority leaching method. Third, the conclusion (1) Bacterial column leaching and bacterial pool immersion (inflation conditions) have good leaching effect on uranium ore, the leaching period is 48d, the leaching rates of slag meter are 89.85% and 87.05%, respectively, and the uranium grades are 0.0104% and 0.0133, respectively. %, acid consumption is 3.38% and 2.15%, respectively. (2) The leaching bacteria have good activity in the fluorine-containing uranium ore leaching system through adaptive domestication, which can improve the rate of uranium leaching. (3) Comprehensive leaching period, acid consumption, slag meter leaching rate and other indicators and industrial actual conditions, it is considered that the bacterial column leaching method can be used as a priority leaching method. 1. High quality imported Compressor energy saving and low noise.Compressor brand Embraco and Danfoss is available for customers to choose. 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