Autotrophic microorganism in-situ leaching uranium mining process under original ore control condition

Abstract

The invention belongs to an in-situ leaching uranium mining process, and particularly relates to an autotrophic microorganism in-situ leaching uranium mining process under an original ore control condition. An autotrophic microorganism in-situ leaching uranium mining process under the original ore control condition comprises the following steps that after strains are put into a stope liquid injection system with the leaching depth being 80-950 m, a large amount of inorganic carbon and inorganic nitride in an ore-bearing and water-bearing layer with the depth being 80-950 m are used as energy, energy for maintaining self breeding and growth is obtained through the chemical energy synthesis effect, and then the self-breeding uranium mining process is completed. And the population number is increased. The method has the remarkable effects that autotrophic microorganisms of inorganic carbon sources and nitrogen sources are utilized to secrete oxidizing substances or complexing substances capable of being identical with metal uranium Luhe in the metabolic process through biological action, and leaching of the sandstone type uranium ore can be achieved only by supplementing part of oxidizing agents or complexing agents. The engineering technical problems that in the traditional microbiological leaching process, strain breeding is difficult, the number of populations is difficult to maintain, and the leaching effect is poor can be effectively solved.

Description

Technical Field

[0001] The present invention belongs to the in-situ leaching process for uranium extraction, and particularly relates to an autotrophic microbial in-situ leaching process for uranium extraction under the original ore-controlling conditions. Background Art

[0002] The traditional in-situ leaching process for uranium extraction mainly includes acid leaching, CO2+O2 or (alkaline method) leaching techniques. In comparison, bacterial leaching extracts ore through the biochemical action of microorganisms, and has the characteristics of low production cost and high leaching efficiency. From the 1960s to the 1990s, iron / sulfur-oxidizing bacteria have been used in different-scale uranium ore production abroad, such as Elliot Lake uranium mine, Agnew Lake uranium mine in Canada, Beverley uranium mine, Ranger uranium, Feicalaus uranium mine in Brazil and the southern mining areas in Kazakhstan, etc. At present, in China, acidophilic sulfur-oxidizing bacteria and acidophilic iron-oxidizing bacteria are still the dominant strains of iron / sulfur-oxidizing bacteria, and the research and application of biohydrometallurgy in different regions and different uranium deposits are carried out. The above-mentioned strains are all heterotrophic microorganisms. After the strains are propagated on the surface, they need to be put into the leaching system, and the uranium minerals are dissolved by the secreted organic acids and other metabolites. However, heterotrophic microorganisms cannot utilize the inorganic energy substances in the ore-bearing aquifer, so such microorganisms cannot reproduce in the leaching environment, and it is necessary to continuously replenish the colony volume on the surface to maintain the leaching effect. On the other hand, due to the diversity and complexity of the underground leaching environment, the strains cultured on the surface often cannot adapt to changes in conditions such as PH, a decrease in the intensity of carbon source supply, or the inhibitory effect of other water-rock reaction products after entering the formation, and the activity or the secretion intensity of enzymes decreases or even completely loses the leaching ability. The above problems are all technical problems that cannot be effectively solved by heterotrophic microbial leaching. Summary of the Invention

[0003] In view of the defects of the prior art, the present invention provides an autotrophic microbial in-situ leaching process for uranium extraction under the original ore-controlling conditions.

[0004] The present invention is realized as follows: An autotrophic microbial in-situ leaching process for uranium extraction under the original ore-controlling conditions, which includes the following steps: After putting strains into the liquid injection system of the stope with a leaching depth of 80-950 m, a large amount of inorganic carbon and inorganic nitrides in the ore-bearing aquifer at the depth are used as energy sources, and the energy for maintaining its own reproduction and growth is obtained through chemosynthesis, so as to realize the growth of the population quantity.

[0005] For the autotrophic microbial in-situ leaching process for uranium extraction under the original ore-controlling conditions as described above, 50-300 mg / L of oxygen or 600-850 mg / L of bicarbonate is added when preparing the leaching agent to strengthen leaching.

[0006] An autotrophic microbial in-situ uranium leaching process under the original uranium-controlling conditions as described above, wherein the pH environment of the groundwater system is 6.4 - 8.0, the total salinity is 3.0 - 15.0 g / L, the whole process of surface treatment of the leaching solution requires a time of less than 1 - 5 h, and the environmental temperature where the microorganisms are located is not lower than 17 degrees Celsius.

[0007] An autotrophic microbial in-situ uranium leaching process under the original uranium-controlling conditions as described above, which includes the following steps

[0008] Step 1: Strain cultivation;

[0009] Step 2: Leaching process.

[0010] An autotrophic microbial in-situ uranium leaching process under the original uranium-controlling conditions as described above, wherein Step 1 includes the following content,

[0011] Step 1.1: Preparation of culture medium

[0012] Add inorganic carbon, nitrogen, ammonia, and nitrate to the culture dish, and use carbon dioxide to control the pH of the system at 6.4 - 8.0 to form a culture medium;

[0013] Step 1.2: Cultivation under simulated conditions

[0014] Place the culture dish inside the pressurizing device, inject nitrogen into the pressurizing device through an air pump, maintain the system pressure at 1.0 - 5.0 Mpa, and at the same time ensure that the system temperature is greater than or equal to 17 °C, continuously cultivate for 20 days, and detect the colony population.

[0015] An autotrophic microbial in-situ uranium leaching process under the original uranium-controlling conditions as described above, wherein Step 2 includes the following content,

[0016] Inject the leaching agent with microorganisms put into the liquid collection tank into the surface pipe network system of the production area through a liquid injection pump and enter the production layer, and continuously adjust the pH value of the leaching agent to control it at 6.4 - 8.0; after the bacteria enter the ore layer and reproduce using inorganic carbon and nitrogen sources and nitrogen sources under the original uranium-controlling conditions, oxidants or complexing agents beneficial to in-situ uranium leaching are generated. Among them, the oxidant reacts with tetravalent uranium to form hexavalent uranium, converting the adsorbed uranium metal element into a free state; the complexing agent is carbonate or bicarbonate that forms a uranyl complex with the free hexavalent metal uranium; according to the different oxidants or complexing agents generated during the reproduction of the strain under the original uranium-controlling conditions, appropriately add the above-mentioned content of oxygen or bicarbonate in the surface pipe network system to ensure a continuous leaching environment for uranium metal. Use a submersible pump or other lifting device to pump out the leaching solution rich in uranyl complex and bacteria population to the surface and enter the next hydrometallurgical treatment process.

[0017] The remarkable effects of the present invention are as follows: By using autotrophic microorganisms with inorganic carbon sources and nitrogen sources, through biological action, during the metabolic process, oxidizing substances or complexing substances that can complex with metallic uranium are secreted. Only by supplementing some oxidants or complexing agents can the leaching of sandstone-type uranium ores be achieved. It can effectively solve the engineering and technical problems such as difficult breeding of bacterial strains, difficult maintenance of population quantity, and poor leaching effect during the traditional microbial leaching process. Specific implementation mode

[0018] This method includes alkaline autotrophic microorganisms (bacteria or fungi). After putting the bacterial strains into the liquid injection system of the stope with a leaching depth of 80 - 950 m, a large amount of inorganic carbon (total carbonate content of the ore deposit: ≥ 0.3%) and inorganic nitrides (total nitrogen content of the ore deposit: ≥ 0.5%) in the ore-bearing aquifer at the depth are used as energy sources. Through chemosynthesis, the energy for maintaining their own reproduction and growth is obtained, and the growth of the population quantity is achieved. At the same time, oxidizing substances are metabolically secreted, and uranium minerals are dissolved through biological adsorption or other action methods to achieve the dissolution of uranium metal. To further enhance the leaching effect, 50 - 300 mg / L of oxygen or 600 - 850 mg / L of bicarbonate should be added when preparing the leaching agent to strengthen the leaching. To ensure the normal reproduction of the bacterial strains, the pH environment of the groundwater system is required to be 6.4 - 8.0, and the total salinity is 3.0 - 15.0 g / L. The whole process of surface treatment of the leaching solution is required to take less than 1 - 5 h to ensure that the environmental temperature where the microorganisms are located is not lower than 17 degrees Celsius. The advantage of this technology is that microorganisms can reproduce using the above substances under the original ore-controlling conditions, forming a large petri dish by combining the entire ore-bearing aquifer with the surface pipe network system of the in-situ leaching mine to enhance the leaching effect.

[0019] The following gives a specific description

[0020] (I) Bacterial strain cultivation

[0021] 1. Preparation of culture medium

[0022] Add inorganic carbon, nitrogen, ammonia, nitrate and other substances to the culture dish, and use carbon dioxide to control the pH of the system at 6.4 - 8.0 to form a culture medium.

[0023] 2. Cultivation under simulated conditions

[0024] Place the culture dish inside the pressurizing device, inject nitrogen into the pressurizing device through an air pump, keep the system pressure at 1.0 - 5.0 Mpa (specific setting is mainly based on the target mining depth), and at the same time ensure that the system temperature is not lower than 17 °C. Continuously cultivate for 20 days and detect the population quantity of the colonies.

[0025] (II) Leaching process

[0026] The leaching agent with microorganisms added completely in the liquid collection tank is injected into the production layer through the injection pump into the surface pipe network system of the mining site, and the pH value of the leaching agent is continuously adjusted to control it at 6.4 - 8.0. After the bacteria enter the ore layer and reproduce using inorganic carbon and nitrogen sources and nitrogen sources under the original ore-controlling conditions, oxidants or complexing agents beneficial for in-situ uranium leaching are generated. Among them, the oxidant reacts with tetravalent uranium to form hexavalent uranium, converting the adsorbed uranium metal element into a free state; the complexing agent (carbonate or bicarbonate) forms a uranyl complex with the free hexavalent metal uranium. According to the different oxidants or complexing agents generated when the bacterial species reproduce under the original ore-controlling conditions, the above-mentioned amounts of oxygen or bicarbonate are appropriately added to the surface pipe network system to ensure a continuous leaching environment for uranium metal. The leaching solution rich in uranyl complex and bacterial flora is pumped out of the surface using a submersible pump or other lifting devices and enters the next hydrometallurgical treatment process.

Claims

1. An autotrophic microbial in-situ uranium leaching process under original uranium-controlling conditions, characterized in that It includes the following steps: After putting strains into the liquid injection system of a stope with a leaching depth of 80 - 950 m, use a large amount of inorganic carbon and inorganic nitrides in the ore-bearing aquifer at the depth as energy sources, and obtain the energy to maintain its own reproduction and growth through chemosynthesis to achieve population growth.

2. The autotrophic microbial in-situ uranium leaching process under original uranium-controlling conditions according to claim 1, characterized in that: Add 50 - 300 mg / L of oxygen or 600 - 850 mg / L of bicarbonate when preparing the leaching agent to strengthen leaching.

3. The autotrophic microbial in-situ uranium leaching process under original uranium-controlling conditions according to claim 2, characterized in that: The pH environment of the groundwater system is 6.4 - 8.0, the total mineralization degree is 3.0 - 15.0 g / L. The whole process of surface treatment of the leaching solution requires a time of less than 1 - 5 h, and the environmental temperature where the microorganisms are located is not lower than 17 degrees Celsius.

4. The autotrophic microbial in-situ uranium leaching process under original uranium-controlling conditions according to claim 3, characterized in that: It includes the following steps Step 1: Strain cultivation; Step 2: Leaching process.

5. The autotrophic microbial in-situ uranium leaching process under original uranium-controlling conditions according to claim 4, characterized in that: Step 1 includes the following content, Step 1.1: Medium preparation Add inorganic carbon, nitrogen, ammonia, and nitrate to the petri dish, and use carbon dioxide to control the pH of the system at 6.4 - 8.0 to form a medium; Step 1.2: Cultivation under simulated conditions Place the petri dish inside the pressurizing device, inject nitrogen into the pressurizing device through an air pump, keep the system pressure at 1.0 - 5.0 Mpa, and at the same time ensure that the system temperature is greater than or equal to 17 °C, continuously cultivate for 20 days, and detect the population quantity of the colonies.

6. The autotrophic microbial in-situ uranium leaching process under original uranium-controlling conditions according to claim 5, characterized in that: Step 2 includes the following content, Inject the leaching agent with microorganisms put in the liquid collection tank into the surface pipe network system of the stope and enter the production layer through a liquid injection pump, and continuously adjust the pH value of the leaching agent to control it at 6.4 - 8.0; after the bacteria enter the ore layer and reproduce using the inorganic carbon and nitrogen sources and nitrogen sources under the original ore control conditions, oxidants or complexing agents beneficial to in-situ uranium leaching are generated. Among them, the oxidant reacts with tetravalent uranium to form hexavalent uranium, converting the adsorbed uranium metal element into a free state; the complexing agent is that carbonate or bicarbonate forms a uranyl complex with the free hexavalent metal uranium; according to the different oxidants or complexing agents generated when the strain reproduces under the original ore control conditions, add the above-mentioned content of oxygen or bicarbonate appropriately in the surface pipe network system to ensure the continuous leaching environment of uranium metal. Use a submersible pump or other lifting devices to pump out the leaching solution rich in uranyl complex and bacteria population to the surface and enter the next hydrometallurgical treatment process.