A method and device for treating lithium residue containing thallium based on chemical leaching and biomineralization

Abstract

The application discloses a kind of based on chemical leaching and biological mineralization thallium-containing lithium slag processing method and device, the method includes the following steps: thallium-containing lithium slag is mixed with leaching agent, after grinding, uniform mixing in sample preparation machine, ball milling, obtain the ore dressing slag;Thallium-containing lithium slag is leached in water, and water leaching slurry is obtained;Water leaching slurry is separated, and elution residue and leaching solution are obtained;Leaching solution is refluxed and recycled;Thallium concentration is higher than 20mg / L leaching solution inoculated solid thallium bacteria agent, and biochemical mineralization reaction is obtained after biochemical slurry;Biochemical slurry is solid-liquid separated, and solid thallium residue and leaching tail liquid are obtained;Leaching tail liquid membrane filtration is carried out.The method and device of the application, the ecological environment risk caused by the migration of thallium in lithium slag is solved, and the enrichment and extraction of thallium are realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lithium slag treatment, and particularly relates to a lithium slag containing thallium treatment method and device based on chemical leaching and biological mineralization. BACKGROUND

[0002] Lithium slag is an industrial solid waste produced by lithium extraction process such as calcination-sulfuric acid / calcium carbonate roasting-water leaching of spodumene or lepidolite. With the rapid development of the new energy industry, the increasing demand for lithium raw materials such as lithium carbonate and lithium hydroxide has led to an increase in lithium smelting activities, and about 600,000 tons of lithium slag can be produced globally each year. Thallium is a rare heavy metal element associated with lithium, sodium and other elements in spodumene and lepidolite, and has strong toxicity, migration and latency. Thallium is often present in aluminosilicate structure in lithium ore, and is enriched in lithium slag during the lithium smelting process. With the dissociation of the dense structure of lithium slag, the environmental migration risk of thallium is significantly increased, which can cause human health and ecological pollution crisis.

[0003] At present, the main treatment methods for lithium slag are landfill or open-air storage, and only a small amount is recycled, such as cement admixture, concrete admixture, and zeolite synthesis raw material. These treatment methods also face the health and ecological risks caused by the migration of heavy metal thallium. Therefore, efficient separation of thallium from lithium slag containing thallium is necessary to eliminate the ecological environmental risk caused by the migration of thallium in lithium slag, and the further resource utilization of lithium slag. The existing technology lacks such process methods. SUMMARY

[0004] Based on the technical problems proposed in the background, the purpose of the application is to provide a lithium slag containing thallium treatment method and device based on chemical leaching and biological mineralization, so as to eliminate the ecological environmental risk caused by the migration of thallium in lithium slag, and realize the enrichment and extraction of thallium.

[0005] The application provides a lithium slag containing thallium treatment method and device based on chemical leaching and biological mineralization, which comprises the following steps:

[0006] (1) mixing lithium slag containing thallium with leaching agent, grinding, uniformly mixing and ball milling in a sample preparation machine to obtain mixed slag;

[0007] (2) leaching the mixed slag obtained in step (1) in water to obtain water leaching slurry;

[0008] (3) separating the water leaching slurry obtained in step (2) into elution slag and leaching liquid;

[0009] (4) recycling the leaching liquid in step (3) to step (2) until the concentration of thallium enriched in the leaching liquid is higher than 50 mg / L;

[0010] (5) inoculating the leaching solution with a thallium-fixing bacterial agent, and obtaining a bio-mineral slurry through a biochemical mineralization reaction;

[0011] (6) separating the bio-mineral slurry obtained in step (5) into a thallium-fixing residue and a leaching tail liquid;

[0012] (7) filtering the leaching tail liquid obtained in step (6) through a 0.22 μm membrane.

[0013] Further, the leaching agent in step (1) comprises at least one of citric acid, oxalic acid, lactic acid, and acetic acid.

[0014] Further, the ball milling condition in step (1) is that the ball-to-material ratio is 2.5-4:1, the rotation speed is 300-600 rpm / min, and the ball milling time is 0.5-3 h.

[0015] Further, the mass ratio of the substances in the ore-dressing residue in step (1) is that lithium residue: leaching agent = 14-24:1.

[0016] Further, the water leaching condition in step (2) is that the liquid-to-solid ratio is 5-15 mL / g, the leaching temperature is 20-60 °C, and the leaching time is 30-90 min.

[0017] Further, the leaching liquid in step (3) is returned to step (2) for recycling when the thallium concentration is not greater than 50 mg / L.

[0018] Further, the thallium-fixing bacterial agent in step (5) mainly comprises at least one of Bacillus subtilis (ATCC 6633), Bacillus cohnii (ATCC 12472), Bacillus cereus (ATCC 11778), Bacillus sphaericus (ATCC 10792), and Bacillus pasteurii (ATCC 7055). Baccilus substilus ) , Bacillus cohnii (ATCC 12472) Baccilus cohnni ) , Bacillus cereus (ATCC 11778) Baccilus cereus ) , Bacillus sphaericus (ATCC 10792) Sporosarcina pasteurii ) , or Bacillus pasteurii (ATCC 7055) Baccilus sphaericus ).

[0019] Further, the biochemical mineralization reaction condition in step (5) is that the temperature is 15-35 °C, the stirring speed is 120-210 rpm, the dissolved oxygen concentration is 0.5-4.5 mg / L, and the pH is 3.0-8.0.

[0020] Further, the bacterial slurry obtained in step (7) is returned to step (5) for recycling, and the filtrate is returned to step (2) for recycling.

[0021] The device for the treatment method of thallium-containing lithium slag based on chemical leaching and biological mineralization comprises a sample preparation machine, a mineralized slag water leaching device, a water leaching slurry solid-liquid separation device, a leaching liquid inoculation device, a biochemical slurry solid-liquid separation device and a tail liquid membrane filtration device.

[0022] The mineralized slag is a uniform mixture of thallium-containing lithium slag and leaching agent, and the lithium slag is activated and reacts with the leaching agent through ball milling.

[0023] The elution residue obtained after solid-liquid separation is verified to have a significantly reduced thallium migration and long-term stability of the elution residue through HJ / T299 "Solid waste leaching toxicity leaching method" and simulated acid rain leaching experiment.

[0024] The leaching liquid obtained through solid-liquid separation is recycled into step (2) to leach the mineralized slag, and when the thallium concentration in the leaching liquid is higher than 50 mg / L, a thallium immobilization bacterial agent is inoculated into the leaching liquid. Through the adsorption and surface shell formation of thallium by microorganisms (microorganisms use the leaching agent as a carbon source and the dissolved calcium in the leaching liquid to mediate carbonate deposition), thallium is adsorbed and included in or wrapped in the carbonate shell, realizing the enrichment and solidification of thallium.

[0025] The leaching liquid of the thallium immobilization residue obtained through solid-liquid separation is filtered through a membrane to obtain bacterial sludge which can be recycled.

[0026] When the mineral is prepared, the type of leaching agent needs to be controlled to ensure that the leaching agent can efficiently reduce, replace and complex thallium and promote the dissolution of thallium.

[0027] When the mineral is prepared, the mass ratio of lithium slag to leaching agent needs to be controlled, and the mass ratio of lithium slag to leaching agent is required to be 14-24:1 to ensure that there is enough leaching agent to participate in the reduction, replacement and complexation of thallium, so that thallium can be efficiently dissolved. When the mass ratio of lithium slag to leaching agent is more than 24:1, the excess of leaching agent will lead to an increase in the dissolution of other heavy metal ions, inhibit the activity of the thallium immobilization bacterial agent and reduce the fixation rate of thallium.

[0028] When ball milling, the ball-to-material ratio, rotation speed and ball milling time need to be controlled, and the ball-to-material ratio is required to be 2.5-4:1, the rotation speed is required to be 300-600 rpm / min, and the ball milling time is required to be 0.5-3 h, so as to ensure that the microstructure of thallium-containing lithium slag can be activated and destroyed, and the leaching agent and thallium-containing lithium slag can be fully mixed and pre-reacted.

[0029] During the water leaching process of the mineralized slag, the solid-liquid ratio, leaching temperature and leaching time need to be controlled. The solid-liquid ratio and leaching temperature are controlled to improve the thallium dissolution performance and avoid thallium remaining in the lithium slag, so as to ensure the thallium stabilization efficiency and the thallium extraction rate of the lithium slag.

[0030] In the biochemical treatment process of the leaching solution, the temperature, stirring speed, dissolved oxygen concentration, pH and microbial inoculation concentration need to be regulated. The pH and temperature are regulated to promote the adsorption of thallium by microorganisms, control the microbial mediated carbonate sediment crystal form to be dense calcite, and avoid the formation of loose barite type carbonate shell on the surface of the microbial cells and the ineffective adsorption of thallium on the surface of the microbial cells; the microbial inoculation concentration and the dissolved oxygen concentration are regulated to promote the efficiency of microbial mediated carbonate deposition, increase the thickness and chemical stability of the carbonate shell, and enhance the long-acting stability of thallium. These regulation methods can ensure the removal rate of thallium from the leaching solution and the long-acting stability of thallium in the thallium immobilization residue.

[0031] The beneficial effects of the method are as follows:

[0032] Controlling the appropriate ingredient ratio can fully activate and complex thallium in the lithium residue, improve the leaching performance of thallium, control the appropriate solid-liquid ratio, leaching temperature and leaching time, and make thallium be efficiently dissolved; and it is beneficial to realize the harmless treatment of the lithium residue and eliminate the environmental risk of thallium dissolution.

[0033] The accumulated thallium in the circulating leaching solution is adsorbed on the surface of the microbial cells and wrapped or embedded in the carbonate shell through the biochemical treatment process mediated by the thallium immobilization bacteria. Controlling the appropriate temperature, stirring speed, dissolved oxygen concentration, pH and microbial inoculation concentration can form a dense calcite carbonate shell on the surface of the microorganisms, which is beneficial to obtain thallium long-acting stable thallium immobilization residue.

[0034] In summary, the present application can eliminate the environmental pollution risk of thallium in lithium residue and enrich and long-acting immobilize thallium. The long-acting harmless treatment process of thallium-containing lithium residue based on chemical leaching-biological mineralization involved in the present application has the advantages of simple process, green and efficient, closed-circuit circulation of leaching water, and avoids secondary pollution of thallium. Considering the huge amount of lithium residue produced every year, the present application has great market application prospect and environmental and ecological significance. BRIEF DESCRIPTION OF DRAWINGS

[0035] The present application will be further described below in conjunction with the drawings and examples.

[0036] Figure 1 The process flow chart of the thallium-containing lithium residue treatment method based on chemical leaching and biological mineralization of the present application is shown.

[0037] Figure 2 The schematic diagram of the leaching and simulation of 100-year acid rain leaching results of the lithium residue and thallium immobilization residue hazardous waste toxicity identification is shown.

[0038] Figure 3 The schematic diagram of the device of the present application is shown. DETAILED DESCRIPTION

[0039] Clearly, the described embodiments are only a part of the embodiments of the present application, and not all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0040] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of description and simplification of the description of the present application, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0041] In addition, the terms "first" and "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated, so that the features with "first" and "second" can explicitly or implicitly include one or more of the features, and in the description of the present application, the meaning of "multiple" is two or more, unless otherwise explicitly and specifically limited.

[0042] The present embodiment provides a method for treating lithium residue containing thallium based on chemical leaching and biological mineralization, referring to Figure 1 , comprising the following steps:

[0043] (1) The lithium residue containing thallium is mixed with a leaching agent, ground, uniformly mixed and then ball milled in a sample preparation machine to obtain a mixed residue;

[0044] (2) The mixed residue obtained in step (1) is leached in water to obtain a water leaching slurry;

[0045] (3) The water leaching slurry obtained in step (2) is separated into solid and liquid to obtain elution residue and leaching solution;

[0046] (4) The leaching solution in step (3) is recycled to step (2) until the concentration of thallium enriched in the leaching solution is higher than 50 mg / L;

[0047] (5) The leaching solution obtained in step (4) with a thallium concentration higher than 20 mg / L is inoculated with a thallium immobilization bacterial agent, and a biochemical mineral slurry is obtained through a biochemical mineralization reaction;

[0048] (6) The biochemical mineral slurry obtained in step (5) is separated into solid and liquid to obtain thallium immobilization residue and leaching tail liquid;

[0049] (7) The leaching tail liquid obtained in step (6) is filtered through a 0.22 μm membrane.

[0050] The leaching agent in step (1) comprises at least one of citric acid, oxalic acid, lactic acid, and acetic acid.

[0051] The ball milling condition in step (1) is a ball-to-material ratio of 2.5-4:1, a rotation speed of 300-600 rpm / min, and a ball milling time of 0.5-3 h.

[0052] The mass ratio of the substances in the ore-dressing slag in step (1) is lithium slag:leaching agent = 14-24:1.

[0053] The water leaching condition in step (2) is a liquid-to-solid ratio of 5-15 mL / g, a leaching temperature of 20-60 °C, and a leaching time of 30-90 min.

[0054] The leaching liquid in step (3) is returned to step (2) for recycling when the thallium concentration is not greater than 50 mg / L.

[0055] The community composition of the thallium immobilization bacteria in step (5) mainly comprises at least one of Bacillus subtilis (Bacillus subtilis), Bacillus cohnii (Bacillus cohnii), Bacillus cereus (Bacillus cereus), Sarcina pastorianus (Sarcina pastorianus), and Bacillus sphaericus (Bacillus sphaericus). Baccilus substilus ) , Bacillus cohnii (Bacillus cohnii) Baccilus cohnni ) , Bacillus cereus (Bacillus cereus) Baccilus cereus ) , Sarcina pastorianus (Sarcina pastorianus) Sporosarcina pasteurii ) , Bacillus sphaericus (Bacillus sphaericus) Baccilus sphaericus ) at least one of.

[0056] The biochemical mineralization reaction condition in step (5) is a temperature of 15-35 °C, a stirring speed of 120-210 rpm, a dissolved oxygen concentration of 0.5-4.5 mg / L, and a pH of 3.0-8.0.

[0057] The slurry obtained in step (7) is returned to step (5) for recycling, and the filtrate obtained is returned to step (2) for recycling.

[0058] Figure 2 A schematic diagram of the leaching and simulation of 100-year acid rain leaching results of the toxicity identification of lithium slag and thallium immobilization slag. It shows that the thallium immobilization slag is less harmful.

[0059] As Figure 3As shown, another aspect of the embodiment provides a device for the above-mentioned thallium-containing lithium slag treatment method based on chemical leaching and biomineralization, which comprises a sample preparation machine 100, a slag water leaching device 200, a water leaching slurry solid-liquid separation device 300, a leaching liquid inoculation device 400, a biochemical slurry solid-liquid separation device 500, and a tail liquid membrane filtration device 600.

[0060] To highlight the technical problems, technical solutions and advantages to be solved by the present application, the specific embodiments are described in detail below.

[0061] In the embodiment and comparative examples of the present application, thallium-containing lithium slag is selected, and the main chemical composition is shown in Table 1.

[0062] Table 1 Element chemical composition of thallium-containing lithium slag

[0063]

[0064] Comparative Example 1

[0065] The thallium-containing lithium slag and citric acid were prepared and ground in a mass ratio of lithium slag: leaching agent = 24:1, and ball milling was performed under the conditions of a ball-to-material ratio of 3:1, a rotation speed of 400 rpm, and a ball milling time of 2 h. The prepared slag was water leached at a liquid-to-solid ratio of 5 mL / g for 60 min. After 31 cycles of leaching, the thallium concentration in the leaching liquid was 20.3 mg / L, and the thallium leaching rate was 65.6%. After solid-liquid separation, the elution slag was subjected to HJ / T299 "Solid Waste Leaching Toxicity Leaching Method" and simulated 100-year acid rain leaching tests, and the leaching concentrations of thallium were 31.5 μg / L and 27.8 μg / L, respectively, which were much higher than the limited value of 5 μg / L in "Inorganic Chemical Industry Pollutant Discharge Standard" (GB 31573-2015). The leaching liquid was subjected to biochemical treatment with a thallium immobilization bacteria agent, the reaction temperature was 25°C, the stirring speed was 180 rpm, the dissolved oxygen concentration was 3 mg / L, the pH was 8.0, the inoculation concentration was 5×10 8 / mL, the thallium immobilization rate in the leaching liquid was 92.7%, and the total thallium immobilization rate in the thallium-containing lithium slag was 60.7%. The thallium immobilization slag was subjected to HJ / T299 "Solid Waste Leaching Toxicity Leaching Method" and simulated 100-year acid rain leaching tests, and the leaching concentrations of thallium were 3.2 μg / L and 3.5 μg / L, respectively, which were lower than the limited value of 5 μg / L in "Inorganic Chemical Industry Pollutant Discharge Standard" (GB 31573-2015). It can be seen that too little leaching agent will seriously affect the experimental results.

[0066] Comparative Example 2

[0067] The thallium-containing lithium slag and citric acid were prepared, ground and ball milled at a mass ratio of lithium slag to leaching agent of 22:1, a ball-to-material ratio of 3:1, a rotation speed of 400 rpm and a ball milling time of 2 h. The obtained prepared slag was water leached at a liquid-to-solid ratio of 5 mL / g and a leaching time of 60 min. After 21 cycles of leaching, the thallium concentration in the leaching solution was 20.1 mg / L, and the thallium leaching rate was 95.7%. After solid-liquid separation, the elution slag was subjected to HJ / T299 “Solid Waste Leaching Toxicity Leaching Method” and simulated 100-year acid rain leaching test, and the leaching concentration of thallium was 2.5 μg / L and 2.8 μg / L, respectively, lower than the limited value of 5 μg / L in “Inorganic Chemical Industry Pollutant Discharge Standard” (GB 31573-2015). The leaching solution was subjected to biochemical treatment with a thallium immobilization bacteria agent, at a reaction temperature of 15°C, a stirring speed of 180 rpm, a dissolved oxygen concentration of 3 mg / L, a pH of 4.0, and an inoculation concentration of 5×10 8 / mL. The thallium immobilization rate in the leaching solution was 79.4%, i.e., the total thallium immobilization rate in the thallium-containing lithium slag was 76.0%. The thallium immobilization slag was subjected to HJ / T299 “Solid Waste Leaching Toxicity Leaching Method” and simulated 100-year acid rain leaching test, and the leaching concentration of thallium was 8.2 μg / L and 9.5 μg / L, respectively, higher than the limited value of 5 μg / L in “Inorganic Chemical Industry Pollutant Discharge Standard” (GB 31573-2015). It can be seen that too low temperature and pH of biochemical treatment will seriously affect the experimental results.

[0068] Comparative Example 3

[0069] The thallium-containing lithium slag and citric acid were prepared, ground and ball milled at a mass ratio of lithium slag to leaching agent of 22:1, a ball-to-material ratio of 3:1, a rotation speed of 400 rpm and a ball milling time of 2 h. The obtained prepared slag was water leached at a liquid-to-solid ratio of 5 mL / g and a leaching time of 60 min. After 21 cycles of leaching, the thallium concentration in the leaching solution was 20.2 mg / L, and the thallium leaching rate was 96.2%. After solid-liquid separation, the elution slag was subjected to HJ / T299 “Solid Waste Leaching Toxicity Leaching Method” and simulated 100-year acid rain leaching test, and the leaching concentration of thallium was 1.4 μg / L and 2.3 μg / L, respectively, lower than the limited value of 5 μg / L in “Inorganic Chemical Industry Pollutant Discharge Standard” (GB 31573-2015). The leaching solution was subjected to biochemical treatment with a thallium immobilization bacteria agent, at a reaction temperature of 25°C, a stirring speed of 180 rpm, a dissolved oxygen concentration of 3 mg / L, a pH of 9.0, and an inoculation concentration of 5×10 8The solidification rate of thallium in the leaching solution was 56.5%, that is, the total thallium solidification rate in the thallium-containing lithium residue was 54.4%. The thallium-containing residue was subjected to HJ / T299 "Solid Waste Leaching Toxicity Leaching Method" and simulated 100-year acid rain leaching test, and the leaching concentration of thallium was 13.5 μg / L and 12.3 μg / L, respectively, which was much higher than the limited value 5 μg / L in "Inorganic Chemical Industry Pollutant Discharge Standard" (GB 31573-2015). It can be seen that the too high pH of the biochemical treatment can also seriously affect the experimental results.

[0070] Example 1

[0071] The thallium-containing lithium residue and oxalic acid were prepared, ground, and ball milled under the conditions of lithium residue: leaching agent = 22:1 (mass ratio of substances), ball-to-material ratio 3:1, rotation speed 300 rpm, and ball milling time 2 h. The obtained prepared residue was water leached under the conditions of liquid-to-solid ratio 5 mL / g and leaching time 30 min. After 24 cycles of leaching, the thallium concentration in the leaching solution was 20.5 mg / L, and the thallium leaching rate was 85.4%. After solid-liquid separation, the eluted residue was subjected to HJ / T299 "Solid Waste Leaching Toxicity Leaching Method" and simulated 100-year acid rain leaching test, and the leaching concentration of thallium was 3.6 μg / L and 4.1 μg / L, respectively, which was lower than the limited value 5 μg / L in "Inorganic Chemical Industry Pollutant Discharge Standard" (GB 31573-2015). The leaching solution was subjected to biochemical treatment by thallium immobilization bacteria, the reaction temperature was 20°C, the stirring speed was 180 rpm, the dissolved oxygen concentration was 3 mg / L, the pH was 5.0, the inoculation concentration was 5×10 8 / mL, the solidification rate of thallium in the leaching solution was 95.9%, that is, the total thallium solidification rate in the thallium-containing lithium residue was 81.9%. The thallium-containing residue was subjected to HJ / T299 "Solid Waste Leaching Toxicity Leaching Method" and simulated 100-year acid rain leaching test, and the leaching concentration of thallium was 1.7 μg / L and 2.1 μg / L, respectively, which was lower than the limited value 5 μg / L in "Inorganic Chemical Industry Pollutant Discharge Standard" (GB 31573-2015).

[0072] Example 2

[0073] The thallium-containing lithium slag was mixed with lactic acid at a mass ratio of lithium slag to leaching agent of 24:1, ground, and ball milled at a ball-to-material ratio of 4:1, a rotation speed of 300 rpm, and a ball milling time of 2 h. The obtained mixture was subjected to water leaching at a liquid-to-solid ratio of 5 mL / g and a leaching time of 60 min. After 23 cycles of leaching, the thallium concentration in the leaching solution was 20.9 mg / L, and the thallium leaching rate was 90.8%. After solid-liquid separation, the elution residue was subjected to leaching tests according to HJ / T299 “Solid Waste Leaching Toxicity Leaching Method” and simulated 100-year acid rain leaching test, and the leaching concentrations of thallium were 2.1 μg / L and 2.5 μg / L, respectively, which were lower than the limited value of 5 μg / L in the “Inorganic Chemical Industry Pollutant Discharge Standard” (GB 31573-2015). The leaching solution was subjected to biochemical treatment with a thallium immobilization bacteria agent at a reaction temperature of 20 °C, a stirring speed of 180 rpm, a dissolved oxygen concentration of 3 mg / L, a pH of 4.5, and an inoculation concentration of 10 9 The thallium-containing lithium slag was mixed with lactic acid at a mass ratio of lithium slag to leaching agent of 24:1, ground, and ball milled at a ball-to-material ratio of 4:1, a rotation speed of 300 rpm, and a ball milling time of 2 h. The obtained mixture was subjected to water leaching at a liquid-to-solid ratio of 5 mL / g and a leaching time of 60 min. After 23 cycles of leaching, the thallium concentration in the leaching solution was 20.9 mg / L, and the thallium leaching rate was 90.8%. After solid-liquid separation, the elution residue was subjected to leaching tests according to HJ / T299 “Solid Waste Leaching Toxicity Leaching Method” and simulated 100-year acid rain leaching test, and the leaching concentrations of thallium were 2.1 μg / L and 2.5 μg / L, respectively, which were lower than the limited value of 5 μg / L in the “Inorganic Chemical Industry Pollutant Discharge Standard” (GB 31573-2015). The leaching solution was subjected to biochemical treatment with a thallium immobilization bacteria agent at a reaction temperature of 20 °C, a stirring speed of 180 rpm, a dissolved oxygen concentration of 3 mg / L, a pH of 4.5, and an inoculation concentration of 10

[0074] Example 3

[0075] The thallium-containing lithium slag was mixed with lactic acid at a mass ratio of lithium slag to leaching agent of 24:1, ground, and ball milled at a ball-to-material ratio of 4:1, a rotation speed of 300 rpm, and a ball milling time of 2 h. The obtained mixture was subjected to water leaching at a liquid-to-solid ratio of 5 mL / g and a leaching time of 60 min. After 23 cycles of leaching, the thallium concentration in the leaching solution was 20.9 mg / L, and the thallium leaching rate was 90.8%. After solid-liquid separation, the elution residue was subjected to leaching tests according to HJ / T299 “Solid Waste Leaching Toxicity Leaching Method” and simulated 100-year acid rain leaching test, and the leaching concentrations of thallium were 2.1 μg / L and 2.5 μg / L, respectively, which were lower than the limited value of 5 μg / L in the “Inorganic Chemical Industry Pollutant Discharge Standard” (GB 31573-2015). The leaching solution was subjected to biochemical treatment with a thallium immobilization bacteria agent at a reaction temperature of 20 °C, a stirring speed of 180 rpm, a dissolved oxygen concentration of 3 mg / L, a pH of 4.5, and an inoculation concentration of 10 9The solidification rate of thallium in the leaching solution was 98.6%, and the total solidification rate of thallium in the thallium-containing lithium residue was 96.2%. The thallium solidification residue was subjected to HJ / T299 "Solid Waste Leaching Toxicity Leaching Method" and simulated 100-year acid rain leaching test, and the leaching concentration of thallium was 1.3 μg / L and 0.9 μg / L, respectively, which was lower than the limited value 5 μg / L in "Inorganic Chemical Industry Pollutant Discharge Standard" (GB 31573-2015).

[0076] Finally, it should be pointed out that the above examples are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the present application, and they should be covered in the scope of the claims of the present application.

Claims

1. A method for treating lithium residue containing thallium based on chemical leaching and biomineralization, characterized in that, The method comprises the following steps: (1) mixing the thallium-containing lithium residue with a leaching agent, grinding and uniformly mixing in a sample preparation machine, and then ball milling to obtain a mixed residue; (2) leaching the mixed residue obtained in step (1) in water to obtain a water leaching slurry; (3) separating the water leaching slurry obtained in step (2) into a washing residue and a leaching solution; (4) recycling the leaching solution in step (3) to step (2) until the concentration of enriched thallium in the leaching solution is higher than 50 mg / L; (5) inoculating the leaching solution obtained in step (4) with a thallium immobilization bacterial agent, and obtaining a biochemical slurry through a biochemical mineralization reaction; (6) separating the biochemical slurry obtained in step (5) into a thallium immobilization residue and a leaching tail liquid; (7) filtering the leaching tail liquid obtained in step (6) through a 0.22 μm membrane. The colony composition of the thallium fixation bacterial agent of step (5) mainly comprises Bacillus subtilis , Bacillus cohnii , Bacillus cereus , At least one of Bacillus pasteurii or Bacillus sphaericus.

2. The method for treating lithium residue containing thallium based on chemical leaching and biomineralization according to claim 1, characterized in that, The leaching agent in step (1) comprises at least one of citric acid, oxalic acid, lactic acid and acetic acid.

3. The method for treating thallium-containing lithium residue based on chemical leaching and biomineralization according to claim 1, characterized in that, The ball milling conditions in step (1) are as follows: a ball-to-material ratio of 2.5-4:1, a rotation speed of 300-600 rpm / min, and a ball milling time of 0.5-3 h.

4. The method for treating lithium residue containing thallium based on chemical leaching and biomineralization according to claim 1, characterized in that, The mass ratio of substances in the mixed residue in step (1) is lithium residue: leaching agent = 14-24:

1.

5. The method for treating thallium-containing lithium residue based on chemical leaching and biomineralization according to claim 1, characterized in that, The water leaching conditions in step (2) are as follows: a liquid-to-solid ratio of 5-15 mL / g, a leaching temperature of 20-60 °C, and a leaching time of 30-90 min.

6. The method for treating thallium-containing lithium residue based on chemical leaching and biomineralization according to claim 1, characterized in that, The leaching solution in step (3) is recycled to step (2) when the thallium concentration is not higher than 50 mg / L.

7. The method for treating lithium residue containing thallium based on chemical leaching and biomineralization according to claim 1, characterized in that, The biochemical mineralization reaction conditions in step (5) are as follows: a temperature of 15-35 °C, a stirring speed of 120-210 rpm, an oxygen concentration of 0.5-4.5 mg / L, and a pH of 3.0-8.

0.

8. The method for treating lithium residue containing thallium based on chemical leaching and biomineralization according to claim 1, characterized in that, The bacterial slurry obtained in step (7) is recycled to step (5), and the filtrate is recycled to step (2).

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