Leaching agent for removing thallium and beryllium in lithium slag and application

Abstract

The invention provides a leaching agent for removing thallium and beryllium in lithium slag and application. The leaching agent comprises a first leaching agent and a second leaching agent. The first leaching agent is an organic acid solution, and organic acid comprises carboxyl and at least one group of hydroxyl, sulfydryl, carbonyl and sulfonic acid group; the organic acid is single organic acid or mixed organic acid; the second leaching agent comprises a cationic agent and a reducing agent, the cationic agent can form at least one of K < + >, NH4 < + >, Mg < 2 + >, Na < + > and Fe < 3 + > in an aqueous solution, and the reducing agent comprises an inorganic reducing agent and / or an organic reducing agent. Organic acid in the first leaching agent can destroy the crystal structure of the lithium slag, and meanwhile groups such as carboxyl and hydroxyl can be complexed with thallium and beryllium ions so that the thallium and beryllium ions can be dissolved out more easily. On the basis, cations in the second leaching agent and the reducing solution accelerate the release of thallium and beryllium through ion exchange and reduction effects. The leaching agent can remove thallium and beryllium in the lithium slag at the same time, and the removal rate of thallium and beryllium is high.

Description

Technical Field

[0001] The invention relates to the field of metallurgical industrial waste slag treatment, in particular to a leaching agent for removing thallium and beryllium from lithium slag and its application. Background Art

[0002] Lithium is widely used in energy storage devices, such as lithium-ion batteries, due to its high energy density and long cycle life. It has now become an important power source in electric vehicles, portable electronic devices and other fields. In the process of extracting lithium from lithium mica ore, a large amount of waste slag is produced. These waste slags contain highly toxic toxic elements such as thallium and beryllium, as well as other valuable metal elements besides lithium. If thallium and beryllium in lithium slag are directly stored or discarded in the wild, it will cause great harm to the environment, including contamination of soil, water sources and atmosphere, and thus pose a threat to the ecosystem and human health.

[0003] Since thallium and beryllium in lithium slag do not have independent physical phases, they often exist as trace elements in aluminosilicate and iron-containing mineral phases, making it difficult to achieve deep detoxification through conventional methods. Existing technologies include high-temperature roasting method and curing agent addition method. High-temperature roasting method: This method destroys the mineral phase structure in the lithium slag at high temperature, thereby fixing elements such as thallium and beryllium in the slag to prevent them from dissolving and polluting water resources. However, this method does not completely remove thallium and beryllium, and has problems such as high energy consumption and small processing scale. Curing agent addition method: By adding a curing agent to combine with thallium to form an inert ceramic material, it is solidified. This method also only solves the problem of thallium dissolution, but does not completely remove thallium and beryllium.

[0004] Therefore, it is necessary to develop a compound leaching agent that can simultaneously detoxify thallium and beryllium in lithium slag, so as to achieve harmless treatment of lithium slag. This is of great significance to the green and environmental protection development of the entire lithium industry. Summary of the invention

[0005] The main purpose of the present invention is to provide a leaching agent for removing thallium and beryllium from lithium slag and its application, so as to solve the technical problem that the existing leaching agent cannot simultaneously dissolve and separate thallium and beryllium from lithium slag.

[0006] To achieve the above object, the present invention provides a leaching agent for removing thallium and beryllium from lithium slag, comprising a first leaching agent and a second leaching agent, wherein the first leaching agent and the second leaching agent are in a separated state.

[0007] The first leaching agent is an organic acid solution, the organic acid includes a carboxyl group and at least one of a hydroxyl group, a thiol group, a carbonyl group, and a sulfonic acid group, and the organic acid is a single organic acid or a mixed organic acid.

[0008] The second leaching agent includes a cationic agent and a reducing agent, wherein the cationic agent can form K + NH4+ Mg 2+ 、Na + , Fe 3+ At least one of the reducing agents, wherein the reducing agent comprises an inorganic reducing agent and / or an organic reducing agent. The inorganic reducing agent can form Fe 2+ or S 2- The organic reducing agent is a thiol compound or thiourea.

[0009] According to an embodiment of the present application, the organic acid is at least one of formic acid, oxalic acid, acetic acid, lactic acid, malic acid, citric acid, succinic acid and thiocarboxylic acid.

[0010] According to an embodiment of the present application, the organic acid is a mixed organic acid. The mixed organic acid includes a first organic acid and a second organic acid. The first organic acid is formic acid or citric acid, and the second organic acid is acetic acid or malic acid. The concentration of the mixed organic acid is 30 to 45 g / . The concentration ratio of the first organic acid to the second organic acid is 5 to 15:1.

[0011] According to an embodiment of the present application, the reducing agent includes an inorganic reducing agent and an organic reducing agent.

[0012] The inorganic reducing agent is ferrous chloride. The organic reducing agent is thiourea. The mass ratio of the inorganic reducing agent to the organic reducing agent is 5 to 15:1.

[0013] According to an embodiment of the present application, the first leaching agent is a mixed organic acid of formic acid and acetic acid, and the concentration ratio of the formic acid to the acetic acid is 5 to 10: 1. The second leaching agent includes ferrous chloride and thiourea. The mass ratio of the ferrous chloride to the thiourea is 5 to 10: 1.

[0014] The present application also provides the use of the above-mentioned leaching agent for removing thallium and beryllium from lithium slag, comprising the following steps:

[0015] The lithium slag is mixed with a first leaching agent, and a first leaching is performed to obtain a solid-liquid mixed material.

[0016] The solid-liquid mixed material is mixed with a second leaching agent, and a second leaching is performed to obtain detoxified lithium slag through solid-liquid separation.

[0017] According to an embodiment of the present application, in the step of mixing the lithium slag with the first leaching agent, the concentration of the first leaching agent is 30-45 g / L. The lithium slag and the first leaching agent are mixed at a liquid-solid ratio of (2.5-10):1 mL / g.

[0018] According to an embodiment of the present application, the step of performing the first leaching includes: leaching for 2 to 3 hours under the conditions that the temperature of the mixed solution is 30 to 60° C. and the stirring speed is 200 to 300 rpm.

[0019] According to an embodiment of the present application, in the step of mixing the solid-liquid mixed material with the second leaching agent,

[0020] The concentration of the second leaching agent is 10-15 g / L. The solid-liquid mixed material and the second leaching agent are mixed at a liquid-solid ratio of (2.5-10):1 mL / g.

[0021] According to an embodiment of the present application, the step of performing a second leaching includes: leaching for 2 to 3 hours under the conditions of a mixed solution temperature of 30 to 60° C. and a stirring speed of 200 to 300 rpm.

[0022] The above-mentioned leaching agent for removing thallium and beryllium from lithium slag, when leaching the lithium slag, the organic acid in the first leaching agent can destroy the crystal structure of the lithium slag, and the groups such as carboxyl and hydroxyl can complex the thallium and beryllium ions to make them easier to dissolve. On this basis, the cations and reducing solution in the second leaching agent accelerate the release of thallium and beryllium through ion exchange and reduction. The above-mentioned leaching agent for removing thallium and beryllium from lithium slag can remove thallium and beryllium from the lithium slag at the same time, and the removal rate of thallium and beryllium is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0024] Figure 1 This is a scanning electron microscope image of lithium slag according to one embodiment of the present application.

[0025] Figure 2 This is a scanning electron microscope image of the detoxified lithium slag according to one embodiment of the present application.

[0026] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with the implementation methods and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] It should be noted that all directional indications (such as up, down, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0029] In addition, in the present invention, the descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0030] Furthermore, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in the field. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0031] An embodiment of the present invention provides a leaching agent for removing thallium and beryllium from lithium slag, comprising a first leaching agent and a second leaching agent, wherein the first leaching agent and the second leaching agent are in a separated state.

[0032] Research has found that thallium and beryllium are often difficult to dissolve in the eutectic product lithium slag after high temperature (700°C) calcination. The reason is that during the formation of the eutectic, thallium and beryllium are fixed in the lithium slag through lattice replacement, mineral phase encapsulation, etc. Therefore, the crystal structure of the lithium mica ore waste slag needs to be destroyed before detoxification.

[0033] Based on this, a leaching agent for removing thallium and beryllium from lithium slag is studied. The leaching agent includes a first leaching agent and a second leaching agent. The first leaching agent and the second leaching agent are stored separately, so the first leaching agent and the second leaching agent leach the lithium slag successively.

[0034] Selecting a composite organic acid as the first leaching agent provides H + The structure of lithium slag can be destroyed. On the other hand, the carboxyl and hydroxyl groups contained in organic acids can complex thallium and beryllium ions to make them easier to dissolve and release. The second leaching agent added can exchange thallium and beryllium in the crystal phase through cations, and can also reduce Tl 3+Tl + Further enhance its dissolution release.

[0035] Specifically, the first leaching agent is an organic acid solution, the organic acid includes a carboxyl group and at least one of a hydroxyl group, a thiol group, a carbonyl group, and a sulfonic acid group, and the organic acid is a single organic acid or a mixed organic acid.

[0036] Exemplarily, the organic acid is a single organic acid, which includes, in addition to a carboxyl group, one or more of a hydroxyl group, a thiol group, a carbonyl group, and a sulfonic acid group.

[0037] Exemplarily, the organic acid is a mixed organic acid, which includes at least two organic acids. The combination of the at least two organic acids includes, in addition to the carboxyl group, one or more of a hydroxyl group, a thiol group, a carbonyl group, and a sulfonic acid group.

[0038] Take the combination of two organic acids as an example, for example, one organic acid includes only a carboxyl group, and the other organic acid includes a carboxyl group and also includes one or more of a hydroxyl group, a thiol group, a carbonyl group, and a sulfonic acid group.

[0039] For another example, both organic acids include a carboxyl group, and also include one or more of a hydroxyl group, a thiol group, a carbonyl group, and a sulfonic acid group.

[0040] Return to the second leaching agent part. The second leaching agent includes a cationic agent and a reducing agent, wherein the cationic agent can form K + NH4 + Mg 2+ 、Na + , Fe 3+ At least one of the reducing agents, the reducing agent comprises an inorganic reducing agent and / or an organic reducing agent; the inorganic reducing agent can form Fe 2+ or S 2- ; The organic reducing agent is a thiol compound or thiourea.

[0041] Wherein, the second leaching agent is a composite agent comprising a cationic agent and a reducing agent.

[0042] Cationic agents can hydrolyze in water to form K + NH4 + Mg 2+ 、Na + , Fe 3+ The cations include, but are not limited to, NH4Cl, KCl, MgCl2, K2SO4, (NH4)2SO4, Na2SO4, FeCl3, etc.

[0043] Inorganic reducing agents can form Fe 2+ or S2- Correspondingly, the inorganic reducing agent is FeCl2, FeS, CuS, etc. It should be noted that Fe 2+ As a reducing substance, it is oxidized to form Fe 3+ , so the inorganic reducing agent also acts as a cationic agent.

[0044] The first leaching agent simultaneously plays the role of destroying the crystal structure of lithium slag and complexing thallium and beryllium ions, and the second leaching agent simultaneously plays the role of ion exchange and reduction. The composite leaching agent has a wide source, widely exists in nature, and is green and pollution-free.

[0045] The above-mentioned leaching agent for removing thallium and beryllium from lithium slag, when leaching the lithium slag, the organic acid in the first leaching agent can destroy the crystal structure of the lithium slag, and the groups such as carboxyl and hydroxyl can complex the thallium and beryllium ions to make them easier to dissolve. On this basis, the cations and reducing solution in the second leaching agent accelerate the release of thallium and beryllium through ion exchange and reduction. The above-mentioned leaching agent for removing thallium and beryllium from lithium slag can remove thallium and beryllium from the lithium slag at the same time, and the removal rate of thallium and beryllium is high.

[0046] In some embodiments, the organic acid is at least one of formic acid, oxalic acid, acetic acid, lactic acid, malic acid, citric acid, succinic acid, and thiocarboxylic acid.

[0047] The mixture of the above-mentioned types of organic acids includes both carboxyl and one or more of hydroxyl, sulfhydryl, carbonyl, and sulfonic acid groups. In some specific embodiments, the types of organic acids are two. Exemplarily, the organic acid is an acetic acid-formic acid mixed acid solution.

[0048] In some embodiments, the organic acid is a mixed organic acid; the mixed organic acid includes a first organic acid and a second organic acid; the first organic acid is formic acid or citric acid, and the second organic acid is acetic acid or malic acid; the concentration of the mixed organic acid is 30 to 45 g / , too low a concentration will result in a low degree of destruction of the crystal structure of the lithium slag, thereby affecting the leaching rate of thallium and beryllium, and too high a concentration will not increase the leaching rate and will result in excessive dosage of reagents and increased processing costs; the concentration ratio of the first organic acid to the second organic acid is 5 to 15:1.

[0049] In some embodiments, the reducing agent includes an inorganic reducing agent and an organic reducing agent;

[0050] The inorganic reducing agent is ferrous chloride; the organic reducing agent is thiourea; the mass ratio of the inorganic reducing agent to the organic reducing agent is 5 to 15:1.

[0051] In some embodiments, the first leaching agent is a mixed organic acid of formic acid and acetic acid, and the concentration ratio of the formic acid to the acetic acid is 5 to 10:1; the second leaching agent includes ferrous chloride and thiourea; the mass ratio of the ferrous chloride to the thiourea is 5 to 10:1.

[0052] The present application also provides the use of the above-mentioned leaching agent for removing thallium and beryllium from lithium slag, comprising the following steps:

[0053] The lithium slag is mixed with a first leaching agent, and a first leaching is performed to obtain a solid-liquid mixed material.

[0054] The solid-liquid mixed material is mixed with a second leaching agent, and a second leaching is performed to obtain detoxified lithium slag through solid-liquid separation.

[0055] The conditions for the first leaching and the second leaching are relatively broad, such as leaching for 1 to 3 hours at a mixed solution temperature of 30 to 80° C. and a stirring speed of 200 to 400 rpm.

[0056] The second leaching agent is added to the solid-liquid mixture in the form of a solid, wherein the cationic agent is hydrolyzed in the solid-liquid mixture to form K + NH4 + Mg 2+ 、Na + , Fe 3+ The reducing agent includes an inorganic reducing agent and / or an organic reducing agent; the inorganic reducing agent can form Fe 2+ or S 2- The organic reducing agent is a thiol compound or thiourea. In this way, the second leaching agent does not need to be added with water to prepare a solution, thereby reducing the total amount of wastewater generated during the entire application process.

[0057] In the application of the leaching agent for removing thallium and beryllium from lithium slag, the crystal structure of the lithium slag is destroyed by organic acid by mixing the lithium slag with the first leaching agent, and at the same time, groups such as carboxyl and hydroxyl groups can complex thallium and beryllium ions to make them easier to dissolve. A second leaching agent is added to the solid-liquid mixture for secondary mixed leaching, and the release of thallium and beryllium is accelerated by ion exchange and reduction. In this application, the lithium slag does not need to be mechanically activated by ball milling, which simplifies the process flow and greatly reduces the processing cost.

[0058] In some embodiments, in the step of mixing the lithium slag with the first leaching agent, the concentration of the first leaching agent is 30-45 g / L. The lithium slag and the first leaching agent are mixed at a liquid-to-solid ratio of (2.5-10):1 mL / g.

[0059] In some specific embodiments, the lithium slag and the first leaching agent are mixed at a liquid-to-solid ratio of (2.5-10):1 mL / g.

[0060] In some embodiments, the step of performing the first leaching comprises: leaching for 2 to 3 hours at a temperature of the mixed solution of 30 to 60° C. and a stirring speed of 200 to 300 rpm.

[0061] In some embodiments, in the step of mixing the solid-liquid mixed material with a second leaching agent,

[0062] The concentration of the second leaching agent is 10-15 g / L. The solid-liquid mixed material and the second leaching agent are mixed at a liquid-solid ratio of (2.5-10):1 mL / g.

[0063] In some embodiments, the step of performing a second leaching comprises: leaching for 2 to 3 hours at a temperature of the mixed solution of 30 to 60° C. and a stirring speed of 200 to 300 rpm.

[0064] In some embodiments, by optimizing the liquid-to-solid ratio, solute concentration, concentration ratio, reaction time, reaction temperature, stirring rate and other conditions of the first leaching agent and the second leaching agent to the lithium slag, the removal rate of thallium and beryllium in the lithium slag is as high as 80%, and the contents of thallium and beryllium in the toxic leaching solution of the detoxified lithium slag are less than 5 μg / L and 10 μg / L, respectively, which meets the requirements of general industrial solid waste.

[0065] The technical solution of the present application is described below in conjunction with specific embodiments.

[0066] Example 1

[0067] This embodiment provides a composite leaching agent for the simultaneous removal of thallium and beryllium in lithium slag (i.e., a leaching agent for removing thallium and beryllium in lithium slag) and its application, and the application includes the following:

[0068] According to the ratio of liquid to solid of 10:1mL / g, 100g of lithium slag was added to 1000mL of acetic acid-formic acid mixed solution (i.e., the first leaching agent) with a concentration of 30g / L, and the temperature of the mixed solution was regulated to react for 2h at 50°C and 300rpm to obtain a solid-liquid mixed material. Among them, in the acetic acid-formic acid mixed solution, water is used as the solvent, and acetic acid and formic acid are solutes. The solubility of acetic acid is 25g / L, and the solubility of formic acid is 5g / L.

[0069] Add ferrous chloride and thiourea (i.e., the second leaching agent) to the solid-liquid mixture so that the total concentration of ferrous chloride-thiourea in the solution is 10 g / L, and adjust the temperature of the mixed solution to react for 2 h at 50° C. and 300 rpm, and then obtain the final lepidolite detoxification slag after solid-liquid separation, see Figure 2 . Figure 2This is a scanning electron microscope image of the detoxified lithium slag magnified 2000 times. After detoxification, the lithium slag changes from agglomerated structure to a petal-like structure, indicating that the crystal structure of the lithium slag is indeed destroyed by the compound leaching agent. The mass ratio of ferrous chloride and thiourea added is 5:1.

[0070] The composition and content of the lithium slag used in this embodiment are shown in Table 1. Figure 1 . Figure 1 This is a scanning electron microscope image of lithium slag magnified 2000 times. The undetoxified lithium slag presents a porous agglomerated structure, and thallium and beryllium are fixed inside the lithium slag by lattice substitution or encapsulation.

[0071] Table 1

[0072] Calcium (wt%) Aluminum (wt%) Silicon (wt%) Sulfur (wt%) Potassium (wt%) Iron (wt%) content 15.34 9.11 11.97 4.73 3.21 1.82 Manganese (wt%) Rubidium (wt%) Cesium (wt%) Strontium (wt%) Thallium (mg / kg) Beryllium (mg / kg) content 0.27 0.33 0.03 0.03 7.51 60

[0073] Example 2

[0074] This embodiment provides a composite leaching agent for the simultaneous removal of thallium and beryllium in lithium slag and its application, and the application includes the following:

[0075] According to the liquid-solid ratio of 5:1 mL / g, 100 g of lithium slag was added to 500 mL of 30 g / L formic acid solution (i.e., the first leaching agent), and the temperature of the mixed solution was adjusted to react at 75°C and 400 rpm for 1 hour to obtain a solid-liquid mixed material.

[0076] Ferrous chloride and thiourea (i.e., the second leaching agent) are added to the solid-liquid mixture so that the total concentration of ferrous chloride-thiourea in the solution is 10 g / L, and the temperature of the mixed solution is regulated at 75°C and 400 rpm for 1 hour, and then the final lithium mica detoxification slag is obtained after solid-liquid separation. The mass ratio of the added ferrous chloride and thiourea is 5:1.

[0077] The lithium slag used in this embodiment is the same as that in Example 1.

[0078] Example 3

[0079] This embodiment provides a composite leaching agent for the simultaneous removal of thallium and beryllium in lithium slag and its application, and the application includes the following:

[0080] According to the ratio of liquid to solid of 2.5:1mL / g, 100g lithium slag was added to 250mL of acetic acid-formic acid mixed solution (i.e., the first leaching agent) with a concentration of 30g / L, and the temperature of the mixed solution was regulated to react for 2h at 50°C and 300rpm to obtain a solid-liquid mixed material. Among them, in the acetic acid-formic acid mixed solution, water is used as the solvent, and acetic acid and formic acid are solutes. The solubility of acetic acid is 25g / L, and the solubility of formic acid is 5g / L.

[0081] Ferrous chloride and thiourea (i.e., the second leaching agent) are added to the solid-liquid mixture so that the total concentration of ferrous chloride-thiourea in the solution is 10 g / L, and the temperature of the mixed solution is regulated at 50°C and 300 rpm for 2 hours, and then the final lithium mica detoxification slag is obtained after solid-liquid separation. The mass ratio of the added ferrous chloride and thiourea is 5:1.

[0082] The lithium mica ore waste residue used in this embodiment is the same as that in Example 1.

[0083] Example 4

[0084] This embodiment provides a composite leaching agent for the simultaneous removal of thallium and beryllium in lithium slag and its application, and the application includes the following:

[0085] According to the ratio of liquid to solid of 5:1mL / g, 100g lithium slag was added to 500mL of acetic acid-formic acid mixed solution (i.e., the first leaching agent) with a concentration of 45g / L, and the temperature of the mixed solution was regulated to react for 2h at 50°C and 300rpm to obtain a solid-liquid mixed material. Among them, in the acetic acid-formic acid mixed solution, water is used as the solvent, and acetic acid and formic acid are solutes. The solubility of acetic acid is 42g / L, and the solubility of formic acid is 3g / L.

[0086] Ferrous chloride and thiourea (i.e., the second leaching agent) are added to the solid-liquid mixture so that the total concentration of ammonium chloride-thiourea in the solution is 15 g / L, and the temperature of the mixed solution is regulated at 50°C and 300 rpm for 2 hours, and then the final lithium mica detoxification slag is obtained after solid-liquid separation. The mass ratio of the added ferrous chloride and thiourea is 5:1.

[0087] The lithium mica ore waste residue used in this embodiment is the same as that in Example 1.

[0088] Comparative Example 1

[0089] This comparative example provides a composite leaching agent for the simultaneous removal of thallium and beryllium in lithium slag and its application, and the application includes the following:

[0090] According to the ratio of liquid to solid of 5:1mL / g, 100g lithium slag was added to 500mL of 30g / L acetic acid-formic acid mixed solution (i.e., the first leaching agent), and the temperature of the mixed solution was regulated to react for 2h at 50°C and 300rpm to obtain a solid-liquid mixed material. Among them, in the acetic acid-formic acid mixed solution, water is used as the solvent, and acetic acid and formic acid are solutes. The solubility of acetic acid is 25g / L, and the solubility of formic acid is 5g / L.

[0091] The lithium mica ore waste residue used in this comparative example is the same as that in Example 1.

[0092] Comparative Example 2

[0093] This comparative example provides a composite leaching agent for the simultaneous removal of thallium and beryllium in lithium slag and its application, and the application includes the following:

[0094] According to the liquid-solid ratio of 5:1mL / g, 100g of lithium slag was added to 500mL of 10g / L ammonium chloride-thiourea mixed solution (i.e., the second leaching agent), and the temperature of the mixed solution was regulated at 50°C and 300rpm for 2h, and then the final lithium mica detoxification slag was obtained after solid-liquid separation. Among them, the mass ratio of ferrous chloride and thiourea added was 5:1.

[0095] The lithium mica ore waste residue used in this comparative example is the same as that in Example 1.

[0096] Example 5

[0097] This embodiment provides a composite leaching agent for the simultaneous removal of thallium and beryllium in lithium slag and its application, and the application includes the following:

[0098] According to the ratio of liquid to solid of 5:1mL / g, 100g of lithium slag was added to 500mL of 30g / L acetic acid-formic acid mixed solution (i.e., the first leaching agent), and the temperature of the mixed solution was regulated to react for 3h at 75°C and 300rpm to obtain a solid-liquid mixed material. Among them, in the acetic acid-formic acid mixed solution, water is used as the solvent, and acetic acid and formic acid are solutes. The solubility of acetic acid is 25g / L, and the solubility of formic acid is 5g / L.

[0099] Ferrous chloride and thiourea (i.e., the second leaching agent) are added to the solid-liquid mixture so that the total concentration of ferrous chloride-thiourea in the solution is 10 g / L, and the temperature of the mixed solution is regulated at 75°C and 300 rpm for 3 hours, and then the final lithium mica detoxification slag is obtained after solid-liquid separation. The mass ratio of the added ferrous chloride and thiourea is 5:1.

[0100] The composition and content of the lithium slag used in this embodiment are shown in Table 2.

[0101] Table 2

[0102] Calcium (wt%) Aluminum (wt%) Silicon (wt%) Sulfur (wt%) Potassium (wt%) Iron (wt%) content 9.11 9.07 12.65 3.41 5.29 1.65 Manganese (wt%) Rubidium (wt%) Cesium (wt%) Strontium (wt%) Thallium (mg / kg) Beryllium (mg / kg) content 0.33 0.46 0.04 0.01 6.92 70

[0103] Example 6

[0104] This embodiment provides a composite leaching agent for the simultaneous removal of thallium and beryllium in lithium slag and its application. Except that the lithium slag used is the same as that in Example 5, the rest is the same as that in Example 2.

[0105] Example 7

[0106] This embodiment provides a composite leaching agent for the simultaneous removal of thallium and beryllium in lithium slag and its application. Except that the lithium slag used is the same as that in Example 5, the rest is the same as that in Example 3.

[0107] Example 8

[0108] This embodiment provides a composite leaching agent for the simultaneous removal of thallium and beryllium in lithium slag and its application. Except that the concentrations of the acetic acid-formic acid mixed solution and the ferrous chloride-thiourea solution are adjusted to 50 g / L and 20 g / L respectively, the rest are the same as Example 1.

[0109] Example 9

[0110] This embodiment provides a composite leaching agent for the simultaneous removal of thallium and beryllium in lithium slag and its application, and the application includes the following:

[0111] According to the ratio of liquid to solid of 5:1mL / g, 100g lithium slag was added to 1000mL of 30g / L acetic acid-malic acid mixed solution (i.e., the first leaching agent), and the temperature of the mixed solution was regulated to react for 2h at 50°C and 300rpm to obtain a solid-liquid mixed material. Among them, in the acetic acid-malic acid mixed solution, water was used as the solvent, and acetic acid and malic acid were used as the solutes. The solubility of acetic acid was 25g / L, and the solubility of malic acid was 5g / L.

[0112] Ferrous chloride and thiourea (i.e., the second leaching agent) are added to the solid-liquid mixture so that the total concentration of ferrous chloride-thiourea in the solution is 10 g / L, and the temperature of the mixed solution is regulated at 50°C and 300 rpm for 2 hours, and then the final lithium mica detoxification slag is obtained after solid-liquid separation. The mass ratio of the added ferrous chloride and thiourea is 5:1.

[0113] The contents of thallium and beryllium in the lithium slag used in this embodiment are 8 mg / kg and 40 mg / kg respectively.

[0114] Example 10

[0115] This embodiment provides a composite leaching agent for the simultaneous removal of thallium and beryllium from lithium slag and its application, wherein the thallium and beryllium contents in the lithium slag used are 10 mg / kg and 50 mg / kg, respectively. The rest is the same as in embodiment 9.

[0116] Embodiment 11

[0117] This embodiment provides a composite leaching agent for the simultaneous removal of thallium and beryllium in lithium slag and its application. The thallium and beryllium contents in the lithium slag used are 7 mg / kg and 38 mg / kg, respectively, and the rest are the same as in Example 9.

[0118] Testing and analysis of results

[0119] The toxicity leaching detection of thallium and beryllium in lithium slag by the composite leaching agent for simultaneous deep detoxification of thallium and beryllium in lithium slag provided in the above-mentioned embodiments and comparative examples and the leach method was referred to HJ / T299-2007 "Solid Waste Leaching Toxicity Leaching Method Sulfuric Acid and Nitric Acid Method", and the concentration of thallium and beryllium after detoxification was detected by referring to HJ700-2014 "Determination of 65 Elements in Water Quality Inductively Coupled Plasma Mass Spectrometry", and the results are shown in Table 3.

[0120] Table 3

[0121]

[0122]

[0123] (1) Comprehensive Examples 1 to 11, Comparative Examples 1 and 2 show that, except for Comparative Examples 1 and 2, which only use a single first leaching agent and a single second leaching agent, resulting in poor detoxification effects, the leaching agents for removing thallium and beryllium from lithium slag in the present application can detoxify thallium and beryllium in lithium slag. Among them, the liquid-to-solid ratio of Examples 3 and 7 is relatively low, and the beryllium in the lithium slag after treatment is greatly reduced, meeting the requirements of general solid waste (less than 20 μg / L), and the lithium slag after treatment in other examples can meet the requirements of Class I solid waste (less than 5 μg / L).

[0124] (2) Comprehensive examples 1 and 3, examples 2 and 4 show that increasing the liquid-solid ratio and increasing the solute concentration of the composite leaching agent (i.e., the leaching agent used to remove thallium and beryllium from lithium slag) are helpful to improve the detoxification effect of lithium slag. Comparing examples 1, 2, 8, comparative example 1 and comparative example 2, it is found that the composite leaching agent is better than a single leaching agent (i.e., a single first leaching agent or a single second leaching agent). In addition, although the liquid-solid ratio is reduced, increasing the solute concentration of the composite leaching agent does not affect the detoxification effect, and the lithium slag after detoxification is still a general solid waste.

[0125] (3) It can be seen from Examples 5 to 7 that the increase in the liquid-to-solid ratio and the increase in the solute concentration of the compound leaching agent have a great influence on the detoxification of beryllium in the lithium mica ore waste slag in Example 5. It can be seen that the use of a larger liquid-to-solid ratio and a high concentration of the compound leaching agent is beneficial to the detoxification of lithium slag.

[0126] (4) It can be seen from Examples 9 to 11 that the lithium slags from different sources can be treated under the optimized conditions to meet the requirements of general industrial solid waste. This is sufficient to prove that the present invention has excellent effects on different lithium slags and also shows the superiority of the invention.

[0127] The above technical solutions of the present invention are only preferred embodiments of the present invention, and the patent scope of the present invention is not limited thereto. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A leaching agent for removing thallium and beryllium from lithium slag, characterized in that: The method comprises a first leaching agent and a second leaching agent, wherein the first leaching agent and the second leaching agent are in a separated state; The first leaching agent is an organic acid solution, the organic acid includes a carboxyl group and at least one of a hydroxyl group, a thiol group, a carbonyl group, and a sulfonic acid group; the organic acid is a single organic acid or a mixed organic acid; The second leaching agent includes a cationic agent and a reducing agent, wherein the cationic agent can form K + NH4 + Mg 2+ 、Na + , Fe 3+ At least one of the reducing agents, the reducing agent comprises an inorganic reducing agent and / or an organic reducing agent; the inorganic reducing agent can form Fe 2+ or S 2- ; The organic reducing agent is a thiol compound or thiourea.

2. The leaching agent for removing thallium and beryllium from lithium slag according to claim 1, characterized in that: The organic acid is at least one of formic acid, oxalic acid, acetic acid, lactic acid, malic acid, citric acid, succinic acid and thiocarboxylic acid.

3. The leaching agent for removing thallium and beryllium from lithium slag according to claim 1, characterized in that: The organic acid is a mixed organic acid; the mixed organic acid includes a first organic acid and a second organic acid; the first organic acid is formic acid or citric acid, and the second organic acid is acetic acid or malic acid; the concentration of the mixed organic acid is 30 to 45 g / L; the concentration ratio of the first organic acid to the second organic acid is 5 to 15:

1.

4. The leaching agent for removing thallium and beryllium from lithium slag according to claim 1, characterized in that: The reducing agent includes an inorganic reducing agent and an organic reducing agent; The inorganic reducing agent is ferrous chloride; the organic reducing agent is thiourea; the mass ratio of the inorganic reducing agent to the organic reducing agent is 5 to 15:

1.

5. The leaching agent for removing thallium and beryllium from lithium slag according to any one of claims 1 to 4, characterized in that: The first leaching agent is a mixed organic acid of formic acid and acetic acid, and the concentration ratio of the formic acid to the acetic acid is 5 to 10:1; the second leaching agent includes ferrous chloride and thiourea; the mass ratio of the ferrous chloride to the thiourea is 5 to 10:

1.

6. A use of a leaching agent for removing thallium and beryllium from lithium slag as claimed in claim 1, characterized in that: The following steps are involved: The lithium slag is mixed with a first leaching agent to perform a first leaching to obtain a solid-liquid mixed material; The solid-liquid mixed material is mixed with a second leaching agent, and a second leaching is performed to obtain detoxified lithium slag through solid-liquid separation.

7. The use of a leaching agent for removing thallium and beryllium from lithium slag according to claim 6, characterized in that: In the step of mixing the lithium slag with the first leaching agent, the concentration of the first leaching agent is 30 to 45 g / L; the lithium slag and the first leaching agent are mixed at a liquid-to-solid ratio of (2.5 to 10): 1 mL / g.

8. The use of a leaching agent for removing thallium and beryllium from lithium slag according to claim 6, characterized in that: The first leaching step includes: leaching for 2 to 3 hours under the conditions that the temperature of the mixed solution is 30 to 60° C. and the stirring speed is 200 to 300 rpm.

9. The use of a leaching agent for removing thallium and beryllium from lithium slag according to any one of claims 6 to 8, characterized in that: In the step of mixing the solid-liquid mixed material with a second leaching agent, The concentration of the second leaching agent is 10-15 g / L; the solid-liquid mixed material and the second leaching agent are mixed at a liquid-to-solid ratio of (2.5-10):1 mL / g.

10. Use of a leaching agent for removing thallium and beryllium from lithium slag according to any one of claims 6 to 8, characterized in that: The second leaching step includes: leaching for 2 to 3 hours under the conditions that the temperature of the mixed solution is 30 to 60° C. and the stirring speed is 200 to 300 rpm.

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