Method for extracting potassium, sodium, rubidium and cesium from lithium residue

Abstract

The application provides a method for extracting potassium, sodium, rubidium and cesium from lithium residue, comprising the following steps: S1, mixing lithium residue and leaching agent to obtain a mixture; the leaching agent comprises Mg(OH)2 and CaO; S2, mechanically activating the mixture to obtain pretreated material; the mechanical activation comprises ball milling the mixture; S3, secondly mixing the pretreated material and water to obtain a first reaction solution; the second mixing is performed at a temperature of 40-70 DEG C; S4, hydrothermally treating the mixture to obtain a second reaction solution; the hydrothermal treatment is performed at a temperature of 120-170 DEG C; S5, performing solid-liquid separation on the second reaction solution to obtain a metal extraction solution and tail residue; the metal extraction solution contains potassium, sodium, rubidium and cesium. The application can realize efficient extraction of potassium, sodium, rubidium and cesium from lithium residue at a lower hydrothermal temperature.

Description

Technical Field

[0001] The invention relates to the treatment of solid waste, in particular to a method for extracting potassium, sodium, rubidium and cesium from lithium slag. Background Art

[0002] Due to the low lithium grade in lepidolite, lithium extraction steps such as sulfate roasting and water leaching produce a large amount of lithium slag, which presents challenges such as difficult storage and high environmental risks. The auxiliary materials used in the roasting process contain large amounts of potassium and sodium salts, resulting in a high alkali content in the lithium slag. Currently, the lithium slag from leaching lepidolite concentrate is often used directly in building materials. However, the potassium and sodium salts remaining in the lithium slag migrate with the water in the pore solution to the surface of the building material. When the water evaporates, they deposit and crystallize on the surface of the building material, forming frosting. Frosting not only affects the appearance but also expands on the surface, causing surface damage and gradually penetrating into the interior of the building material, impacting its structure. Potassium and sodium salts are corrosive to the steel bars in concrete, seriously affecting the durability and service life of the concrete.

[0003] Furthermore, lithium slag contains rare metals such as rubidium and cesium, which are relatively rare in nature and difficult to extract and utilize. Therefore, if lithium slag is directly used in building materials, the rare metals cannot be effectively recovered, resulting in a waste of resources.

[0004] In existing research, lithium slag is typically solidified. However, this solidification process fails to remove potassium and sodium from the slag, nor does it recover rare metals, resulting in low resource utilization of the slag. Therefore, it is necessary to provide a method for extracting potassium, sodium, rubidium, and cesium from lithium slag to solve or at least alleviate the technical problem of how to efficiently extract potassium, sodium, cesium, and rubidium from lithium slag. Summary of the Invention

[0005] The main purpose of the present invention is to provide a method for extracting potassium, sodium, rubidium and cesium from lithium slag, aiming to solve the above-mentioned technical problem of how to efficiently extract potassium, sodium, cesium and rubidium.

[0006] To achieve the above object, the present invention provides a method for extracting potassium, sodium, rubidium and cesium from lithium slag, comprising the steps of:

[0007] S1, mixing lithium slag and a leaching agent to obtain a mixture;

[0008] The lithium slag contains potassium, sodium, rubidium and cesium;

[0009] The leaching agent includes Mg(OH)2 and CaO, and the mass ratio of Mg(OH)2 to CaO is 1:5-6; the mass ratio of the lithium slag to the leaching agent is 0.9-2:1;

[0010] S2, mechanically activating the mixture to obtain a pretreated material; the mechanical activation includes: ball milling the mixture for 1.5 to 5 hours;

[0011] S3, mixing the pretreated material and water for a second time to obtain a first reaction liquid;

[0012] The second mixing is performed at a temperature of 40 to 70° C., and the duration of the second mixing is 0.5 to 5 hours;

[0013] S4, subjecting the first reaction liquid to a hydrothermal treatment to obtain a second reaction liquid;

[0014] The temperature of the hydrothermal treatment is 120-170° C., and the duration of the hydrothermal treatment is 3-6 hours;

[0015] S5, performing solid-liquid separation on the second reaction liquid to obtain a metal extract and tailings; the metal extract contains the potassium element, the sodium element, the rubidium element, and the cesium element.

[0016] Furthermore, the first mixing is performed at 10-40°C.

[0017] Furthermore, the rotation speed of the ball mill is 200-400 rpm; the ball-to-material ratio used in the ball mill is 1-15:1-4.

[0018] Furthermore, the step S2 further comprises: passing the pretreated material through a 200-325 mesh sieve, and taking the sieve residue.

[0019] Furthermore, the mass ratio of the pretreated material to the water is 1:3-15.

[0020] Furthermore, the second mixing is performed at a rotation speed of 100 to 300 rpm.

[0021] Furthermore, the mass proportion of the potassium element in the lithium slag is 5-10%, the mass proportion of the sodium element in the lithium slag is 5-10%, the mass proportion of the rubidium element in the lithium slag is 0.1-2%, and the mass proportion of the cesium element in the lithium slag is 0.05-0.5%.

[0022] Furthermore, the lithium slag contains phases including nepheline, leucite and sodalite, and has a framework-like structure of silicate minerals.

[0023] Furthermore, the lithium slag also contains silicon, calcium, aluminum, iron, sulfur and oxygen in terms of mass percentage.

[0024] Furthermore, the lithium slag includes: leached slag obtained by leaching lithium from lepidolite concentrate after sulfate roasting.

[0025] Compared with the prior art, the present application has at least the following advantages:

[0026] 1、The present application mixes lithium residue and composite alkali leaching agent containing Mg(OH)2 and CaO, and then sequentially carries out mechanical activation, pre-reaction (preliminary mixing and reaction at a temperature of 40-70 DEG C) and hydrothermal reaction, realizing efficient extraction of potassium, sodium, rubidium and cesium elements in lithium residue.

[0027] 2、The hydrothermal reaction temperature of the present application is only about 140 DEG C, compared with the leaching method without mechanical activation and pre-reaction, the present application can realize efficient extraction of potassium, sodium, rubidium and cesium at a lower hydrothermal temperature; that is, compared with the conventional hydrothermal method for leaching alkali metal elements in silicate (temperature >= 200 DEG C), the present application has the advantages of lower energy consumption and high leaching rate, and is suitable for practical application.

[0028] 2、The present application fundamentally solves the problem of removing potassium and sodium elements in lithium residue, reduces the risk of building material damage and steel corrosion caused by internal solidification of potassium and sodium elements; at the same time, the present application realizes recycling and processing of potassium, sodium, rubidium and cesium resources in lithium residue. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only show some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0030] Figure 1 X-ray diffraction pattern of lithium residue in embodiment 1 of the present application.

[0031] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0033] Moreover, 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 ordinary technicians in this field can implement them. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0034] When numerical ranges are given in the examples, it should be understood that unless otherwise specified herein, both endpoints of each numerical range and any value between the two endpoints may be used. Unless otherwise defined, all technical and scientific terms used herein are consistent with the prior art as understood by those skilled in the art and the description of the present invention. Any prior art methods, devices, and materials similar or equivalent to those described in the examples of the present invention may also be used to implement the present invention.

[0035] In order to realize resource recovery in lithium slag and obtain tailings that can be used for building materials and an extract containing potassium, sodium, cesium, and rubidium metal elements, the present invention provides a method for extracting potassium, sodium, cesium, and rubidium from lithium slag, comprising the steps of:

[0036] S1, performing a first mixing of lithium slag and a leaching agent to obtain a mixture.

[0037] The first mixing is mainly for uniformly mixing the lithium slag and the leaching agent. There is no specific limitation on the mixing time and method. The first mixing can be performed at 10-40° C., and is usually performed at room temperature.

[0038] In the present invention, the lithium slag contains potassium, sodium, rubidium and cesium; the mass proportion of the potassium element in the lithium slag is 5-10%, the mass proportion of the sodium element in the lithium slag is 5-10%, the mass proportion of the rubidium element in the lithium slag is 0.1-2%, and the mass proportion of the cesium element in the lithium slag is 0.05-0.5%.

[0039] The lithium slag contains mineral phases such as nepheline, leucite, and sodalite, and has a framework-like structure of silicate minerals. The lithium slag also contains silicon, calcium, aluminum, iron, sulfur, and oxygen. Semi-quantitative analysis using X-ray fluorescence spectroscopy reveals that, in terms of oxide form and by mass percentage, the lithium slag contains 25-35% SiO2, 8-12% CaO, 15-25% Al2O3, 2-3% Fe2O3, and 9-12% SO3. The lithium slag may include or be the leached residue from lithium mica concentrate after sulfate roasting and water leaching.

[0040] The leaching agent includes or is Mg(OH)2 and CaO, and the mass ratio of Mg(OH)2 and CaO is 1:5-6; the mass ratio of the lithium slag and the leaching agent is 0.9-2:1, and can further be 0.9-1.1:1.

[0041] S2, mechanically activating the mixed material to obtain a pretreated material.

[0042] The mechanical activation includes: ball milling the mixed material for 1.5 to 5 hours, preferably 1.5 to 2.5 hours; the ball milling speed can be 200 to 400 rpm, preferably 200 to 300 rpm; in the embodiments and comparative examples of the present invention, the ball milling speed is 200 rpm; the ball-to-material ratio used in the ball milling can be 1 to 15:1 to 4, 1 to 10:1 to 4, or 10:1 to 4. After the mechanical activation is completed, the pretreated material can be sieved through a 200 to 325 mesh sieve, and the undersize can be used as the pretreated material to be used.

[0043] S3, performing a second mixing of the pretreated material and water to obtain a first reaction liquid; the mass ratio of the pretreated material to the water is 1:3-15, and can further be 1:9-11.

[0044] In the present invention, the second mixing is performed at a temperature of 40-70°C or 50-70°C, for a duration of 0.5-5 hours or 2-4 hours; and the rotation speed employed in the second mixing can be 100-300 rpm. The second mixing is merely a conventional heating and mixing process and can be performed in an unsealed hydrothermal reactor or in other containers.

[0045] S4, subjecting the first reaction liquid to a hydrothermal treatment (hydrothermal reaction) to obtain a second reaction liquid.

[0046] In the present invention, the temperature of the hydrothermal treatment is 120-170°C or 140-160°C, and the duration of the hydrothermal treatment is 3-6h or 3-5h or 4-6h; the hydrothermal treatment is carried out in a hydrothermal reactor (high-pressure reactor); in the present invention, the hydrothermal treatment process is a static reaction and does not require stirring.

[0047] S5, performing solid-liquid separation on the second reaction liquid to obtain a metal extract (leaching solution) and tailings; the metal extract contains the potassium element, the sodium element, the rubidium element and the cesium element.

[0048] It should be noted that the lithium mica concentrate is transformed from a layered silicate mineral into a feldspar-like mineral with a framework structure (the lithium slag of the present invention has a feldspar-like mineral with a framework structure), and a large amount of potassium, sodium, sulfate and other substances enter the lattice of the lithium slag. Since the silicate structure of the framework structure is relatively stable, general acids and alkalis cannot leach potassium, sodium, rubidium and cesium elements in the lithium slag. The present invention uses a hydrothermal method to simulate the weathering of silicate minerals in geochemical principles. Under alkaline conditions, OH is firstly reacted with water to form a precipitate. - The method erodes the Si-O and Al-O bonds on the surface of the mineral (the lithium slag of the present invention has Si-O and Al-O bonds), hydrolyzing the silicate minerals and releasing the potassium, sodium, rubidium, and cesium elements in the minerals. Under high temperature and high pressure conditions, the hydrolysis products combine with calcium and magnesium to form a stable precipitate, ultimately achieving the purpose of leaching potassium, sodium, rubidium, and cesium. In addition, the present invention not only requires the use of an alkaline substance as a leaching agent, but also has certain requirements for the selection of the leaching agent; for example, when sodium hydroxide, potassium hydroxide, calcium oxide, and magnesium hydroxide are used alone, the expected results of the present invention are not achieved; unexpectedly, after the combination of calcium oxide and magnesium hydroxide, the present invention can achieve efficient removal of potassium and sodium.

[0049] Further combining mechanical activation and pre-reaction, the present invention achieves efficient removal of potassium, sodium, rubidium and cesium at lower hydrothermal temperatures. In the present invention, after mechanical activation, the lithium slag produces crystal defects or lattice distortion due to mechanical grinding of the surface, thereby causing inhomogeneity (such as structural defects, etc.) on the surface of the lithium slag, exposing more active sites. Under alkaline conditions, the lithium slag is more easily hydrolyzed, and the hydrolysis results in more active ions such as silicon and aluminum, and the concentration increases. During the pre-reaction process, the increase in the concentration of active ions accelerates the initial reaction of the leaching process, providing favorable conditions for the formation of the final product. Compared with the leaching method without mechanical activation and pre-reaction, the overall reaction temperature of the present invention is greatly reduced.

[0050] In the present invention, after the lithium slag is mechanically activated, crystal defects or lattice distortion are generated on the surface due to mechanical grinding, thereby causing unevenness (such as structural defects, etc.) on the surface of the lithium slag, which accelerates the reaction. When compared with samples that have not been mechanically activated, the reaction temperature is reduced.

[0051] This invention is the first to utilize mechanical activation pretreatment combined with a hydrothermal process to increase the leaching rate of potassium, sodium, rubidium, and cesium from the leached residue after lithium extraction from lepidolite, making it suitable for use as building materials and enabling the recovery of valuable metals, particularly rare metal elements. Therefore, this invention fundamentally addresses the issue of potassium and sodium in lithium residue, expands the application of lithium residue in the building materials field, and enables the recovery of resources such as potassium, sodium, rubidium, and cesium.

[0052] The following are specific examples of the present invention:

[0053] Example 1

[0054] Lithium slag (leached slag obtained by water leaching lithium from lepidolite concentrate after sulfate roasting) was obtained. The lithium slag in this embodiment was from a lithium carbonate production enterprise in Yichun City, Jiangxi Province. The subsequent embodiments, comparative examples, and analysis examples all adopted the lithium slag in this embodiment.

[0055] 1. The lithium slag was subjected to quantitative analysis by atomic absorption spectrometry, and the results of some elemental analysis are shown in Table 1.

[0056] Table 1 Content of some elements in lithium slag (wt%)

[0057] element K Na Rb Cs content 6.80 6.11 0.56 0.14

[0058] 2. The lithium slag was subjected to semi-quantitative analysis by X-ray fluorescence spectroscopy. Some chemical analysis results of the lithium slag are shown in Table 2.

[0059] Table 2 Partial chemical analysis results of lithium slag (wt%)

[0060] Components <![CDATA[SiO2]]> CaO <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> <![CDATA[SO3]]> content% 29.07 9.76 19.38 2.65 10.45

[0061] 3. X-ray diffraction test was performed on lithium slag to analyze its physical phase. The results are as follows: Figure 1 As shown, there are phases such as sodalite, leucite and nepheline in lithium slag; lithium slag has a framework-like silicate structure.

[0062] Example 2

[0063] 1. In this embodiment, the steps for extracting potassium, sodium, rubidium and cesium from lithium slag are as follows:

[0064] Step 1: mixing lithium slag, CaO and Mg(OH)2 at room temperature to obtain a mixture; wherein the mass ratio of lithium slag, CaO and Mg(OH)2 is 2:1.7:0.3;

[0065] Step 2: Place the mixed material into a ball mill and mill it for 2 hours at a ball-to-material ratio of 10:1 (mass ratio) to obtain the pretreated material;

[0066] Step 3: Pass the pretreated material through a 200-mesh sieve and take the sieve-free material for later use;

[0067] Step 4: Place the sieved pretreated material and pure water in a polytetrafluoroethylene-lined reactor and pre-react at a temperature of 60°C and a rotation speed of 200 rpm for 3 hours; the liquid-to-solid ratio of pure water to pretreated material is 10:1 (mass ratio);

[0068] Step 5: After the pre-reaction is completed, the polytetrafluoroethylene liner of the reaction kettle is placed in a high-pressure reactor for hydrothermal reaction at a temperature of 140° C. for 5 hours to obtain a reaction solution;

[0069] Step 6: The reaction solution is subjected to solid-liquid separation to obtain a filtrate (metal extract) and a filter residue (tailings).

[0070] 2. Experimental results:

[0071] 1. In this embodiment, the leaching rates of potassium, sodium, rubidium and cesium are shown in Table 3:

[0072] Table 3 Potassium, sodium, rubidium and cesium leaching rate (%)

[0073] element K Na Rb Cs Leaching rate 84.0 96.6 91.9 98.9

[0074] Comparative Example 1

[0075] 1. In this embodiment, the steps for extracting potassium, sodium, rubidium and cesium from lithium slag are as follows:

[0076] Step 1: mixing lithium slag powder (obtained by passing ground lithium slag through a 200-mesh sieve), CaO, and Mg(OH)2 at room temperature to obtain a mixture; wherein the mass ratio of lithium slag powder, CaO, and Mg(OH)2 is 2:1.7:0.3;

[0077] Step 2: placing the mixture and pure water in a polytetrafluoroethylene-lined reactor and placing it in a high-pressure reactor for hydrothermal reaction, wherein the liquid-to-solid ratio of pure water to the mixture is 10:1 (mass ratio), the hydrothermal reaction temperature is 140° C., and the hydrothermal reaction time is 5 h to obtain a reaction solution;

[0078] Step 3: The reaction liquid is subjected to solid-liquid separation to obtain a filtrate and a filter residue.

[0079] 2. Experimental results:

[0080] In this comparative example, the leaching rates of potassium, sodium, rubidium and cesium are shown in Table 4:

[0081] Table 4 Potassium, sodium, rubidium and cesium leaching rate (%)

[0082] element K Na Rb Cs Leaching rate 34.9 48.1 35.4 38.1

[0083] Comparative Example 2

[0084] 1. In this comparative example, the steps for extracting potassium, sodium, rubidium and cesium from lithium slag are as follows:

[0085] Step 1: mixing lithium slag, CaO and Mg(OH)2 at room temperature to obtain a mixture; wherein the mass ratio of lithium slag, CaO and Mg(OH)2 is 2:1.7:0.3;

[0086] Step 2: Place the mixed material into a ball mill and mill it for 2 hours at a ball-to-material ratio of 10:1 (mass ratio) to obtain the pretreated material;

[0087] Step 3: Pass the pretreated material through a 200-mesh sieve and take the sieve-free material for later use;

[0088] Step 4: Place the sieved pretreated material and pure water in a polytetrafluoroethylene-lined reactor, and place it in a high-pressure reactor for hydrothermal reaction. The liquid-to-solid ratio of pure water to pretreated material is 10:1 (mass ratio), the hydrothermal reaction temperature is 140° C., and the hydrothermal reaction time is 5 h to obtain a reaction solution;

[0089] Step 5: The reaction solution is subjected to solid-liquid separation to obtain a filtrate and a filter residue.

[0090] 2. Experimental results:

[0091] In this comparative example, the leaching rates of potassium, sodium, rubidium and cesium are shown in Table 5:

[0092] Table 5 Potassium, sodium, rubidium and cesium leaching rate (%)

[0093] element K Na Rb Cs Leaching rate 77.6 89.8 86.0 91.8

[0094] Comparative Example 3

[0095] 1. In this comparative example, the steps for extracting potassium, sodium, rubidium and cesium from lithium slag are as follows:

[0096] Step 1: mixing lithium slag powder (obtained by passing ground lithium slag through a 200-mesh sieve), CaO, and Mg(OH)2 at room temperature to obtain a mixture; wherein the mass ratio of lithium slag powder, CaO, and Mg(OH)2 is 2:1.7:0.3;

[0097] Step 2: Place the mixture and pure water in a polytetrafluoroethylene-lined reactor and pre-react at 60°C and 200 rpm for 3 hours; the liquid-to-solid ratio of pure water to the mixture is 10:1 (mass ratio);

[0098] Step 3: After the pre-reaction is completed, the polytetrafluoroethylene reactor liner is placed in a high-pressure reactor for hydrothermal reaction; the hydrothermal reaction temperature is 140° C., and the hydrothermal reaction time is 5 hours to obtain a reaction solution;

[0099] Step 4: The reaction liquid is subjected to solid-liquid separation to obtain a filtrate and a filter residue.

[0100] 2. Experimental results:

[0101] In this comparative example, the leaching rates of potassium, sodium, rubidium and cesium are shown in Table 6:

[0102] Table 6 Potassium, sodium, rubidium and cesium leaching rate (%)

[0103] element K Na Rb Cs Leaching rate 41.8 55.3 43.6 49.3

[0104] Example 3

[0105] 1. In this embodiment, the steps for extracting potassium, sodium, rubidium and cesium from lithium slag are as follows:

[0106] Step 1: mixing lithium slag, CaO and Mg(OH)2 at room temperature to obtain a mixture; wherein the mass ratio of lithium slag, CaO and Mg(OH)2 is 2:1.7:0.3;

[0107] Step 2: Place the mixed material into a ball mill and mill it for 2 hours at a ball-to-material ratio of 10:1 (mass ratio) to obtain the pretreated material;

[0108] Step 3: Pass the pretreated material through a 200-mesh sieve and take the sieve-free material for later use;

[0109] Step 4: Place the sieved pretreated material and pure water in a polytetrafluoroethylene-lined reactor and pre-react at a temperature of 60°C and a rotation speed of 200 rpm for 3 hours; the liquid-to-solid ratio of pure water to pretreated material is 10:1 (mass ratio);

[0110] Step 5: After the pre-reaction is completed, the polytetrafluoroethylene reactor liner is placed in a high-pressure reactor for hydrothermal reaction at a temperature of 160° C. for 5 hours to obtain a reaction solution;

[0111] Step 6: The reaction solution is subjected to solid-liquid separation to obtain a filtrate (metal extract) and a filter residue.

[0112] 2. Experimental results:

[0113] In this embodiment, the leaching rates of potassium, sodium, rubidium and cesium are shown in Table 7:

[0114] Table 7 Potassium, sodium, rubidium and cesium leaching rate (%)

[0115] element K Na Rb Cs Leaching rate 90.4 99.6 99.9 99.8

[0116] Comparative Example 4

[0117] 1. In this embodiment, the steps for extracting potassium, sodium, rubidium and cesium from lithium slag are as follows:

[0118] Step 1: mixing lithium slag, CaO and Mg(OH)2 at room temperature to obtain a mixture; wherein the mass ratio of lithium slag, CaO and Mg(OH)2 is 2:1.7:0.3;

[0119] Step 2: Place the mixed material into a ball mill and mill it for 2 hours at a ball-to-material ratio of 10:1 (mass ratio) to obtain the pretreated material;

[0120] Step 3: Pass the pretreated material through a 200-mesh sieve and take the sieve-free material for later use;

[0121] Step 4: Place the sieved pretreated material and pure water in a polytetrafluoroethylene-lined reactor and pre-react at a temperature of 60°C and a rotation speed of 200 rpm for 3 hours; the liquid-to-solid ratio of pure water to pretreated material is 10:1 (mass ratio);

[0122] Step 5: After the pre-reaction is completed, the polytetrafluoroethylene reactor liner is placed in a high-pressure reactor for hydrothermal reaction at a temperature of 100° C. for 5 hours to obtain a reaction solution;

[0123] Step 6: The reaction solution is subjected to solid-liquid separation to obtain a filtrate (metal extract) and a filter residue.

[0124] 2. Experimental results:

[0125] In this embodiment, the leaching rates of potassium, sodium, rubidium and cesium are shown in Table 8:

[0126] Table 8 Potassium, sodium, rubidium and cesium leaching rate (%)

[0127] element K Na Rb Cs Leaching rate 33.9 50.41 36.43 42.09

[0128] Analysis example 1

[0129] 1. This analysis example takes the leaching of potassium and sodium as an example and adopts the following steps:

[0130] Step 1: Grind 100g of lithium slag and pass the ground slag powder through a 200-mesh sieve, and take the sieve underfill for later use;

[0131] Step 2: Weigh 2 g of sieved slag powder, add 1.7 g of CaO and 0.3 g of Mg(OH)2, and add 40 mL of pure water. After thorough mixing at room temperature, pour into a polytetrafluoroethylene-lined autoclave and place in a hydrothermal reaction at 200°C for 5 h.

[0132] Step 3: After the reaction is completed, the hydrothermal reaction liquid is subjected to solid-liquid separation to obtain a filtrate and a filter residue.

[0133] 2. Experimental results:

[0134] 1. In this embodiment, the leaching rates of potassium and sodium are shown in Table 9.

[0135] Table 9 Potassium and sodium leaching rate (%)

[0136] element K Na Leaching rate 95.2 99.4

[0137] Analysis example 2

[0138] 1. This analysis example takes the leaching of potassium and sodium as an example and adopts the following steps:

[0139] Step 1: Grind 100g of lithium slag and pass the ground slag powder through a 200-mesh sieve, and take the sieve underfill for later use;

[0140] Step 2: Weigh 2 g of sieved slag powder, add 2 g of CaO, and add 40 mL of pure water. After thorough mixing at room temperature, pour into a polytetrafluoroethylene-lined autoclave and place in a hydrothermal reaction at 200°C for 5 h.

[0141] Step 3: After the reaction is completed, the hydrothermal reaction liquid is subjected to solid-liquid separation to obtain a filtrate and a filter residue.

[0142] 2. Experimental results:

[0143] 1. In this comparative example, the leaching rates of potassium and sodium are shown in Table 10.

[0144] Table 10 Potassium and sodium leaching rate (%)

[0145] element K Na Leaching rate 82.3 83.1

[0146] Analysis example 3

[0147] 1. This analysis example takes the leaching of potassium and sodium as an example and adopts the following steps:

[0148] Step 1: Grind 100g of lithium slag and pass the ground slag powder through a 200-mesh sieve, and take the sieve underfill for later use;

[0149] Step 2: Weigh 2 g of sieved slag powder, add 2 g of Mg(OH)2, and 40 mL of pure water. Mix thoroughly at room temperature, pour into a polytetrafluoroethylene-lined autoclave, and place in a hydrothermal autoclave at 200°C for 5 h.

[0150] Step 3: After the reaction is completed, the hydrothermal reaction liquid is subjected to solid-liquid separation to obtain a filtrate and a filter residue.

[0151] 2. Experimental results:

[0152] 1. In this comparative example, the leaching rates of potassium and sodium are shown in Table 11.

[0153] Table 11 Potassium and sodium leaching rate (%)

[0154] element K Na Leaching rate 30.9 37.5

[0155] Analysis example 4

[0156] 1. This analysis example takes the leaching of potassium and sodium as an example and adopts the following steps:

[0157] Step 1: Grind 100g of lithium slag and pass the ground slag powder through a 200-mesh sieve, and take the sieve underfill for later use;

[0158] Step 2: 2g of the sieved residue powder was weighed, 2g of NaOH was added, and 40mL of pure water was added. After mixing well at room temperature, it was poured into a polytetrafluoroethylene liner and placed in a high-pressure reaction kettle, and hydrothermal treatment was carried out at a temperature of 200°C for 5h.

[0159] Step 3: After the reaction was completed, the solid-liquid separation of the hydrothermal reaction liquid was carried out, and the filtrate and the filter residue were obtained.

[0160] II. Experimental results:

[0161] 1. In this comparative example, the leaching rate of potassium and sodium is shown in Table 12; N / A means that Na element is introduced in the leaching agent NaOH, and the concentration of Na ion in the final leaching solution is several orders of magnitude higher than that of other elements, which cannot be accurately measured.

[0162] Table 12 Potassium and sodium leaching rate (%)

[0163] element K Na Leaching rate 69.1 N / A

[0164] Analysis example 5

[0165] I. This analysis example takes the leaching of potassium and sodium as an example, and the following steps are adopted:

[0166] Step 1: 100g of lithium residue was ground, and the ground residue powder was sieved through a 200 mesh sieve, and the undersize was taken for use;

[0167] Step 2: 2g of the sieved residue powder was weighed, 2g of KOH was added, and 40mL of pure water was added. After mixing well at room temperature, it was poured into a polytetrafluoroethylene liner and placed in a high-pressure reaction kettle, and hydrothermal treatment was carried out at a temperature of 200°C for 5h;

[0168] Step 3: After the reaction was completed, the solid-liquid separation of the hydrothermal reaction liquid was carried out, and the filtrate and the filter residue were obtained.

[0169] II. Experimental results:

[0170] 1. In this comparative example, the leaching rate of potassium and sodium is shown in Table 13; N / A means that K element is introduced in the leaching agent KOH, and the concentration of K ion in the final leaching solution is several orders of magnitude higher than that of other elements, which cannot be accurately measured.

[0171] Table 13 Potassium and sodium leaching rate (%)

[0172] element K Na Leaching rate N / A 42.55

[0173] The above technical solutions of the present invention are only preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention's description 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 method for extracting potassium, sodium, rubidium and cesium from lithium slag, characterized in that: Including steps: S1, mixing lithium slag and a leaching agent to obtain a mixture; The lithium slag contains potassium, sodium, rubidium and cesium; The leaching agent includes Mg(OH)2 and CaO, and the mass ratio of Mg(OH)2 to CaO is 1:5-6; the mass ratio of the lithium slag to the leaching agent is 0.9-2:1; S2, mechanically activating the mixed material to obtain a pretreated material; The mechanical activation comprises: ball milling the mixture, wherein the ball milling time is 1.5 to 5 hours; S3, mixing the pretreated material and water for a second time to obtain a first reaction liquid; The second mixing is performed at a temperature of 40 to 70° C., and the duration of the second mixing is 0.5 to 5 hours; S4, subjecting the first reaction liquid to a hydrothermal treatment to obtain a second reaction liquid; The temperature of the hydrothermal treatment is 120-170° C., and the duration of the hydrothermal treatment is 3-6 hours; S5, performing solid-liquid separation on the second reaction liquid to obtain a metal extract and tailings; the metal extract contains the potassium element, the sodium element, the rubidium element, and the cesium element.

2. The method for extracting potassium, sodium, rubidium and cesium from lithium slag according to claim 1, wherein The first mixing is performed at 10-40°C.

3. The method for extracting potassium, sodium, rubidium and cesium from lithium slag according to claim 1, wherein The rotation speed of the ball mill is 200-400 rpm; the ball-to-material ratio used in the ball mill is 1-15:1-4.

4. The method for extracting potassium, sodium, rubidium and cesium from lithium slag according to claim 1, wherein The step S2 further includes: passing the pretreated material through a 200-325 mesh sieve, and taking the sieve residue.

5. The method for extracting potassium, sodium, rubidium and cesium from lithium slag according to claim 1, wherein The mass ratio of the pretreated material to the water is 1:3-15.

6. The method for extracting potassium, sodium, rubidium and cesium from lithium slag according to claim 1, wherein The second mixing is performed at a rotation speed of 100 to 300 rpm.

7. The method for extracting potassium, sodium, rubidium and cesium from lithium slag according to claim 1, wherein The mass proportion of the potassium element in the lithium slag is 5-10%, the mass proportion of the sodium element in the lithium slag is 5-10%, the mass proportion of the rubidium element in the lithium slag is 0.1-2%, and the mass proportion of the cesium element in the lithium slag is 0.05-0.5%.

8. The method for extracting potassium, sodium, rubidium and cesium from lithium slag according to claim 1, wherein The lithium slag contains phases including nepheline, leucite and sodalite, and has a framework-like structure of silicate minerals.

9. The method for extracting potassium, sodium, rubidium and cesium from lithium slag according to claim 1, wherein Calculated by mass, the lithium slag also contains silicon, calcium, aluminum, iron, sulfur and oxygen.

10. The method for extracting potassium, sodium, rubidium and cesium from lithium slag according to any one of claims 1 to 9, characterized in that: The lithium slag comprises: leached slag obtained by leaching lithium from lepidolite concentrate after sulfate roasting.

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