Method for extracting potassium, sodium, rubidium and cesium in lithium slag

Abstract

The invention provides a method for extracting potassium, sodium, rubidium and cesium in lithium slag, which comprises the following steps: S1, carrying out first mixing on the lithium slag and a leaching agent to obtain a mixture; the leaching agent comprises Mg (OH) 2 and CaO; s2, mechanically activating the mixture to obtain a pretreated material; the mechanical activation comprises the following steps: carrying out ball milling on the mixture; s3, carrying out second mixing on the pretreated material and water to obtain a first reaction solution; the second mixing is carried out at the temperature of 40-70 DEG C; s4, performing hydrothermal treatment on the mixed solution to obtain a second reaction solution; the temperature of the hydrothermal treatment is 120-170 DEG C; s5, the second reaction liquid is subjected to solid-liquid separation, and a metal extracting solution and tailings are obtained; the metal extracting solution contains a potassium element, a sodium element, a rubidium element and a cesium element. According to the method, efficient extraction of potassium, sodium, rubidium and cesium in the lithium slag can be achieved at the low 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 grade of lithium in lithium mica, a large amount of lithium slag will be produced after lithium extraction steps such as sulfate roasting and water leaching. The lithium slag has problems such as difficult storage and high environmental risks. The auxiliary materials used in the roasting process contain a large amount of potassium salt and sodium salt, which makes the alkali content in the lithium slag high. At present, the lithium slag after leaching of lithium mica concentrate is often directly applied to building materials; however, the potassium salt and sodium salt remaining in the lithium slag will migrate to the surface of the building material with the water in the pore solution. When the water evaporates, it will deposit and crystallize on the surface of the building material to form frost. Blooming not only affects the appearance, but also expands on the surface, causing surface damage, gradually penetrating into the interior of the building material, and affecting the structure of the building material; potassium salt and sodium salt have a corrosive effect on the steel bars in the concrete, seriously affecting the durability and service life of the concrete.

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

[0004] In existing research, lithium slag is usually solidified, but solidification cannot remove potassium and sodium from lithium slag, and recover rare metals, resulting in low resource utilization of lithium slag. In view of this, 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. 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 for the first time to obtain a mixed material;

[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 mixed material to obtain a pretreated material; the mechanical activation includes: ball milling the mixed material, the ball milling time is 1.5 to 5 hours;

[0011] S3, performing a second mixing of the pretreated material and water 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 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 the structure of a framework-like silicate mineral.

[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 lithium mica concentrate after sulfate roasting.

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

[0026] 1. The present invention mixes lithium slag with a composite alkaline leaching agent containing Mg(OH)2 and CaO, and then sequentially performs mechanical activation, pre-reaction (mixing reaction at a temperature of 40 to 70°C in advance) and hydrothermal reaction, thereby achieving efficient extraction of potassium, sodium, rubidium and cesium elements in the lithium slag.

[0027] 2. The hydrothermal reaction temperature of the present invention is only about 140°C. Compared with the leaching method without mechanical activation and pre-reaction, the present invention can achieve 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°C), the present invention has the advantages of lower energy consumption and higher leaching rate, and is suitable for practical application.

[0028] 2. The present invention fundamentally solves the problem of removing potassium and sodium elements from lithium slag, and reduces the risk of building material damage and steel corrosion caused by the use of internally solidified potassium and sodium elements; at the same time, the present invention realizes the recovery and treatment of resources such as potassium, sodium, rubidium and cesium in lithium slag. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] 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.

[0030] Figure 1 This is the X-ray diffraction pattern of the lithium slag in Example 1 of the present invention.

[0031] 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

[0032] 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.

[0033] 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.

[0034] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise specified in the present invention, both endpoints of each numerical range and any value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention are familiar to those skilled in the art and the description of the present invention, and any methods, equipment and materials of the prior art similar or equivalent to the methods, equipment and materials described in the embodiments of the present invention can also be used to implement the present invention.

[0035] In order to realize the recycling of resources in lithium slag, 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 mixed material.

[0037] The first mixing is mainly for mixing the lithium slag and the leaching agent, and there is no specific limitation on the mixing time and method. The first mixing can be carried out at 10 to 40° C., and the first mixing is usually carried out 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 the structure of the lithium slag is a framework-like skeleton silicate mineral. The lithium slag also contains silicon, calcium, aluminum, iron, sulfur and oxygen; using X-ray fluorescence spectroscopy semi-quantitative analysis, in the form of oxides and by mass percentage, the lithium slag contains SiO2 25-35%, CaO 8-12%, Al2O3 15-25%, Fe2O32-3%, SO3 9-12%. The lithium slag may include or be: leached slag after lithium mica concentrate is roasted with sulfate and then leached with water to extract lithium.

[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 to 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 comprises: ball milling the mixed material, the ball milling time is 1.5 to 5 hours, further 1.5 to 2.5 hours; the rotation speed of the ball mill can be 200 to 400 rpm, further 200 to 300 rpm; in the embodiments and comparative examples of the present invention, the rotation speed of the ball mill is 200 rpm; the ball-to-material ratio used in the ball milling can be 1 to 15: 1 to 4 or 1 to 10: 1 to 4 or 10: 1 to 4. After the mechanical activation is completed, the pre-treated material can be passed through a 200 to 325 mesh sieve, and the sieve undersize is taken as the pre-treated 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 to 70°C or 50 to 70°C, the duration of the second mixing is 0.5 to 5 hours or 2 to 4 hours, and the rotation speed of the second mixing can be 100 to 300 rpm. The second mixing is only a conventional heating mixing process, and the second mixing 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 without 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) through a sulfate roasting and water leaching process. 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 hydrothermal reaction system. - The Si-O bonds and Al-O bonds on the surface of the minerals are corroded (the lithium slag of the present invention has Si-O bonds and Al-O bonds), the silicate minerals are hydrolyzed, the potassium, sodium, rubidium and cesium elements in the minerals are released, and the hydrolysis products are combined with calcium and magnesium under high temperature and high pressure conditions to form a stable precipitate, and finally the purpose of leaching potassium, sodium, rubidium and cesium is achieved. In addition, the present invention not only requires the use of alkaline substances as leaching agents, but also has certain requirements for the selection of leaching agents; for example, when sodium hydroxide, potassium hydroxide, calcium oxide and magnesium hydroxide are used alone, the expectations of the present invention are not achieved; unexpectedly, after calcium oxide and magnesium hydroxide are used in combination, the present invention can achieve efficient removal of potassium and sodium.

[0049] Further combined with mechanical activation and pre-reaction, the present invention realizes the efficient removal of potassium, sodium, rubidium and cesium at a lower hydrothermal temperature. In the present invention, after mechanical activation of lithium slag, crystal defects or lattice distortion are generated due to mechanical grinding of the surface, thereby causing the inhomogeneity of the lithium slag surface (such as structural defects, etc.), so that the lithium slag exposes more active sites, and is more easily hydrolyzed under alkaline conditions, and the hydrolysis leads to more active ions such as silicon and aluminum, and the concentration increases; in the pre-reaction process, the increase in the concentration of active ions accelerates the initial reaction of the leaching process, and provides 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 inhomogeneity (such as structural defects, etc.) on the surface of the lithium slag, accelerating the reaction. When compared with samples that have not been mechanically activated, the reaction temperature is reduced.

[0051] The present invention is the first to use mechanical activation pretreatment combined with hydrothermal method to improve the leaching rate of potassium, sodium, rubidium and cesium in the leached residue after lithium extraction from lepidolite, so that it is suitable for consumption in building materials, and realizes the recovery of valuable metals, especially the recovery of rare metal elements. Therefore, the present invention fundamentally solves the problem of lithium slag containing potassium and sodium elements, expands the application of lithium slag in the field of building materials, and realizes 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] Obtain lithium slag (leached slag obtained by leaching lithium from lithium mica concentrate after sulfate roasting). The lithium slag in this embodiment comes from a lithium carbonate production enterprise in Yichun City, Jiangxi Province. The subsequent embodiments, comparative examples and analysis examples all use the lithium slag in this embodiment.

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

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

[0057] element K Na R 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 the lithium slag; the lithium slag has a framework silicate structure.

[0062] Example 2

[0063] 1. In this embodiment, the steps of 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: Put 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 a 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 for 3 hours at a temperature of 60° C. and a rotation speed of 200 rpm; 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 reactor liner 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 R Cs Leaching rate 84.0 96.6 91.9 98.9

[0074] Comparative Example 1

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

[0076] Step 1: mixing lithium slag powder (obtained by passing the 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 reactor liner, and placing the mixture in a high-pressure reactor for hydrothermal reaction, wherein the liquid-solid ratio of pure water to the mixture is 10:1 (mass ratio), the temperature of the hydrothermal reaction is 140° C., and the time of the hydrothermal reaction is 5 hours, 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 R 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:

[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: Put 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 a 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: placing the sieved pretreated material and pure water in a polytetrafluoroethylene-lined reactor, and placing the sieved pretreated material in a high-pressure reactor for hydrothermal reaction, wherein the liquid-solid ratio of pure water to pretreated material is 10:1 (mass ratio), the temperature of the hydrothermal reaction is 140° C., and the time of the hydrothermal reaction 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 R 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:

[0096] Step 1: mixing lithium slag powder (obtained by passing the 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 for 3 hours at a temperature of 60° C. and a rotation speed of 200 rpm; 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 temperature of the hydrothermal reaction is 140° C., the time of the hydrothermal reaction is 5 hours, and a reaction liquid is obtained;

[0099] Step 4: The reaction solution 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 R Cs Leaching rate 41.8 55.3 43.6 49.3

[0104] Example 3

[0105] 1. In this embodiment, the steps of 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: Put 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 a 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 for 3 hours at a temperature of 60° C. and a rotation speed of 200 rpm; 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 R Cs Leaching rate 90.4 99.6 99.9 99.8

[0116] Comparative Example 4

[0117] 1. In this embodiment, the steps of 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: Put 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 a 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 for 3 hours at a temperature of 60° C. and a rotation speed of 200 rpm; 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 R 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-free material for later use;

[0131] Step 2: Weigh 2 g of the 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 fully mixing at room temperature, pour into a polytetrafluoroethylene liner and place in a high-pressure reactor, and perform hydrothermal reaction at a temperature of 200°C for 5 hours;

[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-free material for later use;

[0140] Step 2: Weigh 2 g of the sieved slag powder, add 2 g of CaO and 40 mL of pure water, mix thoroughly at room temperature, pour into a polytetrafluoroethylene liner and place in a high-pressure reactor, and perform 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-free material for later use;

[0149] Step 2: Weigh 2 g of sifted slag powder, add 2 g of Mg(OH)2 and 40 mL of pure water, mix thoroughly at room temperature, pour into a polytetrafluoroethylene liner and place in a high-pressure reactor, and hydroheat 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-free material for later use;

[0158] Step 2: Weigh 2 g of the sieved slag powder, add 2 g of NaOH and 40 mL of pure water, mix thoroughly at room temperature, pour into a polytetrafluoroethylene liner and place in a high-pressure reactor, and hydroheat at 200 ° C for 5 h;

[0159] 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.

[0160] 2. Experimental results:

[0161] 1. In this comparative example, the leaching rates of potassium and sodium are shown in Table 12; N / A means that the leaching agent NaOH introduces the Na element, and the Na ion concentration in the final leachate is several orders of magnitude higher than that of other elements and 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] 1. This analysis example takes the leaching of potassium and sodium as an example, and adopts the following steps:

[0166] Step 1: Grind 100g of lithium slag, and pass the ground slag powder through a 200-mesh sieve, and take the sieve-free material for later use;

[0167] Step 2: Weigh 2 g of the sieved slag powder, add 2 g of KOH and 40 mL of pure water, mix thoroughly at room temperature, pour into a polytetrafluoroethylene liner and place in a high-pressure reactor, and hydroheat at 200 ° C for 5 h;

[0168] 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.

[0169] 2. Experimental results:

[0170] 1. In this comparative example, the leaching rates of potassium and sodium are shown in Table 13; N / A means that the K element is introduced into the leaching agent KOH, and the K ion concentration in the final leachate is several orders of magnitude higher than that of other elements and 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 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 method for extracting potassium, sodium, rubidium and cesium from lithium slag, characterized in that: Includes steps: S1, mixing lithium slag and a leaching agent for the first time to obtain a mixed material; 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, performing a second mixing of the pretreated material and water 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 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 comprises: 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, characterized in that: 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, characterized in that: 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, characterized in that: 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, characterized in that: 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, characterized in that: In terms of mass percentage, 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 includes: leached slag obtained by leaching lithium from lithium mica concentrate after sulfate roasting.

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