Method for removing potassium and sodium in lithium slag

Abstract

The invention provides a method for removing potassium and sodium in lithium slag. The method comprises the following steps: S1, providing the lithium slag; the lithium slag contains a potassium element and a sodium element; s2, grinding the lithium slag to obtain slag powder; s3, the slag powder and an alkaline leaching agent are mixed in water, and to-be-treated liquid is obtained; performing hydro-thermal treatment on the to-be-treated liquid to obtain reaction liquid; the alkaline leaching agent comprises Mg (OH) 2 and CaO, and the mass ratio of Mg (OH) 2 to CaO is 1: (3-8); the temperature of the hydrothermal treatment is 190-240 DEG C; and S4, carrying out solid-liquid separation on the reaction liquid to obtain tailings and a potassium-sodium separation liquid. According to the invention, the problem of removing potassium and sodium elements from the lithium slag can be fundamentally solved, and the potassium and sodium are prevented from damaging building materials along with the lithium slag.

Description

Technical Field

[0001] The invention relates to the field of solid waste resource utilization, and in particular to a method for removing potassium and sodium from lithium slag. Background Art

[0002] Lithium is a strategic metal for new energy, and using lithium mica to extract lithium carbonate is one of the important lithium extraction routes. However, 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 metal content in the lithium slag high. If it is not removed, it is difficult to consume it on a large scale through building materials utilization, which has become a problem restricting the green and sustainable development of the industry.

[0003] At present, the research on lithium slag after leaching of lithium mica concentrate is mostly focused on direct application in building materials, while ignoring the impact of potassium and sodium salts in lithium slag on building materials. The alkali metal elements such as potassium and sodium remaining in lithium slag mainly exist in the crystal lattice of lithium slag as insoluble potassium ions and sodium ions. If they are directly used in building materials, there is a risk of dissolution under long-term sun, rain and weathering. If potassium and sodium are dissolved in the form of alkali, they migrate to the surface of building materials with water in the pore solution, and react with the aggregate in the concrete to produce alkali-aggregate reaction, causing the concrete structure to expand, crack or even be damaged. In severe cases, the concrete structure will collapse, which is one of the important factors affecting the durability of concrete.

[0004] In view of this, it is necessary to provide a method for removing potassium and sodium from lithium slag to solve or at least alleviate the technical problem of how to efficiently remove potassium and sodium from lithium slag. Summary of the invention

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

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

[0007] S1, providing lithium slag; the lithium slag contains potassium and sodium elements;

[0008] S2, grinding the lithium slag to obtain slag powder;

[0009] S3, mixing the slag powder and the alkaline leaching agent in water to obtain a liquid to be treated; and then performing hydrothermal treatment on the liquid to be treated to obtain a reaction liquid;

[0010] The alkaline leaching agent contains a mixed agent, which includes Mg(OH) 2 and CaO, Mg(OH)2 The mass ratio of the lithium slag to CaO is 1:3-8; the mass ratio of the lithium slag to the mixed reagent is 1:0.5-1.5; the temperature of the hydrothermal treatment is 190-240°C, and the duration of the hydrothermal treatment is 2-17h;

[0011] S4, performing solid-liquid separation on the reaction solution to obtain tailings and potassium-sodium separation solution.

[0012] Furthermore, the mass proportion of the potassium element in the lithium slag is 5-10%, and the mass proportion of the sodium element in the lithium slag is 5-10%.

[0013] Furthermore, the lithium slag contains phases including nepheline, leucite and sodalite, and has a framework-like structure of silicate minerals.

[0014] Furthermore, the lithium slag contains SiO 2 25~35%, CaO 8~12%, Al 2 O 3 15~25%,Fe 2 O 3 2~3, SO 3 9~12%.

[0015] Furthermore, the lithium slag includes: leached slag obtained after lithium is extracted by water after the lithium mica concentrate is roasted with sulfate.

[0016] Furthermore, the step S2 further comprises: passing the slag powder through a 200-325 mesh sieve, and taking the sieve residue.

[0017] Furthermore, the mass volume ratio of the alkaline leaching agent to the water is 0.01 to 0.1 g / mL.

[0018] Furthermore, the mass ratio of the water: the sum of the mixed reagent and the lithium slag is 5 to 15:1.

[0019] Furthermore, the mixed agent includes Mg(OH) 2 and CaO, Mg(OH) 2 The mass ratio of CaO is 1:5~6.

[0020] Furthermore, the hydrothermal treatment is carried out in a hydrothermal reactor.

[0021] Compared with the prior art, the present invention has at least the following advantages:

[0022] 1. The present invention adopts an alkaline leaching agent hydrothermal method to remove potassium and sodium elements from lithium slag, and the hydrothermal temperature is 190-240°C. Compared with the conventional high-temperature roasting method (>1000°C), it has the advantages of low energy consumption and short process flow, and is suitable for practical application. The present invention adopts a calcium-magnesium mixed alkaline leaching agent, and elements such as potassium and sodium in the lithium slag are replaced. Calcium and magnesium ions promote the mineral phase reconstruction of lithium slag in an alkaline environment, generate new mineral phases and precipitate in the tailings, and the calcium and magnesium in the tailings do not affect the subsequent use of the tailings as building materials. Compared with other alkaline leaching agents (such as NaOH, KOH, etc.), the cost is lower, the leaching rate of potassium and sodium is higher, and the leaching rate of the toxic element beryllium is lower, which is more conducive to leachate separation and tailings utilization.

[0023] 2. The present invention can fundamentally solve the problem of removing potassium and sodium elements from lithium slag, and reduce the risk of damage to building materials and corrosion of steel bars caused by the technology of internally solidifying potassium and sodium elements in lithium slag; and heavy metals such as thallium and beryllium in the lithium slag are also partially leached rather than completely leached during the hydrothermal process, reducing the risk of heavy metals entering the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] 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.

[0025] Figure 1 is the X-ray diffraction pattern of the lithium slag in Example 1 of the present invention;

[0026] Figure 2 This is the X-ray diffraction pattern of the filter residue in Example 2 of the present invention.

[0027] 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

[0028] 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.

[0029] 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.

[0030] 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.

[0031] In order to efficiently remove potassium and sodium elements from lithium slag, the present invention provides a method for removing potassium and sodium from lithium slag, comprising the steps of:

[0032] S1, provides lithium slag.

[0033] The lithium slag contains potassium and sodium elements; the mass proportion of the potassium element in the lithium slag is 5-10%, and the mass proportion of the sodium element in the lithium slag is 5-10%. The lithium slag usually also contains thallium and beryllium elements, and the mass proportion of the thallium element in the lithium slag is 13*10 -6 ~15*10 -6 %, the mass proportion of the beryllium element in the lithium slag is 50*10 -6 ~70*10 -6 %.

[0034] As a specific description of the lithium slag, the lithium slag contains mineral phases such as nepheline, leucite and sodalite, and the structure is a framework-like backbone silicate mineral. The lithium slag also contains silicon, calcium, aluminum, iron, sulfur and oxygen. In the present invention, the semi-quantitative analysis using X-ray fluorescence spectroscopy shows that the lithium slag contains SiO in the form of oxides and in terms of mass percentage. 2 25~35%, CaO8~12%, Al 2 O 3 15~25%,Fe 2 O 3 2~3%, SO 3 9~12%.

[0035] S2, grinding the lithium slag to obtain slag powder; then the slag powder can be sieved through a 200-325 mesh sieve, and the sieve under is taken as the slag powder to be used.

[0036] S3, mixing the slag powder and the alkaline leaching agent in water to obtain a liquid to be treated; then performing a hydrothermal treatment (hydrothermal reaction) on the liquid to be treated to obtain a reaction liquid;

[0037] In the present invention, the alkaline leaching agent contains or is a mixed agent; the mixed agent includes or is Mg(OH) 2 and CaO, Mg(OH) 2 The mass ratio of Mg(OH) to CaO is 1:3-8; preferably, Mg(OH) 2 The mass ratio of the lithium slag to the mixed reagent is 1:0.5-1.5 or 1:0.9-1.1.

[0038] In the present invention, the mass volume ratio of the alkaline leaching agent to the water can be 0.01-0.1 g / mL or 0.04-0.06 g / mL. To ensure the solid-liquid ratio of the hydrothermal treatment, the mass ratio of the water: the sum of the mixed reagent and the lithium slag can be 5-15:1 or 7-13:1.

[0039] In the present invention, the temperature of the hydrothermal treatment is 190-240°C, and the duration of the hydrothermal treatment is 2-17 hours; preferably, the temperature of the hydrothermal treatment is 195-220°C (specifically 200°C), and the duration of the hydrothermal treatment is 4-6 hours. The hydrothermal treatment is carried out in a hydrothermal reactor. In the present invention, the process of the hydrothermal treatment is a static reaction without stirring.

[0040] S4, performing solid-liquid separation on the reaction liquid to obtain tailings and potassium-sodium separation liquid; the tailings are filter residues from which potassium and sodium are removed.

[0041] In the present invention, the lithium slag is the leached slag after lithium is extracted by water after lithium is roasted with sulfate from lithium mica concentrate. After the lithium is roasted with sulfate and extracted by water, the lithium mica concentrate is converted 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 potassium, sodium, sulfate and other substances enter the lattice of the lithium slag in large quantities. Since the silicate structure of the framework structure is relatively stable, general acids and alkalis cannot leach potassium and sodium elements in the lithium slag. The hydrothermal method is used to simulate the weathering of silicate minerals in geochemical principles. Under alkaline conditions, OH is firstly leached. -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 and sodium 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 and sodium is achieved. It should be noted that the present invention not only requires alkaline substances to be used 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.

[0042] The present invention is the first to use a hydrothermal method to remove potassium and sodium from the leached residue after lithium extraction from lepidolite, making it suitable for consumption as building materials; it can fundamentally solve the problem of lithium slag containing potassium and sodium elements, and expand the application of lithium slag in the field of building materials.

[0043] Specifically, after completing the steps S1-S4, the present invention can efficiently remove the potassium and sodium elements in the lithium slag, obtain the tailings from which a large amount of potassium and sodium are removed, and the tailings can be further used as building materials; compared with the technology of sealing potassium and sodium elements inside lithium slag, the hydrothermal method used in the present invention to remove potassium and sodium elements can fundamentally solve the problem of potassium and sodium alkali metals contained in the lithium slag building material process. In addition, the potassium and sodium elements contained in the potassium and sodium separation liquid obtained by the present invention can also be used for the recovery and resource utilization of potassium and sodium.

[0044] The following are specific examples of the present invention:

[0045] Example 1

[0046] 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 and comparative examples all use the lithium slag in this embodiment.

[0047] 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.

[0048] Table 1 Content of some elements in lithium slag (wt%)

[0049] element K Na Tl Be content 6.80 6.11 <![CDATA[14*10 -6 ]]> <![CDATA[60*10 -6 ]]>

[0050] 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.

[0051] Table 2 Partial chemical analysis results of lithium slag (wt%)

[0052] Components <![CDATA[SiO 2 ]]> CaO <![CDATA[Al 2 THE 3 ]]> <![CDATA[Fe 2 THE 3 ]]> <![CDATA[SO 3 ]]> content% 29.07 9.76 19.38 2.65 10.45

[0053] 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.

[0054] Example 2

[0055] 1. In this embodiment, the method for removing potassium and sodium from lithium slag adopts the following steps:

[0056] 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;

[0057] Step 2: Weigh 2g of sifted slag powder, add 1.7g CaO and 0.3g Mg(OH) 2 , and add 40 mL of pure water, mix thoroughly at room temperature, pour into the polytetrafluoroethylene liner and put into the hydrothermal reactor, and perform hydrothermal reaction at a temperature of 200°C for 5 hours;

[0058] Step 3: After the reaction is completed, the hydrothermal reaction solution is subjected to solid-liquid separation to obtain a filtrate (leaching solution) containing potassium and sodium elements and a filter residue (tailings) from which potassium and sodium are removed.

[0059] 2. Experimental results:

[0060] 1. In this embodiment, the leaching rates of potassium, sodium, thallium and beryllium are shown in Table 3.

[0061] Table 3 Potassium, sodium, thallium and beryllium leaching rate (%)

[0062] element K Na Tl Be Leaching rate 95.2 99.4 21.3 0.92

[0063] 2. In this embodiment, the X-ray diffraction pattern of the filter residue is shown in Figure 2 As shown, it can be seen that: after the reaction, the diffraction peaks of nepheline, leucite and other phases in the original lithium slag disappear, and a new phase, katoite, and incompletely reacted calcium hydroxide and magnesium hydroxide are produced; calcium carbonate is produced when calcium hydroxide combines with carbon dioxide in the air during the drying process of the sample (filter residue).

[0064] Comparative Example 1

[0065] 1. In this comparative example, the method for removing potassium and sodium from lithium slag adopts the following steps:

[0066] 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;

[0067] Step 2: Weigh 2 g of the sieved slag powder, add 1.7 g of CaO and 40 mL of pure water, mix thoroughly at room temperature, pour into a polytetrafluoroethylene liner and place in a hydrothermal reactor, and perform hydrothermal reaction at 200 °C for 5 h;

[0068] Step 3: After the reaction is completed, the hydrothermal reaction liquid is subjected to solid-liquid separation to obtain a filtrate (leaching liquid) and a filter residue (tailings).

[0069] 2. Experimental results:

[0070] 1. In this comparative example, the leaching rates of potassium, sodium, thallium and beryllium are shown in Table 4.

[0071] Table 4 Potassium, sodium, thallium and beryllium leaching rate (%)

[0072] element K Na Tl Be Leaching rate 73.5 72.8 17.4 0.77

[0073] Comparative Example 2

[0074] 1. In this comparative example, the method for removing potassium and sodium from lithium slag adopts the following steps:

[0075] 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;

[0076] Step 2: Weigh 2 g of sifted 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 hydrothermal reactor, and hydrothermal at 200 ° C for 5 h;

[0077] Step 3: After the reaction is completed, the hydrothermal reaction liquid is subjected to solid-liquid separation to obtain a filtrate (leaching liquid) and a filter residue (tailings).

[0078] 2. Experimental results:

[0079] 1. In this comparative example, the leaching rates of potassium, sodium, thallium and beryllium are shown in Table 5.

[0080] Table 5 Potassium, sodium, thallium and beryllium leaching rate (%)

[0081] element K Na Tl Be Leaching rate 82.3 83.1 19.2 0.91

[0082] Comparative Example 3

[0083] 1. In this comparative example, the method for removing potassium and sodium from lithium slag adopts the following steps:

[0084] 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;

[0085] Step 2: Weigh 2g of sifted slag powder and add 2g Mg(OH)2 , and add 40 mL of pure water, mix thoroughly at room temperature, pour into the polytetrafluoroethylene liner and put into the hydrothermal reactor, and hydrothermal at 200 ° C for 5 hours;

[0086] Step 3: After the reaction is completed, the hydrothermal reaction liquid is subjected to solid-liquid separation to obtain a filtrate (leaching liquid) and a filter residue (tailings).

[0087] 2. Experimental results:

[0088] 1. In this comparative example, the leaching rates of potassium, sodium, thallium and beryllium are shown in Table 6.

[0089] Table 6 Potassium, sodium, thallium and beryllium leaching rate (%)

[0090] element K Na Tl Be Leaching rate 30.9 37.5 4.76 0.34

[0091] Comparative Example 4

[0092] 1. In this comparative example, the method for removing potassium and sodium from lithium slag adopts the following steps:

[0093] 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;

[0094] 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 hydrothermal reactor, and hydrothermal at 200 ° C for 5 h;

[0095] Step 3: After the reaction is completed, the hydrothermal reaction liquid is subjected to solid-liquid separation to obtain a filtrate (leaching liquid) and a filter residue (tailings).

[0096] 2. Experimental results:

[0097] 1. In this comparative example, the leaching rates of potassium, sodium, thallium and beryllium are shown in Table 7; N / A means: the leaching agent NaOH contains 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.

[0098] Table 7 Potassium, sodium, thallium and beryllium leaching rate (%)

[0099] element K Na Tl Be Leaching rate 69.1 N / A 29.5 19.2

[0100] Comparative Example 5

[0101] 1. In this comparative example, the method for removing potassium and sodium from lithium slag adopts the following steps:

[0102] 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;

[0103] 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 hydrothermal reactor, and hydrothermal at 200 ° C for 5 h;

[0104] Step 3: After the reaction is completed, the hydrothermal reaction liquid is subjected to solid-liquid separation to obtain a filtrate (leaching liquid) and a filter residue (tailings).

[0105] 2. Experimental results:

[0106] 1. In this comparative example, the leaching rates of potassium, sodium, thallium and beryllium are shown in Table 8; N / A means: the leaching agent KOH contains K element, 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.

[0107] Table 8 Potassium, sodium, thallium and beryllium leaching rate (%)

[0108] element K Na Tl Be Leaching rate N / A 42.55 6.21 32.5

[0109] Comparative Example 6

[0110] 1. In this comparative example, the method for removing potassium and sodium from lithium slag adopts the following steps:

[0111] 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;

[0112] Step 2: Weigh 2g of slag powder after sieving, add 1.7g CaO and 0.3g Mg(OH) 2 , and add 40 mL of pure water, mix thoroughly at room temperature, pour into the polytetrafluoroethylene liner and put into the hydrothermal reactor, and hydrothermal at 180 ° C for 5 hours;

[0113] Step 3: After the reaction is completed, the hydrothermal reaction liquid is subjected to solid-liquid separation to obtain a filtrate (leaching liquid) and a filter residue (tailings).

[0114] 2. Experimental results:

[0115] 1. In this comparative example, the leaching rates of potassium, sodium, thallium and beryllium are shown in Table 9.

[0116] Table 9 Potassium, sodium, thallium and beryllium leaching rate (%)

[0117] element K Na Tl Be Leaching rate 78.57 83.48 18.27 0.75

[0118] Comparative Example 7

[0119] 1. In this comparative example, the method for removing potassium and sodium from lithium slag adopts the following steps:

[0120] 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;

[0121] Step 2: Weigh 2g of slag powder after sieving, add 1.7g CaO and 0.3g Mg(OH) 2 , and add 40 mL of pure water, mix thoroughly at room temperature, pour into the polytetrafluoroethylene liner and put into the hydrothermal reactor, and hydrothermal at 160 ° C for 5 hours;

[0122] Step 3: After the reaction is completed, the hydrothermal reaction liquid is subjected to solid-liquid separation to obtain a filtrate (leaching liquid) and a filter residue (tailings).

[0123] 2. Experimental results:

[0124] 1. In this comparative example, the leaching rates of potassium, sodium, thallium and beryllium are shown in Table 10.

[0125] Table 10 Potassium, sodium, thallium and beryllium leaching rate (%)

[0126] element K Na Tl Be Leaching rate 60.1 63.8 16.3 0.37

[0127] Comparative Example 8

[0128] 1. In this comparative example, the method for removing potassium and sodium from lithium slag adopts the following steps:

[0129] 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;

[0130] Step 2: Weigh 2g of slag powder after sieving, add 1.7g CaO and 0.3g Mg(OH) 2 , and add 40 mL of pure water, mix thoroughly at room temperature, pour into the polytetrafluoroethylene liner and put into the hydrothermal reactor, and hydrothermal at 140 ° C for 5 hours;

[0131] Step 3: After the reaction is completed, the hydrothermal reaction liquid is subjected to solid-liquid separation to obtain a filtrate (leaching liquid) and a filter residue (tailings).

[0132] 2. Experimental results:

[0133] 1. In this comparative example, the leaching rates of potassium, sodium, thallium and beryllium are shown in Table 11.

[0134] Table 11 Potassium, sodium, thallium and beryllium leaching rate (%)

[0135] element K Na Tl Be Leaching rate 34.9 48.1 15.5 0.14

[0136] 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 removing potassium and sodium from lithium slag, characterized in that: Includes steps: S1, providing lithium slag; the lithium slag contains potassium and sodium elements; S2, grinding the lithium slag to obtain slag powder; S3, mixing the slag powder and the alkaline leaching agent in water to obtain a liquid to be treated; and then performing hydrothermal treatment on the liquid to be treated to obtain a reaction liquid; The alkaline leaching agent contains a mixed agent, the mixed agent includes Mg(OH)2 and CaO, the mass ratio of Mg(OH)2 and CaO is 1:3-8; the mass ratio of the lithium slag to the mixed agent is 1:0.5-1.5; the temperature of the hydrothermal treatment is 190-240°C, and the duration of the hydrothermal treatment is 2-17h; S4, performing solid-liquid separation on the reaction solution to obtain tailings and potassium-sodium separation solution.

2. The method for removing potassium and sodium from lithium slag according to claim 1, characterized in that: The mass proportion of the potassium element in the lithium slag is 5-10%, and the mass proportion of the sodium element in the lithium slag is 5-10%.

3. The method for removing potassium and sodium from lithium slag according to claim 1, characterized in that: The lithium slag contains phases including nepheline, leucite and sodalite, and has a structure of framework-like backbone silicate minerals.

4. The method for removing potassium and sodium from lithium slag according to claim 1, characterized in that: Calculated by mass, the lithium slag contains 25-35% SiO2, 8-12% CaO, 15-25% Al2O3, 2-3% Fe2O3, and 9-12% SO3.

5. The method for removing potassium and sodium from lithium slag according to claim 1, characterized in that: The lithium slag includes: leached slag obtained by leaching lithium from lithium mica concentrate after sulfate roasting.

6. The method for removing potassium and sodium from lithium slag according to claim 1, characterized in that: The step S2 further comprises: passing the slag powder through a 200-325 mesh sieve and taking the sieve residue.

7. The method for removing potassium and sodium from lithium slag according to claim 1, characterized in that: The mass volume ratio of the alkaline leaching agent to the water is 0.01 to 0.1 g / mL.

8. The method for removing potassium and sodium from lithium slag according to claim 1, characterized in that: The mass ratio of the water: the sum of the mixed reagent and the lithium slag is 5 to 15:

1.

9. The method for removing potassium and sodium from lithium slag according to claim 1, characterized in that: The mixed reagent includes Mg(OH)2 and CaO, and the mass ratio of Mg(OH)2 to CaO is 1:5-6.

10. The method for removing potassium and sodium from lithium slag according to claim 1, characterized in that: The hydrothermal treatment is carried out in a hydrothermal reactor.

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