Method for recovering waste tungsten slag from tungsten extraction back solution by water immersion

Abstract

This application belongs to the field of waste tungsten recycling technology, specifically a method for recovering waste tungsten slag by water leaching after tungsten smelting. The method includes the following steps: adding EDTA to the leaching solution in the tungsten smelting process to obtain a leaching agent; then mixing the leaching agent with tungsten slag roasting clinker to form a slurry; leaching is carried out in a microwave reactor; the solid material obtained from solid-liquid separation is further leached using the leaching agent; the leaching and solid-liquid separation are repeated at least twice to recover tungsten from the solution. This application enhances the leaching effect and reduces the consumption of water leaching solution by adding appropriate amounts of additives during the leaching process, effectively reducing water waste. Furthermore, the complexing agent EDTA can form stable complexes with other metal ions in the waste tungsten, improving the purity of sodium tungstate. The multi-stage leaching process can significantly improve the leaching rate and purity of sodium tungstate, reduce wastewater generation, and lower environmental burden and treatment costs.

Description

Technical Field

[0001] This application belongs to the field of waste tungsten recycling technology, specifically a method for recovering waste tungsten slag by water leaching after tungsten transfer. Background Technology

[0002] With the increasing depletion of tungsten ore grades and increasingly stringent environmental protection requirements, the efficient and clean treatment of the large amounts of tungsten slag (especially alkaline leaching slag) generated during tungsten smelting has become a key issue restricting the sustainable development of the industry. Besides containing a certain amount of residual tungsten (usually in the form of insoluble tungstates or undecomposed minerals), tungsten slag is also rich in valuable metals such as manganese, iron, scandium, tantalum, and niobium, and is considered an important secondary resource. Traditional acid processes or direct beneficiation recovery processes suffer from low metal recovery rates, heavy pollution, or poor adaptability.

[0003] Against this backdrop, the sodium carbonate roasting-water leaching process, as a mature combined pyrometallurgical activation and wet extraction technology, has been widely studied and applied to the comprehensive recovery of valuable components from complex tungsten slag. The core of this process lies in utilizing the solid-state reaction of sodium carbonate with the target metal oxides in the tungsten slag at high temperatures to generate water-soluble sodium salts. After roasting, the clinker is cooled, crushed, and then leached in hot or warm water. The soluble sodium salts enter the solution, while most impurities such as iron, manganese, and calcium form insoluble substances and remain in the slag.

[0004] The advantages of the sodium carbonate roasting-water leaching process lie in its high recovery rate and good selectivity. However, its high energy consumption, high reagent costs, and equipment investment are also significant drawbacks. First, the large volume of water leaching solution after roasting leads to substantial water consumption. Second, the sodium tungstate solution contains many impurities, requiring additional dilution treatment, which not only increases production costs and time but may also affect the purity of the final product. Furthermore, the large volume of wastewater generated during ion exchange requires separate treatment, increasing environmental burden and treatment costs, and potentially causing environmental pollution. Therefore, developing a method that can simultaneously reduce water consumption and impurity content during tungsten slag recovery, achieving integrated leaching and deep purification, has significant practical implications and application value. Summary of the Invention

[0005] To address the aforementioned issues, this application provides a method for recovering waste tungsten slag by water leaching of ion-exchange liquid after tungsten smelting. The method uses ion-exchange liquid generated during the tungsten smelting ion exchange process instead of fresh water for water leaching, and introduces ethylenediaminetetraacetic acid (EDTA) as a complexing agent. Without adding a dedicated impurity removal step, the method achieves the integration of leaching and deep purification, significantly improving the purity of intermediate products and laying a better raw material foundation for the subsequent preparation of high-purity APT products.

[0006] This application discloses a method for recovering waste tungsten slag by water leaching after tungsten exchange, comprising the following steps: S1. Ethylenediaminetetraacetic acid is added to the ion-exchange solution in the tungsten smelting process to obtain a leaching agent; S2. The calcined tungsten slag clinker is mixed with the leaching agent to form a slurry, and then placed in a microwave reactor for leaching. Solid-liquid separation is performed to obtain solid material and sodium tungstate solution. S3. Mix the solid material with the leaching agent to form a slurry, and repeat the leaching and solid-liquid separation at least twice to obtain filter residue.

[0007] In the above technical solution, EDTA is added to the ion-exchange post-exchange liquid (post-exchange liquid) in the tungsten smelting process to obtain the leaching agent. The main component of the post-exchange liquid is dilute sodium chloride or ammonium chloride solution, and it also contains a small amount of free alkali and a small amount of tungsten. The tungsten slag roasted clinker contains soluble sodium tungstate, and is accompanied by arsenic, phosphorus, fluorine, and metal ions such as calcium, magnesium, and iron. The system contains a large number of fine, insoluble salt precipitates. When the leaching agent is used to leach the tungsten slag roasted clinker, the residual alkalinity can achieve effective leaching of tungsten. When the strong metal complexing agent EDTA is introduced, it can complex the calcium, magnesium, and iron cations in the system, destroy the fine arsenic-phosphorus-fluorine precipitates, release the tungsten encapsulated and adsorbed by the precipitates back into the liquid phase, and at the same time reduce the entry of calcium, magnesium, and iron impurities into the sodium tungstate solution, thus synergistically achieving deep removal of impurities. As a result, the impurity content in the final prepared sodium tungstate solution is significantly lower than that of the traditional process using fresh water. In addition, the entire leaching process is carried out in a microwave reactor. This is because microwaves can quickly and uniformly heat the leaching system, enhance the solid-liquid interface mass transfer, promote the disturbance of the fine precipitate lattice, reduce the activation energy of the EDTA complexation reaction, accelerate the dissociation of the precipitate, and accelerate the release of the encapsulated or adsorbed arsenic, phosphorus, and fluorine impurities, thereby increasing the desorption and dissolution rate of tungsten.

[0008] The main reasons for using leaching agents to perform at least three leaching processes on tungsten slag roasted clinker and solid materials are: 1. Mass transfer kinetics: Due to the time required for the tungsten and impurity ions adsorbed and encapsulated in the pores of solid particles to diffuse from the solid phase to the liquid phase, single-stage leaching results in limited solid-liquid contact time, making it difficult for the encapsulated tungsten to diffuse fully. Multi-stage leaching continuously updates the concentration difference between the solid and liquid phases, enhancing diffusion mass transfer. 2. Impurity balance control: After each stage of solid-liquid separation, the solid enters the next stage of a new leaching agent system, continuously reducing the equilibrium concentration of impurity ions on the solid surface. This facilitates the continuous breakdown of fine precipitates by EDTA, releasing the encapsulated tungsten. 3. Process tolerance: The composition of the raw tungsten slag fluctuates. Setting at least three leaching stages ensures that the tungsten in the leaching residue is stably controlled at a low level even under fluctuating raw material composition conditions. Using only three times the volume of leaching agent for a single-stage leaching cannot achieve the same effect as multi-stage leaching.

[0009] Furthermore, the main component of the ion-exchange solution is at least one of sodium chloride or ammonium chloride, and the pH of the ion-exchange solution is 10-13.

[0010] Furthermore, the amount of ethylenediaminetetraacetic acid added is 0.1wt% to 0.3wt% of the ion-exchange solution.

[0011] Furthermore, the microwave power of the microwave reactor is 10~100W.

[0012] Furthermore, the liquid-to-solid ratio of the leaching is (2~4) mL:1 g.

[0013] Furthermore, the leaching temperature is 40~80℃ and the leaching time is 0.5~1h; The above parameter range represents the optimal operating window obtained through multiple laboratory examples and comparative studies. Deviating from this range can lead to a series of problems, including decreased tungsten leaching rate, increased reagent costs, interference with subsequent processes, and increased wastewater volume. For example, due to the excessive total amount of impurity ions in the solution, if the amount of EDTA added increases, the limited EDTA will be preferentially occupied by these impurity ions, diluting and consuming the effective complexing agent used to break down the fine precipitates encapsulating tungsten. High concentrations of arsenic, phosphorus, fluorine, and calcium iron in the solution will regenerate new fine colloidal precipitates, resulting in secondary adsorption and encapsulation of tungstate ions. Some of the already dissolved tungsten will be re-encapsulated into the solid phase by these newly formed fine precipitates, ultimately leading to increased slag tungsten and soluble tungsten, and a poorer leaching effect. If the amount of EDTA added is insufficient, there will be not enough complexing agent to break down the arsenic-phosphorus-fluorine fine precipitates, and the encapsulated tungsten cannot be completely desorbed into the liquid phase. Therefore, within the window range of EDTA concentration of 0.1wt%~0.3wt%, microwave power of 10~100W, temperature of 40~80℃, and liquid-solid ratio of (2~4)mL:1g, it is possible to achieve the following: EDTA does not undergo significant thermal decomposition; there is sufficient complexing agent to break down the fine encapsulated precipitate; good fluidity ensures solid-liquid mass transfer; and the impurity load will not be overloaded to cause secondary tungsten encapsulation, thus achieving stable low-slag tungsten index.

[0014] Furthermore, before step S2, the method further includes roasting tungsten slag and sodium salt to obtain the tungsten slag roasted clinker.

[0015] Furthermore, the mass fraction of WO3 in the tungsten slag roasted clinker is 1.0%~1.2%.

[0016] Furthermore, the total tungsten content of WO3 in the filter residue does not exceed 0.4 wt% based on WO3, and the soluble tungsten content in the filter residue does not exceed 0.1 wt% based on WO3.

[0017] Furthermore, within the aforementioned parameter range, the total tungsten content of WO3 in the filter residue does not exceed 0.2 wt% (calculated as WO3), and the soluble tungsten content in the filter residue does not exceed 0.05 wt% (calculated as WO3).

[0018] Furthermore, within the above parameter range, the sodium tungstate solutions obtained from leaching are combined, wherein the concentration of As is ≤9.0 mg / L, the concentration of P is ≤13.5 mg / L, and the concentration of F is ≤16.0 mg / L.

[0019] This application proposes a method for recovering waste tungsten slag by water leaching after tungsten exchange, which produces the following beneficial effects: 1. Reduce water waste: By adding appropriate additives during the leaching process, the leaching effect is enhanced, the consumption of water leaching solution is reduced, and water waste is effectively reduced. 2. Improve the purity of sodium tungstate: Add the complexing agent EDTA to form stable complexes with other metal ions in waste tungstate, reduce the impact of impurities on the leaching of sodium tungstate, and improve the purity of sodium tungstate. 3. Reduce production costs and time: Multi-stage leaching process can significantly improve the leaching rate and purity of sodium tungstate, reduce additional dilution treatment, and reduce production costs and time; 4. Reduce environmental burden and treatment costs: Using ion exchange wastewater for multi-stage leaching reduces the amount of wastewater generated, thereby lowering the environmental burden and treatment costs. 5. Reduce environmental pollution risk: Through multi-stage leaching and solid-liquid separation, the wastewater after ion exchange is effectively treated, reducing the risk of environmental pollution. Detailed Implementation

[0020] The technical solutions in the embodiments will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0021] This application discloses a method for recovering waste tungsten slag by water leaching after tungsten exchange, comprising the following steps: S1. Ethylenediaminetetraacetic acid is added to the ion-exchange solution in the tungsten smelting process to obtain a leaching agent; Preferably, the main component of the ion-exchange post-solution in the tungsten smelting process is at least one of sodium chloride or ammonium chloride, and it also contains WO3 at a concentration of 0.6~1.2 g / L, and the pH of the ion-exchange post-solution is 10~13; the amount of ethylenediaminetetraacetic acid added is 0.1wt%~0.3wt% of the ion-exchange post-solution. Specifically, the amount of ethylenediaminetetraacetic acid added can be any one of 0.1wt%, 0.15wt%, 0.2wt%, 0.25wt%, 0.3wt% of the ion-exchange post-solution, or a range between any two.

[0022] S2. The calcined tungsten slag clinker is mixed with the leaching agent to form a slurry, and then placed in a microwave reactor for leaching. Solid-liquid separation is performed to obtain solid material and sodium tungstate solution. Preferably, the tungsten slag roasted clinker is obtained by roasting tungsten slag and sodium salt, and its main components are oxides such as iron oxide and manganese oxide, and it also contains a small amount of sodium tungstate; the mass fraction of WO3 in the tungsten slag roasted clinker is 1.0%~1.2%; the microwave power of the microwave reactor is 10~100W; the liquid-to-solid ratio of leaching is (2~3)mL:1g; the leaching temperature is 40~80℃ and the time is 0.5~1h. Specifically, the mass fraction of WO3 in the tungsten slag roasted clinker can be any one or any two of 1.0%, 1.05%, 1.1%, 1.15%, and 1.2%; the microwave power of the microwave reactor can be any one or any two of 10W, 20W, 40W, 60W, 80W, and 100W; the liquid-to-solid ratio of leaching can be any one or any two of 2mL:1g, 2.2mL:1g, 2.4mL:1g, 2.6mL:1g, 2.8mL:1g, and 3mL:1g; the leaching temperature can be any one or any two of 40℃, 50℃, 60℃, 70℃, and 80℃; and the leaching time can be any one or any two of 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, and 1h.

[0023] S3. Mix the solid material with the leaching agent to form a slurry, and repeat the leaching and solid-liquid separation at least twice to obtain filter residue; Preferably, the total tungsten content in the filter residue, calculated as WO3, does not exceed 0.2 wt%, and the soluble tungsten content in the filter residue, calculated as WO3, does not exceed 0.05 wt%; the sodium tungstate solutions obtained from leaching are combined, wherein the concentration of As is ≤9.0 mg / L, the concentration of P is ≤13.5 mg / L, and the concentration of F is ≤16.0 mg / L.

[0024] In some preferred embodiments of this application, the leaching can be carried out in leaching bottles. Specifically, the method involves: adding EDTA to the ion-exchange post-ion exchange solution in the tungsten smelting process to prepare a leaching agent, wherein the amount of EDTA added is 0.1wt%~0.3wt% of the ion-exchange post-ion exchange solution; loading the leaching agent into at least three leaching bottles, and placing the leaching bottles in a microwave reactor with a microwave power of 10~100W; then loading the tungsten slag clinker into one leaching bottle for the first stage of leaching. The liquid-to-solid ratio of the leaching is (2~3) mL:1 g, the leaching temperature is 40~80℃, and the leaching time is 0.5~1 h. After each leaching stage, the leachate is subjected to solid-liquid separation. The obtained solid material is put into a leaching bottle containing fresh leaching agent for the next stage of leaching. The leaching and solid-liquid separation are carried out at least 3 times to obtain filter residue. The total tungsten content and soluble tungsten content in the filter residue are detected. The sodium tungstate solution obtained from each solid-liquid separation is combined and put into the ion exchange process to recover tungsten.

[0025] The technical solution of this application will be further described below with reference to specific embodiments. The main component of the ion exchange liquid in the tungsten smelting process used in the following embodiments and comparative examples is sodium chloride, and it also contains WO3 at a concentration of 1.0 g / L, and the pH of the ion exchange liquid is 10~13; the tungsten slag roasting clinker used is obtained by roasting tungsten slag and sodium salt, wherein the mass fraction of WO3 is 1.0%.

[0026] Example 1

[0027] EDTA was added to the ion-exchange solution in the tungsten smelting process to prepare a leaching agent, with the amount of EDTA added being 0.1 wt% of the ion-exchange solution. The leaching agent was loaded into three leaching bottles, and the leaching bottles were placed in a microwave reactor with a microwave power of 10 W. Then, the calcined tungsten slag was loaded into one leaching bottle for the first stage of leaching. After each stage of leaching, the leaching solution was subjected to solid-liquid separation. The obtained solid material was fed into a leaching bottle containing fresh leaching agent for the next stage of leaching. A total of three leachings and three solid-liquid separations were performed to obtain filter residue. The liquid-to-solid ratio for each leaching was 2 mL: 1 g, and the leaching temperature was 40 °C for 0.5 h.

[0028] The total tungsten content in the filter residue was 0.11 wt%, and the soluble tungsten content was 0.03 wt%. The sodium tungstate solutions obtained from leaching were combined, and the concentrations of the main impurities were determined. The results showed that As was 8.2 mg / L, P was 12.4 mg / L, and F was 15.1 mg / L.

[0029] Example 2

[0030] EDTA was added to the ion-exchange solution in the tungsten smelting process to prepare a leaching agent, with the amount of EDTA added being 0.3 wt% of the ion-exchange solution. The leaching agent was loaded into three leaching bottles, and the leaching bottles were placed in a microwave reactor with a microwave power of 100W. Then, tungsten slag clinker was loaded into one leaching bottle for the first stage of leaching. After each stage of leaching, the leaching solution was subjected to solid-liquid separation. The obtained solid material was fed into a leaching bottle containing fresh leaching agent for the next stage of leaching. A total of three leachings and three solid-liquid separations were performed to obtain filter residue. The liquid-to-solid ratio for each leaching was 3 mL: 1 g, and the leaching temperature was 80℃ for 1 hour.

[0031] The total tungsten content in the filter residue was 0.09 wt%, and the soluble tungsten content was 0.019 wt%. The sodium tungstate solutions obtained from leaching were combined, and the concentrations of the main impurities were determined. The results showed that As was 8.7 mg / L, P was 13.1 mg / L, and F was 15.8 mg / L.

[0032] Example 3

[0033] EDTA was added to the ion-exchange solution in the tungsten smelting process to prepare a leaching agent, with the amount of EDTA added being 0.2 wt% of the ion-exchange solution. The leaching agent was loaded into three leaching bottles, and the leaching bottles were placed in a microwave reactor with a microwave power of 50 W. Then, the calcined tungsten slag was loaded into one leaching bottle for the first stage of leaching. After each stage of leaching, the leaching solution was subjected to solid-liquid separation, and the obtained solid material was put into a leaching bottle containing fresh leaching agent for the next stage of leaching. A total of three leachings and three solid-liquid separations were performed to obtain filter residue. The liquid-to-solid ratio of each leaching was 2.5 mL: 1 g, the leaching temperature was 60 °C, and the leaching time was 0.8 h.

[0034] The total tungsten content in the filter residue was 0.10 wt%, and the soluble tungsten content was 0.027 wt%. The sodium tungstate solutions obtained from leaching were combined, and the concentrations of the main impurities were determined. The results showed that As was 8.4 mg / L, P was 12.6 mg / L, and F was 15.3 mg / L.

[0035] Example 4

[0036] EDTA was added to the ion-exchange solution in the tungsten smelting process to prepare a leaching agent, with the amount of EDTA added being 0.1 wt% of the ion-exchange solution. The leaching agent was loaded into four leaching bottles, and the leaching bottles were placed in a microwave reactor with a microwave power of 10 W. Then, calcined tungsten slag was loaded into one leaching bottle for the first stage of leaching. After each stage of leaching, the leaching solution was subjected to solid-liquid separation. The obtained solid material was fed into a leaching bottle containing fresh leaching agent for the next stage of leaching. A total of four leachings and four solid-liquid separations were performed to obtain filter residue. The liquid-to-solid ratio for each leaching was 2 mL:1 g, and the leaching temperature was 40 °C for 0.5 h.

[0037] The total tungsten content in the filter residue was 0.10 wt%, and the soluble tungsten content was 0.03 wt%. The sodium tungstate solutions obtained from leaching were combined, and the concentrations of the main impurities were determined. The results showed that As was 7.9 mg / L, P was 11.8 mg / L, and F was 14.6 mg / L.

[0038] Comparative Example 1 The only difference between this comparative example and Example 1 is that pure water is used instead of the ion exchange solution in the tungsten smelting process, and 0.1% by mass of EDTA is added to the pure water to prepare the leaching agent.

[0039] The total tungsten content in the filter residue was 0.18 wt%, and the soluble tungsten content was 0.035 wt%. The sodium tungstate solutions obtained from leaching were combined, and the concentrations of the main impurities were determined. The results showed that As was 17.3 mg / L, P was 22.5 mg / L, and F was 26.8 mg / L. Furthermore, since the ion-exchange post-liquid is not used, the tungsten contained therein cannot be utilized.

[0040] Comparative Example 2 The only difference between this comparative example and Example 1 is that only two leaching bottles are used, and two leaching processes and two solid-liquid separation processes are performed.

[0041] The total tungsten content in the filter residue was 0.30 wt%, and the soluble tungsten content was 0.04 wt%. The sodium tungstate solutions obtained from leaching were combined, and the concentrations of the main impurities were determined. The results showed that As was 24.6 mg / L, P was 31.2 mg / L, and F was 37.5 mg / L.

[0042] Comparative Example 3 The only difference between this comparative example and Example 1 is that no microwave was applied during leaching, i.e., the leaching bottle was not placed in a microwave reactor for leaching.

[0043] The total tungsten content in the filter residue was 0.30 wt%, and the soluble tungsten content was 0.053 wt%. The sodium tungstate solutions obtained from leaching were combined, and the concentrations of the main impurities were determined. The results showed that As was 26.2 mg / L, P was 33.4 mg / L, and F was 39.8 mg / L.

[0044] Comparative Example 4 The only difference between this comparative example and Example 1 is that EDTA was not added to the leaching agent; only the ion-exchange liquid from the tungsten smelting process was used as the leaching agent.

[0045] The total tungsten content in the filter residue was 0.42 wt%, and the soluble tungsten content was 0.09 wt%. The sodium tungstate solutions obtained from leaching were combined, and the concentrations of the main impurities were determined. The results showed that As was 36.7 mg / L, P was 48.2 mg / L, and F was 57.4 mg / L.

[0046] Comparative Example 5 EDTA was added to the ion-exchange solution in the tungsten smelting process to prepare a leaching agent, with the amount of EDTA added being 0.4 wt% of the ion-exchange solution. The leaching agent was loaded into three leaching bottles, and the leaching bottles were placed in a microwave reactor with a microwave power of 120 W. Then, tungsten slag clinker was loaded into one leaching bottle for the first stage of leaching. After each stage of leaching, the leaching solution was subjected to solid-liquid separation. The obtained solid material was fed into a leaching bottle containing fresh leaching agent for the next stage of leaching. A total of three leachings and three solid-liquid separations were performed to obtain filter residue. The liquid-to-solid ratio of each leaching was 4 mL:1 g, and the leaching temperature was 90 °C for 0.5 h.

[0047] The total tungsten content in the filter residue was 0.31 wt%, and the soluble tungsten content was 0.07 wt%. The sodium tungstate solutions obtained from leaching were combined, and the concentrations of the main impurities were determined. The results showed that As was 27.5 mg / L, P was 34.6 mg / L, and F was 41.3 mg / L.

[0048] Comparative Example 6 EDTA was added to the ion-exchange solution in the tungsten smelting process to prepare a leaching agent, with the amount of EDTA added being 0.05 wt% of the ion-exchange solution. The leaching agent was loaded into three leaching bottles, and the leaching bottles were placed in a microwave reactor with a microwave power of 10 W. Then, the calcined tungsten slag was loaded into one leaching bottle for the first stage of leaching. After each stage of leaching, the leaching solution was subjected to solid-liquid separation. The obtained solid material was fed into a leaching bottle containing fresh leaching agent for the next stage of leaching. A total of three leachings and three solid-liquid separations were performed to obtain filter residue. The liquid-to-solid ratio for each leaching was 1 mL:1 g, and the leaching temperature was 20 °C for 0.5 h.

[0049] The total tungsten content in the filter residue was 0.40 wt%, and the soluble tungsten content was 0.10 wt%. The sodium tungstate solutions obtained from leaching were combined, and the concentrations of the main impurities were determined. The results showed that As was 34.1 mg / L, P was 45.3 mg / L, and F was 54.2 mg / L.

[0050] The above description is only a preferred embodiment of this application and does not limit the patent scope of this application. All equivalent structural transformations made using the content of this application's specification under the inventive concept of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. A method for recovering waste tungsten slag by water leaching after tungsten exchange, characterized in that, Includes the following steps: S1. Ethylenediaminetetraacetic acid is added to the ion-exchange solution in the tungsten smelting process to obtain a leaching agent; S2. The calcined tungsten slag clinker is mixed with the leaching agent to form a slurry, and then placed in a microwave reactor for leaching. Solid-liquid separation is performed to obtain solid material and sodium tungstate solution. S3. Mix the solid material with the leaching agent to form a slurry, and repeat the leaching and solid-liquid separation at least twice to obtain filter residue.

2. The method for recovering waste tungsten slag by water leaching after tungsten exchange as described in claim 1, characterized in that, The main component of the ion-exchange solution is at least one of sodium chloride or ammonium chloride, and the pH of the ion-exchange solution is 10-13.

3. The method for recovering waste tungsten slag by water leaching after tungsten exchange as described in claim 1, characterized in that, The amount of ethylenediaminetetraacetic acid added is 0.1wt% to 0.3wt% of the ion-exchange solution.

4. The method for recovering waste tungsten slag by water leaching after tungsten exchange as described in claim 1, characterized in that, The microwave power of the microwave reactor is 10~100W.

5. The method for recovering waste tungsten slag by water leaching after tungsten exchange as described in claim 1, characterized in that, The liquid-to-solid ratio of the leaching is (2~4) mL:1 g.

6. The method for recovering waste tungsten slag by water leaching after tungsten exchange as described in claim 1, characterized in that, The leaching temperature is 40~80℃ and the leaching time is 0.5~1h.

7. The method for recovering waste tungsten slag by water leaching after tungsten exchange as described in claim 1, characterized in that, Before step S2, the method further includes roasting tungsten slag and sodium salt to obtain the tungsten slag roasted clinker.

8. The method for recovering waste tungsten slag by water leaching after tungsten exchange as described in claim 1, characterized in that, The mass fraction of WO3 in the tungsten slag roasted clinker is 1.0%~1.2%.

9. The method for recovering waste tungsten slag by water leaching after tungsten exchange as described in claim 8, characterized in that, The total tungsten content in the filter residue, calculated as WO3, does not exceed 0.2 wt%, and the soluble tungsten content in the filter residue, calculated as WO3, does not exceed 0.05 wt%.

10. The method for recovering waste tungsten slag by water leaching after tungsten exchange as described in claim 8, characterized in that, The sodium tungstate solutions obtained from leaching were combined, wherein the concentration of As was ≤9.0 mg / L, the concentration of P was ≤13.5 mg / L, and the concentration of F was ≤16.0 mg / L.