Method for recovering tungsten from tungsten-containing calcium sulfate slag

Abstract

The invention relates to a method for recovering tungsten from tungsten-containing calcium sulfate slag, which comprises the following steps: S1, soda boiling: taking the tungsten-containing calcium sulfate slag, adding water for size mixing, adding sodium carbonate or sodium bicarbonate into the obtained size, and carrying out solid-liquid separation after reaction to obtain a sodium tungstate solution and residues; s2, acid dissolution: taking the residues in S1, adding water for size mixing, and adding hydrochloric acid into the obtained size to obtain a tungstic acid solution; s3, enriching, namely recycling the sodium tungstate solution obtained in the step S1 as alkali boiled mixed slurry; recycling the tungstic acid solution obtained in the step S2 as acid-soluble slurry mixing liquid; the operation of S1 and S2 is repeated until the tungsten content of the solution reaches 100 g / l, and high-concentration sodium tungstate and tungstic acid are obtained; s4, adsorption; and S5, desorbing to obtain a sodium tungstate solution. The method can realize 100% recovery of tungsten in the tungsten-containing calcium sulfate slag, and has industrial application prospects.

Description

Technical Field

[0001] This invention relates to a process for treating tungsten-containing smelting slag, and more particularly to a method for recovering tungsten from tungsten-containing calcium sulfate slag. Background Technology

[0002] The sulfuric-phosphoric acid decomposition of scheelite (CaWO4) is a commonly used hydrometallurgical process, particularly suitable for processing low- to medium-grade scheelite concentrate or scheelite associated with apatite. Its core principle is to utilize sulfuric acid to provide a strong acid environment for mineral decomposition, while phosphoric acid combines with calcium ions to form calcium phosphate precipitate, promoting the entry of tungstate ions into the solution and preventing the formation of an insoluble calcium tungstate coating. The main steps of this process include:

[0003] Under heating and stirring conditions, a mixture of sulfuric and phosphoric acids reacts chemically with scheelite, decomposing the scheelite at normal pressure and high temperature. This causes tungsten to dissolve into the solution as tungstate (WO42-), while calcium precipitates into the slag as calcium salt.

[0004] The main component of the tungsten smelting tailings produced by this method is calcium sulfate, which also contains some unwashed phosphotungstic heteropoly acid and undecomposed calcium tungstate. The overall tungsten content is 0.6%-0.8%. How to recover this part of the tungsten is of practical significance.

[0005] Patent application CN 110004309 A discloses a method for acid-base combined extraction of tungsten from tungsten minerals. The method includes: Step 1, acid decomposition: mixing tungsten ore with hydrochloric acid solution and adding H2O2 for stirring to obtain solid tungstic acid and an acid decomposition mother liquor; Step 2, sodium carbonate dissolution of solid tungstic acid: mixing the solid tungstic acid with sodium carbonate solution for stirring, and filtering after the reaction to obtain a dissolving residue and a sodium tungstate solution; Step 3, resin ion exchange treatment of the sodium tungstate solution: neutralizing the sodium tungstate solution obtained in Step 2 with sulfuric acid to a pH of 3-6 as a pre-exchange solution, adsorbing tungsten onto the pre-exchange solution using a macroporous weakly basic anion exchange resin, and washing the macroporous weakly basic anion exchange resin adsorbing tungsten with deionized water; after washing, desorption is performed using ammonia water as a desorbent to obtain ammonium tungstate desorption solution, which is further purified and then evaporated and crystallized to obtain ammonium paratungstate. This method is suitable for raw slag such as scheelite or ferrotungsten, but not for slag produced after smelting the raw ore. This is because the tungsten content in the raw ore is much higher than that in the slag, and it is difficult to obtain solid tungstic acid by adding acid to the slag; moreover, the main component of the slag is calcium sulfate, and the decomposition effect after adding acid is not good. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing tungsten recovery methods and provide a method for recovering tungsten from tungsten-containing calcium sulfate slag. This invention utilizes sodium carbonate or sodium bicarbonate to convert the calcium sulfate slag into calcium carbonate. Since calcium carbonate is soluble in hydrochloric acid, the slag is completely dissolved, leaving the tungsten in the solution. Through specific enrichment processes, high-concentration tungstic acid and sodium tungstate are obtained. Using a large-pore anion exchange resin to adsorb and enrich the tungsten, complete tungsten recovery can be achieved.

[0007] When using sodium carbonate, the key reaction equation is as follows:

[0008] Na2CO3+CaSO4=CaCO3↓+Na2SO4

[0009] CaCO3 + 2HCl = CaCl2 + H2O + CO2↑

[0010] The specific plan is as follows:

[0011] A method for recovering tungsten from tungsten-containing calcium sulfate slag includes:

[0012] S1. Alkali boiling: Take tungsten-containing calcium sulfate slag, add water to make slurry, add sodium carbonate or sodium bicarbonate to the slurry, control the pH to be greater than or equal to 9, the temperature to be greater than or equal to 90℃, and after the reaction, perform solid-liquid separation to obtain sodium tungstate solution and residue.

[0013] S2 acid dissolution: Take the residue from S1, add water to adjust the slurry, add hydrochloric acid to the slurry to control the pH=1-2, and obtain a clear solution, which is a tungstic acid solution;

[0014] S3 enrichment: The sodium tungstate solution obtained in S1 is used as the alkali-cooked slurry preparation solution, replacing the water in S1 and reused in the slurry preparation operation; the tungsten acid solution obtained in S2 is used as the acid-soluble slurry preparation solution, replacing the water in S2 and reused in the slurry preparation operation; S1 and S2 operations are repeated. As S1 and S2 are continuously performed, tungsten in the solution is enriched until the tungsten content in the solution reaches 100 g / L, resulting in high-concentration sodium tungstate and tungsten acid;

[0015] S4 adsorption: Take the high-concentration sodium tungstate and tungstic acid obtained in S3 and perform resin adsorption to obtain resin saturated with adsorption.

[0016] S5 Desorption: The saturated resin obtained in S4 is desorbed to obtain a sodium tungstate solution.

[0017] Furthermore, the tungsten-containing calcium sulfate slag is the slag obtained by leaching scheelite with a mixture of sulfur and phosphorus. The specific process includes: acid leaching reaction in an atmospheric pressure reaction tank, with an acidity of 320-380 g / l, a phosphorus concentration of 5-20 g / l, and a temperature controlled above 90℃. The reaction is stirred for 1.5-3 hours, and after the reaction is completed, solid-liquid separation is performed to obtain tungsten-containing calcium sulfate slag.

[0018] Furthermore, the calcium sulfate content in the tungsten-containing calcium sulfate slag is 50-99 wt%, and the tungsten content is 0.6-0.8 wt%, calculated as WO3.

[0019] Furthermore, the solid-liquid ratio of the slurry in S1 is 1:1 to 3.

[0020] Furthermore, the resin adsorption described in S4 uses a macroporous anion exchange resin.

[0021] Furthermore, the resin adsorption in S4 uses macroporous resin D314, and the adsorption flow rate is controlled to be 1-3 BV.

[0022] Furthermore, the desorption described in S5 is performed using a sodium hydroxide solution.

[0023] Beneficial effects: The method for recovering tungsten from tungsten-containing calcium sulfate slag provided by the present invention involves alkaline boiling of the tungsten-containing calcium sulfate slag with sodium carbonate, controlling the pH and reaction temperature, to achieve a tungsten dissolution rate of 45%-48% after alkaline boiling, and complete conversion of calcium sulfate into easily soluble calcium carbonate.

[0024] Furthermore, this invention achieves complete dissolution of the slag by acid dissolution with hydrochloric acid, with the pH controlled between 1 and 2, and all tungsten remains in the solution. The dissolved sodium tungstate and tungstic acid solution are then enriched by adsorption with a large-pore anion exchange resin and desorbed to obtain a high-concentration sodium tungstate product, thus achieving complete tungsten recovery.

[0025] The method provided by this invention has the advantages of strong operability, high recovery rate, and low auxiliary material cost, completely eliminating the shortcomings of traditional recycling methods. This method transforms smelting slag from general solid waste into liquid, which helps to reduce the treatment cost of solid waste slag.

[0026] In summary, this invention solves the problem of tungsten recovery from tungsten-containing calcium sulfate slag. Under the premise of reducing auxiliary material consumption, tungsten recovery can be achieved at 100%, and the slag can be completely transformed from solid to liquid (sodium tungstate and tungstic acid solution), which has reference value for environmental governance. Attached Figure Description

[0027] To more clearly illustrate the technical solution of the present invention, the accompanying drawings will be briefly described below. Obviously, the drawings described below only relate to some embodiments of the present invention and are not intended to limit the present invention.

[0028] Figure 1 This is a process flow diagram provided in one embodiment 1 of the present invention. Detailed Implementation

[0029] Preferred embodiments of the present invention will now be described in more detail. While preferred embodiments of the present invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Where specific techniques or conditions are not specified in the embodiments, they are performed in accordance with techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products. In the following embodiments, unless otherwise specified, "%" refers to weight percentage.

[0030] The main reagents used include:

[0031] Tungsten-containing calcium sulfate slag is the slag produced by the decomposition of scheelite using a mixed sulfuric-phosphoric acid. The process mainly includes: acid leaching reaction of the mixed sulfuric-phosphoric acid and scheelite in an atmospheric pressure reaction tank, with an acidity of 320-380 g / L, a phosphorus concentration of 5-20 g / L, and a temperature controlled above 90℃, under stirring conditions for 1.5-3 hours. Tungsten in calcium tungstate is leached into the solution to form phosphotungstic heteropoly acid. After solid-liquid separation, the filter residue is collected and dried, which is the tungsten-containing calcium sulfate slag. The main component is calcium sulfate, and it also contains 0.6%-0.8% tungsten (calculated as WO3).

[0032] Example 1

[0033] A method for recovering tungsten from tungsten-containing calcium sulfate slag, such as Figure 1 As shown, it includes the following steps:

[0034] S1. Alkali boiling: Weigh 100g of dry tungsten-containing calcium sulfate slag. The slag contains 0.8% WO3. Use 300ml of hot water as a slurry preparation solution and heat the slurry. Add sodium carbonate, control the pH to 9, heat to 90℃, and react for 1.5h. After decomposition, filter to obtain a sodium tungstate solution with a WO3 content of 1.2g / l. The dry weight of the residue after filtration is 74.7g, and the tungsten content of the residue is 0.60%. The tungsten dissolution rate in this process is ((100*0.8)-(74.7*0.6)) / (100*0.8)*100%=44%.

[0035] S2, Acid Dissolution: Take 50g of the dried residue after being boiled with alkali and dried, mix it with 200ml of water to form a slurry, add 120g / L of hydrochloric acid to adjust the pH and dissolve it. Stop adding hydrochloric acid when the pH is between 1 and 2. At this time, the residue will be completely dissolved and a light yellow clear liquid will be obtained, which is a tungstic acid solution with a volume of 268ml and a WO3 content of 1.2g / l.

[0036] S3, Tungsten concentration enrichment of filtrate: The filtrate obtained in S1 is used as the slurry for alkaline boiling, replacing the hot water in S1 and being reused in the slurry preparation operation.

[0037] The low-concentration tungstic acid solution after acid dissolution in S2 is used as the acid-dissolved slurry preparation solution to replace the water in S2 and is reused in the slurry preparation operation.

[0038] Repeat the above S1 and S2 operations. As S1 and S2 are carried out, tungsten in the solution is enriched until the tungsten content in the solution reaches 100 g / L, resulting in high-concentration sodium tungstate (from S1) and tungstic acid (from S2).

[0039] S4. Adsorption: High-concentration sodium tungstate and tungstic acid are used. Sodium tungstate needs to be acidified first to form tungstate ions before adsorption. Specifically, the pH is adjusted using 5-10% dilute hydrochloric acid or dilute sulfuric acid until it is between pH 2 and 5. The adsorbent is adsorbed using large-pore resin D314. The adsorption flow rate is controlled at 2 BV. At this point, the WO3 output from the column is 0.04 g / L. Adsorption is continued until the WO3 output from the column reaches 30 g / L, indicating adsorption saturation, at which point the adsorption operation is stopped.

[0040] S5. Desorption: The saturated resin is washed with water and then desorbed by adding 150 g / L sodium hydroxide solution. The concentration of sodium tungstate (WO3) desorbed is 264 g / L. After washing and transformation, the resin can continue to adsorb acid solutions, achieving 100% tungsten recovery.

[0041] Example 2

[0042] A method for recovering tungsten from tungsten-containing calcium sulfate slag includes the following steps:

[0043] S1. Alkali boiling: Weigh 100g of dry tungsten-containing calcium sulfate slag. The slag contains 0.8% WO3. Use 300ml of hot water as a slurry preparation solution and heat the slurry. Add sodium bicarbonate, control the pH to 9, heat to 95℃, and react for 1.5h. After decomposition, filter to obtain a sodium tungstate solution with a WO3 content of 1.3g / l. The dry weight of the filtered residue is 73.84g, and the tungsten content of the residue is 0.55%. The tungsten dissolution rate of this process is ((100*0.8)-(73.84*0.55)) / (100*0.8)*100%=49.25%.

[0044] S2, Acid Dissolution: Take 50g of the dried residue after being boiled with alkali and dried, mix it with 200ml of water to form a slurry, add 120g / L of hydrochloric acid to adjust the pH and dissolve it. Stop adding hydrochloric acid when the pH is between 1 and 2. At this time, the residue will be completely dissolved and a light yellow clear liquid will be obtained, which is a tungstic acid solution with a volume of 265ml and a WO3 content of 1.2g / l.

[0045] S3, Tungsten concentration enrichment of filtrate: The filtrate obtained in S1 is used as the slurry for alkaline boiling, replacing the hot water in S1 and being reused in the slurry preparation operation.

[0046] The low-concentration tungstic acid solution after acid dissolution in S2 is used as the acid-dissolved slurry preparation solution to replace the water in S2 and is reused in the slurry preparation operation.

[0047] Repeat the above S1 and S2 operations. As S1 and S2 are carried out, tungsten in the solution is enriched until the tungsten content in the solution reaches 100 g / L, resulting in high-concentration sodium tungstate (from S1) and tungstic acid (from S2).

[0048] S4. Adsorption: High-concentration sodium tungstate and tungstic acid are used. Sodium tungstate needs to be acidified first to form tungstate ions before adsorption. Specifically, the pH is adjusted using 5-10% dilute hydrochloric acid or dilute sulfuric acid until it is between pH 2 and 5. The adsorbent is adsorbed using large-pore resin D314. The adsorption flow rate is controlled at 2 BV. At this point, the WO3 output from the column is 0.04 g / L. Adsorption is continued until the WO3 output from the column reaches 30 g / L, indicating adsorption saturation, at which point the adsorption operation is stopped.

[0049] S5. Desorption: The saturated resin is washed with water and desorbed by adding 150 g / L sodium hydroxide solution. The concentration of sodium tungstate (WO3) desorbed is 268 g / L. After washing and transformation, the resin can continue to adsorb acid solutions, achieving 100% tungsten recovery.

[0050] Example 3

[0051] A method for recovering tungsten from tungsten-containing calcium sulfate slag includes the following steps:

[0052] S1. Alkali boiling: Weigh 100g of dry tungsten-containing calcium sulfate slag. The slag contains 0.6% WO3. Use 300ml of hot water as a slurry preparation solution and heat the slurry. Add sodium carbonate, control the pH to 9.5, heat to 90℃, and react for 1.5 hours. After decomposition, filter to obtain a sodium tungstate solution with a WO3 content of 1.2g / L. Dry the residue after filtration. The residue contains 0.60% tungsten. The tungsten dissolution rate in this process is 46%.

[0053] S2, Acid Dissolution: Take 50g of the dried residue after being boiled with alkali and dried, mix it with 200ml of water to form a slurry, add 120g / L of hydrochloric acid to adjust the pH and dissolve it. Stop adding hydrochloric acid when the pH is between 1 and 2. At this time, the residue will be completely dissolved and a light yellow clear liquid will be obtained, which is a tungstic acid solution with a WO3 content of 1.2g / l.

[0054] S3, Tungsten concentration enrichment of filtrate: The filtrate obtained in S1 is used as the slurry for alkaline boiling, replacing the hot water in S1 and being reused in the slurry preparation operation.

[0055] The low-concentration tungstic acid solution after acid dissolution in S2 is used as the acid-dissolved slurry preparation solution to replace the water in S2 and is reused in the slurry preparation operation.

[0056] Repeat the above S1 and S2 operations. As S1 and S2 are carried out, tungsten in the solution is enriched until the tungsten content in the solution reaches 100 g / L, resulting in high-concentration sodium tungstate (from S1) and tungstic acid (from S2).

[0057] S4. Adsorption: High-concentration sodium tungstate and tungstic acid are used. Sodium tungstate needs to be acidified first to form tungstate ions before adsorption. Specifically, the pH is adjusted using 5-10% dilute hydrochloric acid or dilute sulfuric acid until it is between pH 2 and 5. The adsorbent is adsorbed using large-pore resin D314. The adsorption flow rate is controlled to 1 BV. At this point, the WO3 output from the column is 0.04 g / L. Adsorption is continued until the WO3 output from the column reaches 30 g / L, indicating adsorption saturation, at which point the adsorption operation is stopped.

[0058] S5. Desorption: The saturated resin is washed with water and desorbed by adding 150 g / L sodium hydroxide solution. The concentration of sodium tungstate (WO3) desorbed is 265 g / L. After washing and transformation, the resin can continue to adsorb acid solutions, achieving 100% tungsten recovery.

[0059] Example 4

[0060] A method for recovering tungsten from tungsten-containing calcium sulfate slag, such as Figure 1 As shown, it includes the following steps:

[0061] S1. Alkali boiling: Weigh 100g of dry tungsten-containing calcium sulfate slag. The slag contains 0.8% WO3. Use 300ml of hot water as a slurry preparation solution and heat the slurry. Add sodium bicarbonate, control the pH to 9, heat to 95℃, and react for 1.5h. After decomposition, filter to obtain a sodium tungstate solution with a WO3 content of 1.2g / L. Dry the residue after filtration. The residue contains 0.60% tungsten. The tungsten dissolution rate in this process is 47%.

[0062] S2, Acid Dissolution: Take 50g of the dried residue after being boiled with alkali and dried, mix it with 200ml of water to form a slurry, add 120g / L of hydrochloric acid to adjust the pH and dissolve it. Stop adding hydrochloric acid when the pH is between 1 and 2. At this time, the residue will be completely dissolved and a light yellow clear liquid will be obtained, which is a tungstic acid solution with a WO3 content of 1.2g / l.

[0063] S3, Tungsten concentration enrichment of filtrate: The filtrate obtained in S1 is used as the slurry for alkaline boiling, replacing the hot water in S1 and being reused in the slurry preparation operation.

[0064] The low-concentration tungstic acid solution after acid dissolution in S2 is used as the acid-dissolved slurry preparation solution to replace the water in S2 and is reused in the slurry preparation operation.

[0065] Repeat the above S1 and S2 operations. As S1 and S2 are carried out, tungsten in the solution is enriched until the tungsten content in the solution reaches 100 g / L, resulting in high-concentration sodium tungstate (from S1) and tungstic acid (from S2).

[0066] S4. Adsorption: High-concentration sodium tungstate and tungstic acid are used. Sodium tungstate needs to be acidified first to form tungstate ions before adsorption. Specifically, the pH is adjusted using 5-10% dilute hydrochloric acid or dilute sulfuric acid until it reaches a range of 2-5. The adsorbent is adsorbed using large-pore resin D314. The adsorption flow rate is controlled at 3 BV. At this point, the WO3 concentration at the column outlet is 0.04 g / L. Adsorption is continued until the WO3 concentration at the column outlet reaches 30 g / L, indicating adsorption saturation, at which point the adsorption operation is stopped.

[0067] S5. Desorption: The saturated resin is washed with water and then desorbed by adding 150 g / L sodium hydroxide solution. The concentration of sodium tungstate (WO3) desorbed is 260 g / L. After washing and transformation, the resin can continue to adsorb acid solutions, achieving 100% tungsten recovery.

[0068] Comparative Example 1

[0069] A method for recovering tungsten from tungsten-containing calcium sulfate slag includes the following steps:

[0070] S1. Alkali boiling: Weigh 100g of dry tungsten-containing calcium sulfate slag. The slag contains 0.8% WO3. Use 300ml of hot water as a slurry preparation solution and heat the slurry. Add sodium carbonate, control the pH to 9, heat to 90℃, and react for 1.5 hours. After decomposition, filter to obtain a sodium tungstate solution with a WO3 content of 1.2g / L. The dry weight of the filtered residue is 74.7g, and the tungsten content of the residue is 0.60%. The tungsten dissolution rate in this process is 44%.

[0071] S2, Acid Dissolution: Take 50g of the dried residue after alkaline boiling and drying, mix it with 200ml of water to form a slurry, add 120g / L of hydrochloric acid to adjust the pH and dissolve it. Observe the dissolution at different pH values, as follows:

[0072] Table 1. Acid solubility at different pH values

[0073]

[0074]

[0075] As can be seen from Table 1, the slag has the highest dissolution rate when the pH endpoint is between 1 and 2, thus enabling 100% tungsten recovery.

[0076] Comparative Example 2

[0077] A method for recovering tungsten from tungsten-containing calcium sulfate slag includes the following steps:

[0078] S1. Alkali boiling: Weigh 100g of dry tungsten-containing calcium sulfate slag. The slag contains 0.8% WO3. Use 300ml of hot water as a slurry preparation solution and heat the slurry. Add sodium carbonate. See Table 2 for reaction conditions. After the reaction, filter to obtain a sodium tungstate solution. Dry the residue after filtration, test the tungsten content in the residue, and calculate the tungsten dissolution rate. See Table 2.

[0079] Table 2. Results of the alkaline boiling experiment

[0080] Reaction conditions The residue contains tungsten Residue dry weight Tungsten dissolution rate 80℃, pH=9, reaction time 1.5h 0.62％ 85.4g 33.8％ 90℃, pH=8, reaction time 1.5h 0.76％ 84.2g 20％

[0081] As can be seen from Table 2, when the alkaline boiling temperature is below 90℃, there will be less slag dissolution, resulting in a low tungsten dissolution rate. When the pH is below 9, there will be less slag dissolution, making it difficult for tungsten to be boiled into sodium tungstate by alkaline boiling.

[0082] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0083] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0084] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for recovering tungsten from tungsten-containing calcium sulfate slag, characterized in that: include: S1. Alkali boiling: Take tungsten-containing calcium sulfate slag, add water to make slurry, add sodium carbonate or sodium bicarbonate to the slurry, control the pH to be greater than or equal to 9, the temperature to be greater than or equal to 90℃, and after the reaction, perform solid-liquid separation to obtain sodium tungstate solution and residue. S2 acid dissolution: Take the residue from S1, add water to adjust the slurry, add hydrochloric acid to the slurry to control the pH=1-2, and obtain a clear solution, which is a tungstic acid solution; S3 Enrichment: The sodium tungstate solution obtained in S1 is used as the alkali-cooking slurry, replacing the water in S1 and reused in the slurry preparation operation; the tungsten acid solution obtained in S2 is used as the acid-dissolving slurry, replacing the water in S2 and reused in the slurry preparation operation; S1 and S2 operations are repeated. As S1 and S2 are continuously performed, tungsten in the solution is enriched until the tungsten content in the solution reaches 100 g / L, resulting in high-concentration sodium tungstate and tungsten acid; S4 Adsorption: The high-concentration sodium tungstate and tungsten acid obtained in S3 are subjected to resin adsorption to obtain saturated resin; S5 Desorption: The saturated resin obtained in S4 is desorbed to obtain a sodium tungstate solution.

2. The method for recovering tungsten from tungsten-containing calcium sulfate slag according to claim 1, characterized in that: The tungsten-containing calcium sulfate slag is the slag obtained by leaching scheelite with a mixture of sulfur and phosphorus. The specific process includes: acid leaching reaction in an atmospheric pressure reaction tank, with an acidity of 320-380 g / l, a phosphorus concentration of 5-20 g / l, and a temperature controlled above 90℃. The reaction is stirred for 1.5-3 hours. After the reaction is completed, solid-liquid separation is performed to obtain the tungsten-containing calcium sulfate slag.

3. The method for recovering tungsten from tungsten-containing calcium sulfate slag according to claim 2, characterized in that: The calcium sulfate content in the tungsten-containing calcium sulfate slag is 50-99 wt%, and the tungsten content is 0.6-0.8 wt%, calculated as WO3.

4. The method for recovering tungsten from tungsten-containing calcium sulfate slag according to claim 1, characterized in that: The solid-liquid ratio for slurry preparation in S1 is 1:1 to 3.

5. The method for recovering tungsten from tungsten-containing calcium sulfate slag according to claim 1, characterized in that: The resin adsorption described in S4 uses a macroporous anion exchange resin.

6. The method for recovering tungsten from tungsten-containing calcium sulfate slag according to claim 5, characterized in that: The resin adsorption described in S4 uses macroporous resin D314, and the adsorption flow rate is controlled at 1-3 BV.

7. The method for recovering tungsten from tungsten-containing calcium sulfate slag according to any one of claims 1-6, characterized in that: The desorption described in S5 is performed using sodium hydroxide solution.

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