A method for recovering tungsten from tungsten-containing waste by wet method

Abstract

The present invention relates to a method for wet-process recovery of tungsten from tungsten-containing waste, comprising the following steps: S1, obtaining low-cobalt tungsten-containing waste, wherein the mass content of cobalt in the low-cobalt tungsten-containing waste is ≤1%; S2, mixing the low-cobalt tungsten-containing waste with phosphoric acid and hydrogen peroxide, placing the mixture in a sealed space, and heating the mixture for a first reaction; S3, after the first reaction is completed, depressurizing and venting the sealed space, introducing an oxygen-containing gas, and heating the mixture for a second reaction; S4, after the second reaction is completed, discharging the mixture, performing solid-liquid separation, and collecting the filtrate, which is used to recover tungsten. This method solves the problems of equipment corrosion and severe environmental pollution caused by nitrogen oxides in traditional tungsten waste recovery, while achieving high tungsten recovery efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of tungsten recovery, in particular to a method for recovering tungsten from tungsten-containing waste materials by a wet method. Background Art

[0002] The tungsten smelting industry is a highly technological one, with technological advancements continuing in recent years. The introduction of new melting and precision forging processes has increased the production efficiency of tungsten products and ensured product quality. At the same time, tungsten smelting companies are also researching and developing new materials and processes to improve the environmental friendliness and resource efficiency of tungsten smelting. This primarily involves refining and reprocessing tungsten-containing waste generated during production and processing to fully recover the valuable elements.

[0003] Conventional tungsten-containing waste materials on the market mainly come from soft waste materials such as floor materials, dust collection materials, grinding materials and scrap materials generated during the cemented carbide production process.

[0004] In the existing technology, phosphorus-nitric acid mixed acid or nitric-sulfuric acid mixed acid is used to decompose and recover the tungsten-containing waste. The tungsten-containing waste is directly converted into tungstic acid in the mixed acid, and the tungstic acid is then calcined to obtain tungsten oxide products. However, this method produces a large amount of nitrogen oxides during the nitric acid digestion process, which seriously pollutes the environment. At the same time, nitric acid and sulfuric acid are high-concentration strong acids, which are highly corrosive to equipment and have higher requirements for equipment operation.

[0005] For example, patent application CN115386733A discloses a method for recovering tungsten-containing waste by decomposing it using a nitric-sulfuric acid mixed acid solution. The method comprises: S1: adding the tungsten-containing waste to a mixed solution of sulfuric acid and nitric acid and stirring to obtain a solid-liquid mixture; S2: subjecting the solid-liquid mixture obtained in S1 to a stirring leaching reaction at a certain temperature for a period of time. After the reaction is complete, solid-liquid separation is performed, resulting in tungstic acid as the solid phase and a cobalt salt solution as the liquid phase; S3: calcining the solid-phase tungstic acid obtained in S2 to obtain a tungsten oxide product. This method uses a nitric-sulfuric acid mixed acid solution, which poses environmental pollution issues. Summary of the Invention

[0006] The purpose of the present invention is to overcome the environmental pollution problems caused by the existing wet process for recovering tungsten waste and to provide a method for recovering tungsten from tungsten-containing waste by wet method. The method reduces the requirements for equipment used and can ensure a high tungsten leaching rate, thereby having good economic benefits.

[0007] The specific plan is as follows:

[0008] A method for wet recovery of tungsten from tungsten-containing waste comprises the following steps:

[0009] S1: obtaining low-cobalt tungsten-containing waste, wherein the mass content of cobalt in the low-cobalt tungsten-containing waste is ≤1%;

[0010] S2: mixing the low-cobalt tungsten-containing waste with phosphoric acid and hydrogen peroxide, placing the mixture in a sealed space, and heating the mixture to perform a first reaction;

[0011] S3 After the first reaction is completed, the sealed space is depressurized and vented, and oxygen-containing gas is introduced and heated to perform a second reaction;

[0012] S4 After the second reaction is completed, the material is discharged and solid-liquid separation is performed, and the filtrate is collected, and the filtrate is used to recover tungsten.

[0013] Furthermore, the tungsten-containing waste in S1 is derived from floor materials, dust collection materials, grinding materials and waste materials generated in the cemented carbide production process. The tungsten-containing waste is dissolved and filtered by an acid method, and the solid phase is taken to obtain the low-cobalt tungsten-containing waste, wherein the tungsten mass content is 40% to 98% and the carbon mass content is 1 to 6%;

[0014] Preferably, the low-cobalt tungsten-containing waste has a tungsten content of 80% to 98% by mass, a cobalt content of 0.01-1% by mass, and a carbon content of 1 to 6% by mass;

[0015] Preferably, the low-cobalt tungsten-containing waste also contains impurity elements, including at least one of Fe, Cu, Ni, Ta, Ti, Nb, Cr, V, and SiO2.

[0016] Furthermore, the concentration of the phosphoric acid in S2 is 0.5-1.5 mol / L, preferably 0.8-1.3 mol / L; the concentration of the hydrogen peroxide is 3-5 mol / L, preferably 3.5-4.5 mol / L.

[0017] Furthermore, the low-cobalt tungsten-containing waste in S2 is mixed with phosphoric acid and hydrogen peroxide in a solid-liquid ratio of 1:3 to 1:5, preferably 1:3.5 to 1:4.5.

[0018] Furthermore, the temperature of the first reaction in S2 is 100-120° C., preferably 105-115° C.; and the reaction time is 1-2 hours.

[0019] Furthermore, the pressure relief and exhaust in S3 is to reduce the pressure in the reaction system to a pressure of ≤0.05 MPa, preferably 0.01-0.04 MPa, and then introduce the oxygen-containing gas.

[0020] Furthermore, the oxygen-containing gas in S3 is oxygen, and the pressure of oxygen in the reaction system is 0.8~1.1Mpa.

[0021] Furthermore, the temperature of the second reaction in S3 is 130-150° C., preferably 135-145° C.; and the reaction time is 2-4 hours.

[0022] Furthermore, solid-liquid separation is performed, and the mass content of tungsten in the obtained filter residue is ≤2.76%.

[0023] Furthermore, the leaching rate of tungsten in S4 is greater than or equal to 98%.

[0024] Beneficial Effects: The method provided by this invention uses an acidic method to dissolve most of the binder phase (cobalt) from conventional commercially available tungsten-containing waste, obtaining low-cobalt tungsten-containing waste. This is then wet-leached using a combination of phosphoric acid, hydrogen peroxide, and oxygen to obtain a tungsten-containing solution, thereby recovering tungsten from the tungsten-containing waste. This method avoids the use of corrosive strong acids such as sulfuric acid and nitric acid, requires minimal equipment, and addresses the environmental pollution issues associated with traditional recovery methods.

[0025] In the present invention, low-cobalt tungsten-containing waste is reacted with tungsten, carbon, etc. at a certain temperature and in a phosphoric acid medium by utilizing the complexing property of phosphoric acid and the oxidizing property of hydrogen peroxide to generate compounds such as phosphotungstic heteropoly acid and carbon dioxide. As the reaction proceeds, carbon dioxide gradually escapes, and the carbon dioxide partial pressure of the system begins to increase. Simultaneously, due to the consumption and partial decomposition of hydrogen peroxide, the liquid-phase oxidant decreases, and the reaction rate is greatly slowed down. At this time, the gas is exhausted and the pressure is released to discharge the carbon dioxide in the system, thereby reducing the concentration of the product in the system. Thereafter, the temperature is increased and oxygen is introduced to supplement the oxidant. Under certain temperature and pressure conditions, the reaction is promoted to continue, thereby improving the completeness of the reaction, enabling tungsten to be converted into phosphotungstic heteropoly acid to a maximum extent, and achieving a high tungsten recovery rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings. Obviously, the drawings described below only relate to some embodiments of the present invention, but are not intended to limit the present invention.

[0027] Figure 1 This is a process flow chart provided by Example 1 of the present invention. DETAILED DESCRIPTION

[0028] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be realized in various forms and should not be limited by the embodiments set forth herein. In the examples, if specific techniques or conditions are not indicated, the techniques or conditions described in the literature in this area or the product specifications are carried out. Reagents used or instruments that are not indicated by manufacturers are conventional products that can be obtained commercially. In the following examples, if not clearly stated, "%" refers to percentage by weight.

[0029] The tungsten-containing scrap used in the following examples is derived from soft scrap such as flooring, dust collection, grinding stock, and scrap generated during cemented carbide production. Specifically, these scraps are subjected to an acidic method to dissolve most of the binder phase (cobalt). For example, a mixture of 1 mol / L phosphoric acid and 2 mol / L hydrogen peroxide is reacted at room temperature for 6-8 hours in a ratio of 5:1:1 (V:phosphoric acid):V:hydrogen peroxide); m:waste material. The resulting tungsten-containing scrap is used for treatment. This tungsten-containing scrap contains 40% to 98% tungsten by weight, 1-6% carbon by weight, and 0-1% cobalt by weight. It also contains small amounts of other impurities such as Fe, Cu, Ni, Ta, Ti, Nb, Cr, V, and SiO2.

[0030] In the following examples, tungsten content was analyzed by drying and weighing the slag. The tungsten content in the slag was determined by a chemical method according to GB / T 143521-2010, Chemical Analysis Methods for Tungsten Ores and Molybdenum Ores - Part 1, Determination of Tungsten Content. The tungsten content in the residual slag was calculated as: tungsten content / slag weight. The tungsten leaching rate was calculated as: (1 - (leached slag volume * residual slag tungsten content / corresponding raw material volume * raw material tungsten content)) * 100%.

[0031] Example 1:

[0032] A method for wet recovery of tungsten from tungsten-containing waste, referring to Figure 1 , comprising the following steps: S1 obtaining low-cobalt tungsten-containing waste, wherein the mass content of cobalt in the low-cobalt tungsten-containing waste is ≤1%; S2 mixing the low-cobalt tungsten-containing waste with phosphoric acid and hydrogen peroxide, placing the mixture in a sealed space, and heating the mixture for a first reaction; S3 after the first reaction is completed, depressurizing and exhausting the sealed space, introducing oxygen-containing gas, and heating the mixture for a second reaction; S4 after the second reaction is completed, discharging the material and performing solid-liquid separation, collecting the filtrate, and the filtrate is used to recover tungsten.

[0033] Specifically, 300g of tungsten-containing waste (79% tungsten by mass, 1% cobalt by mass, and 6% carbon by mass) was added to 0.9L of a mixed solution of 0.5mol / L phosphoric acid and 3mol / L hydrogen peroxide. The solid-liquid mixture was placed in a 2L autoclave, heated to 100°C, and allowed to react for 1 hour. The pressure was then relieved and vented to a pressure of ≤0.05Mpa, then the temperature was raised to 130°C. Oxygen was introduced at an oxygen pressure of 0.8Mpa. The reaction continued for 3 hours before the material was discharged, the solid-liquid separation was performed, the residue was dried, weighed, and analyzed for residual tungsten content. The residual residue contained 2.76% tungsten, and the tungsten leaching rate was 98.95%.

[0034] Example 2:

[0035] Take 300g of tungsten-containing waste (tungsten mass content of 98%, cobalt mass content of 0.1%, carbon mass content of 1%) and add it to 1.5L of a mixed solution of 1.5mol / L phosphoric acid and 5mol / L hydrogen peroxide. The solid-liquid mixture is placed in a 2L autoclave and heated to 120°C. After reacting for 2 hours, the pressure is released and vented to a pressure of ≤0.05Mpa. The temperature is then raised to 150°C and oxygen is introduced at an oxygen pressure of 1.1Mpa. The reaction is continued for 4 hours before discharging the material, separating the solid and liquid. The residue is dried, weighed, and analyzed for residual tungsten content. The residual residue contains 1.76% tungsten and the tungsten leaching rate is 99.63%.

[0036] Example 3:

[0037] 300g of tungsten-containing waste (tungsten mass content of 69%, cobalt mass content of 0.7%, carbon mass content of 3.8%) was added to a 1.2L mixed solution of 1mol / L phosphoric acid and 4mol / L hydrogen peroxide. The solid-liquid mixture was placed in a 2L autoclave, heated to 110°C, and reacted for 1.5 hours. After decompression and exhaust to a pressure of ≤0.05Mpa, the temperature was raised to 140°C and oxygen was introduced at an oxygen pressure of 1Mpa. The reaction continued for 2 hours before discharging the material, separating the solid and liquid, drying the residue, weighing it, and analyzing the residual tungsten content. The residual residue contained 2.41% tungsten and the tungsten leaching rate was 99.16%.

[0038] Example 4:

[0039] 300g of tungsten-containing waste (40% tungsten by mass, 0.9% cobalt by mass, and 1.6% carbon by mass) was added to a 1.2L mixed solution of 1.5mol / L phosphoric acid and 5mol / L hydrogen peroxide. The solid-liquid mixture was placed in a 2L autoclave, heated to 120°C, and allowed to react for 2 hours. The pressure was then released and vented to a pressure of ≤0.05Mpa. The temperature was then raised to 150°C, and oxygen was introduced at a pressure of 0.9Mpa. The reaction continued for 4 hours before the material was discharged, the solid-liquid separation was performed, the residue was dried, weighed, and analyzed for residual tungsten content. The residual residue contained 1.68% tungsten, and the tungsten leaching rate was 98.86%.

[0040] Example 5:

[0041] 300g of tungsten-containing waste (59% tungsten by mass, 0.9% cobalt by mass, and 2.4% carbon by mass) was added to a 1L mixed solution of 0.5mol / L phosphoric acid and 3mol / L hydrogen peroxide. The solid-liquid mixture was placed in a 2L autoclave and heated to 100°C. After reacting for 1 hour, the pressure was relieved and vented to a pressure of ≤0.05Mpa. The temperature was then raised to 130°C, and oxygen was introduced at an oxygen pressure of 0.8Mpa. The reaction continued for 3 hours before the material was discharged, the solid-liquid separation was performed, the residue was dried, weighed, and analyzed for residual tungsten content. The residual residue contained 2.92% tungsten, and the tungsten leaching rate was 98.18%.

[0042] Comparative Example 1:

[0043] 300g of tungsten-containing waste (79% tungsten by weight, 1% cobalt by weight, and 6% carbon by weight) was added to a 1.5L mixture of 1.5mol / L phosphoric acid and 5mol / L hydrogen peroxide. The solid-liquid mixture was placed in a 2L autoclave and heated to 100°C for one hour. The mixture was then heated to 130°C without depressurization and oxygen was introduced at 0.8MPa for another three hours. The mixture was then discharged, the solid and liquid separated, and the residue dried, weighed, and analyzed for residual tungsten content. The residue contained 15.69% tungsten, with a tungsten leaching rate of 90.38%.

[0044] Comparative Example 2:

[0045] 300g of tungsten-containing waste (79% tungsten by mass, 1% cobalt by mass, and 6% carbon by mass) was added to a 1.5L mixed solution of 1.5mol / L phosphoric acid and 5mol / L hydrogen peroxide. The solid-liquid mixture was placed in a 2L autoclave, heated to 100°C, and allowed to react for 1 hour. The pressure was then released and vented to a pressure of ≤0.05Mpa, then the temperature was raised to 130°C without introducing oxygen. The reaction was continued for 3 hours, and the material was discharged. The solid and liquid were separated, and the residue was dried, weighed, and analyzed for residual tungsten content. The residual residue contained 25.91% tungsten, and the tungsten leaching rate was 86.88%.

[0046] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within 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 scope of protection of the present invention.

[0047] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. To avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0048] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for recovering tungsten from tungsten-containing waste by wet method, characterized in that: The following steps are involved: S1: obtaining low-cobalt tungsten-containing waste, wherein the mass content of cobalt in the low-cobalt tungsten-containing waste is ≤1%; S2: mixing the low-cobalt tungsten-containing waste with phosphoric acid and hydrogen peroxide, placing the mixture in a sealed space, and heating the mixture to perform a first reaction; S3: After the first reaction is completed, the sealed space is depressurized and vented, and oxygen-containing gas is introduced, and heating is performed to carry out a second reaction; S4 After the second reaction is completed, the material is discharged and solid-liquid separation is performed, and the filtrate is collected, and the filtrate is used to recover tungsten.

2. The method for wet recovery of tungsten from tungsten-containing waste according to claim 1, characterized in that: The tungsten-containing waste in S1 comes from floor materials, dust collection materials, and grinding materials generated in the cemented carbide production process. The tungsten-containing waste is dissolved and filtered by an acid method, and the solid phase is taken to obtain the low-cobalt tungsten-containing waste, in which the tungsten mass content is 40% to 98% and the carbon mass content is 1 to 6%.

3. The method for wet recovery of tungsten from tungsten-containing waste according to claim 2, characterized in that: The low-cobalt tungsten-containing waste has a tungsten content of 80% to 98% by mass, a cobalt content of 0.01-1% by mass, and a carbon content of 1-6% by mass.

4. The method for wet recovery of tungsten from tungsten-containing waste according to claim 2, characterized in that: The low-cobalt tungsten-containing waste also contains impurity elements, and the impurity elements include at least one of Fe, Cu, Ni, Ta, Ti, Nb, Cr, and V.

5. The method for wet recovery of tungsten from tungsten-containing waste according to claim 2, characterized in that: The concentration of phosphoric acid in S2 is 0.5-1.5 mol / L; the concentration of hydrogen peroxide is 3-5 mol / L.

6. The method for wet recovery of tungsten from tungsten-containing waste according to claim 5, characterized in that: The concentration of phosphoric acid in S2 is 0.8-1.3 mol / L.

7. The method for wet recovery of tungsten from tungsten-containing waste according to claim 5, characterized in that: The concentration of hydrogen peroxide in S2 is 3.5~4.5 mol / L.

8. The method for wet recovery of tungsten from tungsten-containing waste according to claim 5, characterized in that: The low-cobalt tungsten-containing waste described in S2 is mixed with phosphoric acid and hydrogen peroxide at a solid-liquid ratio of 1:3 to 1:

5.

9. The method for wet recovery of tungsten from tungsten-containing waste according to claim 8, characterized in that: The low-cobalt tungsten-containing waste described in S2 is mixed with phosphoric acid and hydrogen peroxide at a solid-liquid ratio of 1:3.5 to 1:4.

5.

10. The method for wet recovery of tungsten from tungsten-containing waste according to any one of claims 1 to 9, characterized in that: The temperature of the first reaction in S2 is 100-120° C.; and the reaction time is 1-2 hours.

11. The method for wet recovery of tungsten from tungsten-containing waste according to claim 10, characterized in that: The temperature of the first reaction in S2 is 105-115°C.

12. The method for wet recovery of tungsten from tungsten-containing waste according to claim 10, characterized in that: The pressure relief and exhaust in S3 is to reduce the pressure in the reaction system to a pressure of ≤0.05 MPa, and then introduce oxygen-containing gas.

13. The method for wet recovery of tungsten from tungsten-containing waste according to claim 12, characterized in that: The pressure relief and exhaust in S3 is to reduce the pressure in the reaction system to a pressure of 0.01-0.04 MPa, and then introduce oxygen-containing gas.

14. The method for wet recovery of tungsten from tungsten-containing waste according to claim 12, characterized in that: The oxygen-containing gas in S3 is oxygen, and the pressure of oxygen in the reaction system is 0.8-1.1 MPa.

15. The method for wet recovery of tungsten from tungsten-containing waste according to any one of claims 12 to 14, characterized in that: The temperature of the second reaction in S3 is 130-150° C.; and the reaction time is 2-4 hours.

16. The method for wet recovery of tungsten from tungsten-containing waste according to claim 15, characterized in that: The temperature of the second reaction in S3 is 135-145°C.

17. The method for wet recovery of tungsten from tungsten-containing waste according to claim 15, characterized in that: Solid-liquid separation is performed in S4, and the mass content of tungsten in the obtained filter residue is ≤2.76%.

18. The method for wet recovery of tungsten from tungsten-containing waste according to claim 15, characterized in that: The leaching rate of tungsten in S4 is greater than or equal to 98%.

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