A method for improving the crystallization rate of ammonia-soluble tungstate

Abstract

This application belongs to the field of hydrometallurgical technology of tungsten, specifically relating to a method for improving the crystallization rate of ammonia-soluble tungstate, comprising the following steps: adding an appropriate amount of water to tungstate and stirring to obtain a first slurry; adding magnesium hydroxide to the first slurry and stirring to obtain a second slurry; the amount of magnesium hydroxide added is 1%~4% of the mass of tungstate; adding the second slurry to ammonia water, reacting and filtering to obtain a filtrate; the filtrate contains ammonium tungstate. By introducing magnesium hydroxide and optimizing its addition ratio and the timing of the addition of magnesium hydroxide and ammonia water, the formation of ammonium metatungstate is effectively reduced, the crystallization rate of ammonia-soluble tungstate is increased, and the purity and yield of ammonium tungstate are improved; the difficulty and cost of subsequent separation and purification processes are reduced, and production efficiency is improved; the adverse effects of ammonium metatungstate on the quality and performance of downstream ammonium tungstate products are reduced, and the overall performance of the final product is improved; the ammonia-soluble tungstate process is optimized, enhancing its adaptability to different production conditions, making the process more stable and reliable.

Description

Technical Field

[0001] This application belongs to the field of hydrometallurgical technology of tungsten, specifically a method for improving the crystallization rate of ammonia-soluble tungstic acid. Background Technology

[0002] In the production of tungstates, ammoniacal dissolution of tungstate is a crucial step, as its crystallization rate directly affects the purity and yield of ammonium tungstate. In traditional ammoniacal dissolution processes, due to the inherent properties of tungsten, excessive formation of ammonium metatungstate often occurs under the absence of other operating conditions. Currently, there is no research on the formation mechanism and treatment methods of ammonium metatungstate during the ammoniacal dissolution process.

[0003] Excessive formation of ammonium metatungstate during ammonia dissolution of tungstate leads to low crystallinity, affecting both purity and yield. Furthermore, this excessive formation increases the difficulty and cost of subsequent separation and purification processes, ultimately impacting the quality and performance of downstream ammonium tungstate products. Therefore, researching a method to suppress ammonium metatungstate formation during ammonia dissolution is crucial. Summary of the Invention

[0004] To address the aforementioned technical problems, this application provides a method for improving the crystallization rate of ammonia-soluble tungstate, which inhibits the formation of ammonium metatungstate in the ammonia-soluble tungstate process, increases the crystallization rate of ammonium tungstate, thereby reducing the difficulty and cost of subsequent separation and purification processes, and improving the quality and performance of downstream ammonium tungstate products.

[0005] The method for improving the crystallization rate of ammonia-soluble tungstate in this application includes the following steps:

[0006] S1. Add an appropriate amount of water to tungstic acid and stir to obtain the first slurry;

[0007] S2. Add magnesium hydroxide to the first slurry and stir to obtain the second slurry; the amount of magnesium hydroxide added is 1% to 4% of the mass of tungstic acid.

[0008] S3. Add the second slurry to ammonia water, react and filter to obtain filtrate; the filtrate contains ammonium tungstate.

[0009] Based on this technical solution, the inventors discovered that determining the proportion and timing of magnesium hydroxide addition during ammonia dissolution of tungstate can improve the crystallization rate of ammonia-dissolved tungstate, which is key to improving the production efficiency and product quality of ammonium tungstate. This technical solution mainly includes two key steps: first, magnesium hydroxide needs to be added to the slurry-like tungstate (i.e., the first slurry); second, the slurry-like tungstate after the addition of magnesium hydroxide (i.e., the second slurry) needs to be added to ammonia water. Because during the process of dissolving tungstic acid with ammonia, the presence of a locally acidic environment in the reaction system easily leads to the formation of ammonium metatungstate. In step S2, adding an alkaline substance to the first slurry can adjust the pH value of the system and create an alkaline environment. Controlling the amount of alkaline substance added can reduce the introduction of impurities while adjusting the pH value. When choosing an alkaline substance, if sodium hydroxide or potassium hydroxide is used, the introduced sodium and potassium ions are difficult to remove. If calcium hydroxide or barium hydroxide is used, it will react with tungstic acid to form corresponding tungstate precipitates, resulting in tungsten loss. Magnesium hydroxide, on the other hand, does not produce precipitation and is easy to remove impurities. In step S3, adding the second slurry to ammonia water, compared to adding ammonia water directly to the second slurry, can better ensure that the mixture of tungstic acid and ammonia water forms a uniform alkaline environment, thereby inhibiting the formation of ammonium metatungstate.

[0010] Furthermore, after step S3, the following steps are also included: crystallizing the filtrate and filtering to obtain a crystallization mother liquor, which contains ammonium metatungstate; the concentration of WO3 in the filtrate is c1, the volume of the filtrate is V1, the concentration of WO3 in the crystallization mother liquor is c2, the volume of the crystallization mother liquor is V2, and the crystallization rate of ammonium tungstate is calculated to be (1-c2V2 / c1V1)×100%.

[0011] As a preferred embodiment of the method for improving the crystallization rate of ammonia-soluble tungstic acid in this application, in step S1, the amount of water added is 20% to 40% of the mass of tungstic acid.

[0012] As a preferred embodiment of the method for improving the crystallization rate of ammonia-soluble tungstic acid in this application, in step S2, the amount of magnesium hydroxide added is 1.5% to 3% of the mass of tungstic acid.

[0013] As a preferred embodiment of the method for improving the crystallization rate of ammonia-soluble tungstic acid in this application, in step S3, the concentration of ammonia water is 4~6 mol / L.

[0014] As a preferred embodiment of the method for improving the crystallization rate of ammonia-soluble tungstic acid in this application, in step S3, the concentration of WO3 in the filtrate is 150~280 g / L.

[0015] As a preferred embodiment of the method for improving the crystallization rate of ammonia-soluble tungstic acid in this application, the reaction time in step S3 is 2 hours.

[0016] As a preferred embodiment of the method for improving the crystallization rate of ammonia-soluble tungstic acid in this application, the reaction temperature in step S3 is room temperature; in some embodiments of this application, better implementation results can also be obtained at a temperature of 80~200℃ and a pressure of 0.6~2MPa.

[0017] As a preferred embodiment of the method for improving the crystallization rate of ammonia-soluble tungstate in this application, the crystallization rate of ammonium tungstate is ≥84%; more preferably, the crystallization rate of ammonium tungstate is ≥91%.

[0018] This application provides a method for improving the crystallization rate of ammonia-soluble tungstate, which has the following beneficial effects: by introducing magnesium hydroxide and optimizing its addition ratio and the timing of the addition of magnesium hydroxide and ammonia, the formation of ammonium metatungstate is effectively reduced, thereby improving the crystallization rate of ammonia-soluble tungstate and improving the purity and yield of ammonium tungstate; by reducing the excessive formation of ammonium metatungstate, the difficulty and cost of subsequent separation and purification processes are reduced, and production efficiency is improved; the adverse effects of ammonium metatungstate on the quality and performance of downstream ammonium tungstate products are reduced, and the overall performance of the final product is improved; the ammonia-soluble tungstate process is optimized, enhancing its adaptability to different production conditions, making the process more stable and reliable. Detailed Implementation

[0019] 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.

[0020] The technical solution proposed in this application includes the following steps:

[0021] S1. Add an appropriate amount of water to tungstic acid and stir to obtain the first slurry;

[0022] In some embodiments of this application, the amount of water added is 20% to 40% of the mass of tungstic acid; specifically, the amount of water added can be any one or any two of 20%, 25%, 30%, 35%, and 40% of the mass of tungstic acid.

[0023] S2. Add magnesium hydroxide to the first slurry and stir to obtain the second slurry; the amount of magnesium hydroxide added is 1% to 4% of the mass of tungstic acid.

[0024] In some preferred embodiments of this application, the amount of magnesium hydroxide added is 1.5% to 3% of the mass of tungstic acid; specifically, the amount of magnesium hydroxide added can be any one or any two of 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, and 4% of the mass of tungstic acid.

[0025] S3. Add the second slurry to ammonia water, react and filter to obtain filtrate; the filtrate contains ammonium tungstate;

[0026] In some embodiments of this application, the concentration of ammonia water is 4~6 mol / L, and after reacting at room temperature for 2 hours, it is filtered, and the concentration of WO3 in the resulting filtrate is 150~280 g / L. Specifically, the concentration of ammonia water can be any one or any two of 4 mol / L, 4.5 mol / L, 5 mol / L, 5.5 mol / L, and 6 mol / L, and the concentration of WO3 in the filtrate can be any one or any two of 150 g / L, 180 g / L, 200 g / L, 220 g / L, 240 g / L, 260 g / L, and 280 g / L.

[0027] After step S3, the filtrate is crystallized, and the resulting mother liquor contains ammonium metatungstate. The crystallization rate of ammonium tungstate is calculated by using the concentration of WO3 in the mother liquor. The calculation method is as follows: the concentration of WO3 in the filtrate is c1, the volume of the filtrate is V1, the concentration of WO3 in the mother liquor is c2, and the volume of the mother liquor is V2. The calculated crystallization rate of ammonium tungstate is (1-c2V2 / c1V1)×100%.

[0028] The technical solution of this application will be further described below with reference to specific embodiments.

[0029] Example 1

[0030] 100 mL of water was added to 500 g of tungstic acid and stirred to obtain the first slurry; 7.5 g of magnesium hydroxide was added to the first slurry and stirred to obtain the second slurry; the second slurry was added to 4 mol / L ammonia water, reacted at room temperature for 2 h, and then filtered to obtain the filtrate, which contained ammonium tungstate.

[0031] In this embodiment, the crystallinity of ammonium tungstate is 91.31%.

[0032] Example 2

[0033] Add 200 mL of water to 500 g of tungstic acid and stir to obtain the first slurry; add 15 g of magnesium hydroxide to the first slurry and stir to obtain the second slurry; add the second slurry to 6 mol / L ammonia water, react at room temperature for 2 h, and then filter to obtain the filtrate, which contains ammonium tungstate.

[0034] In this embodiment, the crystallinity of ammonium tungstate is 92.42%.

[0035] Example 3

[0036] Add 200 mL of water to 500 g of tungstic acid and stir to obtain the first slurry; add 5 g of magnesium hydroxide to the first slurry and stir to obtain the second slurry; add the second slurry to 6 mol / L ammonia water, react at room temperature for 2 h, and then filter to obtain the filtrate, which contains ammonium tungstate.

[0037] In this embodiment, the crystallization rate of ammonium tungstate is 84.67%.

[0038] Example 4

[0039] Add 200 mL of water to 500 g of tungstic acid and stir to obtain the first slurry; add 20 g of magnesium hydroxide to the first slurry and stir to obtain the second slurry; add the second slurry to 6 mol / L ammonia water, react at room temperature for 2 h, and then filter to obtain the filtrate, which contains ammonium tungstate.

[0040] In this embodiment, the crystallinity of ammonium tungstate is 85.62%.

[0041] Example 5

[0042] Add 200 mL of water to 500 g of tungstic acid and stir to obtain the first slurry; add 15 g of magnesium hydroxide to the first slurry and stir to obtain the second slurry; add the second slurry to 6 mol / L ammonia water, react at 100 °C and 0.8 MPa for 2 h, and then filter to obtain the filtrate, which contains ammonium tungstate.

[0043] In this embodiment, the crystallinity of ammonium tungstate is 88.29%.

[0044] Comparative Example 1

[0045] 15g of magnesium hydroxide was added to 500g of tungstic acid and stirred to obtain a solid mixture. The solid mixture was then added to 6mol / L ammonia water and reacted at room temperature for 2 hours. The mixture was then filtered to obtain a filtrate containing ammonium tungstate.

[0046] The difference between this comparative example and Example 2 is that the tungstic acid was not slurried, and the resulting ammonium tungstate crystallization rate was 80.75%, which was significantly lower than that of Example 2.

[0047] Comparative Example 2

[0048] Add 200 mL of water to 500 g of tungstic acid and stir to obtain the first slurry; add the first slurry to 6 mol / L ammonia water to obtain a mixed system; then add 15 g of magnesium hydroxide to the mixed system, react at room temperature for 2 h, and filter to obtain the filtrate, which contains ammonium tungstate.

[0049] The difference between this comparative example and Example 2 is that the tungstic acid after slurry preparation was directly added to ammonia water, and then magnesium hydroxide was added. The resulting ammonium tungstate crystallization rate was 78.38%, which was significantly lower than that of Example 2.

[0050] Comparative Example 3

[0051] Add 200 mL of water to 500 g of tungstic acid and stir to obtain the first slurry; add 15 g of magnesium hydroxide to the first slurry and stir to obtain the second slurry; add 6 mol / L ammonia water to the second slurry, react at room temperature for 2 h, and then filter to obtain the filtrate, which contains ammonium tungstate.

[0052] The difference between this comparative example and Example 2 is that ammonia water was added to the second slurry, and the resulting ammonium tungstate crystallization rate was 81.48%, which was significantly lower than that of Example 2.

[0053] As can be seen from the examples and comparative examples, in the technical solution of this application, by adjusting the timing of the addition of magnesium hydroxide and ammonia, that is, by adding magnesium hydroxide to the tungstic acid slurry to adjust the pH of the slurry, and then adding the tungstic acid slurry after adding magnesium hydroxide to ammonia, a higher crystallization rate of ammonia-soluble tungstic acid can be obtained; by optimizing the addition ratio of magnesium hydroxide, an even higher crystallization rate can be obtained.

[0054] This application provides a method for improving the crystallization rate of ammonia-soluble tungstate, which has the following beneficial effects: by introducing magnesium hydroxide and optimizing its addition ratio and the timing of the addition of magnesium hydroxide and ammonia, the formation of ammonium metatungstate is effectively reduced, thereby improving the crystallization rate of ammonia-soluble tungstate and improving the purity and yield of ammonium tungstate; by reducing the excessive formation of ammonium metatungstate, the difficulty and cost of subsequent separation and purification processes are reduced, and production efficiency is improved; the adverse effects of ammonium metatungstate on the quality and performance of downstream ammonium tungstate products are reduced, and the overall performance of the final product is improved; the ammonia-soluble tungstate process is optimized, enhancing its adaptability to different production conditions, making the process more stable and reliable.

[0055] 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 improving the crystallization rate of ammonia-soluble tungstic acid, characterized in that, Includes the following steps: S1. Add an appropriate amount of water to tungstic acid and stir to obtain the first slurry; S2. Add magnesium hydroxide to the first slurry and stir to obtain a second slurry; the amount of magnesium hydroxide added is 1% to 4% of the mass of the tungstic acid; S3. Add the second slurry to ammonia water, react and filter to obtain filtrate; the filtrate contains ammonium tungstate.

2. The method for improving the crystallization rate of ammonia-soluble tungstic acid according to claim 1, characterized in that, The process further includes, after step S3: crystallizing the filtrate and filtering to obtain a crystallization mother liquor, wherein the crystallization mother liquor contains ammonium metatungstate; the concentration of WO3 in the filtrate is c1, the volume of the filtrate is V1, the concentration of WO3 in the crystallization mother liquor is c2, the volume of the crystallization mother liquor is V2, and the crystallization rate of the ammonium tungstate is calculated to be (1-c2V2 / c1V1)×100%.

3. The method for improving the crystallization rate of ammonia-soluble tungstic acid according to claim 1, characterized in that, In step S1, the amount of water added is 20% to 40% of the mass of the tungstic acid.

4. The method for improving the crystallization rate of ammonia-soluble tungstic acid according to claim 1, characterized in that, In step S2, the amount of magnesium hydroxide added is 1.5% to 3% of the mass of tungstic acid.

5. The method for improving the crystallization rate of ammonia-soluble tungstic acid according to claim 1, characterized in that, In step S3, the concentration of the ammonia water is 4~6 mol / L.

6. The method for improving the crystallization rate of ammonia-soluble tungstic acid according to claim 1, characterized in that, In step S3, the concentration of WO3 in the filtrate is 150~280g / L.

7. The method for improving the crystallization rate of ammonia-soluble tungstic acid according to claim 1, characterized in that, In step S3, the reaction time is 2 hours.

8. The method for improving the crystallization rate of ammonia-soluble tungstic acid according to claim 1, characterized in that, In step S3, the reaction temperature is room temperature.

9. The method for improving the crystallization rate of ammonia-soluble tungstic acid according to claim 1, characterized in that, The crystallinity of the ammonium tungstate is ≥84%.