Preparation method of superfine high-purity tungsten powder

Abstract

The application provides a preparation method of superfine high-purity metal tungsten powder and relates to the technical field of tungsten powder preparation. The tungsten-containing raw material is prepared into tungsten-containing slurry, and then reduction precipitation reaction is carried out, high-reducibility organic acid system and low-temperature hydrothermal decomposition method are used to realize the preparation of superfine high-purity metal tungsten powder, the method is simple in operation, safe and environment-friendly, the product has small particle size, and large-scale industrial production can be easily realized, and the method has good application prospect.

Description

A method for preparing ultrafine high-purity metallic tungsten powder Technical Field

[0001] This invention relates to the field of tungsten powder preparation technology, and in particular to a method for preparing ultrafine high-purity metallic tungsten powder. Background Technology

[0002] Tungsten metal possesses excellent physicochemical properties such as corrosion resistance, high melting point, and high high-temperature strength, making it widely used in aerospace, military, and nuclear power industries. With continuous societal development, the demand for tungsten metal is increasing, consequently placing higher demands on its production methods. Currently, the main methods for producing tungsten powder are as follows:

[0003] (1) Tungsten oxide hydrogen reduction method: Tungsten oxide is reduced by hydrogen in two steps under high temperature conditions to obtain tungsten powder. Although this method is mature, the equipment is simple, and no impurities are introduced, multiple hydrogen reductions are required to fully reduce tungsten oxide, resulting in low production efficiency. (2) Molten salt electrolysis method: Tungsten powder is obtained by electrolyzing Na2WO4 in a molten salt system at around 800℃. Compared with the tungsten oxide hydrogen reduction method, this method shortens the process flow and has strong raw material adaptability, but the electrolysis efficiency is low and it is currently difficult to directly produce industrially. (3) Self-propagating high temperature reduction method: Active metals are used as reducing agents. The heat released by the combustion of the reducing agent itself is used to reduce tungsten oxide or tungstate to obtain tungsten powder. This method is simple, the product purity is high, and it is energy-saving and environmentally friendly. However, the combustion rate and reaction process of the reduction process are difficult to control, and there are still many technical problems in practical applications.

[0004] Chinese patent CN107008920A discloses a method for preparing tungsten powder using reducing organic acids. This method involves adding a reducing organic acid to an ammonium tungstate solution, heating and concentrating the solution to obtain a concentrate, and then calcining the concentrate under a protective atmosphere to obtain tungsten powder. While this method yields a product with high purity, the solution concentration process is time-consuming and energy-intensive, and the calcination process also consumes a large amount of energy, making it unsuitable for large-scale industrial production.

[0005] Therefore, overcoming the above problems and developing a simple, safe, environmentally friendly, and easily industrialized process for preparing ultrafine high-purity tungsten powder is one of the technical issues that needs to be addressed. Summary of the Invention

[0006] To address the above problems, this invention provides a method for preparing ultrafine high-purity tungsten powder. By utilizing a highly reducing organic acid system and a low-temperature hydrothermal decomposition method, ultrafine high-purity metallic tungsten powder is prepared. The method for preparing ultrafine high-purity tungsten powder according to this invention includes the following steps:

[0007] (1) Dissolve the tungsten-containing raw material in deionized water, add oxalic acid and ascorbic acid, mix well and obtain tungsten-containing slurry;

[0008] (2) The tungsten-containing slurry was subjected to a reduction precipitation reaction. After the reaction was completed, the reaction system was cooled to room temperature, filtered, and washed to obtain ultrafine high-purity tungsten powder.

[0009] Furthermore, in step (1), the tungsten-containing raw material is one or more of tungsten oxide, tungstic acid, tungstate, and tungsten-containing minerals.

[0010] Furthermore, the tungsten oxide is WO3, WO2, or WO3. 2.90 WO 2.72 One or more of them.

[0011] Furthermore, the tungstate is one or more of ammonium tungstate, sodium tungstate, and calcium tungstate.

[0012] Furthermore, the tungsten-bearing mineral is one or both of wolframite and scheelite.

[0013] Furthermore, in step (1), the concentration of tungsten ions in the tungsten-containing slurry is 8-25 g / L, the concentration of oxalate is 80-350 g / L, and the concentration of ascorbic acid is 20-150 g / L. The above concentration range is preferred, but the technical solution of the present invention is not limited to the above concentration range.

[0014] Furthermore, in step (2), the reduction precipitation reaction is carried out under stirring conditions.

[0015] Furthermore, the stirring speed is 300–500 r / min.

[0016] Preferably, the stirring speed is 500 r / min.

[0017] Furthermore, in step (2), the reaction temperature of the reduction precipitation reaction is 100℃~220℃, and the reaction time is 30min~180min.

[0018] Preferably, in step (2), the reaction temperature of the reduction precipitation reaction is 140℃~160℃, and the reaction time is 60min~90min.

[0019] Preferably, in step (2), the reaction temperature of the reduction precipitation reaction is 140°C and the reaction time is 60 min.

[0020] Furthermore, in step (2), the precipitation rate of tungsten in the reduction precipitation reaction is ≥99.4%, and the purity of tungsten powder is ≥99%.

[0021] Because the standard electrode potential of tungsten ions is relatively low (E θ (W3+ Because the concentration of tungsten ions in aqueous solution is 0.1V, it is difficult to prepare tungsten powder by directly reducing tungsten ions in aqueous solution. Therefore, this invention introduces an oxalic acid-citric acid reduction system. In this reduction system, as the reaction temperature increases, the C-C bonds in the H₂C₂O₄ molecule break, significantly improving the reducing power of the organic acid reduction system. Furthermore, this invention utilizes hydrothermal decomposition to promote the decomposition of some organic acid molecules and generate reducing gas CO, further enhancing the reducing power of the organic acid reduction system (E). θ (H(C 2 O 4 ) - / CO 2 ()=-0.511V). Finally, this invention utilizes the combination of oxalic acid and organic acid, taking advantage of their synergistic effect to lower the reduction reaction temperature and reduce the reaction pressure.

[0022] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0023] This invention utilizes a highly reducing organic acid system and a low-temperature hydrothermal decomposition method to prepare ultrafine, high-purity metallic tungsten powder. The method is simple to operate, safe and environmentally friendly, produces small-sized products, and is easy to scale up for industrial production, showing promising application prospects. Detailed Implementation

[0024] This invention provides a method for preparing ultrafine high-purity tungsten powder, comprising the following steps:

[0025] (1) Dissolve the tungsten-containing raw material in deionized water, add oxalic acid and ascorbic acid, mix well and obtain tungsten-containing slurry;

[0026] (2) The tungsten-containing slurry was subjected to a reduction precipitation reaction. After the reaction was completed, the reaction system was cooled to room temperature, filtered, and washed to obtain ultrafine high-purity tungsten powder.

[0027] In one embodiment, in step (1), the tungsten-containing raw material is one or more of tungsten oxide, tungstic acid, tungstate, and tungsten-containing minerals.

[0028] In one embodiment, the tungsten oxide is WO3, WO2, or WO3. 2.90 WO 2.72 One or more of them.

[0029] In one embodiment, the tungstate is one or more of ammonium tungstate, sodium tungstate, and calcium tungstate.

[0030] In one embodiment, the tungsten-bearing mineral is one or both of wolframite and scheelite.

[0031] In one embodiment, in step (1), the concentration of tungsten ions in the tungsten-containing slurry is 8-25 g / L, the concentration of oxalate is 80-350 g / L, and the concentration of ascorbic acid is 20-150 g / L.

[0032] In one embodiment, in step (2), the reduction precipitation reaction is carried out under stirring conditions.

[0033] In one embodiment, the stirring speed is 300–500 r / min.

[0034] In one embodiment, the stirring speed is 500 r / min.

[0035] In one embodiment, in step (2), the reaction temperature of the reduction precipitation reaction is 100℃~220℃, and the reaction time is 30min~180min.

[0036] In one embodiment, in step (2), the reaction temperature of the reduction precipitation reaction is 140℃~160℃, and the reaction time is 60min~90min.

[0037] In one embodiment, in step (2), the reaction temperature of the reduction precipitation reaction is 140°C and the reaction time is 60 min.

[0038] In one embodiment, in step (2), the precipitation rate of tungsten in the reduction precipitation reaction is ≥99.8%, and the purity of the tungsten powder is ≥99%.

[0039] The technical solution provided by the present invention will be further described below with reference to the embodiments.

[0040] Example 1

[0041] Preparation of tungsten-containing solution: Dissolve 0.7g ammonium paratungstate in 20mL of deionized water, then add 1.5g ascorbic acid and 4g oxalic acid, mix well to form a slurry, and then add it to a reaction vessel. Set the stirring speed to 500r / min and react at 140℃ for 60min. After the reaction is completed, cool to room temperature, filter and wash to obtain the precipitate.

[0042] ICP testing and calculations showed that the tungsten precipitation rate in the solution was 99.8%. Based on testing and calculations, the purity of the tungsten powder was greater than 99%.

[0043] Example 2

[0044] Preparation of tungsten-containing solution: Dissolve 0.5g of tungsten trioxide in 15mL of deionized water, then add 1.5g of ascorbic acid and 4g of oxalic acid, mix well to form a slurry, and then add it to a reaction vessel. Set the stirring speed to 400r / min and react at 160℃ for 45min. After the reaction is completed, cool to room temperature, filter and wash to obtain the precipitate.

[0045] ICP testing and calculations showed that the tungsten precipitation rate in the solution was 99.4%. Based on testing and calculations, the purity of the tungsten powder was greater than 99%.

[0046] Example 3

[0047] Preparation of tungsten-containing solution: Dissolve 0.8g of tungsten trioxide in 25mL of deionized water, then add 1.5g of ascorbic acid and 4g of oxalic acid, mix well to form a slurry, and then add it to a reaction vessel. Set the stirring speed to 300r / min and react at 160℃ for 90min. After the reaction is completed, cool to room temperature, filter and wash to obtain the precipitate.

[0048] ICP testing and calculations showed that the tungsten precipitation rate in the solution was 99.8%. Based on testing and calculations, the purity of the tungsten powder was greater than 99%.

[0049] Comparative Example 1

[0050] The steps for preparing tungsten powder by hydrothermal decomposition of pure oxalic acid are as follows:

[0051] Add 4g of oxalic acid, 0.8g of ammonium paratungstate, and 25mL of deionized water to a reaction vessel. Set the stirring speed to 300r / min and react at 140℃ for 45min. After the reaction is complete, cool to room temperature, filter, and wash to obtain the precipitate.

[0052] ICP analysis revealed that the tungsten precipitation rate in the solution was only 10.5%.

[0053] Therefore, it can be seen that the technical solution of the present invention can achieve efficient precipitation of tungsten ions under low-temperature hydrothermal conditions.

[0054] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for preparing ultrafine high-purity tungsten powder, characterized in that, The process includes the following steps: (1) dissolving tungsten-containing raw materials in deionized water, adding oxalic acid and ascorbic acid, mixing well to obtain tungsten-containing slurry; (2) subjecting the tungsten-containing slurry to a reduction precipitation reaction, and after the reaction is completed, cooling the reaction system to room temperature, filtering and washing to obtain ultrafine high-purity tungsten powder; in step (2), the reaction temperature of the reduction precipitation reaction is 100℃~220℃, and the reaction time is 30 min~180 min; in step (2), the precipitation rate of tungsten in the reduction precipitation reaction is ≥99.4%, and the purity of tungsten powder is ≥99%.

2. The method for preparing ultrafine high-purity tungsten powder according to claim 1, characterized in that, In step (1), the tungsten-containing raw material is one or more of tungsten oxide, tungstic acid, tungstate, and tungsten-containing minerals.

3. The method for preparing ultrafine high-purity tungsten powder according to claim 2, characterized in that, The tungsten oxide is WO3, WO2, or WO3. 2.90 WO 2.72 One or more of them.

4. The method for preparing ultrafine high-purity tungsten powder according to claim 2, characterized in that, The tungstate is one or more of ammonium tungstate, sodium tungstate, and calcium tungstate.

5. The method for preparing ultrafine high-purity tungsten powder according to claim 2, characterized in that, The tungsten-bearing mineral is one or both of wolframite and scheelite.

6. The method for preparing ultrafine high-purity tungsten powder according to claim 1, characterized in that, In step (1), the concentration of tungsten ions in the tungsten-containing slurry is 8~25 g / L, the concentration of oxalate is 80~350 g / L, and the concentration of ascorbic acid is 20~150 g / L.

7. The method for preparing ultrafine high-purity tungsten powder according to claim 1, characterized in that, In step (2), the reduction precipitation reaction is carried out under stirring conditions.