Method for preparing ultra-coarse tungsten carbide powder by doping sodium

Abstract

The invention belongs to the technical field of powder metallurgy, and particularly relates to a method for preparing ultra-coarse tungsten carbide powder by doping sodium, which adopts sodium ions in waste liquid obtained by washing tungstic acid to realize uniform distribution of sodium element in the preparation process of tungstic acid, and ensures that no new impurity is added in the process by controlling the related proportion, and also can ensure the uniformity of the sodium element and the yield of the ultra-coarse tungsten carbide powder. The content of sodium in the product can be controlled, and meanwhile, the discharge of waste liquid is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of powder metallurgy, and in particular relates to a method for preparing ultra-coarse tungsten carbide powder by doping with sodium. Background Art

[0002] Ultra-coarse cemented carbide generally refers to WC-based cemented carbide with an average WC grain size greater than 6μm, and the grain size of WC is closely related to the performance of cemented carbide. Ultra-coarse cemented carbide often has the advantages of high thermal conductivity and good toughness. The traditional method of preparing ultra-coarse tungsten powder is to add alkali metal to tungsten trioxide, prepare coarse-grained tungsten powder after hydrogen reduction, obtain coarse-grained WC powder through high-temperature carbonization, and then prepare coarse-grained cemented carbide through wet grinding, forming, and sintering processes. However, this method belongs to liquid-solid doping, and when sintering to tungsten powder, it is easy for tungsten powder to grow abnormally, resulting in uneven grain size.

[0003] In the prior art, the Chinese patent application with publication number CN102219261A mentioned a sodium doping process in the crystallization process of ammonium tungstate solution, but the process is relatively complicated, involving steps such as adjusting ammonia, raising the sodium carbonate concentration, and soaking, and only for sodium carbonate. The Chinese patent application with publication number CN104445416A is improved on the basis of the above patent, and the scheme limited to sodium carbonate is expanded to most sodium salts. However, this method is also improved on the basis of ammonium paratungstate, and it is also necessary to control in the evaporation crystallization step to ensure the crystallization rate. Therefore, it is necessary to provide a new method for preparing ultra-coarse tungsten carbide powder. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the main purpose of the present invention is to provide a method for preparing ultra-coarse tungsten carbide powder by doping with sodium.

[0005] To solve the above technical problems, according to one aspect of the present invention, the present invention provides the following technical solutions:

[0006] A method for preparing ultra-coarse tungsten carbide powder by doping with sodium comprises the following steps:

[0007] S1. Add water to the waste liquid obtained by washing with tungstic acid to obtain a mixed waste liquid;

[0008] S2, adding sodium tungstate solution to the mixed waste liquid for reaction, filtering to obtain tungstic acid and filtrate;

[0009] S3, washing the tungstic acid with an acid solution, and then rinsing with pure water to obtain a waste liquid and washed tungstic acid, and the waste liquid is returned to step S1 for recycling;

[0010] S4, tungstate ammonia solution is evaporated and crystallized to obtain APT, APT is calcined to obtain ultra-coarse tungsten powder, and then high-temperature carbonization is performed to obtain ultra-coarse tungsten carbide powder.

[0011] As a preferred embodiment of the method for preparing ultra-coarse tungsten carbide powder by doping with sodium described in the present invention, wherein: in the step S1, the acid concentration of the waste liquid is 8-16wt%.

[0012] As a preferred embodiment of the method for preparing ultra-coarse tungsten carbide powder by doping with sodium described in the present invention, wherein: in the step S1, the sodium ion content of the waste liquid is 300-700 ppm.

[0013] As a preferred embodiment of the method for preparing ultra-coarse tungsten carbide powder by doping with sodium described in the present invention, wherein: in the step S1, the volume ratio of the waste liquid to water is 1:(0.5-5).

[0014] As a preferred embodiment of the method for preparing ultra-coarse tungsten carbide powder by doping sodium described in the present invention, wherein: in the step S2, the volume ratio of the mixed waste liquid and the sodium tungstate solution is (2-4):1.

[0015] As a preferred embodiment of the method for preparing ultra-coarse tungsten carbide powder by doping with sodium described in the present invention, wherein: in the step S2, the concentration of the sodium tungstate solution is 200-300 g / L, calculated as tungsten trioxide.

[0016] As a preferred embodiment of the method for preparing ultra-coarse tungsten carbide powder by doping with sodium described in the present invention, in step S3, the concentration of the acid solution is 10-20wt%, and the liquid-to-solid ratio of the acid solution to tungstic acid is (2-4) mL:1g.

[0017] As a preferred embodiment of the method for preparing ultra-coarse tungsten carbide powder by doping with sodium described in the present invention, in the step S3, the tungstic acid is washed with acid solution for 1 hour and then rinsed with pure water.

[0018] As a preferred embodiment of the method for preparing ultra-coarse tungsten carbide powder by doping with sodium described in the present invention, wherein: in the step S3, the acid concentration of the waste liquid is 8-16wt%.

[0019] As a preferred embodiment of the method for preparing ultra-coarse tungsten carbide powder by doping with sodium described in the present invention, in step S4, the average particle size of the ultra-coarse tungsten carbide powder is 25-28 μm.

[0020] The beneficial effects of the present invention are as follows:

[0021] The present invention provides a method for preparing ultra-coarse tungsten carbide powder by doping with sodium, wherein sodium ions in waste liquid obtained by washing with tungstic acid are used to achieve uniform distribution of sodium elements in the process of preparing tungstic acid, and by controlling relevant proportions, it is ensured that the process does not add new impurities, and the uniformity of sodium elements can be ensured, and the sodium content in the product can be controlled, while reducing the discharge of waste liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0023] Figure 1 The present invention is a schematic flow chart of the method for preparing ultra-coarse tungsten carbide powder by doping with sodium.

[0024] Figure 2 This is an electron microscope image of the ultra-coarse tungsten carbide powder prepared in Example 1 of the present invention.

[0025] Figure 3 This is an electron microscope image of the ultra-coarse tungsten carbide powder prepared in Example 2 of the present invention.

[0026] Figure 4 This is an electron microscope image of the ultra-coarse tungsten carbide powder prepared in Comparative Example 1 of the present invention.

[0027] Figure 5 This is an electron microscope image of the ultra-coarse tungsten carbide powder prepared in Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0028] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] According to one aspect of the present invention, the present invention provides the following technical solution:

[0030] like Figure 1 As shown, a method for preparing ultra-coarse tungsten carbide powder by doping with sodium comprises the following steps:

[0031] S1. Add water to the waste liquid obtained by washing with tungstic acid to obtain a mixed waste liquid;

[0032] S2, adding sodium tungstate solution to the mixed waste liquid for reaction, filtering to obtain tungstic acid and filtrate, and centrally treating the filtrate;

[0033] S3, washing the tungstic acid with an acid solution, and then rinsing with pure water to obtain a waste liquid and washed tungstic acid, and the waste liquid is returned to step S1 for recycling;

[0034] S4, tungstate ammonia solution is evaporated and crystallized to obtain APT, APT is calcined to obtain ultra-coarse tungsten powder, and then high-temperature carbonization is performed to obtain ultra-coarse tungsten carbide powder.

[0035] The main components of the washing waste liquid after preparing tungstic acid are washed sodium ions (300-700ppm), potassium ions, cobalt ions, and vanadium ions (these three ion components are not in the same dimension as sodium ions); the acid concentration is 8-16wt%. Tungstic acid is repeatedly prepared with this waste liquid, so that sodium doping is uniform, and then ultra-coarse tungsten powder and ultra-coarse tungsten carbide powder with uniform sodium doping are prepared.

[0036] Preferably, in step S1, the acid concentration of the waste liquid is 8-16wt%. Specifically, the acid concentration of the waste liquid can be, for example, any one of 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt% or a range between any two thereof.

[0037] Preferably, in step S1, the sodium ion content of the waste liquid is 300-700 ppm. Specifically, the sodium ion content of the waste liquid can be, for example, any one of 300 ppm, 350 ppm, 400 ppm, 450 ppm, 500 ppm, 550 ppm, 600 ppm, 650 ppm, 700 ppm or any range between two thereof.

[0038] Preferably, in step S1, the volume ratio of the waste liquid to water is 1:(0.5-5). Specifically, the volume ratio of the waste liquid to water can be, for example, any one of 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5 or a range between any two thereof.

[0039] Preferably, in step S2, the volume ratio of the mixed waste liquid to the sodium tungstate solution is (2-4): 1. Specifically, the volume ratio of the mixed waste liquid to the sodium tungstate solution can be, for example, any one of 2: 1, 2.5: 1, 3: 1, 3.5: 1, 4: 1, or a range between any two thereof.

[0040] Preferably, in step S2, the concentration of the sodium tungstate solution is 200-300 g / L in terms of tungsten trioxide.

[0041] Preferably, in step S3, the concentration of the acid solution is 10-20wt%, and the liquid-solid ratio of the acid solution to tungstic acid is (2-4)mL:1g. By controlling the amount of acid solution used for washing tungstic acid, it is ensured that the waste liquid used to prepare tungstic acid after washing is sufficient, and the sodium in the prepared tungsten carbide powder is neither too little to cause insufficient grain growth, nor too much to cause high sodium in the prepared tungstic acid and enrichment. Specifically, the acid solution is hydrochloric acid, and the concentration of the acid solution can be, for example, any one of 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt%, or a range between any two of them.

[0042] Preferably, in step S3, the tungstic acid is washed with acid solution for 1 hour and then rinsed with pure water.

[0043] Preferably, in step S3, the acid concentration of the waste liquid is 8-16wt%. Specifically, the acid concentration of the waste liquid can be, for example, any one of 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt% or a range between any two thereof.

[0044] Preferably, in step S4, the average particle size of the ultra-coarse tungsten carbide powder is 25-28 μm.

[0045] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0046] Example 1

[0047] A method for preparing ultra-coarse tungsten carbide powder by doping with sodium comprises the following steps:

[0048] S1, mixing 360 mL of waste liquid obtained by washing with tungstic acid having an acid concentration of 16 wt% and a sodium ion content of 651 ppm with 440 mL of water to obtain a mixed waste liquid;

[0049] S2, adding 400mL of sodium tungstate solution with a concentration of 250g / L in terms of tungsten trioxide to the mixed waste liquid for reaction, and obtaining 142g of tungstic acid and filtrate after filtration, and the filtrate is centrally processed;

[0050] S3, tungstic acid is washed with 560mL of 10wt% hydrochloric acid for 1h, and then rinsed with pure water to obtain waste liquid and washed tungstic acid, and the waste liquid is returned to step S1 for recycling;

[0051] S4, tungstic acid ammonia solution evaporates and crystallizes to obtain APT, APT is calcined to obtain ultra-coarse tungsten powder, and then high-temperature carbonization is performed to obtain ultra-coarse tungsten carbide powder, such as Figure 2 As shown, the average particle size of the ultra-coarse tungsten carbide powder is 26.5 μm.

[0052] Example 2

[0053] A method for preparing ultra-coarse tungsten carbide powder by doping with sodium comprises the following steps:

[0054] S1, mixing 500 mL of waste liquid obtained by washing with tungstic acid having an acid concentration of 12 wt% and a sodium ion content of 423 ppm with 250 mL of water to obtain a mixed waste liquid;

[0055] S2, adding 200mL of sodium tungstate solution with a concentration of 300g / L in terms of tungsten trioxide to the mixed waste liquid for reaction, and obtaining 65g of tungstic acid and filtrate after filtration, and the filtrate is centrally processed;

[0056] S3, tungstic acid is washed with 200 mL of 20 wt% hydrochloric acid for 1 hour, and then rinsed with pure water to obtain waste liquid and washed tungstic acid, and the waste liquid is returned to step S1 for recycling;

[0057] S4, tungstic acid ammonia solution evaporates and crystallizes to obtain APT, APT is calcined to obtain ultra-coarse tungsten powder, and then high-temperature carbonization is performed to obtain ultra-coarse tungsten carbide powder, such as Figure 3 As shown, the average particle size of the ultra-coarse tungsten carbide powder is 27.2 μm.

[0058] Example 3

[0059] A method for preparing ultra-coarse tungsten carbide powder by doping with sodium comprises the following steps:

[0060] S1, mixing 500 mL of waste liquid obtained by washing with tungstic acid having an acid concentration of 8 wt% and a sodium ion content of 358 ppm with 100 mL of water to obtain a mixed waste liquid;

[0061] S2, adding 150mL of sodium tungstate solution with a concentration of 200g / L in terms of tungsten trioxide to the mixed waste liquid for reaction, and obtaining 33g of tungstic acid and filtrate after filtration, and the filtrate is centrally processed;

[0062] S3, tungstic acid is washed with 120mL of 15wt% hydrochloric acid for 1h, and then rinsed with pure water to obtain waste liquid and washed tungstic acid, and the waste liquid is returned to step S1 for recycling;

[0063] S4, evaporating and crystallizing the tungstic acid ammonia solution to obtain APT, calcining the APT to obtain ultra-coarse tungsten powder, and then carbonizing it at high temperature to obtain ultra-coarse tungsten carbide powder, wherein the average particle size of the ultra-coarse tungsten carbide powder is 27.8 μm.

[0064] Comparative Example 1

[0065] The difference from Example 1 is that the acid concentration of the waste liquid in step S1 is 4wt% and the sodium ion content is 208ppm, and the waste liquid comes from: tungstic acid is washed with 700mL of 10wt% hydrochloric acid for 1h, and then rinsed with pure water to obtain the waste liquid.

[0066] The tungsten carbide powder obtained in this comparative example is as follows Figure 4 As shown, the average particle size of the tungsten carbide powder is 16.4 μm. Too much acid solution is used when washing tungstic acid, resulting in a low sodium ion content in the waste liquid, which is insufficient to support the preparation of ultra-coarse tungsten carbide powder by adding sodium.

[0067] Comparative Example 2

[0068] The difference from Example 1 is that in step S2, 800 mL of a sodium tungstate solution having a concentration of 250 g / L in terms of tungsten trioxide is added to the mixed waste liquid for reaction, and 215 g of tungstic acid and a filtrate are obtained after filtration, and the filtrate is centrally processed;

[0069] The tungsten carbide powder obtained in this comparative example is as follows Figure 5 As shown, the average particle size of the tungsten carbide powder is 13.6 μm, less waste liquid is used in the acid dissolution of sodium tungstate, and the sodium ion content in the acid dissolution process is insufficient to support the preparation of ultra-coarse tungsten carbide powder by adding sodium.

[0070] The present invention uses sodium ions in the waste liquid obtained by washing with tungstic acid to achieve uniform distribution of sodium elements in the process of preparing tungstic acid, and controls the relevant proportions to ensure that the process does not add new impurities, while ensuring the uniformity of the sodium element, and can also control the sodium content in the product, while reducing the discharge of waste liquid.

[0071] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for preparing ultra-coarse tungsten carbide powder by doping with sodium, characterized in that: The steps include: S1. Add water to the waste liquid obtained by washing with tungstic acid to obtain a mixed waste liquid; S2, adding sodium tungstate solution to the mixed waste liquid for reaction, filtering to obtain tungstic acid and filtrate; S3, washing the tungstic acid with an acid solution, and then rinsing with pure water to obtain a waste liquid and washed tungstic acid, and the waste liquid is returned to step S1 for recycling; S4, tungstate ammonia solution is evaporated and crystallized to obtain APT, APT is calcined to obtain ultra-coarse tungsten powder, and then high-temperature carbonization is performed to obtain ultra-coarse tungsten carbide powder.

2. The method for preparing ultra-coarse tungsten carbide powder by doping with sodium according to claim 1, characterized in that: In step S1, the acid concentration of the waste liquid is 8-16 wt%.

3. The method for preparing ultra-coarse tungsten carbide powder by doping with sodium according to claim 1, characterized in that: In step S1, the sodium ion content of the waste liquid is 300-700 ppm.

4. The method for preparing ultra-coarse tungsten carbide powder by doping with sodium according to claim 1, characterized in that: In step S1, the volume ratio of the waste liquid to water is 1:(0.5-5).

5. The method for preparing ultra-coarse tungsten carbide powder by doping with sodium according to claim 1, characterized in that: In step S2, the volume ratio of the mixed waste liquid to the sodium tungstate solution is (2-4):

1.

6. The method for preparing ultra-coarse tungsten carbide powder by doping with sodium according to claim 1, characterized in that: In step S2, the concentration of the sodium tungstate solution is 200-300 g / L in terms of tungsten trioxide.

7. The method for preparing ultra-coarse tungsten carbide powder by doping with sodium according to claim 1, characterized in that: In step S3, the concentration of the acid solution is 10-20 wt%, and the liquid-to-solid ratio of the acid solution to tungstic acid is (2-4) mL:1 g.

8. The method for preparing ultra-coarse tungsten carbide powder by doping with sodium according to claim 1, characterized in that: In the step S3, the tungstic acid is washed with acid solution for 1 hour and then rinsed with pure water.

9. The method for preparing ultra-coarse tungsten carbide powder by doping with sodium according to claim 1, characterized in that: In step S3, the acid concentration of the waste liquid is 8-16 wt %.

10. The method for preparing ultra-coarse tungsten carbide powder by doping with sodium according to claim 1, characterized in that: In the step S4, the average particle size of the ultra-coarse tungsten carbide powder is 25-28 μm.

Images