KR100359643B1 - A manufacturing process of ultra-granule tungsten carbide dust by soppy system mixing - Google Patents

Abstract

The present invention relates to a method for producing ultra-fine tungsten carbide powder by a wet mixing method, focusing on the raw material synthesis process in a wet manner, and after mixing the raw material in a wet state immediately after synthesis of the raw material to increase the uniformity without milling process It is an object to make it possible to omit the molding step even after drying.

As a raw material for the production of fine WC powders, powdered tungsten compounds (CaWO ₄ , APT-Ammonium Para Tungstate) or heavy stone solutions (Na ₂ WO ₄ , (NH) ₄ WO ₄ solution, etc.) 1.5 To grow tungstic acid (H ₂ WO ₄ , Tungstic Acid) by growing the particles by adding them to a solution of -2.0 equivalents to prevent colloidation;

Wet mixing by adding carbon to the prepared tungstic acid slurry;

It is characterized in that it comprises a step of drying the mixture to react 1.2 times as it is in a lump.

According to the present invention, it is possible to manufacture tungsten carbide powder without milling and molding process, which is an essential process for conventional dry mixing, since it is mixed with the subsidiary material in a wet state immediately after synthesis of raw materials, thereby making it economically effective. .

Description

A manufacturing process of ultra-granule tungsten carbide dust by soppy system mixing

The present invention relates to a method for producing ultrafine tungsten carbide powder by a wet mixing method.

According to the existing manufacturing method, it is a dry mixing method of mixing the raw powder and the sub-raw powder. Therefore, milling is required for a long time to increase the uniformity, and a molding (to pelletize) process must be added to prevent the powder from scattering after mixing. There was a dissolution.

The present invention focuses on the raw material synthesis (H ₂ WO ₄ ) process in order to make up for the disadvantages of the prior art by mixing with the raw material immediately in the wet state after the synthesis of raw materials to increase the uniformity without milling process and molding process after drying The purpose is to be able to omit.

Looking at the specific method of the present invention.

As a raw material for preparing fine WC powders, 1.5 to 2.0 equivalents of tungsten compounds in powder form (CaWO ₄ , APT-Ammonium Para Tungstate) or a solution containing sodium stones (Na ₂ WO ₄ , (NH) ₄ WO ₄ solution, etc.) and inorganic acids After reacting, tungstic acid (H ₂ WO ₄ , Tungstic Acid) slurry prepared by crystallizing particles to prevent colloidation is used.

Since the appropriate amount of reagent (inorganic acid) is activated to have the best reactivity, the crystallization is carried out by adding the used raw material (heavy stone material). Can be synthesized (see Table 1).

Tungstic acid precipitate prepared in this manner is washed 4 to 6 times by Decantation method to prepare a slurry state. Among them, a small amount is taken and dried to measure the content of WO _{3 in} the slurry. 2.5 to 4.5 equivalents of carbon was added to the measured WO ₃ content to add 1: 0.3 to 1.5 volume ratio of distilled water. Then, Ball was added to the Ball Mill Jar, mixed, and dried at 100 to 200 ° C. to ingot. Make it state.

After the first reaction at 900-1200 ° C. in a vacuum atmosphere as it is in the form of agglomerates, the reaction can be continued at 1200-1600 ° C. in a hydrogen atmosphere to produce an average 0.2-0.5 μm fine WC powder without coarse particles. will be.

Comparison Raw material method CaWO ₄ Minutes APT Powder Na ₂ WO ₄ solution (NH ₄ ) ₂ WO ₄ solution Remarks Hydrochloric acid consumption (equivalent) The present invention 1.8 1.8 2.0 2.0 Conventional 4.0 4.0 5.0 5.0 Average yield rate (%) The present invention 99.5 99.7 98.6 98.2 Average value of three times for each raw material Conventional 95.7 96.5 72.8 67.3 Filtration time (min) The present invention 4 to 6 3 to 5 7-8 7-8 Filtration amount and filtration conditions are same Conventional 120 to 180 120 to 180 120 to 180 120 to 180

Example 1

① A solution of about 1.5 to 2.0 equivalents of hydrochloric acid reaction equivalent to WO ₃ of APT or CaWO ₄ powder is diluted to the appropriate concentration by adding pure water.

② Prepare HNO ₃ solution with 0.2 ~ 0.3N concentration in the same amount as the solution in ① and warm it to 70 ~ 80 ℃.

③ APT or CaWO ₄ powder prepared while mixing the dilutions of ① well at a rate of 30-40 min to react. At this time, the reaction temperature is maintained at 85 ± 5 ℃. After about 1 hour, the solution of ② is added and reacted for 1 to 2 hours.

④ After the reaction is complete, wash the precipitate 4 ~ 5 times by Decantation method, take a certain volume (for example, 10ml) out of slurry, put it in an evaporating dish, dry it at 150 ℃ for time, evaporate the water completely and weigh it. ₂ The content of WO ₃ in WO ₄ is calculated.

⑤ Measure the total volume of slurry, add 4.2 equivalents of carbon based on the content of WO ₃ and add 0.5 times the volume of distilled water to wet mix for 8 hours in the Ball Mill Jar.

⑥ Charge the mixture of H ₂ WO ₄ slurry and carbon powder into the dryer and dry at 150 ℃ for 4 hours to solidify into a lump. It is charged into Graphite Crusible as it is and reacted for 1 hour at 1100 ° C in a vacuum atmosphere for 3 hours, followed by 2 hours of reaction at 1400 ° C in a hydrogen atmosphere for 1 hour to cool. A micronized tungsten carbide powder of 탆 could be prepared.

Example 2

① Prepare the sodium hydroxide solution (Na ₂ WO ₄ solution or (NH ₄ ) ₂ WO ₄ solution) at a concentration of about 400 to 450 g / l based on WO ₃ .

(2) Dilute the solution of about 1.5 to 2.0 equivalents of hydrochloric acid reaction equivalent to WO ₃ of the barite solution to the appropriate concentration by adding pure water.

③ Heat HNO ₃ solution with 0.2 ~ 0.3N concentration in the same amount as the solution in ② and warm it to 80 ℃.

④ The solution of item ① is added to the solution of item ② at a rate of about 40 to 60 min. The reaction temperature is maintained at 85 ± 5 ° C. for 1 hour, and then the solution of item ③ is added for 1 to 2 hours. .

⑤ After the reaction, the reactants are thoroughly washed 5 ~ 6 times by Decantation method, take a certain volume (for example 10ml) out of slurry and put it in an evaporating dish and dry it at 110 ℃ for 4 hours to completely evaporate moisture and weigh it. The content of WO ₃ in H ₂ WO ₄ is calculated.

⑥ Measure the total volume of slurry and add 4.35 equivalents of carbon based on the content of WO ₃ and add 1.2 times of the volume of slurry to wet mix in Ball Mill Jar for 12 hours.

⑦ The mixture of H ₂ WO ₄ slurry and carbon powder is charged into a drier and dried at 110 ° C. for 36 hours to harden into a lump. It was loaded into Graphite Crusilble as it is and reacted for 1 hour at 1050 ° C. in a vacuum atmosphere for 4 hours, followed by a second reaction at 1300 ° C. in a hydrogen atmosphere for 1 hour to cool. A micronized tungsten carbide powder of 탆 could be prepared.

According to the present invention as described above, since the raw material is mixed with the subsidiary materials in a wet state immediately after synthesis, the uniformity can be increased without the milling process, and the mixed powder is ingot after the drying process, so that the molding process can be omitted.

Therefore, the present invention is an invention having a useful effect of being able to manufacture tungsten carbide powder without the milling and molding process, which is an essential step in the existing dry mixing, so that it can be economically processed.

Claims (3)

As a raw material for preparing fine WC powders, 1.5 to 2.0 equivalents of powdered tungsten compounds (CaWO ₄ , APT-Ammonium Para Tungstate) or sodium hydroxide solutions (Na ₂ WO ₄ , (NH) ₄ WO ₄ solution, etc.) Growing a particle by adding it to an inorganic acid solution to prevent colloidation and producing tungstic acid (H ₂ WO ₄ , Tungstic Acid), Wet mixing by adding carbon to the prepared tungstic acid slurry; Method for producing ultrafine tungsten carbide powder by wet mixing, characterized in that the mixture is dried and subjected to the 1.2th reaction as it is in a lump. The method of claim 1, Method for producing ultrafine tungsten carbide powder by wet mixing, characterized in that the mixing amount of carbon is added 2.5 to 4.5 equivalents based on WO ₃ content and distilled water is added at a ratio of 1: 0.3 to 1.5 with respect to the slurry volume. . The method of claim 1, A method for producing ultrafine tungsten carbide powder by wet mixing, characterized in that the first reaction is carried out at 900 to 1200 ° C. in a vacuum atmosphere and subsequently at 1200 to 1600 ° C. in a hydrogen atmosphere when the dried product is reacted.