Process for preparing molybdenum powder by reduction of ammonium molybdate-doped molybdenum powder

Abstract

This invention discloses a process for preparing molybdenum powder by reducing molybdenum powder with ammonium molybdate doping, belonging to the technical field of molybdenum powder preparation methods. The process includes: placing a mixture of ammonium dimolybdate and molybdenum powder as raw material in a quartz crucible, covering it with a lid, and subjecting it to microwave heating treatment; cooling the treated material to obtain a microwave-treated product; and then reducing the microwave-treated product with hydrogen to obtain molybdenum powder, wherein the mass of the molybdenum powder is 10-20% of the mass of the ammonium dimolybdate. This invention can significantly reduce the production cycle and cost of producing molybdenum powder from ammonium molybdate, and obtain high-purity molybdenum powder.

Description

Technical Field

[0001] This invention relates to the technical field of process preparation methods for molybdenum powder, and particularly to a process method for preparing molybdenum powder using ammonium molybdate doped with molybdenum powder as a raw material. Background Technology

[0002] Traditional molybdenum powder production processes use ammonium molybdate as raw material. The ammonium molybdate is calcined in a rotary kiln to produce molybdenum trioxide, which is then reduced to molybdenum dioxide via high-temperature hydrogen reduction. Finally, the molybdenum dioxide is reduced to molybdenum powder via high-temperature hydrogen reduction. This production method is time-consuming, costly, has low kiln thermal efficiency, high energy consumption, and is prone to ammonia leakage, resulting in a poor working environment in the production workshop. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide a process for preparing high-purity molybdenum powder using ammonium molybdate-doped molybdenum powder as raw material via hydrogen reduction. This method can significantly reduce the production cycle and cost of producing molybdenum powder from ammonium molybdate, thereby obtaining high-purity molybdenum powder.

[0004] The technical solution of the present invention is as follows:

[0005] A process for preparing molybdenum powder by reduction of ammonium molybdate-doped molybdenum powder, characterized in that it includes:

[0006] (1) Place the raw material mixture in a quartz crucible, cover it with a lid, microwave heat it, and then let it cool naturally to obtain the microwave-treated product;

[0007] (2) The microwave-treated material is reduced with hydrogen in a high-temperature reduction furnace to obtain molybdenum powder;

[0008] The raw material mixture includes ammonium dimolybdate and molybdenum powder with a doping mass of 10-20% of the mass of ammonium dimolybdate.

[0009] The above-described process method of this invention utilizes microwave treatment. Microwaves have the characteristics of rapid and efficient energy transfer, and can directly act on polar molecules in materials. They can uniformly penetrate into the interior of the material, ensuring simultaneous heating of the internal and external parts, guaranteeing heating consistency and reaction uniformity, and significantly accelerating the reaction rate and shortening the reaction time. This significantly improves upon the problems of long production time, high production costs, low kiln thermal efficiency, high energy consumption, and poor working environment in existing technologies.

[0010] In the microwave processing method of this invention, considering that ammonium dimolybdate has poor microwave absorption capacity during microwave heating, a specific proportion of molybdenum powder is added to absorb microwave energy and conduct the required heat through the molybdenum powder. When the mixture of ammonium dimolybdate and molybdenum powder reaches a certain temperature, the ammonium dimolybdate can decompose and release ammonia gas. At high temperature, the ammonia gas further decomposes to produce hydrogen gas, which reacts with molybdenum trioxide to generate molybdenum dioxide. The resulting material can be reduced to molybdenum powder in one step.

[0011] In the above process method of the present invention, the obtained microwave-treated product is a mixture of molybdenum trioxide, molybdenum dioxide, and molybdenum powder, and the chemical reaction includes:

[0012] (NH4)2Mo2O7→2MoO3+2NH3+H2O

[0013] 2NH3→N2+3H2

[0014] MoO3 + H2 → MoO2 + H2O

[0015] MoO2 + 2H2 → Mo + 2H2O

[0016] According to some preferred embodiments of the present invention, the microwave heating treatment includes: setting the microwave power to 1500-3600W, and continuing microwave treatment for 20 minutes after the temperature of the quartz crucible reaches the set temperature.

[0017] According to some preferred embodiments of the present invention, the set temperature is 450-550°C.

[0018] According to some preferred embodiments of the present invention, the temperature of hydrogen reduction is 950°C.

[0019] According to some preferred embodiments of the present invention, the quartz crucible has a diameter of 160 mm, a height of 150 mm, and a thickness of 8 mm, and its cover plate has a diameter of 160 mm, a height of 10 mm, and a thickness of 8 mm.

[0020] According to some preferred embodiments of the present invention, the particle size of the molybdenum powder in the raw material mixture is 2.5-4 μm.

[0021] According to some preferred embodiments of the present invention, in the hydrogen reduction, the hydrogen flow rate is 16 m³ / s. 3 / h, the loading amount of the microwave processed material in the boat is 0.20kg / boat, and the pushing speed is 18min / pass.

[0022] The beneficial effects of this invention include:

[0023] The process of this invention uses microwave calcination with ammonium molybdate and molybdenum powder as raw materials instead of the traditional method of calcination with ammonium molybdate. Through microwave calcination, the raw materials are converted into a mixture of molybdenum trioxide, molybdenum dioxide, and molybdenum powder. During this process, ammonium molybdate decomposes to produce ammonia gas, which can be further decomposed into hydrogen and nitrogen gas at high temperature. The hydrogen gas produced can be reduced to molybdenum dioxide with molybdenum trioxide at high temperature, which improves the utilization rate of ammonia gas and reduces ammonia emissions. The mixture obtained by microwave treatment can be directly reduced to molybdenum powder in one step by high-temperature hydrogen, reducing one reduction step, shortening the production process, and reducing production costs. Detailed Implementation

[0024] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] In the following embodiments, the quartz crucible used has a diameter of 160 mm, a height of 150 mm, and a thickness of 8 mm; its cover plate has a diameter of 160 mm, a height of 10 mm, and a thickness of 8 mm.

[0026] The ammonium dimolybdate in the raw material mixture is dried ammonium dimolybdate, which is sieved through an 80-mesh Taylor sieve. The particle size of the molybdenum powder used is 2.5-4 μm, which is also sieved through an 80-mesh Taylor sieve.

[0027] Example 1

[0028] Molybdenum powder is prepared through the following process steps:

[0029] (1) Place the raw material mixture in a quartz crucible, cover it with a lid, set the microwave power to 3600W, turn on microwave heating, start timing when the crucible temperature reaches 450℃, remove the quartz crucible after 20min and let it cool naturally to obtain the microwave-treated product; wherein the raw material mixture includes 240g of ammonium dimolybdate and molybdenum powder with a mass of 10% of the mass of ammonium dimolybdate.

[0030] (2) The microwave-treated material was reduced to molybdenum powder in a high-temperature reduction furnace by passing hydrogen through it in one step. The reduction process is as follows: reduction temperature: 950℃; hydrogen flow rate: 16m³ / h 3 / h; Pushing speed: 18min / track; Loading capacity: 0.20kg / boat.

[0031] The molybdenum powder obtained from the reduction was tested and found to fully comply with the requirements of GB / T3461-2016.

[0032] Example 2

[0033] Molybdenum powder is prepared through the following process steps:

[0034] (1) Place the raw material mixture in a quartz crucible, cover it with a lid, set the microwave power to 3600W, turn on microwave heating, start timing when the crucible temperature reaches 450℃, remove the quartz crucible after 20min and let it cool naturally to obtain the microwave-treated product; wherein the raw material mixture includes 240g of ammonium dimolybdate and 15% of the mass of molybdenum powder doped with ammonium dimolybdate.

[0035] (2) The microwave-treated material was reduced to molybdenum powder in a high-temperature reduction furnace by passing hydrogen through it in one step. The reduction process is as follows: reduction temperature: 950℃; hydrogen flow rate: 16m³ / h 3 / h; Pushing speed: 18min / track; Loading capacity: 0.20kg / boat.

[0036] The molybdenum powder obtained from the reduction was tested and found to fully comply with the requirements of GB / T3461-2016.

[0037] Example 3

[0038] Molybdenum powder is prepared through the following process steps:

[0039] (1) Place the raw material mixture in a quartz crucible, cover it with a lid, set the microwave power to 3600W, turn on microwave heating, start timing when the crucible temperature reaches 450℃, remove the quartz crucible after 20min and let it cool naturally to obtain the microwave-treated product; wherein the raw material mixture includes 240g of ammonium dimolybdate and 20% of the mass of molybdenum powder doped with ammonium dimolybdate.

[0040] (2) The microwave-treated material was reduced to molybdenum powder in a high-temperature reduction furnace by passing hydrogen through it in one step. The reduction process is as follows: reduction temperature: 950℃; hydrogen flow rate: 16m³ / h 3 / h; Pushing speed: 18min / track; Loading capacity: 0.20kg / boat.

[0041] The molybdenum powder obtained from the reduction was tested and found to fully comply with the requirements of GB / T3461-2016.

[0042] The above embodiments are preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A process for preparing molybdenum powder by reduction of ammonium molybdate-doped molybdenum powder, characterized in that, It includes: (1) Place the raw material mixture in a quartz crucible, cover it with a lid, microwave heat it, and then let it cool naturally to obtain the microwave-treated product; (2) The microwave-treated material is subjected to hydrogen reduction in a high-temperature reduction furnace at a temperature of 950°C to obtain molybdenum powder; The raw material mixture includes ammonium dimolybdate and molybdenum powder with a doping mass of 10-20% of the mass of ammonium dimolybdate; The microwave heating treatment includes: setting the microwave power to 1500-3600W, and continuing microwave treatment for 20 minutes after the temperature of the quartz crucible reaches the set temperature of 450-550℃. The particle size of the molybdenum powder in the raw material mixture is 2.5-4μm.

2. The process method according to claim 1, characterized in that, The quartz crucible has a diameter of 160 mm, a height of 150 mm, and a thickness of 8 mm, and its cover plate has a diameter of 160 mm, a height of 10 mm, and a thickness of 8 mm.

3. The process method according to claim 1, characterized in that, In the hydrogen reduction process, the hydrogen flow rate is 16 m³ / s. 3 / h, the loading amount of the microwave processed material in the boat is 0.20kg / boat, and the pushing speed is 18min / pass.