Process method for preparing molybdenum powder through reduction of ammonium molybdate doped molybdenum powder

Abstract

The invention discloses a technological method for preparing molybdenum powder through reduction of ammonium molybdate doped molybdenum powder, and belongs to the technical field of technological preparation methods of molybdenum powder. The process method comprises the following steps: putting a mixture of ammonium dimolybdate and molybdenum powder as a raw material into a quartz crucible, covering with a cover plate, carrying out microwave heating treatment, and cooling to obtain a microwave treatment substance; the microwave treatment object is subjected to hydrogen reduction, molybdenum powder is obtained, and the mass of the molybdenum powder is 10-20% of the mass of ammonium dimolybdate. According to the method, the production cycle and the production cost of preparing the molybdenum powder from the ammonium molybdate can be remarkably reduced, and the high-purity molybdenum powder is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of a process for preparing molybdenum powder, and in particular to a process for preparing molybdenum powder by taking ammonium molybdate doped with molybdenum powder as a raw material. Background Art

[0002] The traditional molybdenum powder production process uses ammonium molybdate as raw material, calcines ammonium molybdate in a rotary kiln to generate molybdenum trioxide, then reduces the molybdenum trioxide to molybdenum dioxide through high-temperature hydrogen reduction, and finally reduces the molybdenum dioxide to molybdenum powder through high-temperature hydrogen reduction. This production method takes a long time to produce, has high production costs, low kiln thermal efficiency, high energy consumption, and ammonia is prone to leakage during the production process, resulting in a poor working environment in the production workshop. Summary of the invention

[0003] In view of the defects of the prior art, the purpose of the present invention is to provide a process method for preparing high-purity molybdenum powder by using ammonium molybdate-doped molybdenum powder as raw material through a hydrogen reduction method. This method can significantly reduce the production cycle and production cost of preparing molybdenum powder from ammonium molybdate, and obtain high-purity molybdenum powder.

[0004] The technical solution of the present invention is as follows: The process for preparing molybdenum powder by reducing ammonium molybdate-doped molybdenum powder is characterized in that it comprises: (1) placing the raw material mixture in a quartz crucible, covering it with a cover plate, subjecting it to microwave heating treatment, and then cooling it naturally to obtain a microwave-treated product; (2) reducing the microwave-treated product with hydrogen in a high-temperature reduction furnace to obtain molybdenum powder; The raw material mixture includes ammonium dimolybdate and molybdenum powder doped with a mass of 10-20% of the mass of ammonium dimolybdate.

[0005] The above process method of the present invention uses microwave treatment. Microwaves have the characteristics of fast and efficient energy transmission, can directly act on polar molecules in the material, can evenly penetrate into the material, ensure that the inside and outside are heated at the same time, ensure the consistency of heating and the uniformity of reaction, and can significantly accelerate the reaction speed and shorten the reaction time. It can significantly improve the problems of the prior art such as long production time, high production cost, low kiln thermal efficiency, high energy consumption, and poor working environment in the production workshop.

[0006] In the process method of the present invention, in the microwave treatment, considering that the wave absorption ability of ammonium dimolybdate in the microwave heating process is very poor, a specific proportion of molybdenum powder is doped, so that the specific proportion of molybdenum powder absorbs microwave energy to perform the required heat conduction. When the mixture of ammonium dimolybdate and molybdenum powder reaches a certain temperature, the ammonium dimolybdate can decompose and release ammonia. At high temperature, the ammonia decomposes to produce hydrogen and reacts with molybdenum trioxide to produce molybdenum dioxide. The obtained material can be reduced to molybdenum powder in one step.

[0007] In the above process of the present invention, the microwave-treated product obtained is a mixture of molybdenum trioxide, molybdenum dioxide and molybdenum powder, and the chemical reactions performed include: (NH 4 ) 2 Mo 2 O 7 →2MoO 3 +2NH 3 +H 2 O 2NH 3 →N 2 +3H 2 MoO 3 +H 2 →MoO 2 +H 2 O MoO 2 +2H 2 →Mo+2H 2 O According to some preferred embodiments of the present invention, the microwave heating treatment comprises: setting the microwave power to 1500-3600 W, and after the temperature of the quartz crucible reaches the set temperature, continuing the microwave treatment for 20 minutes.

[0008] According to some preferred embodiments of the present invention, the set temperature is 450-550°C.

[0009] According to some preferred embodiments of the present invention, the temperature of the hydrogen reduction is 950°C.

[0010] 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.

[0011] 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.

[0012] According to some preferred embodiments of the present invention, in the hydrogen reduction, the flow rate of hydrogen is 16m 3 / h, the boat loading amount of the microwave-treated material: 0.20 kg / boat, and the boat pushing speed is 18 min / track.

[0013] The beneficial effects of the present invention include: The process method of the present invention adopts a microwave calcination method using ammonium molybdate and molybdenum powder as raw materials to replace the traditional method of calcining ammonium molybdate as the raw material. The raw materials are converted into a mixture of molybdenum trioxide, molybdenum dioxide and molybdenum powder through microwave calcination. In this process, ammonium dimolybdate decomposes to produce ammonia, and the ammonia can be further decomposed into hydrogen and nitrogen under a high temperature environment. The hydrogen produced can be reduced with molybdenum trioxide under high temperature conditions to produce molybdenum dioxide, thereby improving the utilization rate of ammonia and reducing ammonia emissions. The mixture obtained by microwave treatment can be directly reduced to molybdenum powder in one step with high-temperature hydrogen, thereby reducing one reduction process, shortening the production process flow and reducing production costs. DETAILED DESCRIPTION

[0015] The technical scheme of the present invention is clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0016] The quartz crucible used in the following examples has a crucible 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.

[0017] The ammonium dimolybdate in the raw material mixture is dry ammonium dimolybdate, which is sieved through an 80-mesh Taylor sieve. The particle size of the molybdenum powder used is 2.5-4um, which is sieved through an 80-mesh Taylor sieve.

[0018] Example 1 Molybdenum powder is prepared by the following process steps: (1) placing a raw material mixture in a quartz crucible, covering it with a cover plate, setting the microwave power to 3600 W, turning on microwave heating, and starting timing when the crucible temperature reaches 450° C., taking out the quartz crucible after 20 minutes and cooling it naturally to obtain a microwave-treated product; wherein the raw material mixture comprises 240 g of ammonium dimolybdate and doped molybdenum powder having a mass that is 10% of the mass of ammonium dimolybdate; (2) In a high-temperature reduction furnace, the microwave treated material is reduced to molybdenum powder in one step by passing hydrogen. The reduction process is as follows: reduction temperature: 950°C; hydrogen flow rate: 16m 3 / h; boat pushing speed: 18min / lane; boat loading: 0.20kg / boat.

[0019] The molybdenum powder obtained by reduction was tested and found to fully meet the requirements of GB / T3461-2016.

[0020] Example 2 Molybdenum powder is prepared by the following process steps: (1) placing a raw material mixture in a quartz crucible, covering it with a cover plate, setting the microwave power to 3600 W, turning on microwave heating, and starting timing when the crucible temperature reaches 450° C., taking out the quartz crucible after 20 minutes and cooling it naturally to obtain a microwave-treated product; wherein the raw material mixture comprises 240 g of ammonium dimolybdate and 15% of the mass of molybdenum powder doped with ammonium dimolybdate; (2) In a high-temperature reduction furnace, the microwave treated material is reduced to molybdenum powder in one step by passing hydrogen. The reduction process is as follows: reduction temperature: 950°C; hydrogen flow rate: 16m 3 / h; boat pushing speed: 18min / lane; boat loading: 0.20kg / boat.

[0021] The molybdenum powder obtained by reduction was tested and found to fully meet the requirements of GB / T3461-2016.

[0022] Example 3 Molybdenum powder is prepared by the following process steps: (1) placing a raw material mixture in a quartz crucible, covering it with a cover plate, setting the microwave power to 3600 W, turning on microwave heating, and starting timing when the crucible temperature reaches 450° C., taking out the quartz crucible after 20 minutes and cooling it naturally to obtain a microwave-treated product; wherein the raw material mixture comprises 240 g of ammonium dimolybdate and 20% of the mass of molybdenum powder doped with ammonium dimolybdate; (2) In a high-temperature reduction furnace, the microwave treated material is reduced to molybdenum powder in one step by passing hydrogen. The reduction process is as follows: reduction temperature: 950°C; hydrogen flow rate: 16m 3 / h; boat pushing speed: 18min / lane; boat loading: 0.20kg / boat.

[0023] The molybdenum powder obtained by reduction was tested and found to fully meet the requirements of GB / T3461-2016.

[0024] The above embodiments are preferred implementations of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A process for preparing molybdenum powder by reducing ammonium molybdate-doped molybdenum powder, characterized in that: It includes: (1) placing the raw material mixture in a quartz crucible, covering it with a cover plate, subjecting it to microwave heating treatment, and then cooling it naturally to obtain a microwave-treated product; (2) reducing the microwave-treated product with hydrogen in a high-temperature reduction furnace to obtain molybdenum powder; The raw material mixture includes ammonium dimolybdate and molybdenum powder doped with a mass of 10-20% of the mass of ammonium dimolybdate.

2. The process according to claim 1, characterized in that: The microwave heating treatment comprises: setting the microwave power to 1500-3600W, and continuing the microwave treatment for 20 minutes after the temperature of the quartz crucible reaches the set temperature.

3. The process according to claim 2, characterized in that: The set temperature is 450-550°C.

4. The process according to claim 1, characterized in that: The temperature of the hydrogen reduction is 950°C.

5. The process 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.

6. The process according to claim 1, characterized in that: The particle size of the molybdenum powder in the raw material mixture is 2.5-4 μm.

7. The process according to claim 1, characterized in that: In the hydrogen reduction, the flow rate of hydrogen is 16m 3 / h, the boat loading amount of the microwave-treated material: 0.20 kg / boat, and the boat pushing speed is 18 min / track.