Process for green preparation of molybdenum powder by ammonia gas and hydrogen relay reduction of ammonium molybdate

A green technology of ammonium molybdate, which is applied in the field of green preparation of molybdenum powder by the relay reduction of ammonium molybdate with ammonia and hydrogen, can solve the problem of reducing the efficiency of gas-solid reduction and product yield, and cannot realize the relay of ammonia and hydrogen Reduction process, increasing NH and other issues, to achieve the effects of less adsorption and storage of other impurities, reduced hydrogen consumption, and good surface stability

Pending Publication Date: 2022-04-12
ZHENGZHOU UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

And the reaction product Mo 4 o 11 and the MoO produced by the reaction 2 And water vapor will sinter to form eutectic eutectic, which will cause serious hardening of the material, thereby increasing NH 3 The inward diffusion and the resistance of the reduction product water vapor to the outward diffusion, thereby reducing the gas-solid NH 3 Reduction efficiency and product yield
Therefore, in the existing molybdenum powder reduction process, the relay reduction process of ammonia and hydrogen cannot be realized

Method used

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  • Process for green preparation of molybdenum powder by ammonia gas and hydrogen relay reduction of ammonium molybdate
  • Process for green preparation of molybdenum powder by ammonia gas and hydrogen relay reduction of ammonium molybdate
  • Process for green preparation of molybdenum powder by ammonia gas and hydrogen relay reduction of ammonium molybdate

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Embodiment 1

[0052] A green process for preparing molybdenum powder through the relay reduction of ammonium molybdate by ammonia and hydrogen, comprising the following steps:

[0053] (1) Ammonium molybdate is carried out roasting treatment in the atmosphere of nitrogen, the temperature of roasting is 540 ℃, the roasting time is 2.2h, generates molybdenum trioxide, ammonia gas and steam, and the ammonia gas and water vapor that produce Water vapor is dried and separated, ammonia and water vapor are dried and separated, and then the water vapor is removed by bottom blowing air supply to obtain dry ammonia;

[0054] (2) Reducing molybdenum trioxide with dry ammonia to generate molybdenum dioxide, water vapor and nitrogen, the molar ratio of ammonia to molybdenum trioxide is 2:3, and the reduction temperature is 400°C;

[0055] (3) Molybdenum dioxide is reduced with hydrogen, the molar ratio of hydrogen to molybdenum dioxide is 2.5:1, and the temperature is 850°C to obtain molybdenum powder. ...

Embodiment 2

[0057] A green process for preparing molybdenum powder through the relay reduction of ammonium molybdate by ammonia and hydrogen, comprising the following steps:

[0058] (1) Ammonium molybdate is carried out roasting treatment in the atmosphere of nitrogen gas, the temperature of roasting is 545 ℃, and roasting time is 2.1h, generates molybdenum trioxide, ammonia gas and steam, and the ammonia gas and water vapor that produce Water vapor is dried and separated, ammonia and water vapor are dried and separated, and then the water vapor is removed by bottom blowing air supply to obtain dry ammonia;

[0059] (2) Reducing molybdenum trioxide with dry ammonia gas to generate molybdenum dioxide, water vapor and nitrogen, the molar ratio of ammonia gas to molybdenum trioxide is 1:1, and the reduction temperature is 450°C;

[0060] (3) Molybdenum dioxide is reduced with hydrogen, the molar ratio of hydrogen to molybdenum dioxide is 2.4:1, and the temperature is 900°C to obtain molybde...

Embodiment 3

[0062] A green process for preparing molybdenum powder through the relay reduction of ammonium molybdate by ammonia and hydrogen, comprising the following steps:

[0063] (1) Ammonium molybdate is carried out roasting treatment in the atmosphere of nitrogen, the temperature of roasting is 550 ℃, and roasting time is 2h, generates molybdenum trioxide, ammonia gas and steam, and the ammonia gas and water that produce Steam is dried and separated, ammonia and water vapor are dried and separated, and then the water vapor is removed by bottom blowing air supply to obtain dry ammonia;

[0064] (2) Reducing molybdenum trioxide with dry ammonia to generate molybdenum dioxide, water vapor and nitrogen, the molar ratio of ammonia to molybdenum trioxide is 4:3, and the reduction temperature is 525°C;

[0065] (3) Using hydrogen to reduce molybdenum dioxide, the molar ratio of hydrogen to molybdenum dioxide is 2.25:1, and the temperature is 950°C to obtain molybdenum powder.

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Abstract

The invention relates to an environment-friendly process for preparing molybdenum powder by continuously reducing ammonium molybdate with ammonia gas and hydrogen, which comprises the following steps of: roasting ammonium molybdate serving as a raw material, drying and recycling the ammonia gas generated by decomposition, reducing the emission pollution of ammonia gas and ammonia water, taking the ammonia gas as a reducing agent to participate in a reduction reaction, and recycling the ammonia gas to obtain the molybdenum powder. The conversion from harm to benefit is realized; according to the process, the ammonia gas generated by roasting ammonium molybdate is recycled to be used for reducing molybdenum trioxide to obtain molybdenum dioxide, the molybdenum dioxide is in an equiaxial cubic shape, and then the molybdenum dioxide is subjected to two-stage reduction with hydrogen to form compact polyhedral metal particles. Compared with a pure two-stage hydrogen reduction method, the molybdenum powder obtained through relay reduction of the ammonia gas and the hydrogen is better in sintering performance and higher in compactness; ammonia is used for replacing part of hydrogen to serve as a reducing agent for reduction, under the ideal condition, hydrogen consumption can be reduced by 1 / 3, the production cost is remarkably reduced, harm is turned into benefit, and the greenization of the molybdenum powder preparation process is achieved.

Description

technical field [0001] The invention belongs to the technical field of preparation of molybdenum powder, and in particular relates to a green preparation process of molybdenum powder through the relay reduction of ammonium molybdate with ammonia and hydrogen. Background technique [0002] At present, the commonly used molybdenum powder preparation process in industrial production is a hydrogen two-stage reduction process. The process flow chart is as follows: figure 1 shown. Industrial molybdenum oxide undergoes ammonia immersion-crystallization process to obtain polycrystalline ammonium molybdate, which is used as the precursor for preparing molybdenum powder. Ammonium molybdate will produce high-purity MoO after roasting 3 and by-product NH 3 with water vapor. Throughout the process, a large amount of NH 3 Spills will corrode equipment, affect product quality, and pollute the environment. In the subsequent waste gas treatment process, it is necessary to neutralize th...

Claims

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Application Information

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IPC IPC(8): B22F9/28
Inventor 车玉思孙紫昂杜胜敏宋建勋何季麟
Owner ZHENGZHOU UNIV
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