Views:2 Author:Site Editor Publish Time: 2021-12-27 Origin:Site
The production methods of molybdenum mainly include the production methods of molybdenum powder and molybdenum products.
The common production methods of molybdenum powder include reduction method, hydroxyl thermal decomposition method and molybdenum chloride pyrolysis method. The molybdenum chloride steam pyrolysis method has a simple preparation process and can produce high-purity molybdenum powder with a small particle size. However, the raw materials used in the invention have high requirements, and problems such as exhaust gas emissions must be dealt with during the preparation process.
Among them, the hydrogen reduction method is the most widely used, its production cost is low, it is easy to carry out industrial-scale production, and the purity of the molybdenum powder produced is relatively high, and its particle size is generally in the micron level. The preparation process mainly includes the following three types:
1. Use ammonium molybdate as raw material to obtain molybdenum trioxide through roasting, and then reduce the molybdenum dioxide by hydrogen, and then reduce it to molybdenum powder;
2. Using ammonium molybdate as raw material, reducing to obtain molybdenum dioxide, and then to obtain molybdenum powder;
3. Using ammonium molybdate as raw material, molybdenum powder is prepared by a reduction method.
The hydroxy molybdenum pyrolysis method uses molybdenum hydroxy as a raw material, and the molybdenum hydroxy material is subjected to steam thermal decomposition in a N2 atmosphere under normal pressure and a temperature of 350-1000°C. Nucleation, crystallization and growth of crystal nuclei in the gas phase state, therefore, the prepared molybdenum powder is finer, has higher chemical purity and good sinterability, and the method can be used for industrialized large-scale production.
The production methods of molybdenum products include arc melting-casting method and powder metallurgy, mainly powder metallurgy. The production process is roughly as follows: mixing-forming-sintering-hanging forging-machining. In addition, molybdenum alloys can also be produced by the arc melting-casting method, which is mainly to melt pure molybdenum with an electric arc and add a certain amount of doped alloying elements according to the weight percentage, and then use conventional casting methods to obtain the molybdenum alloy