Method for preparing molybdenum powder by molybdenum trioxide

Abstract

The invention provides a method for preparing molybdenum powder by molybdenum trioxide. The method includes the steps: firstly, sieving the molybdenum trioxide by a 40-mesh sieve to obtain oversize materials and then throwing the sieved oversize materials into a ball mill for ball-milling to obtain molybdenum trioxide powder; secondly, performing primary hydrogen reduction treatment for the molybdenum trioxide powder by a primary reduction furnace in hydrogen atmosphere to obtain molybdenum dioxide; thirdly, performing secondary hydrogen reduction treatment for the molybdenum dioxide by a secondary reduction furnace in the hydrogen atmosphere to obtain rough molybdenum powder; and fourthly, sieving the rough molybdenum powder and then uniformly mixing the rough molybdenum powder in a mixer to obtain finished molybdenum powder. The method is simple in preparation process, safe, reliable and suitable for industrial batch production. The molybdenum powder prepared by the method can meet the technical requirement of the national standard GB / T3461-2006, and can be widely used for preparing raw materials for molybdenum and molybdenum alloy products such as molybdenum slabs, molybdenum bar billets, molybdenum ejector headers and molybdenum special-shaped parts.

Description

technical field [0001] The invention belongs to the technical field of rare metal powder metallurgy, and in particular relates to a method for preparing molybdenum powder by using molybdenum trioxide. Background technique [0002] Molybdenum trioxide is an indispensable compound for the production of molybdenum products, and the density of molybdenum trioxide is 4.69g / cm 3 , with a melting point of 795°C and a boiling point of 1155°C, easy to sublimate, insoluble in water, soluble in ammonia water and strong alkali solution, capable of generating molybdate, and can be reduced by hydrogen, carbon, and aluminum at high temperatures. The most widely used molybdenum trioxide is MoO 3 High-purity molybdenum trioxide with a mass percentage of not less than 99.95%. [0003] In the industrial production process, molybdenum trioxide is usually prepared by roasting ammonium molybdate as raw material. Since the roasting process of ammonium molybdate is accompanied by the generation ...

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Problems solved by technology

However, the sieve after passing molybdenum trioxide through a 40-mesh sieve seriously affects the follow-up production of molybdenum products due to poor fluidity, severe and hard agglomeration, high moisture content, and obvious color differences.

Up to now, high-quality molybdenum powder cannot be prepared from the sieve by the conventional hydrogen reduction process. There are two main reasons. The feeding method of screw feeding is adopted, and the sieve material behind the national 40-mesh sieve of molybdenum trioxide is often stuck in the screw feeder due to the larger block particles, which causes damage to the equipment and leads to production paralysis; the other is that even if Using a push-type multi-tube furnace, because the particle size of the sieve is too large, and the core of the particles is hard due to the existence of water, the hydrogen reduction process cannot fully react, resulting in oxygen, potassium, sodium, etc. in the molybdenum powder produced. The content seriously exceeds the standard and cannot meet the technical requirements of molybdenum processed products

[0005] The method commonly used in the current industrial production is to return the molybdenum trioxide through the 40-mesh sieve to the molybdenum trioxide production line for re-roasting treatment, which leads to a significant increase in energy consumption and cost; or the sieve Shangwu is regarded as inferior product and sold at a reduced price, causing a large loss of profits for the production company

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