Process for preparing metal magnesium by normal pressure thermal reduction method

Abstract

The invention belongs to the field of non-ferrous metal metallurgy, and relates to a process for preparing metal magnesium from a serpentine mineral serving as a raw material by a normal pressure thermal reduction method. The method is characterized in that: the serpentine mineral is taken as the raw material, calcium carbide is taken as a reducing agent, calcium oxide is taken as an auxiliary agent, calcium fluoride is taken as a catalyst, and thermal reduction reaction is performed under normal pressure so as to obtain magnesium vapor. The method comprises the following processes of: firstly, calcining the serpentine mineral at the temperature of between 500 and 750 DEG C to remove crystal water; secondly, mixing calcinate, the calcium carbide and the calcium oxide in a weight ratio of 30-60:24-50:7-20, adding 5 to 10 weight percent of catalyst and pressing the mixed materials into pellets under the pressure of 50MPa; and finally, feeding the pellets into a reduction furnace, raising the temperature to 1,000 to 1,200 DEG C, reducing magnesium in the pellets to obtain the magnesium vapor and condensing into a magnesium crystal in a magnesium condenser. The process can be performed under normal pressure, decarburization is not needed in the whole reaction process, and the process is low-carbon and environmental-friendly.

Description

technical field [0001] The invention belongs to the field of nonferrous metal smelting, and relates to a method for preparing magnesium metal by thermal reduction under normal pressure conditions by using serpentine minerals as raw materials and calcium carbide as a reducing agent. Background technique [0002] Magnesium is one of the widely distributed elements in the earth's crust. It has excellent physical properties and is widely used in aerospace, transportation, microelectronics and other fields. It is known as "the green engineering material with the most development potential and application prospects in the 21st century." . [0003] The industrial production of magnesium mainly includes electrolysis method and silicothermal method (Pidgeon method). The electrolysis method generally uses anhydrous magnesium chloride as the raw material, and the metal alloy is the cathode and anode. Direct current electrolysis is introduced in the molten state of magnesium chloride, a...

AI Technical Summary

Problems solved by technology

However, the technical and economic indicators of silicothermal magnesium smelting are not ideal, and there are mainly the following main problems: 1) The quality requirements for raw materials are high. At present, only dolomite ore can be used, and its magnesium oxide and magnesium content are far lower than Serpentine; 2) The cost of ferrosilicon as a reducing agent is relatively high; 3) The reduction reaction requires vacuum conditions, which makes it difficult to achieve continuous production, and the production scale of the magnesium plant is small; 4) The reduction temperature is high, the service life of the reduction tank is short, and the production High cost; 5) Energy waste and environmental pollution are serious, and the growth of magnesium production is at the expense of the environment and resources

[0005] It can be seen from the above technical background that most of the currently researched processes for producing magnesium metal need to be carried out under vacuum, which is difficult to achieve the purpose of continuous production and scale expansion, and most of the raw materials required for the preparation of magnesium metal currently use magnesium oxide and its mineral dolomite or magnesite, while serpentine, another magnesium-rich mineral, has been poorly studied

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