Method for preparing magnesium metal by calcined dolomite through carbon-thermal reduction

Abstract

The invention relates to a method for preparing magnesium metal by calcined dolomite through carbon-thermal reduction, which has the characteristics of energy saving, low carbon and environmental protection. The calcined dolomite is employed as a raw material, coke, coal or petroleum coke are taken as a main reducing agent, a functional material A is selected as an auxiliary reducing agent and a catalysis flux, and a functional material B is a displacement-type catalysis flux. The method comprises the following steps: fragmenting and pulverizing calcined dolomite, coke and the functional material A and the functional material B, mixing materials for molding and filling in a reduction jar, performing vacuum reduction under vacuum degree of 1-20Pa and reduction temperature of 1200-1300 DEG C to obtain the crude magnesium with purity of more than 91%. According to the invention, coke is taken as the main reducing agent for substituting ferrosilicon with high energy consumption, the by-product gas is taken as heat source of a production system, the production cost for magnesium metal by the technology in the invention is lower than that of the magnesium metal by a pidgeon process by more than 30%, production cycle is shortened to 8 hours from 12 hours, equipment utilization rate is increased, and characteristics of low carbon, energy saving and environmental protection are the most important highlights.

Description

[0001] 1. Technical field: vacuum metallurgy. 2. Background technology: [0002] From 2000 to today, China’s magnesium metal enterprises have turned to the 10,000-ton level, and their total production capacity has exceeded 800,000 tons / year, while the world’s magnesium metal consumption is more than 600,000 tons / year, which means that the supply exceeds demand It is an indisputable fact, how to solve this contradiction and make the enterprise out of the predicament, focus on analyzing magnesium smelting by silicothermal method (Pidgeon method) and smelting magnesium by carbothermal method. [0003] 1. Silicon thermal method (Pidgeon method) Pidgeon method for magnesium smelting is a method commonly used in China. Its advantages are: ①The scale can be large or small, and raw materials can be obtained locally; ②The cost is relatively low compared with the electrolytic method; ③The technology is not difficult to master; ④The economic benefits were considerable in the 1990s; ⑤The ...

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Problems solved by technology

Disadvantages of the Pidgeon method for magnesium smelting: 12-14 tons of dolomite is required to produce 1 ton of metal magnesium ingot; 8-10 tons of anthracite and bituminous coal are consumed; 5-6 tons of by-product reduction slag have not been found so far. Use, pollute the environment; labor intensity is high, and the dust pollution in the raw material workshop is serious

[0004] Carbothermal magnesium smelting, a device was built in Europe and the United States in the 1920s and 1930s, and its reaction temperature was as high as 2300 ° C. At this temperature, the by-product CO and There is a reversible reaction in the reduction of magnesium. When the reaction temperature exceeds 1300°C, the reversible reaction increases rapidly. When the reaction temperature increases by 10 degrees, the reaction speed increases by 2-3 times; the reacted magnesium powder and high-temperature CO are also prone to explosion. At the same time, such high-temperature gas separation. The cooling equipment is too complicated. In the 1950s, the carbothermal magnesium smelting enterprises have all stopped production, but the research on carbon reduction magnesium smelting has not stopped since the last century. The main progress is the use of magnesium oxide and carbon Reduction, the reduction temperature is higher than 2300 °C, and the temperature is higher than 1300 °C. Jiangfa magnesium smelting stainless steel reduction tank will soften and have no strength. This type has only built some experimental devices and has no industrialization. Because of the cost of ferrosilicon as a reducing agent Too high is not conducive to the survival of magnesium enterprises in the society, so the invention and smelting technology of energy-saving and environment-friendly carbon reduction magnesium smelting must be carried forward

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