Three methods of producing metallic magnesium
Magnesium metal is a new light corrosion resistant metal material developed in the twentieth century, the application of magnesium metal is mainly concentrated in magnesium alloy production, aluminum alloy production, steel desulfurization, aviation and military four fields, widely used in automobile manufacturing, light industry, metallurgy, chemical industry, electronic industry and instrument manufacturing. Magnesium alloy's excellent performance and beautiful posture are favored by computer, home appliances, mobile phones and other manufacturers.
Magnesium metal has low specific gravity, high strength per unit weight, high chemical stability, so that aluminum magnesium alloy and magnesium die casting are popular, magnesium metal industry has been rapid development. Magnesium alloy has the advantages of high strength, heat resistance, wear resistance and light weight, making it gradually replace plastic products and heavy steel parts in the automobile industry, mainly replacing the original engine, steering wheel, seat base and so on. General Motors, for example, has 15 pounds (6.8 kilograms) of magnesium molded parts in its Polaris V-8 engine, which it assembles in Cadillacs. In the mid-1990s the company was making 25,000 to 30,000 cars a year and needed magnesium for that alone. Demand from General Motors (GM), which produces more than 9m cars a year, and Toyota (TM), which produces almost as many as GM, is enough to keep the industry excited.
There are three main methods to produce magnesium metal by silicon thermal method:
(1) Pijiang method: first of all, the dolomite is calcined and mixed with ferrosilicon and fluorite to make pellets, and then it is heated and reduced in a vacuum furnace at 1100℃ to generate magnesium vapor and other substances, and then the magnesium vapor is condensed and recycled into magnesium ingot. The production of magnesium metal by this method has high energy consumption and heavy operation.
(2) Magnetherm method: This method is to reduce the calcined dolomite of the group with ferrosilicon in a sealed arc furnace with carbon graphite lining and fixed graphite electrode, and to produce magnesium metal by adding bauxite or alumina as flux. This method has low raw material consumption, high yield and less environmental pollution. Disadvantages are poor product quality, high silicon content, long non-production time.
(3) BolGNAO method: the calcined dolomite and ferrosilicon are released into the internal thermal vacuum reduction furnace through the pressure group, and the magnesium metal vapor is condensed into magnesium metal externally by electric heating (reduction temperature is generally 1250℃). Dolomite magnesium smelting in addition to the above methods and horizontal vacuum graphite resistance reduction furnace silicon heat and so on
