Magnesium-based alloys
These are normally delivered as alloyed ingots from the primary producers (see Magnesium Alloys Encyclopedia). Magnesium alloys are used for pressure die casting, structural applications, numerous lightweight applications (automotive, hand tools, computers, etc.), and where the metal's damping capacity is of importance. The magnesium-based magnox alloys are used in extruded form as canning materials in gas-cooled nuclear reactors (Calder Hall) because of their low neutron absorption area. Uses of magnesium for uranium and nuclear applications account for less than 1% of the market in the Western world.
Aluminum Alloys
Magnesium is largely used as an alloying element in aluminum alloys. Aluminum-magnesium alloys have improved ductility, enhanced resistance to saltwater corrosion, and improved cryogenic properties. User forms are ingots weighing 1-25 kg or sows weighing 250-500 kg. The market growth of this application depends on the growth of aluminum and the recycling efficiency of aluminum scrap, particularly beverage cans.
Desulfurization and Nodularization
In the iron and steel industry, magnesium is used for desulfurization and nodularization. Particulate magnesium, alone or blended with other ingredients is injected into crude iron melts. The typical magnesium consumption for desulfurization of low-iron steel is 0.5 kg per ton of steel. Magnesium also triggers the transformation of laminar carbon to globules in nodular iron. For this purpose, the metal is either added with ferrosilicon as an alloying element or directly in the form of lumps, impregnated coke, or granules. Magnesium has a modifying effect on nonmetallic inclusions in steel. Effect and user forms are currently being studied.
Chemical applications
These include the use of magnesium as a reagent in the production of titanium and zirconium by the Kroll process, the reduction of uranium fluoride to uranium metal, and the production of beryllium and hafnium. Titanium constitutes by far the largest user segment in this group, the magnesium being added in ingot form. Magnesium chloride from the Kroll process is electrolyzed to recover magnesium and chlorine. The normal magnesium requirement to compensate for losses is 0.1 t per ton of titanium.
Magnesium raspings for the production of metallic uranium have a specified limited content of boron, cadmium, and rare-earth elements including gadolinium, samarium, europium, and dysprosium.
The use of particulate magnesium, raspings, or turnings in Grignard syntheses has been declining, due primarily to restricted use of tetraethyl lead.
Powders
Magnesium powders gained importance during World War II, when large quantities were used for pyrotechnics and explosives. Currently, they are being used to (a) manufacture Grignard reagents, which are organometallic halides such as ethyl magnesium chloride (C2H5MgCl) used in organic syntheses to produce pharmaceuticals, perfumes, and other fine chemicals; (b) effect chemical reductions, as in the manufacture of beryllium and uranium; (c) act as a light source in flares and photoflash bombs; (d) modify metallurgical properties of other metals, such as in the production of ductile iron and the removal of sulfur from hot iron products of blast furnaces; and (e) function as additives in electric welding electrode flux. At one time, magnesium powders were extruded into sections for structural applications; however, they are no longer used for production of such parts.
Almost all powder is produced from pure magnesium, although some magnesium-aluminum alloy powder containing up to 50% aluminum is used for photoflash bombs and for desulfurizing hot metal. Powder is produced by a variety of methods of comminution of solid or liquid metal.
Other Uses
The electronegative character of magnesium is used for corrosion abatement as sacrificial soil and hot-water tank anodes. European restrictions on aluminum in drinking water have encouraged the use of magnesium anodes for hot-water tanks. Magnesium batteries for military purposes and rescue systems combine light weight and high energy content.
The precise end applications of magnesium alloys are regarded to in our Products/Uses section.
Besides commercial applications, which magnesium found in modern automotive, aerospace, and defense industries it is widely used in curing many complicated diseases. For more information on this topic, see the specialized article Magnesium in Medicine. |
