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While Dow has been pioneering the extraction of magnesium from water, others have been studying how to extract magnesium from rock. TVA scientists are working on the Carolinas' abundant magnesium silicate called olivine, of which 27% is recoverable magnesium (in contrast to sea water's .1%). When this ore is mixed with hydrochloric acid, magnesium chloride is formed which can be treated by electrolysis just like that from water. Because olivine is so rich in metal and TVA power sells cheaply, experiments have been launched at Georgia Tech in the hope of making this a major U.S. source of cheap magnesium.
Danger Up, Price Down. A radically different "carbothermic" process is being tried in the West on two other very common ores, brucite (Mg(OH)2) and magnesite (MgCO3). When either of these is baked it forms magnesium oxide, and the trick is first to vaporize this by heating it to 3,800° F. in the presence of carbon and then cool it to around 380° in 1/1000th of a second with a blast of cold gas. During the heating, the carbon takes the oxygen away from the magnesium, and during the cooling the magnesium is precipitated as a fine powder too fast to recombine with the oxygen. This is called the Hansgirg process, and RFC has financed a $9,250,000 plant at Los Altos, near Palo Alto, Calif., to make 15,000 tons a year. The difficulty with the process is that the hot powdered magnesium is violently explosive. Already there has been a fatal magnesium explosion at Los Altos.
A variation of this process is being perfected by Metallurgist Henry Alfred Doerner of the U.S. Bureau of Mines who claims that when a chill spray of oil is substituted for the Hansgirg cooling gas the magnesium is rendered nonexplosive by an easily removable oily film which forms on the powder grains. The process has been developed at Washington State College and will probably be used in a 12,000-ton plant at Spokane where magnesium deposits adjoin Grand Coulee's cheap power.
The backers of both these processes hope to get magnesium for 12¢, 10¢, perhaps even less a pound. Dow is skeptical about the Hansgirg process (Dow turned it down), but Dow itself has cut the price of magnesium from $5 in 1915 to 50¢ in 1925 to 30¢ in 1931 and is said to have sold magnesium to Germany before the war as low as 21¢ a lb. Dow's magnesium costs are inextricably tied up with other chemicals, notably bromine, which are recovered simultaneously. If some of Dow's first costs can be written off against emergency production for rearmament, most chemists expect Dow can keep its prices well in line with competition.
Blown Up, Flown Up. Although powdered magnesium is explosive, solid magnesium is no more combustible than aluminum or iron, both of which also burn in foil or powder form. (To prove this point one metallurgist went about smoking a magnesium pipe.) But today less than 5% of U.S. magnesium goes into military pyrotechnics and scavenging; 95% goes into definitely nonflammable alloys of which about 80% goes into airplanes.