New Magnesium Methods

New production peaks were being reached last week in magnesium, vital war metal in flares, tracer bullets, incendiary bombs (it burns) and airplane construction (it weighs a third less than aluminum). Magnesium figures are smoked with secrecy. But that there is a magnesium boom was clear from the remarks of WPB's magnesium production chief Philip Danforth Wilson in Mining & Metallurgy: "Of all the metals in the war program the demand for and production of magnesium have increased percentagewise the most. . . . 1939 production was 3,350 tons; the war program now provides for nearly 100 times, that amount annually."

When war came, Dow Chemical Co. was the only domestic producer pouring the silver-white ingots in any quantity. Probably the Dow process, chemically and electrically cajoling the metal from Michigan brine wells and Texas sea water (TIME, Nov. 17, 1941), bulks largest in the new increased capacity. But in recent months new producers using other processes have swelled the total. Some use variations of the Dow method to recover magnesium from waste liquors of ammonia soda and. potash manufacture. Others are for the first time commercially smelting the widespread U.S. magnesium ores.

Several of the new magnesium makers (Ford among them) use the little-known ferrosilicon process developed by Canada's Lloyd Montgomery Pidgeon. Requiring minimum plant-construction time, the Pidgeon process has been recommended by the National Academy of Sciences as promising the quickest yield with the least risk. Unlike electrolytic methods, it does not require great power. Since it uses dolomite (magnesium-calcium carbonate, one of the most plentiful limestones), plants can be almost anywhere.

At Ford, dolomite is powdered, calcined (burned in a kiln) and mixed with ferrosilicon--an electric-furnace product of silicon and iron long used in steelmaking. The mixture is pressed into briquettes and charged into furnaces. When these are heated under vacuum, magnesium vapor is given off, and it crystallizes as on removable steel sleeves.

Also important in the magnesium boom is the electrolytic process of Basic Magnesium's gargantuan plant near Las Vegas, Nev. This method was originated in Germany by I. G. Farbenindustrie and also successfully used in England. Magnesite (the carbonate), plentiful and high in metal content, is calcined, then converted to the chloride from which the metal is reduced electrolytically. Now operated for the Government, the plant has been shipping magnesium since August.

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