The actual period of magnesium during World War II varies depending on what country is mentioned. Traditionally, in the U.S., 1941 is considered as the starting time of the war, but for Europeans and others, the time was much earlier.
Table 1. World production of magnesium in 1938
Source: The History of Magnesium, Major CJP Ball
The German industry was quietly developing magnesium production in the 1930's. By 1938, they produced more magnesium than the total of all of the magnesium producers in the world. The military need for magnesium in Germany required the continued expansion of the industry to a peak of 34,000 tons per year (tpy) in Germany itself. The Germans also built new plants at Mossienbaum, Austria, 20,000 tpy and at Heroya, Norway, 10,000 tpy. Another plant of 24,000 tpy capacity was built at Vienna, Austria, but was destroyed by bombing before completion. In 1944, the plants operating in Germany were Aken, 12,000 tons; Stassfurt, 12,000 tons; Bitterfeld, 4,000 tons; Heringen, 6,000 tons. (9)
In Great Britain, magnesium production was expanded by fully utilizing the existing magnesium plants and by expanding on the existing technology. The production reached a peak in 1943 at 32,000 tons divided up between Magnesium Elektron with 10,000 tons at Lowerhouse; 5,000 tons at Clifton Junction; Murex, Ltd, 6,000 at Rainham; 5,000 tons at Moss End; Magnesium Metals, 1,000 tons at Swansea; International Alloys, 5,000 tons at Cardiff.
Australia, in 1941, built a 1,000-tpy magnesium production plant using the Murex process (thermic reduction of magnesite with calcium carbide). The production never reached rated capacity and the plant, operated by BHP, was shutdown in 1944.
In Switzerland, the plant at Maartigny-Bourg produced magnesium in small quantities until 1947.
In Italy, in 1939, the Samis/Aosta Company was formed to operate the I.G. dolomite-ferrosilicon thermal reduction process. It produced 350 tpy until 1945 when it was closed. The Societe Anonima Italiana per il Magnesio e Leghi de Magnesio was founded in 1938 to erect a plant at Bolzano to operate the Amati process for the extraction of magnesium from the oxide. The Amati process used large internally heated retorts with special large briquettes placed on trays and lowered into the retort. Condensed magnesium crowns from this process were reported to weigh over 450 kg. This plant reached an output of over 4,000 tpy at its peak in 1943. (9)
In France, two modern plants improving on the original electrolytic plants were built at Jarrie, Isere and St. Auban in the Basses-alpes. These plants produced 3,000 tpy using the I.G. process during the first part of the war. During occupation, the plant production dropped to 400 tpy. Lab work done on a thermal reduction process in the 1931-1938 period, but no plant was built. This work was the basis for the Magnetherm process installed in 1964. (9)
In Japan, in 1942, there were six plants producing magnesium. Two plants in Korea and one in Taiwan were operated by Japanese companies. The metal produced in these plants was obtained from magnesite and brines by electrolysis and carbothermic production. Seawater was not used and no silicothermic methods were employed. Production of magnesium by the Japanese doubled during World War II and all of it was used as an alloying element in aluminum, for fighter planes (mainly the Zero), in pyrotechnics, and other war materials. By December 1945, 16 plants were operating in Japan, Korea, and Taiwan to supply Japan's war requirements. (9)
The 10,000-tpy German plant built in Norway in 1940 only operated for several years and was destroyed by bombs.
During the war, Russia increased magnesium production at Solikamsk. The plant at Zaporozhye, in the Dnieper Basin, came under danger from attacking forces. Much of the equipment was moved and key members of the plant staff were transferred to Solikamsk to assist in expanding magnesium production. After the close of the war, the 12,000-ton capacity plant at Aken in East Germany and the 20,000-ton capacity plant in the Soviet zone in Austria, were dismantled and taken to Russia. (10)
The largest major expansion of magnesium production came in the U.S. during 1940-1943. In 1940, Dow doubled the size of their Midland , Michigan plant which used brine for the source of magnesium chloride. At the same time, Dow started construction of its Freeport, Texas plant, which would use seawater as a magnesium chloride source. From 1941-1943, 15 magnesium plants were built in the U.S., 13 by the U.S. government. Of these, eight employed electrolytic processes, six used silicothermic processes, and one used the carbothermic process. U.S. production capacity reached 291,000 tpy in 1943.
In Canada, Dr. L. M. Pidgeon of the Canadian Research Council developed the thermal process that became known as the Pidgeon Process. This process used calcined dolomite and 75% FeSi ground, blended and briquetted into pellets that were charged into closed end, externally heated retorts. A 5,000-tpy plant was built at Haley, Ontario and quickly ramped up in production. This plant is still in operation today.
Table 2. Magnesium production capacity in 1943
Source: Magnesium & Magnesium compounds, IC 8201, US Bureau of Mines, 1963.