386 



UNITED STATES MINERAL RESOURCES 



the whole industrial capacity of the world. When we 

 can do without steel, we can do without manganese. 



Manganese is introduced in the steel-making proc- 

 ess primarily as the alloy ferromanganese (about 78 

 percent Mn, 15-18 percent Fe), as spiegeleisen 

 (about 15-20 percent Mn, the rest largely Fe), as 

 silicomanganese (about 66 percent Mn, 12-20 per- 

 cent Si), or as manganese metal added to the con- 

 verter of whatever type may be used or to the ladle. 

 Ferromanganese, which accounts for more than 75 

 percent of consumption, is made by smelting an ore 

 with a Mn/Fe ratio of 7 : 1 or greater. For a succinct 

 discussion of the consumption, uses, and processes 

 involved in the manganese industry, the reader is 

 referred to the manganese chapter in the U.S. Bu- 

 reau of Mines publication "Mineral Facts and Prob- 

 lems" (Sheridan, 1970). 



The United States is now completely dependent 

 upon foreign sources of manganese, for the last 

 domestic manganese mine closed in 1970. 



Salient data from U.S. Bureau of Mines Minerals 

 Yearbooks on domestic and world production of man- 

 ganese ores and domestic consumption of ferroman- 

 ganese and imports of these materials are given in 

 table 74. 



Table 74. — Production, imports, and consumption of man- 

 ganese ore and concentrates and ferromanganese, 1966, 

 1970, and 1971, in millions of short tons 



Ore and concentrates: 



Domestic production, >35 percent Mn 0.014 



World production, >30 percent Mn 19.1 



Imports, >35 percent Mn ^- 2.6 



Ferromanganese : 



Domestic consumption 1.0 



Imports for consumption .25 



Principal suppliers of manganese ore to the United 

 States in 1971 were (in order of importance) : Brazil, 

 Gabon, Republic of South Africa, Zaire (ex-Kinshasa 

 Congo) , and Ghana. Principal suppliers of ferroman- 

 ganese were the Republic of South Africa, France, 

 and India, in that order. In 1970, manganese ore was 

 produced by 40 countries, of which 11 produced 96 

 percent, six produced 84 percent, and three produced 

 63 percent. With the exception of a few hundred tons 

 of ferromanganese imported from Yugoslavia, none 

 of the U.S. manganese supply in 1971 came from the 

 socialist countries. 



EXPLOITATION 



The necessity for manganese in the steel-making 

 process to avoid brittleness in the steel was recog- 

 nized in 1856 by Mushet, whose discovery made the 



Bessemer converter practical. Since then, increasing 

 world production of manganese has closely paralleled 

 that of steel. In the middle of the 19th century, the 

 United States was largely self-sufficient in man- 

 ganese. Major deposits were found in the U.S.S.R., 

 Brazil, and India in the late 19th century, and large 

 deposits were found in Africa, Brazil, Cuba, and 

 Mexico in subsequent decades. The most recent sig- 

 nificant discoveries were those in Amapa, Brazil 

 (>30 million tons), and the Kalahari basin. South 

 Africa (> 3,000 million tons), in the 1940's, in Gabon 

 (200 million tons) in the 1950's, and at Groote Ey- 

 landt in Australia (about 75 million tons) in the 

 1960's ; the carbonate deposits of Molango, Mexico 

 (>15 million tons), were also discovered in the 

 1960's. Despite unparalleled consumption since World 

 War II, known reserves of commercial-grade ore are 

 now far greater than at any time in the past; the 

 grade of the ore used is nearly as high as it ever was, 

 and the price is lower in constant dollars than for 

 many years. 



Production from various sources in the United 

 States in the 20 years from 1943 to 1963, the period 

 of maximum production, is shown in figure 45. It 

 should be remembered that the curve entitled "Low- 

 grade purchases for stockpile" represents noncom- 

 mercial manganiferous material, most of which con- 

 tained 15-17 percent manganese, that was then and 

 is still unusable as a source of manganese without 

 concentration. This production, the carlot purchases, 



TT 



Manganese ore production 

 (as defined by U.S. Bureau 

 of Mines) 



Productio 

 (All below 

 by Th 



1943 1945 1947 1949 1951 1953 1955 1957 1959 1961 1963 



Figure 45. — Domestic manganese ore production (metallurgi- 

 cal grade), 1943-63, distributed according to sources of 

 output. Modified from Brooks (1966, p. 75). 



