Bureau of Mines / Minerals yearbook: Metals and minerals 1978-79
Year 1978-79, Volume 1 (1978-1979)
Zlobik, Alvin B.
Slag: iron and steel, pp. 821-833 ff. PDF (824.2 KB)
821Slag-Iron and Steel Alvin B. Zlobik1 Combined sales and usage of iron and steel slag in 1978 and 1979 totaled 36.9 million tons2 and 35.8 million tons, respectively. Iron slags totaled 28.4 million tons in 1978 and 27.5 million tons in 1979; steel slag totaled 8.5 million tons and 8.3 million tons in these respective years. Total sales value for 1978, $101 million, was 23% higher than in 1977 and increased further to $111 million in 1979. Average value per ton of iron slag was $3.04 in 1978 and increased 10% to $3.35 in 1979. Average value per ton of steel slag increased 30% to $2.24 in 1979. DOMESTIC PRODUCTION Iron slags sold or used in 1978 increased 10% in tonnage to 28.4 million tons and 21% in value to $86.4 million. Sales/use of expanded iron slag increased significantly, 30% in quantity and 50% in value over that in 1977. Sales of iron slag in 1979 decreased 3% in quantity but increased 7% in value from that in 1978. The average value per ton of all iron slags in 1978 was $3.04 while the average value in 1979 was $3.35. Steel slags sold or used in 1978 and 1979 totaled 8.5 million tons and 8.3 million tons and had values of $14.5 million and $18.5 million, respectively. Pennsylvania, Ohio, and Indiana, in that order, were the leading producing States during the 1978-79 period. Steel slags were processed at 39 operations in 15 States during 1979. In 1978, approximately 75% of iron and steel slag products in the United States were shipped to market by truck; 82% were shipped by truck in 1979. Rail and waterway shipments averaged 12% and 4%, respectively, during the 1978-79 period. The remaining material was used onsite. CONSUMPTION AND USES There were no known imports or exports of iron or steel slags in the 1978-79 period. As usual, most domestic slags were consumed in the construction industry. Most salable iron slag banks in the United States have been exhausted, and the availability of iron slag is largely dependent on newly produced blast-furnace iron from iron and steel plants. An undetermined tonnage of steel slag banks exists. Before it can be utilized, some steel slag requires a natural aging process in order to minimize expansion, due to the hydration of free lime, during end use. Some iron and steel slags are high in metallic iron content and un suitable for sale to the construction industry; however, these high iron slags can be recycled to the blast furnaces. Air-cooled iron blast-furnace slag continued to be the most important slag product in terms of both tons processed and in the number of different types of use. Locally, iron slag is competitive with sand and gravel and crushed stone, principally for use as aggregate. Air-cooled iron slag shows excellent bonding characteristics when mixed with portland cement to make concrete. It also shows high stability when used in asphaltic concretes and high skid resistance when used in bituminous road surfacing.
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