GB1139373A - System for producing carbonized and prereduced iron ore pellets - Google Patents

Abstract

1,139,373. Iron ore pellets. McDOWELLWELLMAN ENG. CO. 2 Feb., 1967, No. 5171/67. Heading C1A. [Also in Division C7] Partially reduced iron ore pellets are produced by (a) mixing the ore with a flux and carbonaceous material, (b) forming moist pellets ¢-1¢" in diameter, (o) charging the pellets on to a travelling grate to form a bed 10-20 inch deep, through which heating gases are passed, (d) passing the pellets through a drying zone at 300-600‹ F., (e) passing the pellets through a zone at 1800-2200‹ F. in which carbonization and reduction of 15-40% of the Fe occurs, and (f) reversing the direction of gases in the latter part of the reducing zone. The ore mixture may be ground to -10 mesh (Tyler) with 50%-325 mesh, and pelletized in a rotating pan or drum with water and optionally binders, e.g. starch, sulphite liquor, lime, salts, or bentonite. The flux may be limestone and sand, and the carbonaceous material may be coke, charcoal, lignite, anthracite, or bituminous coal. The gas flow in (d), (e) and (f) is 200-300, 100-200, and 25-200, SCFM/sq. ft. of wind box area, resp. The exhaust gases from (e) may be mixed with air and recycled to the drying zone or used in step (f). The bed may be ignited in step (e) with a gas flame, air being drawn through the bed, or with recycled exhaust gases which have been passed through a burner and mixed with O 2 - depleted air or N 2 . The pellets may be further reduced to 60-90% free Fe in a subsequent zone at 2400-2500‹ F.