The method of oxidizing roasting pellets

摘要

1439488 Heat treatment of magnetite ores ALLIS-CHALMERS CORP 28 Sept 1973 [4 Oct 1972] 45482/73 Heading C1A Hand discrete pellets are produced from "green" pellets of finely divided magnetite ore by transporting on a travelling grate through at least drying and pre-burning stages so that 60- 80% Fe 3 O 4 is oxidized to Fe 2 O 3 , tumbling in a rotating kiln fitted with a fuel burner (gas stream at 2100-2450‹ F.) so that a further 2-10% Fe 2 O 4 is oxidized, discharging the pellets (at approx. 2400‹ F.) to a cooler divided into zones, air being provided in the first and second cooler zones to complete the oxidation of the Fe 3 O 4 , heated air from the first cooler zone being used in the kiln and then in the pre-burner and drier, heated air at 600-700‹ F. from the second cooler zone being used in the drier. The pellets may be transported through the cooler on a second travelling grate. The drying zone may be subdivided into two zones and air from the second cooler at 600-700‹ F. used in either or both.