OXY-COAL INJECTION AT CLEVELAND IRONWORKS

This paper presents the technical background and progress to date of the joint British Steel/Hoogovens/ILVA project to demonstrate the feasibility of high rates of coal injection (up to 400 kg/thm) at Cleveland Ironworks. The project, which is supported by the ECSC (European Coal and Steel Community) commenced in April 1988 and comprises two years pilot plant studies and plant installation/commissioning, followed by two years works trials. Before the ECSC supported programme, a pilot blast furnace had been constructed at Teesside Laboratories specifically to test oxy-coal injection. The two tuyere furnace has a nominal capacity of 100 kg h-1 with a hearth diameter of 0.5 m. The unit was used to demonstrate injection rates in excess of 400 kg/thm with an all oxide burden and coke rates of less than 250 kg/thm with a burden containing directly reduced iron. The Cleveland merchant ironplant produces foundry iron (1.5-4 wt-%Si) and ferromanganese. The trials are being performed on no. 4 furnace which has a 5.6 m hearth, 12 tuyeres, and an effective volume of approximately 600 m3. The plant has been equipped with coal injection facilities, oxygen injection facilities, and enhanced instrumentation and data gathering equipment. In addition, movable throat armour has been installed to give improved burden distribution control. Plant trials are performed during the foundry iron campaigns, which are typically 10 weeks in duration and are separated by ferromanganese campaigns of about 15 weeks. The first trial was performed in May-June 1990 and comprised equipment hot commissioning and increase of the coal injection rate to 150 kg/thm. The second trial took place in November-December 1990 and demonstrated stable operation at 250 kg coal/thm. The third trial took place from late May to early July 1991 and included stable operation at a coal injection rate of 300 kg/thm. The final trial to demonstrate higher levels of injection has been scheduled for 1992.