Campaigns and relines of blast furnace no 1 at the Oita steelworks of Nippon Steel Corp

Objective. In January 1993, blast furnace no. 1 at the Oita steelworks ended its second campaign after an operating period of 13.5 years. It was immediately relined for a third furnace campaign. Described are the 23 years of operating experience and the evolution of the blast furnace unit since its commissioning in 1972. One of the aims of the third campaign is to achieve a life span of more than 15 to 17 years. Summary. When blown in for the first time on 19th April 1972, blast furnace no. 1 in Oita had a hearth diameter of 14.0 m. Its life during the first campaign spanned 7 years, and during the second campaign 13.5 years. The amount of hot metal produced from 1972 to 1993 was 20.5 mill. t in the first campaign and 40.8 mill. t in the second campaign. When the second reline for the third campaign was carried out, many new operating techniques were adopted. The main techniques include a thin stack lining incorporating newly developed, so-called fourth-generation staves, automation of the casthouses, slag granulation by means of screw conveyors, dry gas cleaning in bag filters, etc. After modernisation and enlargement to a hearth diameter of 14.7 m, blast furnace no. 1 was blown in for a third time on 18th May 1993. Its hot metal production in October 1994 was around 11,500 t/day.