Latest Blast Furnace Relining Technology at Nippon Steel

Nippon Steel's blast furnaces in operation are nine at present, reduced by half in number, compared to those in the middle of the 1970s when large blast furnaces of the 5,000 m 3-class inner volume began to be constructed. During that time, given the increasingly urgent imperatives for total-cost reduction, such as each furnace's upward flexibility in production, longer service life, labor savings, shorter relining periods, etc., we have vigorously pressed forward with the development and industrialization of corresponding equipment technologies. Some of the new equipment technologies achieved against this background include: the inner-volume expansion during relining, the hearth-wall life extension by the improved quality of carbon blocks, the shaft life extension by the adoption of copper staves, mechanization of cast house works, and shortening a relining period by the large block method. The application of these technologies has resulted in substantial functional improvement and life extension of blast furnaces, while at the same time making it possible to minimize production decrease needed during relining. This paper describes salient features of these latest blast furnace relining technologies.