Since the introduction of the pure oxygen top-blowing BOF to Japan in 1957, the technology of BOF steelmaking, and the associated technologies, has advanced rapidly. The pure oxygen bottom-blowing BOF (Q-BOP) was introduced in 1977. The top-and bottom-blowing BOF (combined blowing process) was developed by each company because of the importance of direct agitation of molten steel. Recently, the BOF process has been further advanced to have multiple functions, such as hot metal pretreatment, introduced in l989~1), and other capabilities.In the beginning, the main refractories used in the BOF were dolomite-based bricks, such as stabilized dolomite or high-fired magnesia-dolomite, but damage due to thermal and structural spalling with slag penetration was a big problem. After that, magnesia-carbon bricks (hereafter, MgO-C bricks) were tested in the BOF in 1978, to better resist the operating conditions, with very good results. Consequently, the range of use of MgO-C bricks was rapidly expanded to include the whole lining, and that practice has continued to the present.
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