Development of the continuous dephosphorization and decarburization process using BOF

The authors propose a new refining process, by which hot metal is dephosphorized and decarburized continuously in the same basic-oxygen furnace, with intermediate deslagging following dephosphorization. After decarburization, slag is kept inside the furnace and reused to dephosphorize the next charge so as to minimize the quantity of slag discharge. Experiments were made to clarify the properties of this process, using an 8-ton experimental converter. The results confirmed high productivity or a higher rate of dephosphorzation achievable with an increased rate of oxygen blowing and the addition of iron ore. Because of the dephosphorization by low-basicity slag and the hot recycling of decarburization-slag to dephosphorize the neat charge, lime consumption was relatively low. The proper conditions of this process, such as the slag composition for dephosphorization, rate of oxygen supply, bottom agitation, and rate of intermediate deslagging, are also discussed, based on the experimental results.