Abstract
Since its invention until the 1950s, the iron blast furnace was viewed as a strange ‘black box’. Its operation was largely empirical and much of the information needed for monitoring and control of the process was yet to be known. More complete information was needed concerning the process such as the reduction of iron-bearing raw materials, the distribution of materials throughout the stack, the size, location, and structure of the fusion zone, and the transfer of silicon, sulfur, and carbon to the slag and metal. Hence, to obtain a better understanding of the blast furnace process, some iron-makers came up with the idea of quenching the contents of the furnace following normal operations. This was done in a neutral nitrogen atmosphere. The quenched contents were then sampled for analysis. Thus, this paper was written to discuss such works, spanning from the early 1950s to the 1970s. Care has been taken to include most of their findings and readers who have a fair amount of iron-making knowledge should be able to see and understand the in-furnace phenomena as the ‘black box’ unfolds itself. Most of the text will be focused on two important studies into the matter, the first being the U.S. Bureau of Mines case in 1959 and the next being the Iron and Steel Institute of Japan (ISIJ) studies in the 1970s. The contribution of these works to modern day blast furnace operation is also discussed in the paper.