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The processes of formation and melt-down of the softening-melting zone are discussed based on the results of dissection of water-quenched blast furnaces.

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Syn op sis The jJrocesses oj Jormation and melt-down oj the softening-meltillg zOlle discussed based on the results oj dissection oj water-quenched blast Jurnaces. (I) Iron ore granules oj 1111 ore layer are gradllal(y transformed Jrom lumpy to softenillg and then half-mollell state and jillalfy molten dowlI. T his transformation is mainfy ifected by hot reducing gases passing through the ore layer. (2) T wo p rocesses m~y be considered Jor metal melt-down. Gne is the Jormation oJ" icicles" }Tom a mixture oj metal lJarticles and molten slag. Th e other is the rapid carburization oj the metallic iron which contacls hot coke at about 1 500"C. Silicon is 1I0t yet transferred into the metallic iroll in either oj these IJrocesses. (3) The origillal slag Jormed ill granules ~f pellets and lumpy ore is rich ill F eO. After the separa tioll oj grallules, it blends with slag Jrom sinter. The cOlllellt oj FeO ill the slag blend further decreases by gas reductioll. COllsequentfy, the F eO content oj the slag just bifore melt-dowlI is onfy a Jew I}ercellt. (4) The compositiolls ~f dropped metal and slag evidentfy chanRe after the shut-dowlI oj the blast. T herifore, it is very difficult to estimate the change in comj}ositioll during the dropping process.