Formation and Melt-down of Softening-Melting Zone in Blast Furnace

Abstract

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.