Investigation on the Dripping Behavior of Primary Slag Melt in the Cohesive Zone of the Blast Furnace Through Iron or Oxide Funnel

报道了日本进口铁矿石中氧化铝含量逐年增加，高铝烧结矿的使用给高炉运行带来的一些问题。由于日本炼铁公司使用的铁矿石全部从澳大利亚、巴西等海外进口，因此应尽快解决矿石品位较低所带来的问题。由于高炉内的现象十分复杂，目前还不清楚氧化铝对高炉运行有害影响的真正机理，但一般认为，烧结矿中的氧化铝主要对烧结矿还原过程中形成的初熔体的行为起重要作用。在此背景下，本研究旨在阐明氧化铝对高炉运行有害影响的机理。采用炉渣通过铁漏斗或氧化物漏斗滴入的方法，模拟了在高炉黏结区烧结中形成的初熔体的行为。讨论了碱度、A12O3和Fe_tO_< bbb_o含量对五种炉渣滴料温度和漏斗截住率的影响。研究发现，在烧结矿中形成的共晶熔体对炉渣在高炉中的滴落行为或炉渣在还原铁和矿石颗粒细孔间的滞留现象起着重要作用。Al_2O_<>增加了熔渣在漏斗上的保持度，在酸性和低Fe_tO_< bbb_o的渣中其作用尤为显著。分析认为，随着Al_2O_<>的矿渣率的增加，会对烧结矿的抗渗性能和间接还原率产生不利影响。

Alumina content in the iron ore imported to Japan is increasing year by year and some problems for the blast furnace operation due to the use of the high alumina containing sinter are reported. Since all of iron ore used in Japanese iron making companies is imported from overseas such as Australia, Brazil and so on, the problems caused by the lower grade ore should be solved as soon as possible. Though the true mechanism of harmful effect of alumina on the blast furnace operation is not known up till now due to the very complex phenomena in the blast furnace, it is generally considered that the alumina in the sinter would act the important role mainly on the behavior of primary melt formed in the sinter during the reduction. Keeping such background in view, this study aims to clarify the mechanism of harmful effect of alumina on the blast furnace operation. The behavior of primary melt, which is formed in the sinter at the cohesive zone of the blast furnace has been simulated by dripping molten slag through iron or oxide funnel. The effects of basicity, A12O3 and Fe_tO_<>O contents in the five kinds of slags on the dripping temperature) and hold-up on the funnel have been discussed. It was found that the eutectic melt formed in the sinter would play important role for the dripping behavior of slag melt in the blast furnace or hold-up phenomenon of slag melt among fine pore in reduced iron and ore particle. Al_2O_<>increases the hold-up degree of the slag melt on the funnel and its effect becomes much significant in the acidic and low Fe_tO_<>O containing slag. It was estimated that the increase of the slag hold-up by Al_2O_<> in the ore could result in the harmful effect on the permeability resistance and indirect reduction rate of the sinter in the blast furnace.