The Behavior of Softening and Melting of Hematite Pellet and Sinter during Heating in a Reducing Atmosphere

Abstract

The softening and melting characteristics of some pellets and sinter during the reduction and the heating were examined by using an X-ray TV apparatus. The structure of the samples after the experiment were also examined by a microscope and an electron microprobe analyzer. For the runs without load, the melt-down temperatures varied from 1 250 °C to the melting point of iron according to the reducing conditions and rose with the increasing reduction degree. An application of load lowered the melt-down temperature of each sample, which strongly depended upon the properties of the formed slag. The EPMA analysis shows that the slag containing a small amount of iron oxide is formed in Hirohata P. of high melt-down temperature, but much iron oxide, about 50 %, is contained in the slag formed in Robe River P., which melts at a low temperature.

The effects of MgO and Al2O3 behaviours on softening–melting properties of high basicity sinter

“…The cohesive zone in terms of thickness and position mainly determined by softening-melting properties of burden is the most important factor to determine the operation stability and productivity of blast furnace [8]. A large number of investigations on softening-melting properties of pellet have been conducted, thus softening-melting mechanism of pellet has been clearly understood [9][10][11][12][13][14][15]. The improvement of dripping temperature [16], softening temperatures [17] and permeability [18,19] of sinter during reduction with increasing basicity were also reported.…”

Experimental study of thermoplastic properties of agglomerate

“…Its shape, thickness and position significantly affect furnace productivity and fuel efficiency. The temperature properties of iron ore burden are essential, given the creation of blast furnace melting-softening zone [3,4]. Usually, consideration is being given to the softening starting temperature, softening finishing temperature and melting temperature which are defined as the temperature at which burden pressure drop is about 1 kPa or burden contraction reaches 4 -10 %, as the temperature whereupon pressure drop falls down to 0.5 kPa or contraction attains 40 %, and as the temperature when pressure drop progresses significantly [3,5].…”

A review of high-temperature experimental techniques used to investigate the cohesive zone of the ironmaking blast furnace

“…a transition from granular to softened material, and finally to molten liquids, through further heating and reduction [4]. Characterisation of the softening and melting (S&M) behaviour of ferrous burden materials began in the early 1940s [5][6][7][8]; however, the major breakthroughs in understanding the BF's complex internal process phenomena really only occurred in the 1970s, when several Japanese BFs were quenched and dissected to investigate their internal conditions [9][10][11]. Several distinct zones, including the CZ, were identified in these investigations, through examining the chemical and physical characteristics of ferrous materials at different stages of reduction and morphology.…”

“…It is clear that the CZ plays a key role in BF operations, given that its shape, thickness and position significantly affect both fuel efficiency and furnace productivity [12]. Aside from operational control actions, such as ore/coke ratio distributions, the formation of the CZ is thought to be governed by the S&M properties of ferrous burden [6]. Subsequently, various methods were developed to study the S&M characteristics, including high-temperature experimentations, physical models or simulators, as well as various numerical simulations of the BF [6][7][8][12][13][14][15][16][17][18][19][20].…”

“…Aside from operational control actions, such as ore/coke ratio distributions, the formation of the CZ is thought to be governed by the S&M properties of ferrous burden [6]. Subsequently, various methods were developed to study the S&M characteristics, including high-temperature experimentations, physical models or simulators, as well as various numerical simulations of the BF [6][7][8][12][13][14][15][16][17][18][19][20]. Most experimental studies use laboratory-scale furnaces run under simulated BF conditions [12][13][14][15][16][17][21][22][23][24], allowing either the routine assessment of ferrous burden materials or a better understanding of their behaviours in the CZ.…”