Jingsong Wang

Viscosity and viscosity estimation model of fully liquid slags in TiO2–Al2O3–CaO–SiO2 and TiO2–Al2O3–CaO–SiO2–MgO systems with high TiO2 concentration and low mass ratio of CaO to SiO2

Abstract The present paper focuses on the viscosity of high titanium containing slags in the process of titanomagnetite smelting by taking the TiO2–Al2O3–CaO–SiO2 quaternary system with TiO2 in the range from 23 to 43%, Al2O3 in the range from 3 to 12% and basicity (mass ratio of CaO/SiO2) in the range from 0·3 to 0·7 as the object. Experimental determinations of the viscosity were carried out in the temperature range from 1573 to 1873 K using the rotation cylinder method. The effects of TiO2, Al2O3, basicity and temperature on viscosity were studied. The experimental results indicated that the viscosity decreased with increasing TiO2 concentration and basicity, and increased with increasing Al2O3 concentration. Based on the experimental data of the TiO2–Al2O3–CaO–SiO2 quaternary system, a new viscosity model was proposed by modifying the Urbain model. The new model was applied successfully to predict the viscosity of TiO2–Al2O3–CaO–SiO2 and TiO2–Al2O3–CaO–SiO2–MgO systems in the fully liquid condition with high TiO2 concentration and low basicity over a wide range of composition and temperature using one set of model parameters.

Effect of high alumina iron ore of gibbsite type on sintering performance

Abstract The fundamental properties and utilisation feasibility in the sintering production of a newly developed commercial iron ore resource were studied at laboratory scale in the present work. The new iron ore contained medium iron content and high of alumina of gibbsite type. The ore is a typical limonite, which could help to reduce the production cost of hot metal. The assimilation and fluidity properties of the new kind of high alumina iron ore were investigated, comparing with other kinds of limonite and magnetite iron ores. The effect of addition of the iron ore on sintering process was also performed in a sintering pot, and the properties of the sinter samples were then examined. The results showed that the melt formation and fluidity properties of the high alumina iron ore were not good, and it had adverse effect on sinter quality. The yield and strength of the sinter samples gradually decreased with the increasing of high alumina iron ore blending ratio from 7 to 27·3 wt-%. The reducibility first increased then decreased, and the low temperature reduction degradation characteristics changed in an opposite trend correspondingly. The softening–melting property of the sinter samples also deteriorated in the experiment and might have a negative influence on the blast furnace operation.

Study on the interaction behaviour between lump and sinter under the condition of oxygen blast furnace

This research report describes the influence of the reducing atmosphere of oxygen blast furnace (OBF) and traditional blast furnace (TBF) on the softening and melting behaviour of lump and lump-sinter mixed burdens assessed by using the softening and melting test. The results reveal that in the OBF atmosphere, the softening and melting properties of lump ore is improved compared with that of the TBF, since the development of reduction degree increased the quantity of the iron phase in the burden particle, and decreased the quantity of slag phase with low melting temperature. In addition, the analysis on the microstructure of burden particles revealed that the interaction effect also occurred at the interface between lump and sinter particles in OBF case. Meanwhile, the scanning electron microscope images shows that the interface is still distinguishable when the samples of OBF case reached 60% contraction ratio (1379°C), whereas in the case of TBF, the interface almost disappeared above 40% contraction, and became completely undistinguishable at 60% contraction ratio (1290°C). This illustrates that, under the OBF condition, the starting temperature of interaction is raised, and the effect intensity is weakened.

Desulphurisation mechanism of direct reduction and melting in carbon bearing pellets

Abstract The iron nugget process which utilises carbon bearing pellets is a flexible, economical and environmentally friendly iron making process. Iron nuggets which have physicochemical properties similar to those of pig iron can be obtained in a short time through high temperature smelting reduction. Sulphur content has an important influence on the quality of the iron nuggets produced. The behaviour of sulphur in the carbon bearing pellets was studied during heating at 1450°C using chemicals of analytical reagent grade as raw materials. The effect of reduction conditions, such as reduction temperature, C/O mole ratio, reducing agent species, basicity and additive agent, on the sulphur content in iron nuggets and slag after separation was investigated. Sulphur disperses in pellets in the initial stage of reduction as a result of reagent mixing. As reduction and melting proceed, sulphur is accumulated at several points in iron and slag. Slag demonstrates a strong desulphurisation ability. Very high temperatures are not conducive for reducing the sulphur content in iron nuggets. Sulphur content in iron nuggets decreases with increasing C/O ratio, basicity and the addition of Na2CO3 as a desulphurisation agent. Iron and slag can be well separated to yield high quality iron nuggets by controlling the process parameters.

Reduction behaviour of ferrous burden under simulated oxygen blast furnace conditions

Abstract The reduction behaviour of sinter and pellets was investigated by a programmable reduction apparatus to simulate the traditional blast furnace (TBF) and the oxygen blast furnace (OBF). The starting temperature for reduction of sinter and pellet in the OBF decreased 60 and 150°C compared with that in the TBF and, by the time the temperature reached 1100°C the reduction degree of sinter and pellet was 100.0 and 98.7% in the OBF compared to 94.0 and 83.1% in the TBF. The trends of the reduction rate of sinter and pellet were consistent in OBF and TBF. There are two peak values at about 60 and 80 min and in the OBF the third peak value of pellet emerged at 40 min. In addition, the mineral microstructures of the ferrous burden were characterised by means of SEM and the area proportion of metallic iron zone was obtained by SEM photos.

Strength and high temperature behaviour of carbon composite pellets containing BOF fine dust

Abstract Steel plants produce significant amounts of dust and sludge during iron and steel production. These wastes contain valuable elements, such as Fe, Cr, Ni, C, K and Na and should be handled properly to prevent them from polluting the environment. In order to utilise the BOF fine dust, the effects of the dust on cold bonded pelletising, solid state reduction and reduction melting behaviours of composite pellets made from iron ore and anthracite with added BOF fine dust were investigated at laboratory scale. The BOF dust was found to improve the cold compressive strength of the wet green carbon composite pellet, and increased with increasing dust content. Almost four times the amount of dust was needed to get the same effect on the strength of the pellet when it was used to replace bentonite. The carbothermic reduction of the composite pellet proceeded effectively at temperatures above 1200°C. The BOF dust had a positive effect on the reduction rate of the pellet, and the rate increased with increased dust content. The reduction of iron oxide was topochemical and conformed to a shrinking core kinetic model. The dust was found to improve the iron and slag melting separation rate of reduced pellets at 1400°C when its content was less than 23·11 wt-%. The liquidus temperature of the slag would decrease with the content of BOF dust increasing from zero to ∼30 wt-% and then increase if the content continued to become more in the experiment. Utilising the BOF dust as the binder and flux to adjust the composition of the slag system can potentially reduce the slag ratio and production cost compared with using bentonite and limestone. This work can help to find a new process for the effective utilisation of BOF dust in a more appropriate and environmentally friendly way.

Comprehensive analysis on material and exergy balances of oxygen blast furnace

ABSTRACT The OBF process is widely studied as an alternative ironmaking process, due to the social pressure of energy and environment at present. A comprehensive mathematical model of the OBF process is established, which is based on material and exergy balances. The process parameters of the OBF with different oxygen enriched blast were calculated through the model. The calculation results demonstrated that the material balance of carbon input in the OBF process decreased by 6.7% (OBF-I) and 22.4% (OBF-II) compared to the TBF process. Also, the industrial oxygen consumption increased from 185.88 m3 (OBF-I) to 228.32 m3 (OBF-II). The exergy output and the total exergy loss of the OBF-I process decreased by 1.5% and 5.6%, respectively, and those in the OBF-II process decreased by 16.60% and 30.81%. Due to the exergy indices in OBF-II process all improved, the OBF-II process was a significantly efficient ironmaking process compared to the TBF.