Wear-Model-Based Analysis of the State of Blast Furnace Hearth

The condition and state of the hearth of the blast furnace is of considerable importance since the life length of the refractories governs the campaign length of the furnace, but it is also of significance as it affects the drainage of iron and slag and the hot metal temperature and composition. The paper analyses the hearth of a blast furnace using a model of the lining wear based on the solution of an inverse heat conduction problem, studying the changes in the lining state throughout the campaign. Different operation states are detected, characterized by smooth and efficient hot metal production and by erratic behavior with large disturbances in the hearth state. During the periods of poor performance, the hearth exhibits a cycling state with stages of excessive skull growth on the unworn refractory, followed by periods of dissolution of the skull and lining erosion. An explanation of the transitions is sought by a stating and solving a force balance for the deadman with the aim to clarify whether it is floating or sitting. A connection between the thermal cycles in the hearth and the hot metal sulfur content is finally demonstrated.

Experimental and modelling studies of the transient tribological behaviour of a two-phase lubricant under complex loading conditions

The transient tribological phenomenon and premature lubricant breakdown have been widely observed in metal forming, leading to excessive friction at the contact interfaces. In this research, the transient tribological behaviour of a two-phase lubricant were studied under complex loading conditions, featuring abrupt interfacial temperature, contact load, and sliding speed changes, thus representing the severe interfacial conditions observed in warm/hot metal forming applications. The strong experimental evidence indicates that the evolution of friction was attributed to the physical diminution and chemical decomposition effects. As such, a visco-mechanochemical interactive friction model was developed to accurately predict the transient tribological behaviour of the two-phase lubricant under complex loading conditions. The new friction model exhibited close agreements between the modelling and experimental results.

THERMALIZATION AND IONIZATION OF METAL ATOMS OF OPERATING ENVIRONMENT AT A METAL ION-SPATTERING SOURCE

Fast atoms sputtered on a hot metal surface were suggested for thermalization at a metal ion-sputtering source and for further desorption into a discharge with temperature, which is equal to the temperature of the surface. In the suggested construction of the source, atom thermalization process is realized on an interior surface of an anode of the Penning discharge cell in an oscillation area of ionizing electrons. It has been experimentally shown that the proposed method of thermalization of Fe atoms increases the fraction of Fe+ ions in the extracted ion beam by three times.

Video registration of physicochemical processes in BOF cavity at bath top blowing at application oxygen lances of various designs. Report 1. Facility and methodology of the study

Interaction of the upper oxygen jets with the BOF bath considerably effects the hot metal refining flow. To optimize the lances designs and methods of BOF bath blowing, information is needed on the actual physical and technical phenomena taking place during top blowing of BOF bath by groups of ultrasonic and sonic oxygen jets. It was shown that obtaining the information is possible at high temperature simulation of the BOF bath blowing by application oxygen lances of various designs and video registration. Results of previous studies by filming of the blowing in a BOF and OHF presented. Description of modern facilities of high temperature simulation within a multi-purpose 160 and 60‒80 kg BOFs, equipped by special manholes for observation and registration by video camera the physicochemical processes taking place on the surface of the bath presented. In particular the manholes made it possible to observe the processes taking place at various methods of top and combined blowing of the BOF bath by application regular, two-circuit and double-flow oxygen lances. A methodology of test heats carrying out presented, which ensured obtaining important practical information on forming and variation of dimensions of the reaction zone. In particular, information was obtained about the interaction of ultrasonic and sonic oxygen jets with the metal melt, development of afterburning, emission out of reaction zone C to CO2 in the subsonic and sonic oxygen jets with forming high temperature flares directed on the BOF bath surface or penetrated in the foamed slag, emissions of slag-metal suspension out the BOF, forming of metal-slag sculls on the lance tube during the blowing with various level of foamed slag-metal emulsion.

Prospects of steel industry development accounting ecological restrictions

Discussion of many years on consequences of man’s activity effect on environment at present moved to a practical aspect. New ecological and economical limits dictate a necessity to reduce the carbon intensity of metallurgical processes. It was noted that the technological couple “blast furnace – basic oxygen furnace” is a basic method of steel production, based on utilization of coke as a fuel and reducing component. Distribution of metallurgical capacities by types of fuel used shown, which confirms application of carbon-containing fuel-reducing additions in overwhelming majority of technological processes of iron production. Data on projects reducing carbon intensity of metallurgical industry presented, most of which aimed at changing the technology of BF process. Experience of steel industry of Japan on perfection machinery and technology of BF production considered, which enabled to reduce total consumption of reducing agents down to figure less down to 450 kg/t of hot metal, which is the best index among countries of the world. It was shown that increase of a blast furnace volume results in change of BF process technology. Such an increase also results in decrease of carbon consumption – blast furnaces of large volume have lower specific consumption of fuel and reducing agent. The specific coke rate in blast furnaces of large volume is by 71 kg/t of hot metal less comparing with blast furnaces having volume less 1000 m3, and the total fuel consumption in large blast furnaces is by 51 kg/t of hot metal lower. Accounting necessity to decrease the carbon footprint in steel products, basic ways of steel industry technologies development can be enlargement of facilities with shutdown of small and not effective capacities, changing sinter and BF charges structure with increase of more qualitative raw materials and pellets, application of alternative kinds of fuel and reducing additions.