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The damage of the copper stave will affect the sustainable production of the blast furnace and is not conducive to improving the economic efficiency of the blast furnace. The formation of a stable slag crust is crucial for the longevity of the copper stave. In this study, the flow properties and crystallization characteristics of the slag crust in a blast furnace with the copper stave running for 10 years without damage in China were analyzed. The phase precipitation during the cooling process was calculated by FactSage software. The phase composition and micromorphology of the slag crust were studied in detail by XRD and SEM–EDS. The results show that the slag phase in the slag crust is a CaO-SiO2-Al2O3-MgO-FeO slag system with high alumina content (33.62 ~ 35.72%) and low magnesium oxide content (2.68 ~ 3.84%). The melting characteristic temperature of the slag crust in the belly and the bosh is between 1127–1303 °C and 1287–1500 °C, respectively, and the characteristic temperature of the cold side of the slag crust is higher than that of the hot side, which was mainly resulted from the tendency of gehlenite and magnesia-aluminum spinel in the slag phase to precipitate during the cooling process. With the increase of the basicity of the slag phase, the precipitation temperature and amount of gehlenite increase, resulting in the characteristic temperature of the slag crust in the bosh significantly higher than that in the belly. The increase of FeO content reduces the initial precipitation temperature of crystals, and the increase of cooling strength is beneficial to the slagging on the copper stave, which provides a theoretical basis for the stable operation of the slag crust on copper stave blast furnace.

Slag crusts on the cooling stave of a blast furnace offer greatly protection for the furnace wall. Frequent forming and shedding of slag crusts (FSSCs) cause severe erosion on the wall, which affects the life of a blast furnace. However, it is very difficult to detect the FSSCs directly because of restrictions imposed by the structure of a blast furnace and detecting costs. This paper presents a soft-sensing method based on two-dimensional decision fusion to detect the state of slag crust (SSC) of a blast furnace. First, a soft-sensing scheme for SSC is put forward on the basis of features of slag crusts and the temperature detected in cooling stave. Next, methods for calculating a temperature threshold (TT) and a change-rate threshold of temperature (CRTT) are presented according to the characteristics of slag crusts. Finally, a two-dimensional decision method is presented by fusing the TT and CRTT to determine the SSC of the blast furnace. The experiment results based on industrial data demonstrate the effectiveness of the method.

The crust lining formed by the material being processed acts as a gasdynamic protector of the walls of the apparatus, and gives reliable service at a gas-flow temperature of about 3000°C with exposure to corrosive iron oxides. The structure of the slag —metal crust is stratified, i.e., the inner surface of the apparatus is represented by a crust of metal only, so that the products of smelting are protected from contamination by elements and their compounds from the refractory lining.

Studies conducted at the Krivorozhstal' combine blast furnaces have shown that fusion of the crust can be established from the change in the total content of alkali metals in the slag. After the furnaces were blown out for repairs the remaining lining and crust were inspected. It was found that the lining of the uncooled part of the stock remained in relatively good shape with the greatest amount of lining wear seen between the second row of stack coolers and bosh coolers. The composition and structure of the slag crust for different regions of the furnaces were analyzed and various physicochemical properties leading to crust formation and behavior were assessed. It was concluded that the systematic determination of the fraction of K/sub 2/O in the alkali compounds in the furnace slag will permit monitoring of the conditions of the slag crust in the furnace and, in the event of the onset of its collapse, will enable measures to be taken to stabilize the heating of the furnace.

Current aspects of the developing of modern self-shielding flux-cored wires composition for arc welding of low-alloyed steels are considered. Advantages and disadvantages of flux-cored wires of carbonate-fluorite, oxide and oxide-fluoride types of are shown in comparison. The effectiveness of gas shielding of molten metal at welding with self-shielding flux-cored wires of carbonate-fluorite type is analyzed considering the thermal properties of their cores. It is shown that to improve reliability of gas shielding at welding using the wires of this type it is important not only to ensure generation of sufficiently large volume of shielding gases at thermal destruction of the wire core, but also to control this process, providing gas evolution at all stages of heating and melting of the wire. The results of complex thermal analysis of the wire core mixtures containing, for example, lithium carbonate show substantially large heat losses for heating and melting of the wire core, which are accompanied by the development of energy-intensive processes of thermal destruction of core components. It is shown that the limitation of lithium carbonate content in the wire at the level of not more than 2 wt. % allows not only to preserve welding arc burning stability at the acceptable level but also to provide effective gas shielding of molten metal and easy separation of slag crust. The control of thermochemical reactions in the core is achieved by selection of its proper composition to ensure favorable melting of flux-cored wire and electrode metal transfer to the welding pool. Results of metallographic examinations of distribution and composition of non-metallic inclusions in metal of the welds made with wires of the oxide and oxide-fluoride types are presented. Main properties of the developed self-shielding flux-cored wires and recommendations on welding are given in conjunction with prospective fields of their application.

Proper burden distribution is an important way to improve conditions of a blast furnace, which indicate the stability and energy consumption. However, it is difficult for operators to recognize the stability and energy consumption at the same time and adjust them through burden distribution, due to complex iron-making mechanism. Therefore, this article presents a two-stage decision-making method for the burden distribution parameters based on recognizing the conditions. First, the stability and energy consumption are recognized, respectively, according to the classification of stability of slag crust (SSC) and the gas utilization rate (GUR). And then, two prediction models are presented for the SSC and GUR to predict the conditions. Finally, the burden distribution parameters are determined in two stages, where edge parameters of the burden distribution are determined at first according to the SSC, and then, center parameters are determined according to the GUR. Experimental results based on industrial data show that the proposed method provides an effective decision-making way for improving the conditions.

The processes of formation of the skull and liquid film between the mold and surface of the billet effect on quality indicators and stability of the continuous casting of steel. A number of theoretical studies devoted to the forecast of skull thickness and the film of liquid slag are known. However, these studies do not take into account the mutual influence of formation processes of skull and film, as well as formation of shell thickness of the billet. In this connection, the paper presents a mathematical model of interrelated thermal processes developed by the authors in the system of layers “copper wall of crystallizer – skull – film of liquid slag – crust of ingot”. The model makes it possible to predict the dynamics of formation of the thickness of the ingot crust, slag skull and the layer of liquid slag along the height of the mold and the length of liquid friction portion in it, depending on casting speed, temperature of casting steel and melting of the slag, thickness of the slab and working layer of the copper wall. The adequacy of the model to the object is determined by such parameters, as surface temperature of the billet, thickness of the crust, specific heat flux in the mold and temperature of the working wall. An example of application of the developed model is shown, in which the effect of casting speed on length of the liquid friction portion in the mold is investigated. It was found that at speeds of 0.8; 1.0 and 1.2 m/min the slag layer is retained for 0.331; 0.415 and 0.498 m from the meniscus of the metal, respectively. At the same time, the thickness of the skull reaches a maximum value of 0.77 mm. Further formation of the preform occurs in the absence of lubrication in the mold. The possibility of using the developed model by technologists for selecting the chemical composition of casting powder, which provides the required length of the liquid slag section, is indicated by the designers when choosing the mold profile, taking into account the thickness of the skull, and, also for educational purposes.

The composition of the ladle slag in units designed for the secondary treatment of steel needs to be optimized in order to increase the service life of the units’ linings. On the one hand, the slag subjects the refractories to chemical wear. On the other hand, under certain conditions the slag is capable of forming a protective crust inside the units. The Nizhniy Tagil Metallurgical Combine has chosen certain refractories for the most heavily worn part of the lining of its vacuum chambers, since only the installation of a lining of a differentiated design that equalizes the rate of wear around the lining’s perimeter will allow the desired effect to be obtained from optimizing the composition of the slag. An efficient composition for the slag was also chosen, the slag having high contents of MgO and Al2O3. The use of such a slag helps form a protective slag crust of the composition MgO·Al2O3 on spinel refractories having the compositions MgO·Cr2O3 and MgO·Al2O3.

The formation of dense layers of slag crust in a rotary furnace when normal electrocorundum sludge is used in the charge to make mullite-corundum fireclay depends on the chemical-mineral composition of the charge and the components of the crust, wetting processes, and the effect of lower compounds of titanium on the physico-chemical processes which take place.

Results are presented from an analysis of the motion of gas flows created by fuel-burning devices in existing electric-arc steelmaking furnaces and recommendations are made on how to efficiently arrange this equipment in the furnace. Controlled annular motion of the aerodynamic flows in the part of the working space between the furnace wall and the electrodes increases convective heat transfer to the cold solid charge, forms a reliable and uniform slag crust on the water-cooled wall, and alleviates the deposition of process dust on the electrodes. A numerical study is performed using the SolidWorks Flow Simulation program and boundary conditions that reflect the actual operating conditions in the furnaces.

The use of schungite as a partial replacement for coke is practiced in Russia at a number of metallurgical plants, both in the production of foundry iron (its primary use) and in making conversion pig iron. The largest amount of coke is replaced when foundry iron is being made, the replacement coefficient in this case having a value within the range 0.8–1.3. Studies that included continuous monitoring of the temperature of the carbon blocks in blast furnaces with volumes of 1719, 3200, and 5580 m3 unambiguously demonstrate that the thickness of the slag crust in blast furnaces increases with the use of schungite. Protecting the lining of the hearth through the use of schungite is also accompanied by a decrease in coke consumption.

respect to the other parameters including the consumption coefficients for the main materials (pig iron, scrap, lime) and the sulfur and phosphorus contents of the finished steel there were no significant differences between urtite and fluorspar. ' Visual monitoring of the blowing operation showed no important deviations from the perscribed conditions. The slags were nearly indentical in terms of chemical composition, but the slags at the first sampling were more viscous and settled somewhat more rapidly in the case of heats on which urtite was used. It should be noted that with a mean urtite consumption of 1 ton per heat, the quality of preparation of the scrap metal has an influence on the blowing and slag regimes. The percentage of heats on which scrap was cold-charged from there scoops was within the range 25.8-31.2% for both urtite and fiuorspar. For the most part, either it was necessary to correct the slag regime on these heats on resort to forced pumping of the slag. The number of heats on which additional blowing was necessary was 4.1% greater in the case of urtite. The use of urtite yielded a non-foamy, more concentrated slag and the heat proceeded quietly, Almost no metallization of the oxygen lance occurred and a dense slag crust formed on the lining of the converter. The formation of such a crust might have been one reason for the converter's longer compaign. The use of urtite as a slag thinner in place of fluorspar in the production of about 1.25 million tons of steel at the West Siberian Metallurgical Combine has saved more than 1 million rubles.

On the assumption of one dimensional axial heat flow a mathematical model is developed for describing the temperature profile in small ESR units. The model considers the regions both above and below the slag level and allowance is made for the development of a slag crust on the electrode near the top slag level. The governing equations are solved numerically and the computed results appear to be in agreement with experimental data reported on a laboratory scale ESR unit, employing 1 in. electrodes.

A study was made of the effect of the alkali content of the charge on the smelting parameters of blast furnaces of the Krivorozhhstal' and Dnepropetrovsk combines. CaO/(Si/sub 2/O + FeO) was taken as the index of basicity. Samples of slag crust were taken during an overhaul on a blast furnace at the Dnepropetrovsk plant. The gradual reduction in the content of alkalis over the height of the hearth is described. The behavior of alkalis during blowing-in and blowing-out of the furnace was determined. Spontaneous slippage of the crust can be avoided by optimizing the slag regime. The ratio of oxides in the slag Al/sub 2/O/sub 3/:MgO was chosen. Statistical analysis was used to interpret data from trial heats and obtain the relationship between the alkali content of the slag and the value of the ratio Al/sub 2/O/sub 3/:MgO. A 6-8% increase for the MgO content of the slag was recommended as both accurate and necessary for removing alkalis from blast furnaces at plants in the Ukraine.