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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.

Copper staves have been widely applied in large blast furnaces especially those whose inner volumes exceed 2000 m3 due to high cooling capacity. In the past decade, copper staves suffered severe damages in some blast furnaces, which not only shortened their campaign lives, but also caused huge economic losses. In order to make out this phenomenon, the damage mechanism of copper staves was investigated via analyzing the chemical composition, thermal conductivity, metallographic aspects and microstructure in this paper. As a result, the working state was more likely to damage copper staves instead of their materials. At the beginning, the poor quality of the coke and the large bosh angle promoted the development of edge airflow, which intensified the erosion of refractory materials, resulting in the fall-off of slag crusts and damage of cooling water pipes. After repair, the cooling capacity of copper staves still declined, causing the temperature to rise easily, consequently, hydrogen attack happened when the temperature reached 370 &deg, C, which degraded the performance of copper staves. Therefore, copper staves were worn too quickly to form slag crusts, which finally failed under the hydrogen attack and the scouring of the edge airflow at high temperatures.

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 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.

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.