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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.

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.

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.