Aspects of the reduction of vanadium in blast fumaces and its transfer to the pig iron have been studied quite extensively by V. V. Mikhailov, P. G. Shtengel'meier, S. V. Shavrin, A. F. Chentsov, and others [1][2][3][4][5] 9]. They determined that the amount of vanadium transferred to the pig iron depends on the basicity and volume of the slag, the temperature of the pig, and other factors. These conclusions were based on the results of laboratory studies or averaged indices of trial heats conducted over a relatively long period of time. However, the averaging of the indices resulted in some "smoothing" of isolated anomalies in the data.We refined the initial relations on the basis of data from chemical analyses (more than 1000 taps on each blast furnace at the Chusovoi Metallurgical Plant). The method used to analyze data on the taps involved grouping them on the basis of various factors and determining the average index for the taps in the different groups. We then used the program Microsoft Excel to determine the relations and constructed regression curves ( Figs. 1 and 2).It was established that the amount of vanadium present in the slag in the form of V205 increases with a decrease in the temperature of the pig iron. If the temperature of the pig increases, then so does the vanadium distribution coefficient L v (Tables 1, 2, 3).It was also determined that in certain taps (V205 > 0.6) the dependence of the Si and V contents of the pig iron on the content of C205 in the slag did not conform to the general law that was established. For example, when the concentrations of these elements in the pig iron was sufficiently high, the V205 content of the slag in the corresponding heats was significantly higher than in the other groups of taps.In several of the trial heats, it was observed that vanadium could undergo sublimation in the high-temperature zones of the blast furnace [1, 8]. It can be suggested that some of the vanadium sublimes and accumulates in the form of a slag crust near the bosh. The crust begins to slide down the furnace after it has reached a certain critical mass. This is accompanied by a sudden increase in the W203 content of the slag, while the vanadium content of the pig remains nearly unchanged. The process just described is more pronounced on a small blast furnace (such as blast furnace No. 1), which may be due to the composition of the slag, the more intensive operation of the furnace, or features of its profile. This matter requires further study. When the crust slid down the furnace, the concentration of vanadium in the hearths of furnaces Nos. 1 and 2 increased by t8.2% and 19.3%, respectively. Figure 3 shows the dependence of the total mass of vanadium in the pig iron and slag on the mass of vanadium in the slag.It should be mentioned that an increase in the V203 content of the slag is accompanied by an increase in the silicon content of the pig iron, i.e., by an increase in temperature in the hearth. The rise in temperature also results in sliding of the slag crust.Analysis of the data ...
The process of the reduction of vanadium in a blast furnace is determined to a significant extent by the structure of the stock, the charging regime (including the cyclicity of the charging operation), the charging sequence, stockline level, the burden ratio, and the operating regime of the revolving distributor. The profile of the charge materials and the position and height of the ore ridge in the top of the furnace are important parameters, since they determine the nonuniformity of the distribution of the gas flow and, thus, the use of the reducing potential of the gas [1][2][3].In constructing the logical-statistical balance model in [4], an attempt was made to account for the nonuniformity of the gas-flow distribution as part of the analysis of the smelting process. The nonuniformity coefficient ~t was introduced. The coefficient is equal to unity for an ideal distribution, while deviations are recorded in fractions such as 0.95. Here, some of the gas (in the given example, 0.05) is released from the furnace, by-passing the ore-bearing materials.If the nonuniformity of the gas distribution across the furnace is linked with a heat-transfer and mass-transfer characteristic of the operation of the furnace -the ratio m of the water equivalents of the charge and the gas -then the range of theoretical and practical problems that can be solved [5, 6] where n a is the number of the section in which the value of a is greatest.It follows from Eq. (1) that the gas distribution across the furnace may be ideal when a = m. Using (1) with known/.t, m, and n, we can determine a. We can then use Eq. (2) to find d and, after performing calculations with the two-dimensional model, we can analyze the work done by the gas along and across the furnace.To determine the validity of the proposed model, we studied the operation of a 1033-m 3 furnace at the Chusovoi Metallurgical Plant. During the study period (August 18-22, 1998), the iron-ore-based part of the charge consisted of 60% Kachkanar pellets, 30% imported sinter, and 10% local sinter. The productivity of the furnace was 1620 tons/day; coke rate was 546 kg/ton; the furnace was operated on an air blast heated to 892~ the consumption of natural gas was 31 m 3.Chusovoi Metallurgical Plant and the Institute of Metallurgy (in the Ural Division of the Russian Academy of Sciences).
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