A monte carlo approach for simulation of heat flow in sand and metal mold castings (virtual mold modeling)
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Fig. 3—Activity coefficients of cuprous sulfide and ferrous sulfide as a function of cation fraction of ferrous sulfide. A plot of the ratio of gFeS /gCuS0.5 (right-hand scale) shows the relative drop in the two individual activity coefficients.
cuprous sulfide and ferrous sulfide decrease. To determine the relative decrease of the two activity coefficients, the ratio of the activity coefficient of ferrous sulfide to that of cuprous sulfide is also plotted in Figure 3 (right-hand axis). The ratio increases as ferrous sulfide decreases, implying that the drop in the activity coefficient of cuprous sulfide is greater than that for the activity coefficient of ferrous sulfide as the concentration of aluminum sulfide in the matte increases. For a pure ferrous sulfide flux, the activity coefficient for cuprous sulfide (given in Table I) was found to be 2.87, which compares very well with the 2.6 reported by Wang et al.[3] and is only a bit lower than the 4.1 reported by Jimbo et al.[2] The removal of copper from molten ferrous alloys is possible with the use of a sulfide-based flux, although because of the high sulfur pickup and the added cost of subsequent removal, it is not a very practical solution. Several conclusions can be drawn from the results of this study, in which varying compositions of ferrous sulfide and aluminum sulfide were used as a flux. 1. The presence of aluminum sulfide reduces the activity coefficient of cuprous sulfide because of the effects of the trivalent aluminum ion on the monovalent cuprous cation in the mixture. 2. The distribution coefficient for copper (LCu) varies with flux composition. The maximum value of LCu was '30 at an initial cation fraction of 0.18 ferrous sulfide. As the ferrous sulfide content of the molten aluminum sulfide increases from zero, the equilibrium concentration of cuprous sulfide increases. However, as the ferrous sulfide concentration increases, the activity coefficient of cuprous sulfide increases faster than that of ferrous sulfide because the effect of the polyvalent cation (Al3+) is greater on the monovalent cuprous cation than on the divalent ferrous cation. Combined, the two competing effects result in maximizing the distribution coefficient. 3. A copper content of '0.4 wt pct in carbon-saturated iron can be reduced to below 0.10 wt pct (actually, 0.07 wt pct in our experiment at this composition) by using a flux with a cation fraction of 0.18FeS and 0.82AlS1.5, with an initial weight one-fourth that of the metal. METALLURGICAL AND MATERIALS TRANSACTIONS B
1. P.J. Koros and J. Chipman: J. Met., 1956, vol. 206, pp. 1102-04. 2. I. Jimbo, M.S. Sulsky, and R.J. Fruehan: Proc. W.O. Philbrook Memorial Symp., Toronto, Apr. 17-20, 1988, ISS-AIME, Warrendale, PA, 1988, pp. 133-44. 3. C. Wang, T. Nagasaka, M. Hino, and S. Ban-Ya: Iron Steel Inst. Jpn. Int., 1991, vol. 31, pp. 1300-08. 4. C. Wang, T. Nagasaka, M. Hino, and S. Ban-Ya: Iron Steel Inst. Jpn. Int., 1991, vol. 31, pp. 1309-15. 5. O.J. Kleppa: in Thermodynamics in Geology, NATO Advanced Study In
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