OCR Text |
Show process. The first step in the process is the use of a chemical equilibrium code to calculate the composition of both the liquid and solid phases of a slag mixture as a function of temperature based on the chemical analysis of the slag, such as that given by the ASTM ash analysis. These calculations also account for the oxidizing or reducing nature of the environment. The calculations used in this work were performed using Aerodyne's chemical equilibrium code (2) which contains a multicomponent ideal solution model. (Species whose liquid phases are considered in the Ideal solution are: AX2O3, Si02, CaO, Ti02, FeO, Fe304, MgSi03, Mg2Si01+, NaA£Si308, and KA£Si206.) The thermochemical data used by the code consisted of JANAF table data (3) for the gaseous species and some of the condensed slag species, and USGS data (4) for slag species not present in the JANAF compilation. Liquid phase thermochemical data was estimated for some species when this data did not exist in the literature. For these species, the liquid data was extrapolated from the solid phase data using a procedure described elsewhere (5). The second step in the process of extending viscosity formulas is the calculation of the effect of the solids present in the slag mixture on the viscosity of the mixture. An analytical expression for the viscosity of a two-phase mixture as a function of the amount of solids and the liquid viscosity is given by Goldsmith and Mason (6) to be: « C~ I/O*- ^t>-<L. ^mixture = ^liquid O + 2 « 5 c + a c >• (D 4, y***~&-* In this formula, Wmixture *s t n e viscosity of the two phase mixture, uliquid is the liquid phase viscosity, c is the volume concentration of solids, and a is an interaction coefficient whose value was taken to be 9.15 (based on the discussion in reference 6). The above expression is valid for solids present in the shape of spheres, which means that its use in predicting the viscosity of a slag mixture is an approximation. Its use can be justified, though, both by the fact that the shape of the solids has only a second order effect on the viscosity of the mixture and by the position that a more detailed treatment of this effect is not warranted at this time. The third step in the extension process is the conversion of the liquid phase composition given by the chemical equilibrium code to the 3-3 |