Binary slag

A Method of Incorporating the Composition into the Calculation of the O K X-ray Emission Spectrum of the Glassy State SiOj—Na O Binary Slag with the DV-Xa Molecular Orbital Calculation... 

KEYWORDS SiOj—NajO binary slag, glassy state, 0 K X-ray emission spectmm, paitid density of states as a fimction of NajO content, basicity... 

Previously we have proposed a method to incorporate the NajO content into the calculation of the Sijp partial density of states (PDOS) of the SiO,—Na20 binary slag (4-6). The Si PDOS agreed well with the expaimental Si X-ray emission spectra of the binary slag (5,6). Furthennore, with this method we were able to explain the reason for the change in the shape of the Si Kg X-ray emission spectrum of the slag as its metal oxide content changes. 

Figure 1 The molar volume of binary slag systems as a function of composition showing the individual x.V. contributions.

Values of Yq are often taken to be the surface tension of the pure components, Y and have also been obtained by iterative procedures. Figure 4a shows a typical plot of Y as a function of x for a binary slag and the individual x Yi contributions have also been included. These methods work well for certain slag mixtures but break down when surface-active constituents, such as P205 are present. These components migrate preferentially to the surface and cause a sharp decrease in the surface tension and consequently only very small concentrations are required to cause an appreciable decrease in Y. Thus some unreported or undetected impurity could have a marked effect on the surface tension of the slag and thereby produce an apparent error in the value estimated by the model. In this respect surface tension differs from all the other physical properties which are essentially bulk properties. 

Figure 4 The composition dependence of Y, qY, 2 2 binary slag systems with (a) non-surface-...

Many reactions encountered in extractive metallurgy involve dilute solutions of one or a number of impurities in the metal, and sometimes the slag phase. Dilute solutions of less than a few atomic per cent content of the impurity usually conform to Henry s law, according to which the activity coefficient of the solute can be taken as constant. However in the complex solutions which usually occur in these reactions, the interactions of the solutes with one another and with the solvent metal change the values of the solute activity coefficients. There are some approximate procedures to make the interaction coefficients in multicomponent liquids calculable using data drawn from binary data. The simplest form of this procedure is the use of the equation deduced by Darken (1950), as a solution of the ternary Gibbs-Duhem equation for a regular ternary solution, A-B-S, where A-B is the binary solvent... 

Equation (S.21) is normally used in metallic systems for substitutional phases such as liquid, b.c.c., f.c.c., etc. It can also be used to a limited extent for ceramic systems and useful predictions can be found in the case of quasi-binary and quasi-temary oxide systems (Kaufman and Nesor 1978). However, for phases such as interstitial solutions, ordered intermetallics, ceramic compounds, slags, ionic liquids and aqueous solutions, simple substitutional models are generally not adequate and more appropriate models will be discussed in Sections 5.4 and 5.5. 

Primarily because of industrial interests in glass and slags, and, to a less extent, of the relative ease of experimentation, most of the binary liquid oxide systems studied have been silicates and borates. Hence these will be the only systems to be discussed in this section. 

A key factor for successful MHD operation is the degree of interaction between plasma potassium seed and the slag medium. Using slag activity data from the present studies, it is possible to predict conditions under which plasma seed will be continuously depleted by slag absorption of alkali. Plante et al. ( ) presented similar arguments earlier, based on their data for the binary oxide systems. A more definitive analysis can now be made from the present data on complex synthetic and actual slag systems. 

New Model for Calculating the Surface Tension of Slags. Figure 4a shows the surface tension of two slag constituents which are not surface active. For a binary mixture with one surface active component the surface tension-composition relationship will have the form of that shown in Figure 4b wlwre 2 denotes the surface-active constituent, f we assume that xY for component 1 is unaffected, then the term Y2X2 the partial molar contribution of the surface... 

Under direct zinc smelting conditions, if the CO/COz is controlled above 3 at temperatures above 1300 C, the Fe-S-0 matte as shown in Table 1 can be approximately considered as a FeO-FeS binary system. Consequently, the composition of slag can be estimated from Figure 3 and is presented in Table n. 

Fredriksson. R, Seetharaman, S., Thermodynamics Activities of FeO in some Binary FeO-Containing Slags , Steel Res., 75,240-246 (2004) (Calculation, Experimental, Thermodyn., 23)... 

Several researchers have reported the sensitivity of alkali-sulphate activated slag mixtures to imprecise dosages of alkaline activators [28, 29]. The results presented in section 5.1,2 also showed that the compressive strength fell as the CKD/BPD content of the binary and temaiy paste mixtures increased. The lower strength due to a high alkali metal content in the pore solution can be attributed to the location of the ettringite precipitation [30],... 

The influence of fly ash, ground blast-furnace slag and other micro-fillers on the properties of high performance concrete is positive. As for ordinary concretes, these mix components densify the structure, and because of their pozzolanic properties they take part in hydration processes. Partial replacement of Portland cement by fly ash and ground slag enables a decrease in the cost of materials, improves the workability and reduces the heat of hydration. In practice, the majority of concrete structures are made with binary or ternary blended cements, which means that more than one additional binder is used with Portland cement. 

In the Table V, it is presented the different slag compositions calculated, based on the mass balance with low-grade hematite ore, and in the Table VI is presented the different characteristics of each sample such as binary and quaternary basicity, liquidus temperature, the final percentage (slag-metal), etc. 

Table VI. Characteristics of binary and quaternary basicity, liquidus temperature and the final percentage of slag used with low-grade hematite ore.

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