Slags electrical conductance

The principles pertaining to carbon blast furnace hearths apply as well to submerged-arc furnace hearths. In some processes, such as in d-c arc furnaces, the electrical conductance of carbon is a most important factor. The long life of carbon linings in these appHcations is attributable to carbon s exceptional resistance to corrosive slags and metals at very high temperatures. 

The properties of slags are dependent not only upon chemical composition, but upon other factors also. The most pronounced deviations from additivity rules based on composition arise in the estimation of those properties which involve ionic transport eg. electrical conductivity. However surface tension values estimated from additivity rules are frequently in error as bulk thermodynamic properties do not apply at surfaces. Furthermore, virtually all the physical properties of slags are, to some extent, dependent upon the structure of the slag (viz. the length of silicate chains, degree of crystallinity etc.) thus estimation procedures have to accommodate these structural factors, where possible. 

In Portland slag cements the electrical conductivity was foimd to decline with increasing slag content. The following are average values [in (fl.m)" ] found in cements with different slag contents (w/c=0.50, water-saturated pastes) (Hinrichs 1987) ... 

Characteristics of the slag or flux are not allowed to change (e.g. electrical conductivity, metallurgical properties, etc)... 

It is significant to point out that the present method is based on the relationship between interionic associations and their consequential effects on slag viscosities, which was shown by Seetharaman et al [7], In principle, any property that reflects the interionic interactions and the structural evolution, cluster behavior at different temperature intervals should show the same characteristic. If agglomeration or atomic rearrangement is manifested in the viscosities of slags, other physical properties like electrical conductivity should reflect this phenomenon as well. 

In the Falconbridge furnace (5,6) it was found that the interface between slag and matte was rendered immobile, probably by the presence of solid chromites. In the Cominco electric furnace, semi-solid precipitates have also been found to be present at the slag/bullion interface therefore, as a first tqjproximation, the interface between slag and bullion was considered to be immobile. Consequently, both sides of the interface were treated as non-slip walls. With this boundaty condition, heat was transferred across the interface only by conduction. Therefore, continuity of the heat flux across the interface was prescribed. Similarly, for electrical power computation, continuity of magnetic vector potential. A, at the interflice was prescribed. 

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