Use of converter slags in blast-furnace smelting

Donetsk Scientific-Research Institute of Ferrous Metallurgy (DonNIIchermet). Enakievo Metallurgical Plant. Translated from Metallurg, No. 12, pp. 37–38, December, 1990     

Evaluation of the activity and molecular form of bi in cu smelting slags: Part I. ternary silicate slags

The thermodynamic behavior of bismuth in the chemical systems associated with copper processing is not well understood. This study was designed to further the understanding of the physical chemistry of bismuth in slags that have similar compositions to those found in copper extractive metallurgical processing. The silicate system investigated was the FeO-Fe₂O₃-SiO₂ ternary system in which bismuth was dissolved using an isopiestic experimental technique. Bismuth vapor pressures of 1 • 10⁻⁵ atm and 7.5 • 10⁻⁴ atm were used, and the silicates were equilibrated with this vapor at temperatures of 1458 K and 1523 K. In these experiments, the slag composition was varied such thatP _{O 2} ranged from 10⁻¹² to 10⁻⁸ atm. Bismuth was found to enter the silicate slag in both neutral and oxidic molecular forms. The oxidic form identified was that of BiO. The data suggest that the activity coefficient of neutral bismuth, γ_Bi, is dependent on the solubility of that species in slag, even at the low concentrations observed in this study. It has been hypothesized, based on the large diameter of neutral Bi, that only a limited number of sites are available to accommodate neutral Bi, and that as the limit is approached γ_Bi increases significantly. That hypothesis is shown to be consistent with the experimental results obtained in the present work as well as the results obtained by other investigators.     

Evaluation of the activity and molecular form of bi in cu smelting slags: Part I. ternary silicate slags

The thermodynamic behavior of bismuth in the chemical systems associated with copper processing is not well understood. This study was designed to further the understanding of the physical chemistry of bismuth in slags that have similar compositions to those found in copper extractive metallurgical processing. The silicate system investigated was the FeO-Fe₂O₃-SiO₂ ternary system in which bismuth was dissolved using an isopiestic experimental technique. Bismuth vapor pressures of 1 ? 10^?5 atm and 7.5 ? 10^?4 atm were used, and the silicates were equilibrated with this vapor at temperatures of 1458 K and 1523 K. In these experiments, the slag composition was varied such thatP _{O 2} ranged from 10^?12 to 10^?8 atm. Bismuth was found to enter the silicate slag in both neutral and oxidic molecular forms. The oxidic form identified was that of BiO. The data suggest that the activity coefficient of neutral bismuth, γ_Bi, is dependent on the solubility of that species in slag, even at the low concentrations observed in this study. It has been hypothesized, based on the large diameter of neutral Bi, that only a limited number of sites are available to accommodate neutral Bi, and that as the limit is approached γ_Bi increases significantly. That hypothesis is shown to be consistent with the experimental results obtained in the present work as well as the results obtained by other investigators.     

Viscosity of slags

The experimental determination of the viscosity of slags proves to be difficult. Therefore models for calculation have been developed. The Urbain‐III‐model is very often used for slags. In order to further improve its accuracy, the Forschungsgemeinschaft Eisenhüttenschlacken (FEhS) modified this model by adjusting the coefficients of Weymann's temperature relation in dependence of the CaO/SiO₂‐basicity of the slag: η = A.T.exp(10³.B/T) with A = f (C/S‐basicity); B = f (x_oxides). Viscosities calculated by means of this modified model fit well with measured values. It has been shown that the application of this model enables the optimisation of metallurgical reactions and processes. Furthermore it should be possible to optimise those properties of the solidified slag which are influenced by the viscosity of the liquid slag. Thus the production of construction materials could be further improved to fulfil the highest quality requirements.     

Viscosity estimation of slags

The viscosity of silicate melts and slags is a property difficult to measure accurately using sophisticated apparatus, it is both time consuming and expensive. The use of models to estimate the viscosity is the first step to be carried out, mainly with metallurgical slags involving numerous components. The proposed model is an experimental one based on accurate data for pure binary and ternary melts. From this data, using a simple hypothesis on the behaviour of unusual compounds, it is possible to estimate the viscosity of a complex melt. This estimation is used as a first approximation and can be amended, if necessary, by only a few direct measurements.     

Processing of metallurgical slags

Magnitogorsk Metallurgical Combine. Translated from Metallurg, No. 10, p. 38, October, 1990.     

Basicity of lime-alumina-silica slags

Emf measurements with the aid of a diffusion cell on liquid slags of the system CaO-Al₂O₃-SiO₂ at 1600°C. Determination of a linear relationship between sulphur capacities and emf values. Assumption that emf values taken from this type of cell represent a relative basicity index. Interpretation of the results with special regard to the behaviour of amphoteric Al₂O₃.