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A fayalite based slag is formed during the smelting process of secondary copper containing resources. Of particular importance is the slag viscosity which quantifies the flow properties of the slag and affects the reaction kinetics, the refractory corrosion in the smelter and operational practice. In the present work, a high temperature rheometer system has been employed to study the rheological behavior of the industrial slag system FeO-ZnO-SiO2-Al2O3-CaO (FeO/SiO2 = 1–1.5, ZnO = 6–8 wt %, CaO = 1.5 wt % and Al2O3= 4.5 wt %) at 1150 °C with iron saturation. The slag behaves as a shear thinning fluid. The degree of shear thinning was quantified by fitting the flow curve with the Oswald-De Waele power law model. The relation between the slag composition and the flow behavior index has been discussed.

Formation of freeze-linings from aggressive process slags is used in industrial pyrometallurgical processes to protect the furnace wall. In this laboratory study, the formation of freeze-linings from fayalite-based (FeO-SiO2-Al2O3-CaO) slags was investigated. This was performed with a gas-cooled probe at 1200 °C under protective atmosphere. The microstructure of the freeze-linings formed on the samples was characterized using scanning electron microscopy (SEM). The influence of cooling rate, slag agitation and slag composition on the freeze-lining formation was studied by varying the gas-flow rate, rotating the crucible and changing the CaO and Al2O3 contents in the fayalite-based slag, respectively. The results indicate that fayalite (Fe2SiO4) precipitated from the slag and grew into large columnar crystals along the heat gradient from the cooled probe to the bath slag. The thickness of the freeze-lining increased with increasing cooling rate, while an increase in the slag agitation and the CaO and Al2O3 contents in the slag decreased the thickness of the freeze-lining. These macroscopical observations are discussed with respect to the microstructural evolution in the formed freeze-lining samples.