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The slag in pyrometallurgical operations plays a major role affecting the life of furnace refractory. As such, comprehensive mineralogical and chemical slag examination, physical property determination including the slag melting point or liquidus, and viscosity are necessary for precise understanding of a slag. At the RHI Technology Center Leoben, Austria, the main objective of slag characterization work is to reach a better understanding of refractory corrosion. This corrosion testwork is performed at the laboratory and pilot scale. Typically, corrosion tests are performed in an induction furnace or rotary kiln, with the main purpose being the improved selection of the most suitable refractory products to improve refractory performance in operating metallurgical furnaces. This article focuses on characterization of samples of six non-ferrous, customer-provided slags. This includes slag from a copper Peirce-Smith converter, a short rotary furnace for lead smelting, a titania-processing furnace, and a Ni-Cu top blowing rotary converter (TBRC) plant.

A thermochemical approach was implemented to study the dissolution mechanisms of a wide range of refractory oxides and silicates in slags of the nonferrous metals industry and electric arc furnaces. First of all, the slags have been characterized regarding their working range, phase assemblage, and melting behavior. Subsequently, the interactions of different combinations of refractory and slag have been examined, and emphasis has been placed on the determination of possible reaction products formed during dissolution and the solubilities of the refractory oxides and silicates in various slags. Direct dissolution, decisive in the case of high corrosion rates, as well as indirect dissolution have been described. Varying operation conditions (e.g., temperature, atmosphere) have been incorporated into the investigations. In addition to the thermochemical calculations, the solubility of magnesia in fayalite slags has been determined experimentally with the quenching method and the calculated results have been compared to published corrosion studies of other authors. These studies revealed that thermochemical calculations are a suitable tool to examine melt corrosion. The thermochemical approach provides information that can be incorporated into product development and in the operation mode, giving a proper choice of process conditions.

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