Abstract

In conventional pyrometallurgical reactors, aggressive liquid slags, salts and metals attack refractory materials leading to the continuous dissolution of the refractory. Refractories are mainly used as a thermal insulator as well as providing resistance to the chemical corrosion. The presence of corrosive slags, forced convection, and high process temperatures in the pyrometallurgical reactors can lead to the rapid degradation of the lining; imposing extra costs on processing in terms of downtime and repair costs.

The focus of the present study is on the detailed characterisation of the phase chemistry and slag interactions with refractories. As a result of characterisation of end-of-life industrial refractory samples and selected experimental studies a new methodology has been developed that can be used to enhance refractory life. The systematic approach includes the analysis of “as received” slag samples from smelters, post-mortem analysis, isothermal laboratory tests under controlled conditions, and FactSage predictions in order to predict the conditions for minimum refractory wear.

The chemical dissolution of refractory into the slag occurs through infiltration of liquid into refractory via pores as well as selective attack of the refractory components. As a result of the refractory/slag interaction, the chemical reaction products are a new solid phase(s), or a liquid phase (direct dissolution), or a combination of both liquid and solid phases. This study focuses on the modification of the slag chemistry to prevent the direct dissolution of refractory components into the slag and also to block the pores with newly formed solid phases. It has been shown that with accurate information on the slag/refractory phase equilibrium self-healing refractory systems can be designed and operated by judicious selection of the slag composition to obtain optimum slag/refractory combinations.