The benefits and knowledge gained in refractory testing with slag and nickel matte

Abstract

Post-mortem studies of the lining refractories in the top-blown rotary converter (TBRC) at Stillwater Mining Company showed severe corrosion due to slag attack and high levels of sulphur. This led to a two-year collaborative project aimed at obtaining a better understanding of the wear phenomena and improving the refractory lining life in the TBRC. Initially, a complete phase chemical characterization was carried out. This was followed by FactSageTM calculations based on the slag and matte samples provided. The information from these sources fed into rotary kiln tests conducted at various process temperatures with several selected magnesia-chromite and alumina-chromia bricks in combination with a calcium ferritic slag. During the second year of the investigation a detailed test programme with nickel matte and preselected refractory brands was undertaken in the pilot TBRC at the University of Leoben, Austria. The detailed phase chemical investigation and the results and outcome of the tests are described in detail. A vital insight has been gained into the properties of a slag-matte system not previously studied. Additionally, the refractory wear trigger in the TBRC vessel has been identified, using timelapse techniques, as the high-Temperature spikes resulting from this highly exothermic desulphurization reaction. To limit refractory wear in service, the high-Temperature spikes should be retarded by restricting the availability of fuel and the oxygen.