Corrosion of refractories in lead smelting reactors

• Main Author: Wei, Lingxuan
• Format: Others
• Language: English
• Published: 2009
• Online Access: http://hdl.handle.net/2429/11475

Corrosion of refractories by slag is a complex phenomenon which, depending on the particular system, involves many processes, such as chemical wear (corrosion) and physical or mechanical wear (erosion), which may act synergistically. No single model can explain all cases of corrosion nor can it explain all corrosion mechanisms of a particular refractory in different environments, but the knowledge of the microstructure combined with the chemistry of the systems are necessary to understand the corrosion mechanism of a refractory material. There is no systematic study on the corrosion of refractories used in lead smelting reactors (KIVCET furnace and TBRC) in literature so far. In the present work, the available literature concerning corrosion of refractories in lead-smelting reactors was reviewed. By using different analytical methods such as sessile drop technique, SEM/EDS and XRD, the interfacial phenomena at the slag-refractory interfaces were investigated, and microstructural studies on different refractory specimens were carried out. It was observed that above 1150° C, the KIVCET slag tends to separate into two phases: a liquid and a solid. The liquid mainly consists of SiO₂, CaO and PbO, while the solid primarily contained Fe₂O₃ and ZnO in the form of zinc ferrite (ZnFe₂O₄) spinel. It was proposed that ZnO from the KIVCET slag could also react with Cr₂0₃ and Fe₂0₃ from the magnesite-chrome brick and reacted slag to form spinel-type phases: zinc chromite (ZnCr₂0₄) and zinc ferrite (ZnFe₂O₄) respectively. The volume changes accompanying these reactions could lead to microcracks in the matrix of the brick, and eventually cause the failure of the brick. Laboratory evaluation of the corrosion behavior of various refractory materials against industrial slags from KIVCET and TBRC furnaces was performed using both dynamic and static corrosion tests. The corrosion rating on nine different magnesite-chrome bricks was estimated, and the possible corrosion mechanism was discussed. It was found that the rebonded fused grain type of magnesite-chrome bricks have superior performance compared with direct bonded type when used in contact with KIVCET slag and the alumina-chromia bricks performed better than magnesite-chrome bricks under similar conditions. === Applied Science, Faculty of === Materials Engineering, Department of === Graduate