Periclase-Carbon Refractories for Operation in the Mouth of a Converter Vessel

Abstract

The performance of periclase-carbon refractories cemented with a phenolic bond that are intended for use in the lining of the cone section of the oxygen converter vessel has been studied by x-ray diffraction and petrography techniques. The results obtained provide a basis for further improvement of the oxygen converter technology and refractory fabrication.In this paper, we report on the results of a study of the wear of periclase-carbon refractories used for the lining of the mouth of a converter vessel. Our interest in this subject stems from the observation that excessive wear of this part of the refractory lining has been the major reason for the decommissioning of oxygen converters at the DMW JSC. Specimens for inspection were sampled from the refractory lining of the mouth of a converter vessel with a service life of 1600 heats. The specimens were analyzed for phase composition on a DRON-2 x-ray diffractometer (MoK a -radiation); diffraction patterns were measured in the range of 2q = 5 -70°. Macro and microtextures of the specimens were inspected using a Neophot-21 light microscope in the bright and dark field in polarized light. Photographic pictures were taken using a Nicon COOI PIX 5700 digital camera.The specimens were inspected by using a layer-by-layer surface removal technique to a depth of 100 mm. A comparison of the textures of used and intact refractory materials (Fig. 1) allowed easy identification of the changes that the refractory had undergone during service.The slag crust in post-service specimens displayed a mosaic-like crack pattern; most cracks (named the "old" cracks by convention) were impregnated with secondary periclase (Fig. 2) that formed owing to oxidized magnesium vapors extended from the bulk to the surface. New cracks could also be identified that required some time to become filled with secondary periclase. Acicular periclase crystals were observed to occur in the pores (Fig. 3a ). The pores were formed because of the evolution of magnesium vapors and