Decarburization of periclase-carbon and aluminum-periclase-carbon ladle refractories

Abstract

In this paper, the processes of decarburization of periclase-carbon and aluminum-periclase-carbon ladle refractories were investigated. Decarburization processes take place already at the stage of drying and heating the lining after repair, during its heat treatment on gas or electric stands. These processes cause irreparable damage to refractories even before the ladle is put into direct operation (before contact with molten steel). One of the ways to increase resistance of carbon-containing refractories against oxidation is the use of antioxidants (Al, SiC, Si, etc.), which are introduced into the composition of the raw mixture at the manufacturing stage. Their action is based on priority oxidation compared to carbon. Antioxidants act in a certain temperature range, which opens up wide opportunities for development of energy- and resource-saving temperature modes for lining heat-treatment. The authors made mogravimetric analysis of periclase-carbon and aluminum-periclase-carbon non-ignited resin-bonded refractories of AMC 78-8/7HG, RI-MC175LC (RI); MayCarb 284-AX (MAYERTON) grades used in the execution of working layers of steel ladle linings. Thermogravimetric analysis of refractory samples was carried out on a LABSYS evo TG DTA DSC 1600 derivatograph when heated to a temperature of 1100 °C at a speed of 15 °C/min. X-ray phase analysis was performed on an XRD-6000 X-ray diffractometer. The results of thermogravimetric analysis are presented in the form of derivatograms. It was established that the maximum rate of carbon oxidation in all cases is reached at a temperature of 700 – 750 °C. Therefore, in order to implement a low-carbonizing first heating of the ladle after repair, temperature modes are recommended for refractories of the studied brands, including low-temperature (up to 500 °C) lining exposure.