Non-Isothermal Reaction Kinetics Study of MgO-C Refractories with Added Low-Ash Content Graphite

摘要

Magnesia-carbon (MgO-C) is widely used in metallurgical furnaces due to its excellent slag thermal shock and corrosion resistance properties. Carbon is non-wettable by slag, which protects MgO, but oxidises in the presence of oxygen. An experiment was undertaken to investigate the oxidation resistance of MgO-C in non-isothermal conditions through evaluation of kinetic laws. MgO-C samples with 2,8 % ash content graphite and resin binder were prepared and their oxidation behaviour with respect to weight loss was determined in a specially designed furnace. Samples were fired from 700 to 1400 °C at heating rates of 3,5,7 and 9 K per minute. Their continuous weight loss was measured at 50 K intervals. In order to find the mechanism(s) associated with oxidation of MgO-C samples, a reduced time '0' plot analysis was carried out for the samples. For all temperatures and samples, the initial oxidation mechanism was observed to obeya chemical reaction-controlled second order chemical mechanism followed by diffusion processes at higher temperatures.