Non-Isothermal Reaction Kinetics Study of MgO-C Refractories with Added Low-Ash Consent Graphite
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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 ‘∅’ 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.
Keywordsmagnesia-carbon oxidation kinetics reduced time plot analysis
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