Study of thermogravimetric curves of LD Slag size fractions in oxygen and nitrogen atmosphere and effect of FeO and free lime on weight loss at different temperatures

Abstract

The thermogravimetric (TG) method offers a new approach to the study of the thermal degradation of LD Slag fines, which is a by-product produced in the Tata Steel plant, Jamshedpur during the steel making process. TG curves for LD Slag fines of different particle sizes in oxygen and nitrogen atmosphere from 100 to 900 °C were compared to each other to find the variation in the weight loss. Effect of FeO and free lime on weight loss of LD Slag fines was also discussed. Weight loss in the temperature range of 450–550 °C and then up to 700 °C confirmed the presence of calcium hydroxide, magnesium hydroxide, calcium silicate hydrate and calcite in LD Slag fines. Except −6.0 + 2.0 mm LD Slag fines, the weight loss in oxygen atmosphere is more than nitrogen atmosphere for other size fractions. The higher weight loss in nitrogen atmosphere than the oxygen atmosphere was attributed to the decomposition of calcium silicate hydrate and hydrated aluminate phases. Higher free lime values in finer LD Slag fractions than the coarser LD Slag fractions confirmed more volumetric stability of coarser LD Slag size fractions than the finer fractions due to powdering in the cooling process.