A Thermo-gravimetric Approach for Quantification of Carbon Sources from Coal-char and Coke Mixture of Interests

Abstract

Blast furnace sludge contains carbon, which can originate from both coal-char and coke. Naturally, it becomes difficult to assign this unutilized carbon to a specific source. Conventional chemical analysis can only predict the total carbon content. This work therefore focuses on the quantification of carbon from the mixture of two different carbon sources using thermo-gravimetric methodology. To establish the methodology, synthetic char has been prepared under different conditions and suitably chosen for this study. Prepared char and coke fines have been heated separately to understand their individual performance. Further, coal-char and coke are mixed in known proportions (wt.%) and subjected to controlled heating under combination of synthetic air and inert atmosphere. Optimized heating profile consists of heating the mixture under inert environment, followed by an isothermal zone of around 12 hrs. Subsequently, the mixture is heated again in inert condition and followed by an isothermal zone of around 4 hrs. The controlled heating and holding time ensure weight loss of known carbon sources occurring separately. Weight loss of the mixture at lower isotherm is solely from carbon from coal-char, and at higher isotherm it is due to coke fines. The ratio of measured weight loss due to carbon sources has been agreed well with the known proportion inside the mixture. This derived process parameters have been found to be equally applicable for the complete range of mixing proportion. Subsequently, developed methodology is applied for different blast furnace sludge samples for quantification of carbon sources.