A comparative study on the nature of carbon deposits formed in different coke ovens and their formation pathways as evidenced through graphitisation and mineralogical compositions

Abstract

Formation of carbon deposits during coal carbonisation is a persistent problem in coke ovens. The nature of carbon deposits depends on the type of oven and how the deposits are formed under the operating conditions of the oven. The situation is even more complicated in the Indian scenario considering the higher content of mineral matter in coal. A comparative study on the characteristics of carbon deposits originating from different ovens is essential to develop an efficient solution for their removal. In the present study, a deposit from the base of stamp charged coke oven was compared with the goose neck deposit of top charge oven using multiple analytical techniques. Relatively higher graphitisation was observed in the carbon deposit from stamp charge oven as proven by Raman and X-ray diffraction analysis. The same deposit contained higher mineral matter (8.9%), particularly Fe₂O₃ (8.54%) which could act as the catalyst for the graphitisation process. Higher thermal reactivity was observed in carbon residue from stamp charge oven, which resulted in higher mass loss (37%) compared to top charge oven one (28%). Petrographic and morphological analysis confirmed the abundance of spherulitic carbons in both deposits, however, owing to the increased residence time for the gaseous by-products in the stamp charge oven, the molecular arrangement of carbon structure was highly compact and globular. Solubility tests revealed that the organic solvents were more efficacious in solubilising ∼20% to 25% of the carbonaceous clinker at ambient temperatures. To summarise, this article characterised and demonstrated the catalytic graphitisation potential of Fe-rich deposits isolated from coke ovens and their attainable downstream application.