Laboratory scale investigation on maximising utilisation of carbonaceous inerts in stamp charging to improve coke quality and yield

Abstract

Stamp charging has been established as a versatile technology which not only improves the coke properties that can be obtained from a given coal blend, but also broadens the coal base for cokemaking, permitting the use of inferior coals without impairing the coke quality. To produce high strength coke at least cost, Tata Steel ventured into stamp charging in combination with 40–45% low ash imported coals. Research carried out by R&D, Tata Steel revealed that stamp charging has the potential power to digest even non-softening carbonaceous inerts, if the coal blend is suitably designed. Addition of such inerts would enhance the carbon content in the resultant coke. However, the use of these inerts calls for judicious selection of other components of the coal blend and optimisation of the blend proportion, or otherwise these inerts may have an adverse impact on the coke quality. Addition of such materials would also contribute to higher coke yield, since the volatile matter contents of these materials are very low. A quantum jump in the coke yield can be envisaged only if the addition of these low ash carbonaceous inerts is substantial (>10%). Therefore, it is imperative to design the base stamp charge coal blend so that it has enough fluidity to assimilate these infusible inerts and still produce coke with high coke strength after reaction. The present paper describes the scope of utilising low ash carbonaceous inerts such as fluid coke and anthracite optimally in the stamp charging blend by replacing the present imported semisoft coal with high fluidity imported coals. The laboratory scale experimentation and the results obtained with respect to improvement in coke properties and yield have been described. The results are also supported by the microscopic investigation of the coke samples.