Impact of Oven Bulk Density and Coking Rate on Stamp-Charged Metallurgical Coke Structural Properties

摘要

Coke samples obtained by carbonizing a commercial coal blend in a pilot-scale moveable wall slot-oven were studied to evaluate the influence of oven bulk density and coking rate on coke structural quality. Coke samples were investigated using the coke strength after reaction (CSR) test, gas adsorption techniques, optical microscopy, and X-ray diffraction analyses. The results show that an increase in oven bulk density and coking rate led to an increase in CSR, a phenomenon attributed to enhanced coal particle adhesion and improved plasticity during the plastic stage. Surface area, total porosity, pore area, and cell wall measurements indicate that the compact nature of coal charge under high oven bulk density and accelerated events under a rapid coking rate result in limited pore structural development, leading to a less porous coke. An increase in coke oven bulk density resulted in the growth of carbon forms and also improved the degree of crystallization. However, the proportion of less-reactive carbon forms and extent of crystallization decreased with an increase in coking rate, a limitation ascribed to a lack of sufficient time to fully develop when a faster coking rate is employed. Furthermore, as indicated by a decrease in the range of CSR and structural properties, coke quality homogeneity along the oven width improved with higher oven bulk density and coking rate. A positive relationship was found between CSR and crystallite height, as well as between CSR and carbon forms development Contrary to literature reports, a weak relationship was found between CSR and surface area; however, the importance of all pore sizes was shown by a positive relationship between CSR and total porosity.