Comprehensive evaluation of inherent mineral composition and carbon structure parameters on CO2 reactivity of metallurgical coke

Abstract

In order to obtain a comprehensive understanding of the influence of both inherent minerals and carbon crystalline structure parameters on coke reactivity index (CRI), 30 industrial metallurgical cokes were selected and their mineral composition were quantitatively determined by X-ray diffractometer (XRD) and TOPAS software, the influence of inherent minerals was further investigated by the TGA. The mineral catalysis index (MCI) and carbon crystalline structure parameters were correlated with the CRI. The results show that: (1) CRI can be expressed as function of MCI with R2 equal to 0.6548: CRI = 7.7037MCI + 6.8564; (2) Main crystalline minerals in cokes include mullite, quartz and cristobalite (the sum is more than 80%), oldhamite, anhydrite and hedenbergite also exist in coke with small amount. The reactivity index improved linearly, from 0.049 increased to 0.059 (increased 20.41%) with addition of 8% CaS, which indicate that CaS has an apparent catalytic effect on coke gasification; (3) Both carbon structure and MCI have a significant influence on coke’s CRI. When MCI < 3, carbon structure is the primary factor affecting the CRI, with Lc, La and fa increasing, CRI decreased; when MCI ≥ 3, CRI increased with Lc, La and fa, the mineral composition is the principal factor affecting the CRI.