Comparison of semi-coke with traditional pulverized coal injection and iron ore sintering fuels based on chemical structure and combustion behavior

Substantial semi-coke has been produced through the industrialized low-temperature pyrolysis process, which has great potential as an alternative fuel for pulverized coal injection (PCI) and iron ore sintering. X-ray diffraction, Raman spectroscope, and thermal analysis were used to compare the carbon chemical structure and combustion reactivity of semi-coke, pulverized coal, and coke breeze. The results show that the average volatile matter content in 46 types of semi-cokes is 8.94 wt.%. The fluctuation range of the characteristic parameters of the semi-coke chemical structure is d 002 = (0.352–0.379) nm and A D1 / A G = (2.51–7.92), while the fluctuation range of the characteristic parameters of pulverized coal is d 002 = (0.348–0.373) nm and A D1 / A G = (1.71–9.03) (where d 002 means the interlayer spacing between the aromatic planes, and A D1 / A G is an index that characterizes the degree of disorder of the char structure through the area ratio of the defect peak band D1 to the perfect graphite peak band G); the overlap between these ranges is relatively high. Contrarily, the fluctuation range of the characteristic parameters of coke breeze is d 002 = (0.343–0.350) nm and A D1 / A G = (0.75–2.51), which is markedly different from that of semi-coke. Semi-coke combustion reactivity is close to that of pulverized coal, but considerably better than that of coke breeze. In terms of chemical structure and combustion reactivity, semi-coke can be used as an alternative fuel for PCI; however, when used for sintering alternative fuel, matching of the heat supply and demand in the later sintering stage must be scrupulously analyzed.