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.

Automated summary

Through the industrialized low-temperature pyrolysis process, substantial semi-coke has been produced, which has similar carbon chemical structure and combustion reactivity to pulverized coal and coke breeze, and has the potential to be used as an alternative fuel for PCI and iron ore sintering. However, careful analysis of heat supply and demand matching is required for sintering with semi-coke as an alternative fuel.