8th International Congress on Science and Technology of Ironmaking - ICSTI 2018

Pulverized Coal Injection (PCI) into the Blast Furnace (BF) is well-known process for cost saving of the BF. Most of the ironmaking companies are trying to enhance the amount of Pulverized Coal Ratio (PCR) for the purpose of cost reduction. Two key factors, flowability and combustibility, of pulverized coal should be estimated to achieve higher PCR under stable operation condition. The flowability, which depends on characteristic property of coals, influences the even distribution of coal injection across all tuyeres. For Hyundai steel PCI facility (PW type), the flowability of pulverized coal plays more important role for stable injection due to dense phase transfer system. The combustibility also determines permeable and thermal conditions inside raceway through rapid reactions, combustion followed by volatilization. In this study, both of flowability and combustibility were estimated with a powder flow tester and a drop tube furnace, for measuring shear stress and burn-out of pulverized coal, respectively. 10 kinds of coal brands were analyzed to investigate the effect of coal properties, such as volatile matter, H/C ratio, ash composition, inertinite texture, and size distribution, on the two factors. Suitable ranges of those properties obtained from laboratory tests for stable and high efficiency of PCI operation were verified in long period practical operation in actual BF.