使用済みプラスチック高炉原料化技術の進展

摘要

To contribute to the effective recycling of materials for the benefit of the global environment, the utilization of waste plastics as injectant for blast furnaces is urgently desired. JFE Steel has developed and installed waste plastics recycling process at East Japan and West Japan works in 2000. On the basis of the experimental results by raceway hot model, simultaneous injection was investigated and the combustibility of plastics was enhanced because the combustion heat of the adhered pulverized coal promoted the gasification rate of the plastics. To increase the hardness of plastics, technology for combined agglomeration of the plastics with CaCO_3 has been developed and it was confirmed that the strength of granulated plastics doubled in comparison with normal plastics. CaCO_3 also had the effect of lowering the melting temperature of the raceway-shell by assimilation. Simultaneous injection and combined agglomeration technologies have been successfully introduced at an actual blast furnace, resulting in a remarkable decrease in the RAR (Reducing Agent Rate) and the permeability in the lower part.%使用済みプラスチック高炉原料化の稼動当初の目的は， 使用済みプラスチックのリサイクルと鉄鋼業における省 エネ，炭酸ガス排出量削減である。現在でも，その趣旨 は変わっていないが，鉄鋼業の急激な環境変化（高生産 性，低還元材比操業）もあり，本稿で記載したような使 用済みプラスチック高炉原料化の改善（燃焼・ガス化率 向上，高炉炉内通気性改善）を行っている。