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节能减排是钢铁工业目前面临的重要挑战,而废塑料作为一种可再生清洁能源和还原剂替代焦粉、无烟煤等化石燃料在炼铁工业中已经获得大量关注。把废塑料、褐铁矿粉、无烟煤以及黏结剂混合制取含碳球团,在管式加热炉内做直接还原实验。废塑料在高温下裂解释放热量,为球团的预热和直接还原提供外加热源。同时,与无内配塑料含碳球团对比,内配废塑料的含碳球团孔隙率增大,这样有利于反应中还原气体的传质,从而促使含碳球团的还原率随之提高。对影响含碳球团直接还原的因素如C/O摩尔比、还原时间、内配废塑料种类及其质量分数进行实验研究。实验结果表明:在实验设定条件下,含碳球团直径10mm,还原温度1 350℃,内配质量分数为4%的聚碳酸酯(PC)在还原时间6min时,球团孔隙率最高,达74%;此时还原率最高,达98.89%。含碳球团还原体系在反应过程中,内配一定比例的废塑料,可以缩短还原时间,降低还原温度,提高球团的还原效率。
Energy saving and emission reduction are the major challenges currently facing the steel industry. Waste plastics, as a renewable clean energy and reductant, replace coke powder, and fossil fuels such as anthracite have received a great deal of attention in the ironmaking industry. The waste plastics, limonite powder, anthracite and binder mixture of carbon-containing pellets made in the tube furnace direct reduction experiments. Waste plastic pyrolysis at high temperatures to release heat for pellet preheating and direct reduction provide an additional source of heat. At the same time, compared with no inner with plastic carbon-containing pellets, the porosity of the carbon-containing pellets with waste plastics increases, which is conducive to the mass transfer of the reducing gas in the reaction, thereby promoting the reduction rate of the carbon-containing pellets . Factors that affect the direct reduction of carbon-containing pellets such as C / O molar ratio, reduction time, the type of waste plastics and the mass fraction within the experimental study. The experimental results show that the polycarbonate pellets with the diameter of 10mm and the reduction temperature of 1 350 ℃ with the mass fraction of 4% are the highest in the reduction time of 6min, Up to 74%; at this time the highest recovery rate, up to 98.89%. Carbonaceous pellet reduction system in the reaction process, with a certain percentage of waste plastics, can shorten the reduction time, reduce the reduction temperature, improve pellet reduction efficiency.