Experimental Research On Direct Reduction Of Carbon-containing Pellet Immixed With Waste Plastics

Energy conservation and emissions reduction is an important challenge to the iron andsteel industry. Waste plastic considered as renewable clean energy and reducing agent havegained attention as possible substitutes for fossil-based such as coke powder and anthracitein the iron-making industry. At the same time, manufacturing Direct Reduction Iron (DRI)by coal-based direct reduction technology has been used widely at present in the globalbecause of short process, less pollution, low energy consumption. The iron ore resources iswealthy highly in Baotou of Inner Mongolia. Among them, limonite of total iron contentbetween30%to40%is most common. The main processing method above limonite ismineral processing and agglomeration, but the utilization rate is bitty， the energyconsumption is high-up, and the environmental pollution is severe. In view of the abovesituation, we deal with limonite by direct reduction technology in order to prepare ironbeads in this paper.In this article, a certain percentage waste plastic particles of different types be seenas auxiliary reducing agent and catalyst were mixed with limonite powder of Bayan Obomine that be seen as iron raw material and anthracite of Gu Yang colliery that be seen asmain reducing agent for producing carbon-containing iron ore roasted pellets in order toproduce DRI by direct reduction in a muffle furnace. First of all, the effects of reductiontemperature, time, molar ratio of carbon to oxygen (C/O), species and percentage contentof waste plastic on reduction rate of carbon-containing iron ore roasted pellets were studiedby single factor and orthogonal experiments. The single factor experiments results showthat the heat released by waste plastic combustion was used as the heat source of pelletpreheating and reduction. Compared with carbon-containing pellets without plasticaddition, the porosity of carbon-containing pellets with plastic addition is higher, whichmakes the process of reducing gas transfer in the pellets easier, so that reduction rate ofcarbon-containing pellets increase gradually. This technology lays the theoreticalfoundation for direct reduction process of transit hearth furnace in industrial. The orthogonal experiments results show that the main affecting factors of reduction rateinclude reduction temperature, followed by reduction time, species of waste plasticparticles and content of waste plastic particles. Under the optimum conditions of reductiontime of5min, temperature of1350℃, C/O of1.2and content of polyethylene of4%, thereduction rate of pellets can reach up to99.89%. Moreover, adding2%CaF2in the ballingprocess makes slag and iron separate apparently, and separated slag pulverize naturally.This is conducive to further screening for high-quality DRI.