Study On Reduction Intensity And Disintegration Of Iron Ore Pellets At Low Temperature Gas-based Direct Reduction

Abstract:The traditional blast furnace ironmaking technology has a series of problems such as pressure from environmental protection, shortage of coking coal resources and so on. Gas-based direct reduction as cutting-edge technology is a effective method to solve these problems. China has basis in reality for application of coal gasification-direct reduction technology. There are problems of degradation and reduction intensity significantly reduced in Coal gas base reduction process for producing direct reduced iron (DRI). This paper is a research for the effect of temperature and reducing gas composition on the reduction intensity and disintegration of oxide pellets in gas-based direct reduction process and gangue on the reduction intensity and disintegration of iron ore briquette in coal gasification direct reduction. The main conclusions are as follows.The temperature and reducing gas composition significantly affect the reduction intensity and disintegration of iron pellets:(1) the reduction temperature increased from450℃to600℃, the drum strength and compressive strength decreased at first and then increased. The pellets has the lowest strength at550℃. Reducing atmosphere H2/(H2+CO) increased from0.3to0.7, the drum strength and compressive strength gradually increased.(2) Affected by the reducing atmosphere and temperature, the structure of pellet becomes loose, gap increasing with the reduction process of Fe2O3to Fe3O4and FeO in gas-based direct reduction. With the temperature and H2content increasing,the pellets have less damage to structures and the reduction intensity and disintegration of pellets have improved.Gangue components have significant effect on the reduction intensity and disintegration in coal gas-based direct reduction process.(1) CaO and SiO2can enhance the reduction intensity of iron ore briquette, and improve reduction desintegration indicators. The right amount of MgO is beneficial to improve the strength. The iron ore briquette has the best index when the content of MgO is0.61%. The variation of Al2O3 content in the range of0～1.55%has no significant influence on the reduction intensity and desintegration.(2) The microstructure of reduced briquette are corresponding obvious with the reduction intensity. CaO, SiO2and the right amount of MgO can reduce structural damage of the briquette. However, the structures of Al2O3briquette and pure mineral briquette were severely damaged.