Experimental Study On Preparation And Metallurgical Characteristics Of Oxidized Pellets For Gas-based Shaft Furnace Direct Reduction

After taking into account the conditions of the domestic iron resources and the development of iron and steel industry, the abundance of domestic non-coking coal resources, combinated the coal-gasification and gas-based shaft furnace as new precess of direct reduction, which is the important way of getting rid of coking coal resources shortage, changging the energy structure and improving the steel structure of products, solving scrap steel shortages and scrap steel quality deteriorated gradually. Qualified oxidized pellets which used for gas-based shaft furnace and proper shaft furnace reduction process condition is the foundation and precondition of the development of the coal-gasification shaft furnace direct reduction process.This paper studied on preparation of direct reduction of oxidized pellets by gas-based shaft furnace and metallurgical characteristics based on three kinds of domestic iron ore raw material; Then, examined reduction behaviour and reduction swelling of pellets during different temperature and reduction atmosphere through carried out direct reduction experiment by simulating gas-based shaft furnace process condition; Finally, preparation of pellet use pure hematite as raw material through adding different content of SiO2、CaO、MgO respectively, studied on the mechanism of gangue composition influence on the performance of the reduction swelling of pellets during H2and CO atmosphere, provide the theory basis and experimental parameters for producting high quality oxidized pellets through developing shaft furnace gas direct reduction process in our country.Through the study, the conclusions could be drawn as follows:(1) Oxidized pellets could be used for gas-based direct reduction based on three kinds of domestic iron concentrate. Shanxi oxidized pellets with better comprehensive metallurgical performance:RI is75.74%, RDI+3.15is97.03%, RSI is16.78%.(2) The temperature risen, the content of H2increased in the reduction atmosphere, which could improve the reduction progress obviously. The pellets with well performance of reduction and strength index after reduction, which could meet shaft furnace practical production requirements.(3) The RSI of the pellets gradually increased with the rise of temperature and decreased with the increasing of the content of H2in the reduction atmosphere during the temperature extent and reduction atmosphere in the test.(4) Preparation of high grade oxidized pellets base on pure hematite, the volume of pellets swell obviously; which could be improved reduction swelling performance through adding proper SiO2、 CaO and MgO, but the content of CaO could not too much.