Thermal compressive strength of pellet during reduction process under hydrogen-rich atmosphere
Hydrogen-rich smelting and increasing the proportion of pellets into blast furnace are important ways to promote the low-carbon blast furnace ironmaking.Taking iron ore oxidized pellets as the object,the effects of re-ducing atmosphere and temperature on the thermal compressive strength of pellet were experimentally investigated,and the evolution law of the thermal compressive strength of pellet under different conditions was clarified.The re-sults show that the thermal compressive strength of pellet decreases with the increase of reducing gas(CO or H2)concentration during the isothermal reduction process,and the decrease of thermal compressive strength of pellet at 900 ℃ is significantly higher than that at 700 ℃.When the volume fraction of H2 increases from 0 to 40％,the thermal compressive strength of pellet slowly decreases from 865 N to 757 N at 700 ℃,and significantly decreases from 632 N to 29 N at 900 ℃.During the non-isothermal reduction process,when the reduction temperature increa-ses from 500 ℃ to 900 ℃,the thermal compressive strength of pellet under the inert atmosphere gradually decreases from 1 551 N to 1 016 N,and that under the non-hydrogen-rich atmosphere decreases from 1 495 N to 244 N,and that under hydrogen-rich atmosphere decreases from 1 275 N to 289 N.As the temperature is less than 800 ℃,the thermal compressive strength of pellet under hydrogen-rich atmosphere is higher than that under non-hydrogen-rich atmosphere,and when the temperature is greater than 800 ℃,the thermal compressive strength of pellet under hy-drogen-rich atmosphere is slightly lower than that under non-hydrogen-rich atmosphere.This study could provide theoretical basis and data support for hydrogen-rich smelting and large proportion pellet smelting.
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