Morphology Change and Carburization Characteristic of Iron Ore-Coal Composite During Reduction under a Simulated Condition of Blast Furnace

Abstract

Ironmaking process by Blast Furnace (BF) method contributes about 70% of CO 2 emission and energy consumption in steel works. To aim at the sustainable development and environmental protection, decreasing CO 2 emission and energy consumption is always an indispensable task. Using iron ore-coal composite as the raw material of BF is a promising way to mitigate the above issue.In this study, we conducted an experiment procedure which is to simulate the reduction of an iron orecoal composite travelling from the top zone to the cohesive zone of BF. Reduction behavior, morphology changes and carburization characteristic of the composites with the variables of C/O (Carbon to Oxygen) ratio were investigated.As C/O ratio was increased from 0 to 0.6, the reduction rate of composite was accordingly enhanced. It was found that the composite is swelling severely when C/O ratio was lower than 0.4. The swelling occurred in the temperature range from 800°C to 1 100°C which was just under the stage of reduction from wustite to iron. The composite is shattering obviously starting from 1 160°C when C/O ratio was higher than 0.4. It is because the remained free carbon is surplus in reduced iron, causing shattering and powdering. Hence, C/O = 0.4 was suggested to the composite for being charged into BF.

Swelling Behavior of Iron Ore Pellets during Reduction in H2 and N2/H2 Atmospheres at Different Temperatures

“…The maximum RSI was observed at 1000 °C in both H 2 and N 2 /H 2 atmospheres. In a study by Huang et al, [ 33 ] where one of the materials used was an iron ore concentrate with a low content of CaO (0.08 mass%) and high Fe met and SiO 2 (67.13 and 2.73 mass%, respectively), under 50% N 2 /CO/CO 2 atmosphere, the maximum swelling index was also observed at 1000 °C. This can be attributed to an increase in the reduction rate of the iron oxide pellets through their pores at the higher temperatures.…”

Interface Behavior and Interaction Mechanism between Vanadium-Titanium Magnetite Carbon Composite Briquette and Sinter in Softening-Melting-Dripping Process

“…[15][16][17][18][19] Simultaneously, the CCB was widely applied to process low-grade and composite iron ore due to its outstanding reducibility. [20][21][22][23] Vanadiumtitanium magnetite carbon composite briquette (VTM-CCB) was prepared by briquetting the VTM concentrates and coal fine mixtures followed heat treatment. Our previous researches 24,25) indicate that the VTM-CCB exhibits excellent metallurgical properties such as compressive strength, reduction degradation property and reduction swelling property, and meets the requirements of BF smelting.…”

Effect of Silica in Ash of Coke on Carburization and Melting of Iron

“…[9][10][11][12][13] These reports suggest that the realization of direct contact between reduced iron and carbon from coke, and the minimization of the effect of ash on the carburization are important for the acceleration of iron melt formation by carburization. Other studies have focused on the followings; the suggestion of different types of carbonaceous materials as reducing and carburizing agents for accelerating the iron melt formation by carburization in iron ore-carbon composite; 14) the effect of surface texture and type of carbonaceous materials on the melt formation; [15][16][17][18] the effect of basicity and surrounding gas on the melt formation; 19,20) the carburization mechanism by direct contact between iron and carbon through slag; [21][22][23] the melting behavior of iron through coke bed; 24) the effect of sulfur on the carburizing behavior, 25) and so on. However, although the physical effects of ash on the carburization behavior have been reported, there are no reports focusing on the chemical effect of ash.…”