Utilization of Low Grade Iron Ore (FeOOH) and Biomass Through Integrated Pyrolysis-tar Decomposition (CVI process) in Ironmaking Industry: Exergy Analysis and its Application

Abstract

Effective utilization of low grade iron ore (FeOOH) and biomass represents a promising method to reduce the dependency on fossil fuels and decrease raw material costs in the ironmaking industry. A process system diagram was made and a comparison of exergy losses in conventional methods was conducted to evaluate the proposed system, integrated pyrolysis-tar decomposition over a porous ore through Chemical Vapor Infiltration (CVI) process. As the main product, the CVI ore was employed for energy storage based on carbon deposition and pre-reduced ore, Fe3O4 as a product of proposed system that consisted of three units: pyrolysis, CVI, and dehydration-separation. The exergy of CVI ore increased significantly owing to exergy recovery through tar decomposition. In the basis of 3.86%wt carbon deposition (experimental value) and producing of 1 000 kg metallic Fe, the exergy loss of the proposed system was found to decrease by about 17.6% compared to that in conventional systems by the recovery of both chemical and thermal tar exergy. The exergy loss decreased drastically to 37.0% when the expected carbon deposition was attained (10%wt). The CVI ore offered great chance to replace the coke breeze as a heat source in sinter plant. With regard to experimental value, the sinter plant could be operated without using additional coke breeze when the CVI ore content was 70% to total input ore. The total enthalpy of CVI ore consisted of the oxidation of deposited carbon and Fe3O4 in the ratio of 60.2% and 39.8%, respectively. Based on these results, the proposed system proffered effective biomass and low grade ore utilization as well as led to decrease in CO2 emissions by the ironmaking industry.

Reduction Reactivity of Low Grade Iron Ore-Biomass Pellets for a Sustainable Ironmaking Process

“…The CVI method directs the formation of nanoscale distances between carbon-iron ore, which causes the reduction rate to occur faster [12]. Investigation of Cahyono et al [13] showed that using the CVI method in a sinter plant could significantly decrease coke breeze and CO 2 emissions in the ironmaking sector. Another study indicated that the reduction rate of composites with the CVI method was higher than that of a mixture of dehydrated iron ore and coke [14].…”

Sustainable Iron-Making Using Oxalic Acid: The Concept, A Brief Review of Key Reactions, and An Experimental Demonstration of the Iron-Making Process

“…Global crude steel production rose by 3.9% from 1.71 Gt in 2018 to 1.78 Gt in 2019, and continued growth is projected in the years to come . The iron and steel industry is, however, one of the most energy-intensive industrial sectors. − CO 2 emissions from this industry amounted to approximately 2.0 Gt in 2019, accounting for 24% of the total amount emitted directly from industries . The majority of CO 2 is generated in the iron-making process, which generally employs a blast furnace (BF).…”

“…Extensive R&D efforts have been invested in alternative approaches to iron-making from the iron ore, which are largely classified into two types: direct reduction (DR) and smelting reduction processes. − ,− In DR, the iron oxides in iron ore are reduced using reducing gas (H 2 and CO) produced from natural gas or coal in reactors such as shaft furnaces and fluidized bed reactors. The reduction occurs at temperatures below the melting point of iron, producing so-called direct reduced iron or sponge iron.…”

Exergy analysis of conventional and hydrothermal liquefaction–esterification processes of microalgae for biodiesel production

“…Exergy is one of the thermodynamic concepts which is able to examine process efficiency in a more comprehensive way [16]. Performing exergy analysis on similar process will be useful to justify the most energy efficient process configuration.…”