Effects of Charcoal Carbon Crystallinity and Ash Content on Carbon Dissolution in Molten Iron and Carburization Reaction in Iron-Charcoal Composite

Abstract

Charcoal use instead of fossil fuel is one of the possible technologies for mitigation of CO2 emission in the steel industry because charcoal can be considered as "carbon-neutral" material. In this study, the possibility of utilization of charcoal as carbon source for carburization reaction was examined; more specifically effects of carbon crystalinity and ash in charcoal on carbon dissolution into molten iron and iron carburization reaction in iron-charcoal composite were investigated. Two kinds of experiments were carried out. One is measurement of charcoal carbon dissolution rate in iron bath. Another is observation of isothermal reaction between iron and charcoal in a composite sample. Several kinds of charcoal with relatively low ash content were applied as experimental samples. Charcoal samples were treated with several heating patterns to control their carbon crystallinity. Additionally, charcoal samples were treated with acid solutions, HCl and HF, to control the ash content in them. From these investigations, following results were revealed. Charcoal heat-treated at low temperature, 1 273 K, has advantage for carbon dissolution reaction into iron bath. Charcoal ash strongly prevents the carburization reaction between iron and carbon in the composite sample.

Effects of Ash Amount and Molten Ash’s Behavior on Initial Fe–C Liquid Formation Temperature due to Iron Carburization Reaction

“…In previous works, 9,18) it was found that carbon structure of fixed carbon has an obvious effect on carburization reaction. In order to focus on effects of ash and fixed carbon on the reaction, volatile matter of every material was removed by 3 600 seconds heat treatment at 1 273 K under Ar atmosphere in this study.…”

“…18) Residues amount of ash were measured by gravimetric measurement after combustion at 1 088 K under air atmosphere as JIS M 8812. The residues amounts of ash after the acid treatment were dependent on duration of this treatment as shown in Fig.…”

“…Various investigations [8][9][10][11][12][13][14][15][16][17][18] about iron carburization reaction in ironmaking process have been reported. It has been generally considered that sources of carburization reaction are coke which has direct contact with metallic iron and carbonaceous gas surrounding there.…”

“…There were many reports, which focused on effect of the ash on this reaction. [11][12][13][14][15][16][17][18] However, their discussions were based on comparison among different kinds of carbon sources; coke, coal, graphite, etc. In other words, they could not exclude effects from other factors, especially carbon crystallinity.…”

Novel Approach Towards Biomass Lignin Utilization in Ironmaking Blast Furnace

“…Intensive work is being done to mitigate the CO 2 emissions in steel industry by partial substitution of fossil fuels (coal and coke) with renewable source of energy such as biomass. [7][8][9][10][11][12][13][14][15] One of biomass materials which could be used as binder for briquettes and reducing agent in blast furnace is lignin. Lignin is considered as the second most abundant renewable biomass on the earth after cellulose and it represents about 30% of the total raw biomass.…”