Abstract of Recent Work: Advanced Pilot Plant Testing of Illinois Coal for Blast Furnace Injection
Background: A potentially new use for Illinois coal is its use as a fuel injected into a blast furnace (see Figure 1) to produce molten iron as the first step in steel production. Because of its increasing cost and decreasing availability metallurgical coke is now being replaced by coal injected at the tuyere area of the furnace where the blast air enters (see Figure 2).
Petrography - petrographic analysis of material collected from an active blast furnace showed that coal derived char is entering into the raceway of the blast furnace (see figure 3).
Reactivity - the reactivity of the Illinois Basin yield chars with significantly higher reactivities in both air and CO2 than chars from higher rank Appalachian coals and blast furnace coke (see Figure 4). These results indicate that the chars from the lower rank coals should have a superior burnout rate in the tuyere and should survive in the raceway environment for a shorter time.
Pilot Plant TestingObjectives: The overall purpose of this study is to evaluate the combustion of Illinois coal, during the blast furnace injection process, and to determine the suitability of Illinois coal to become a feed coal in this process. This investigation is significant to the use of Illinois coal in that the research to date suggests that coals of low fluidity and moderate to high sulfur and chlorine contents are suitable feedstocks for blast furnace injection.
A) Illinois Basin coals showed higher combustion rates resulting in higher coal burnout than the Appalachian coal tested under the same conditions. B) Illinois Basin coals showed higher char combustion reactivities than the Appalachian coal tested under the same conditions. C) These results indicate that when injected under the same conditions as the Appalachian coal the Illinois Basin coals will put less char into the raceway and that this char will burnout more quickly.
Procedures: This work advanced earlier pilot plant testing with the Canadian Centre for Mineral and Energy Technology (CANMET) Energy Research Laboratories in Ottawa, Canada by running injection tests on the Herrin No. 6 coal under conditions that match the experimental conditions that are now being studied in the ironmaking industry. These conditions include oxygen enrichment of the blast air (up to 25% O2), increased coal particle size (granular coal 1-3mm), and coal blends (in this case Herrin No. 6 coal and a higher BTU Appalachian coal).
Results: The results of the current research support the following conclusions:
Crelling, John C., 1996, Pilot plant testing of Illinois coal for blast furnace injection: Ironmaking Conference Proceedings-Iron and Steel Society of A.I.M.E, v. 55, p. 51-55.
Crelling, John C., 1995, Coal combustion under conditions of blast furnace injection: Ironmaking Conference Proceedings-Iron and Steel Society of A.I.M.E, v. 54, p.73-79.
Crelling, John C., Thomas, K. Mark, and Marsh Harry, 1992, Aspects of the combustion reactivity of coal macerals: Ironmaking Proceedings-Iron and Steel Society of A.I.M.E, v. 51, p.407-413.