Carbonized Wood as a Blast Furnace Pulverized Coal Substitute: A Techno-Economic Assessment

Abstract

Substitution costs for employing carbonized wood as an alternative reducing agent in the blast furnace were assessed in dependence to its carbonization severity. This study aims to demonstrate a method of defining a most beneficial bioreductant pretreatment strategy considering also its implications on blast furnace fuel demand and, furthermore, variance in published carbonization results. With statistical methods a direct relation between reductant carbonization expense and contribution to the iron reduction process was established for a Monte Carlo style comparison of bioreductants from varied carbonization severities simply based on their probable chemical composition. Two mathematical methods, a simple calculation based on the reduction potential and a more sophisticated but less generic blast furnace model, were employed and compared. Three scenarios, differing in the placement of the carbonization plant in relation to the wood production sites and the steel works, were evaluated accordingly for two reference years 2023 and 2030. Irrespective of the selected method, intermediate carbonization severities, with char yields between 30 and 40 mass percent, gave superior results. Likewise, both models are largely indifferent concerning the location of the carbonization facilities. Results show that, from a European perspective, such a substitution may prove economically advantageous for the upcoming years.