Developing uses of alternative raw materials in cokemaking (ALTERAMA)
Final report - Study
Different alternative raw materials and briquetting conditions were evaluated to reduce costs and emissions, preserve coke quality and safeguard coke oven operation. Hydrous pyrolysis could not transform pine Kraft lignin into coking biocoal. Biomass-containing briquettes caused a decrease in the fluidity of coking coals, but addition of 2 wt% sawdust decreased the coking pressure of a dangerous coal without deteriorating its quality. Small size briquettes had higher negative impact on the CSR than large ones. The amount of PAHs evolving from biomass-containing briquettes produced with... paraffin and molasses as binders was lower than that from coal. The partial briquetting process was successfully adapted to increase the bulk density of the coke oven charge. The briquetting process was optimised with small size briquettes (5 cm3 format) and using crude tar and bitumen as binders. The use of brown coal as binding agent also provided good thermal stability, coking properties and coke quality at competitive cost. The amount of briquettes should not exceed around 25 wt% to avoid reducing the lifetime of coke oven batteries. A full turn-key installation of a partial briquetting process resulted in rather high CAPEX and OPEX. Therefore, it was not possible to achieve the targeted economic feasibility within the specific constraints and requirements of the voestalpine coking plant. Most commercially-available surfactants increased coal blend bulk density more than oil, offering opportunities for increasing coke yield. None had adverse effects on carbonisation or coke quality. Surfactants were more environmentally-friendly than oil, and some offer value-inuse benefits for industry.