Lowering the carbon consumption and fossil CO2emissions is a priority in blast furnace (BF) ironmaking. Renewablebiomass is one option that can play an important role in future low-carbon ironmaking particularly in the countries rich inbiomass resources. In this study, full-scale trials to investigate the impact of briquettes containing torrefied sawdust on theBF efficiency and process stability have been conducted. Briquettes containing 1.8% of torrefied pelletized sawdust (TPS),86.2% of steel mill residues, and 12% cement with sufficient mechanical strength have been produced on industrial scale. Thebio-briquettes were charged at two different rates: 37% ( ~ 39 kg/tHM) and 55% ( ~ 64 kg/tHM) bio-briquettes to the SSABBF No. 4 in Oxelösund. The gas utilization was higher during bio-briquette-charging periods without change in pressuredrop up to 55% bio-briquettes, indicating sustained shaft permeability. BF dust generation or properties did not change significantly.Measurements of the top gas composition using mass spectrometry did not indicate release of hydrocarbon fromTPS in connection to the charging of bio-briquettes. Evaluation of process data has been carried out using a heat and massbalance model. The evaluation of operational data in the model indicated lowering of thermal reserve zone temperature by45 °C and reduction in carbon consumption by ~ 10 kg/tHM when charging 55% bio-briquettes compared to the referencecase. The total CO2emission was reduced by about 33–40 kg/tHM when using 55% bio-briquettes.
Validerad;2019;Nivå 2;2019-09-27 (johcin)