Biochar application in Steel Industry
Renewably sourced biomass materials (wood, crops, animal waste, landfill gas, biofuel, etc.) are considered a carbon-neutral resource in life cycle analysis (LCA) that considers the energy consumption not only in biomass establishment but also harvesting, transport, drying and pyrolysis, wherein pyrolysis co-products are captured or utilised. The reduction in carbon emissions is therefore due to biomass’s carbon neutrality. Furthermore, in using biomass as a partial replacement of fossil fuels across steel manufacturing, biomass serves as both a solid fuel and reductant source.
In steelmaking processes, various technical, environmental, and economical evaluations of biomass applications have been conducted. Potential application areas range from sintering, cokemaking, ironmaking (both in BF and DRI) and even to steelmaking processes, wherein small amounts of processed biomass are utilized as recarburiser, replacing calcined anthracite. In steel applications, slow or low temperature pyrolysis (torrefaction) are preferred as these maximise solids (biochar) production.
Advantages of biomass
Carbon neutrality (potential reduction of CO2 emission by 0.69–1.21 t/t-steel)
Low ash and sulphur content
Potential low alkalis and impurities depending on biomass source
Controlled VM using different pre-processing methods
Processing of biomass has the potential to yield other beneficial products e.g. liquid pyrolysis oils which could be processed into sustainable transport fuels, wood vinegar and syngas
Potential Application Areas in Steel Plants
- Use of biochar in sintering process
- Use of biochar in blast furnace iron making for bio-injection via tuyeres
- Use of biochar in blast furnace iron making for biomass based top-charging