Modelling and optimisation of biomass injection in ironmaking blast furnaces

Biomass is a renewable and potentially carbon-neutral energy source and can be a promising alternative to fossil fuels in the ironmaking industry. Pulverised biomass injection (PBI) is the most promising technology to use biomass-based materials in ironmaking blast furnaces (BFs). This paper reviews key aspects of recent research relating to biomass combustion in the raceway region: experimental studies, numerical studies, and the application of the research findings to optimise BF practice. In the experimental part, the pretreatment of raw biomass to produce pyrolysed biochar products for improving applicability in BFs is reviewed. The properties of raw biomass and biochar are compared with the main requirements for injection into BFs, and the process tests that have been employed at lab- and pilot-scales are reviewed. In the modelling part, a comprehensive overview of mathematical modelling of biomass combustion in BFs is presented, ranging from turbulent flow to heat transfer and mass transfer, as well as key reaction models for simulating the lower part of the BF. With respect to the application of the research, in-furnace phenomena understanding, operation optimisation, and facility design are reviewed, including the co-firing of biomass and coal. In addition, heat and mass balance modelling has been used to demonstrate the operating window of feasible operations using PBI. Life cycle assessment has been reviewed to demonstrate PBI's environmental credentials. Based on the aspects reviewed, conclusions have been drawn on the strengths, limitations, and outlook of PBI studies. This paper offers a comprehensive review of the combustion of biomass in BFs and should prove useful for process understanding, design and optimisation towards green ironmaking technology.