Evaluation of concentrated solar thermal energy for iron ore agglomeration

The iron and steelmaking industry is actively seeking to reduce its overall carbon footprint with major research and investment directed towards fossil fuel-free steelmaking. In this paper, we present a novel iron ore agglomeration process that produces a Lime Magnetite Pellet (LMP) feed using concentrated solar flux as the energy source that significantly reduces the CO2 emissions compared to existing pellet making processes. The process has been tested under laboratory experiments inside a solar simulator-electric furnace hybrid reactor setup. A detailed mass and energy balance analysis of the process was conducted for estimation of the emission reduction as well as for estimating the solar flux requirement at various percentages of fuel to solar flux substitution. The preliminary economics of the solar-based LMP process was also investigated. The estimated capital cost of a 2 Mtpa (million tonnes per annum) plant was between AU$165 M and AU$142 M assuming a solar reactor thermal efficiency of 50% and 80%, respectively. The payback period was likely to be 15–20 years (50% efficiency) and 7–9 years (80%). At current achievable reactor efficiencies, a solar-based LMP process is not economically attractive. However, with further development in reactor design, heliostat cost reductions and improvements in thermal storage performance, a solar-based LMP process could potentially be commercialised.