Optimisation of influencing factors for iron recovery rate in melting reduction ironmaking using response surface methodology

Melting reduction ironmaking is hailed as an environmentally sustainable and broadly implemented technique in the realm of iron production. Scholars and researchers from across the globe have dedicated significant resources and efforts towards the study, refinement and advancement of this pivotal field. The current study undertakes experiments on the iron ore melting reduction process scrutinising the impact of C/O, alkalinity, temperature and holding time on the pig iron yield and the iron recovery rate. The experimental conditions of the study revealed that the increase in C/O led to a decline in both the yield of pig iron and the iron recovery rate. It is noteworthy that, in the C/O range between 0.8 and 1.0, the iron recovery rate decreased from 94.54% to 87.52%. Additionally, there was an observable decrease in pig iron yield and iron recovery rate as alkalinity increased, with the lowest point being an alkalinity of 2.0. The iron recovery rate gradually increased with the rise in temperature, peaking at 94.13% at 1500 °C. Moreover, the iron recovery rate initially increased and then decreased with the increase in holding time, finally reaching its highest value of 94.77% after 40 min. Model equations were formulated using the response surface methodology to optimise the relevant parameters, and they aligned well with the experimental data. Under optimal conditions with a C/O of 0.72, an alkalinity of 1.15, a temperature of 1544 °C and a holding time of 33 min, the iron recovery rate achieved an impressive 98.6294%. The iron recovery had a correlation coefficient (R2) of 0.988, and analysis of variance confirmed that the C/O, alkalinity and temperature had the most significant impact on the iron recovery rate.