Pilot-scale recovery of iron from refractory specularite ore using hydrogen-based mineral phase transformation technology: Process optimization, mineral characterization, and green production

Specularite, as a subspecies of hematite, is a potentially important iron resource, primarily distributed in South America. However, it is difficult to process by traditional methods due to their special properties. In this work, a study on specularite was conducted using grinding-hydrogen-based mineral phase transformation-magnetic separation technologies. The results showed that the iron concentrate produced in pilot-scale experiments meets excellent specifications, with a grade greater than 67% and recovery over 97%. In addition, the system operated with good stability, and its pollutant discharge complied with national standards. Following the further optimization of the process, the optimization process Ⅱ, namely magnetic separation-tailings with HMPT-magnetic separation, has demonstrated significant economic advantages. This process yielded an iron concentrate with a grade of 68.22% and a recovery of 97.20%, resulting in a net profit of about $9.75/h. Vibrating sample magnetometer (VSM) and scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) analyses were used to characterized the material and its products. The results indicate that the magnetic properties of specularite have significantly improved, and the ore structure become looser and more holes, thereby enhancing the separation of iron minerals from gangue minerals. In summary, this research provided a reliable method for the efficient, green, and low-cost utilization of specularite on an industrial scale in the future.