Effect and Mechanism of CaO on Iron Recovery and Desulfurization by Reduction Roasting-Magnetic Separation of High-Sulfur Cyanide Tailings

Abstract

The increasing demand for iron ore in the world causes the continuous exhaustion of mineral resources. The utilization of iron in secondary resources has become of focus. The present study was carried out to recover iron from high-sulfur cyanide tailings by coal-based reduction roasting-magnetic separation. The mechanism of CaO to increase iron recovery and reduce sulfur was investigated by observing CO and CO2 gas composition produced by the reaction, mineral composition and microstructure, distribution characteristics of sulfur, and the intercalation relationship between iron particles and gangue minerals. The results showed that the addition of CaO could increase the gasification rate of the reducing agent, increase the amount of CO2 gas produced, promote the reduction of iron minerals, and improve the metallization degree of iron. When CaO was not added, sulfur was mainly transformed into troilite, which was closely connected with iron particles and was difficult to remove by grinding and magnetic separation. With the addition of CaO, CaO preferentially formed oldhamite with active sulfur, which reduced the formation of troilite. Oldhamite was basically distributed in an independent gangue structure. There was a clear boundary between iron particles and gangue minerals. Oldhamite could be removed by grinding-magnetic separation.

Combining ozone and ultrasound technology to remove S2− in Bayer liquor

“…However, flotation desulfurization process is unstable due to the large fluctuation of raw ore composition [11] . Roasting desulfurization faces the problems of cost and energy consumption [12] , [13] . Desulfurization by precipitation faces the problems of introducing impurities and high costs [14] .…”

Deep Insight on the Occurrence Feature of Iron Minerals in a Cyanide Leaching Residue and Its Effective Recovery with Magnetic Separation

“…Another technical route of roasting-magnetic separation was proposed to process a cyanide leaching residue, in which hematite is the main iron mineral, and a magnetite concentrate assaying 61.78% iron grade with 60.67% iron recovery was produced [10]. A similar process was used to recover iron from a high-sulfur cyanide tailing; under strong reduction conditions, a reduced iron product with 90.68% Fe and 92.71% iron recovery was obtained [11]. Liu et al proposed a process of chlorination roasting-carbothermic reduction-magnetic separation for the treatment of an Au-bearing cyanide residue and produced an iron concentrate containing 82.17% Fe, with a total Fe recovery of 79.68% [1].…”