Desulfurization mechanism of high-sulfur coal by heating reduced iron powder and magnetic separation

The clean conversion of high-sulfur coal has become one of the top priorities of today's social energy pollution situation and economic development. In this paper, guided by the exploration of high-quality desulfurization technology, the desulfurization method of “reduced iron powder + heat treatment + magnetic separation” is proposed. The effects of the heating temperature, heating time, and coal-to-iron powder ratio on desulfurization were investigated. The morphology of sulfur in high-sulfur coal before and after desulfurization was characterized by field emission scanning electron microscopy , X-ray diffraction, and Fourier transform infrared spectroscopy . The results showed that part of the sulfur content in raw coal is transferred into recovered iron by the “reduced iron powder + heat treatment + magnetic separation”. Optimized desulfurization was achieved when the temperature was 600 °C for 1 h with a coal to iron ratio of 5:2. The desulfurization rate reached 80.09%. The pyrite was reduced into pyrrhotite and was subsequently magnetically separated. The carbon-sulfur bonds of sulfone , organic sulfonic acid , and aromatic sulfide were broken. This study realizes the centralized capture of reduced iron powder by sulfur in coal, which provides a new method and option for clean coal production and is conducive to improving the carrying capacity of the environment for harmful sulfides. • Reduced iron powder under heat treatment improved the desulfurization effect. • More than 76.32% organic sulfur was removed. The total sulfur rate reached 80.09%. • The desulfurization mechanism of inorganic sulfur and organic sulfur was analyzed. • Self-made pulverized coal magnetic separation device, better observe reaction process.