Behavior of trace elements and mineral transformations in the super-high organic sulfur Ganhe coal during gasification

Abstract

A coal containing high concentrations of hazardous trace elements F, V, Cr, Se, Mo, Cd, and U was selected for the gasification experiment based on the Lurgi fixed-bed pressurized gasifier. The feed coal was a super-high organic sulfur coal sampled from the Ganhe Mine, Yanshan Coalfield, Yunnan Province, China. Fluorine, Ga, Se, Cd, In, Tl, Pb, and Bi were volatilized during gasification, whereas V, Mo, and U were significantly enriched in the residue. The erosion of the gasifier internals resulted in the abnormal enrichment of Cr and Ni in the residue, with the maximum concentrations of Cr and Ni of 26,073 μg/g and 23,982 μg/g, respectively. Except for quartz, other minerals in the feed coals were transformed. The newly formed phases such as mullite, hercynite, magnetite, Fe aluminosilicate, and Al-Si-O-glass containing Fe-Ca-Mg-V-K-Ti were identified in the gasification residue. Pyrite was transformed to elemental iron in some cases. Pyrrhotite with a magnetite rim, representing the high temperature transformation product of pyrite, was observed in the gasification residue by scanning electron microscopy.