Abstract:

Sulfur in coal is the main carrier of many hazardous trace elements. Based on sulfur form analysis, inductively coupled plasmamass spectrometry and Xray diffraction, the distribution of sulfur and hazardous trace elements in coal from the Qinshui Basin were analyzed and the influence of sulfur on hazardous trace elements was discussed. The occurrence modes of sulfide in coal were identified under microscope and scanning electron microscope with Xray energy dispersive spectrometer (EDX). The results show that organic sulfur is the main type of sulfur in coal, accounting for 78% of total sulfur. Pyritic sulfur only dominates in some highsulfur coals of the Taiyuan Formation. The microscopic occurrence modes of pyrite mainly include framboidal pyrite, thinlayer pyrite, euhedral crystals, nodular pyrite, massive pyrite and finegrained pyrite accumulations, and the occurrence modes of marcasite mainly include polysynthetic marcasite, plate marcasite and spearhead marcasite, some of which coexist with pyrite. Hazardous trace elements in coal from the Qinshui Basin are low and will not affect the environment during coal mining and coalbed methane development. Pyrite is the main carrier of As, Se and Hg, while organic sulfur determines the content of U in coal. It is suggested that the influence of seawater during and after peat swamp stage is the key reason for high total sulfur and pyritic sulfur in coal of the Taiyuan Formation. Sulfur in coal of the Taiyuan Formation has diverse sources and pyrite in coal of the Taiyuan Formation is characterized by multistage evolution.

Key words: coal, sulfur, pyrite, trace elements, Qinshui Basin