Sulfur content in coal formed during different geologic periods in the Guangxi Province and the relationship with the depositional environment

Abstract

To understand the distribution regularity of sulfur in coal formed during different geologic periods and their related controlling factors, we obtained statistics on the sulfur content in the coal samples from different regions of the Guangxi Province. Based on the results, we drew the following conclusions. First, the contents of the sulfur forms vary significantly in the coal samples. The sulfide and organic sulfur content account for a relatively high proportion of the total sulfur content while the sulfate sulfur content is relatively low (i.e., 1.29–15.72%, average = 4.83%). Between these factors, the sulfide sulfur content in early Carboniferous coal is slightly higher than the organic sulfur content, while the organic sulfur content in late Permian, Early Jurassic, and Tertiary coal is higher than the sulfide sulfur content, represented by Heshan coal. Second, coals formed in early Carboniferous, late Permian, and Early Jurassic mainly contain high-sulfur coals. In contrast, Neogene coals, with relatively poor sulfur content, are the major source of low-sulfur coals in the Guangxi Province. In this study, the sulfur content in coal formed in early Carboniferous and late Permian is ≥ 4%; thus, this coal belongs to the super-high organic sulfur (SHOS). Finally, we discuss the spatial distribution characteristics of the sulfur content in coals formed during various geologic periods and their controlling factors. The results indicate that the content and form depend on the paleogeographic conditions during the geologic period of formation.