Distribution of arsenic in coals of Yunnan Province, China, and its controlling factors

Abstract

The As concentration and its distribution patterns in Southwestern Chinese coal beds of two of the most important coal-forming periods, Late Permian and Neogene, are analyzed. More than 700 samples from 26 mining districts have been collected and tested for As concentration. The As content and distribution in coal can be significantly changed by the combined effects of many factors, including the geochemistry of the source region and the tectonic and depositional environment of the basin and surrounding paleo-watershed. The As distribution in Neogene coals of Yunnan Province reflects to some extent their primary distribution patterns during peat accumulation. Because As is a sulphophile element, two As distribution types can be distinguished, based on the correlation coefficient between As and total S contents. In the high-rank Permian coals, especially those affected by hydrothermal and tectonic activities, significant secondary As enrichment in coal is likely to occur. Thus, to optimally utilize coal resources, it is important to investigate the distribution, occurrence and concentration of As in coal during resource exploration and evaluation to identify As-rich zones in the coal beds.