Enrichment of arsenic, lead, and antimony in Balingian coal from Sarawak, Malaysia: Modes of occurrence, origin, and partitioning behaviour during coal combustion

The concentrations of mineral-forming elements and trace elements in coal and coal ashes from Balingian coalfield, Sarawak, Malaysia were assayed and their modes of occurrence, enrichment origin, and partitioning behaviour during coal combustion were studied as well. Balingian coal is high in As, Cu, Pb, Sb, Th and Zn. Of particular concern are As (as high as 181 ppm). Pb (325 ppm) and Sb (96 ppm), all of which are highly enriched in Balingian coal relative to their respective coal Clarke values. Arsenic, Pb and Sb in the coal are mostly organic, and to a lesser extent, they are bound to discrete minerals in the form of aluminosilicates. During coal combustion in the power plant, a substantial portion of organically associated As, Pb and Sb in the coal vaporize and are released into the atmosphere, whereas Ba and Mn are highly enriched in the coal ashes as compared to the raw coal. The As, Pb and Sb anomalies observed in Balingian coal may be related to a large Sb-As, and probably Pb mineralization in the vicinity of the coalfield, with some localised epigenetic infiltration of these elements from the surrounding rocks by circulating groundwaters. (C) 2012 Elsevier B.V. All rights reserved.