Coal mining in China is continually increasing, and the associated emitted coal mine dust is of growing environmental and occupational concern. In this study, deposited coal mine dust (DD) was analysed in three different regions of an active, highly-volatile bituminous open-pit coal mine in the Xingjian Province, Northwest of China: coal working fronts, tailings handling sites, and road traffic sites. Samples were analysed for particle size, and geochemical and mineralogical patterns, and then compared with the respirable DD fractions (RDDs, <4 μm) separated from DD samples. Online measurements of ambient air concentrations of particulate matter (PM10 and PM2.5), black carbon (BC) and ultrafine particles (UFP) were performed in the same mine zones where DD was sampled. Furthermore, the RDD samples were subjected to analysis of specific biological response or toxicological indicators (oxidative potential, OP). The results demonstrated: i) large differences in particle size and composition among DD from tailings handling, road traffic and coal working front sites, ii) a strong influence of the DD moisture contents and ash yields on particle size, and, accordingly, on the potential dust emissions, iii) an enrichment of multiple elements (such as Nb, Th, Cr, Sr, Li, As, Pb, Cu, Zr and Ni) in the RDD from coal working fronts compared with their contents in the worked parent coal seams, mostly attributed to mining machinery, tyre and brake wear emissions and to deposition of dust emitted from gangue working zones, iv) low OP values of the RDD emitted from the studied mine, which works a high-quality coal, with OP being influenced by Mn, sulphate and anatase (TiO2) contents, and v) the impact of specific mining operations and mine areas on the levels of air pollutants, such as high PM from tailings handling in the upper parts of the mine or the high UFP levels in the bottom of the mine (due to vehicle and machinery emissions and lower dispersive conditions). The data presented here demonstrate the necessity of extracting the more deeply respirable size fraction of coal mine dusts in future studies on the health effects of these materials because this finer fraction is mineralogically and geochemically different from the parent rocks.

This study was supported by Generalitat de Catalunya (AGAUR 2017 SGR41), Spain; by the National Science Foundation of China (grant 41972180); the Program of Introducing Talents of Discipline to Universities (grant B14031) and Overseas Top Scholars Program for the Recruitment of Global Experts, China and by the Spanish Ministry of Science and Innovation (Excelencia Severo Ochoa, Project CEX2018-000794-S). Pedro Trechera is contracted by the ROCD (Reducing risks from Occupational exposure to Coal Dust) project supported by the European Commission Research Fund for Coal and Steel; Grant Agreement Number-754205.

Peer reviewed