Assessment of Influential Range and Characteristics of Fugitive Dust in Limestone Extraction Processes

AbstractFugitive dust emission from limestone extraction areas is a significant pollution source. The cracking operation in limestone extraction areas easily causes high total suspended particulate (TSP) concentrations in the atmosphere, occasionally exceeding the 1-hr national emission standard of Taiwan (500 μg/m3). The concentration and size distribution were measured at different distances (0.05–15 km) in the extraction areas. The highest hourly concentrations of TSP, PM10(suspended particulate matter [PM] smaller than 10 μm), and PM2.5(suspended PM smaller than 2.5 μm) are 1111, 825, and 236 μg/m3, respectively, during the cracking process. Measurement results obtained from the Micro-Orifice Uniform Deposit Impactor indicated that the mass median aerodynamic diameter is ∼0.7 μm, with the geometric standard deviation exceeding 7. In addition, the emission factors are 0.143 and 0.211 kg/t for both vertical well and stair extraction operations, respectively. Experimental results demonstrate that the corresponding TSP control efficiencies for spraying water, planting grass, setting short walls, paving gravel roads, and establishing vertical well transportation are ∼55, 50, 44, 22, and 30%, respectively. Furthermore, the PM10control efficiencies are ∼45, 41, 54, 35, and 30%, respectively, whereas the PM2.5control efficiencies are roughly 23, 31, 15, 11, and 10%, individually.