Field measurements on emission characteristics, chemical profiles, and emission factors of size-segregated PM from cement plants in China.

Cement manufacturing is a major contributor to ambient particulate matter (PM) pollution in China, threatening urban and regional air quality improvement. Here, we tested the typical outlets (kiln tail, kiln head, and coal mill) in one shaft kiln and three rotary kilns to investigate the mass concentrations, size distributions, and chemical compositions of size-segregated PM. Results show that the concentrations of PM in most samples are lower than the strict local emission standards (10 mg/Nm3). We show that the characteristic chemical compositions in PM for most tested outlets are Ca and Ca2+, while for shaft kiln are K, S, K+, and SO42-, and organic carbon. Elemental carbon accounts for a relatively high proportion of PM emitted from coal mills. Meanwhile, unstable and abnormal operating conditions and variations on feed coal compositions will cause high levels of NH4+ and Cl- in PM from the kiln tail/head. Besides, the emission factors (EFs) of PM2.5, PM10, and PM after air pollution control devices for typical outlets of cement plants are calculated, which fall in ranges of 0.16-2.48, 1.49-18.46, and 3.32-35.35 g/(t of clinker), respectively. It suggests that mass emission characteristics, source profiles, and EFs of PM have changed notably as emission standards become more stringent. We believe the newly detailed size-segregated PM EFs and chemical profiles will help update and compile the refined emission inventory for current cement production in China.