Identification of Natural Nearly or Nanoscale Particles in Bituminous Coal: An Important Form of Elements in Coal

Nanoparticles are ubiquitous in nature and are also found in raw coal, which plays an irreplaceable role in the global economy. In this study, raw coal samples were obtained from Gaojiapu Coal Mine in Shanxi Province, China. The elementary composition of nanoparticles was determined using energy-dispersive X-ray spectroscopy. The structural and chemical characteristics of nanoparticles were analyzed using transmission electron microscopy. Results revealed that there were multiple types of nanoparticles in the raw coal, such as S-, Ca-, Ba-, Ni-, Cr-, Si-, Sr-, and V-bearing nanoparticles. These nanoparticles exhibited various sizes and complex, irregular shapes. Our findings revealed that elemental nanoparticles occur in raw coal. These nanoparticles include celestite and barite nanoparticles. In addition, nanoparticles with Ni, Cr, and V in composition are also included in raw coal. These nanoparticles, which contain heavy metal elements, have great potential to harm the human body. Meanwhile, compared with the characteristics of nanoparticles produced by coal combustion, the nanoparticles in raw coal may be an important potential source of the nanoparticles produced by coal combustion.