The periodic law of trace elements in coal —A case study of the 5# coal from the Weibei Coalfield

To better understand the 5# coal (late Paleozoic) from the Weibei Coalfield, nine samples were collected in different locations of the 5# coal seam. The correlation coefficients between 51 trace elements including organic carbon, as well as ash, were calculated by statistical method. The variations of the squares of correlation coefficients with the first ionization energy, as well as ion radii of the corresponding elements, were comparatively investigated. The results show that the distribution law of the trace elements is in accordance with the chemical element periodic law and can be theoretically explained in detail. The distribution law is also suitable to the stable coal layer formed under the function of the coal accumulation, such as that in the Ordos Basin.