Distribution and Migration of Trace Elements during Flotation in Ge-Rich Low-Rank Coal from Wulantuga Coal Mine, Inner Mongolia, China

Abstract

The high-Ge low-rank coal in Wulantuga Coal Mine, Inner Mongolia, China, has a high utilization value due to its enrichment of critical element Ge. However, it is also enriched with toxic elements such as Be, F, As, and Hg; therefore, the coal should be cleaned before use. In this study, the flotation experiment, X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier transform infrared (FTIR) analysis, and the release experiment for the high-Ge low-rank coal from Wulantuga were carried out, and the results are as follows. (1) The total mineral content of the feed coal is higher than that of the cleaned coal and tailing, and the content of the functional group −OH is also increased, indicating that the moisture in the cleaned coal is increased after flotation. (2) Argillation occurred and some minerals (dihydrate gypsum and kaolinite) and elements were released into the water during flotation, so the ash yield and the percentage of TiO2, Al2O3, Fe2O3, MgO, and CaO of the cleaned coal and tailing are lower than those of feed coal. (3) The concentrations of elements Li, Be, F, Mn, Zn, Sr, Hg, Tl, and Pb of the cleaned coal are higher than those of tailing, indicating that these elements are more likely to occur in organic matter or fine-grained mineral embedded in organics, but the concentration of other elements such as Ge, As, Sb, and W in the cleaned coal is lower than that of tailing, suggesting that these elements are weakly associated with organics or occur in minerals. (4) After flotation, trace elements Be, Cs, Ti, Ge, Sb, and W enriched in the feed coal were removed in large quantities, while F, As, and Hg were difficult to remove; therefore, other preparation methods should be tried. (5) The release experiment showed that the release rate of chalcophile and siderophile elements and rare earth elements and yttrium (REY) is relatively higher. In addition to those of Be, Ga, Sr, and Cs, the release rate of most elements is relatively low.

Ultra-repeatability measurement of calorific value of coal by NIRS-XRF

“…NIRS is an absorption spectroscopy technique based on near-infrared diffuse reection, with a wavelength of 780-2526 nm. The spectral absorption in NIRS originates from the overtones of hydrogen-containing groups' stretching vibrations such as O-H, N-H, C-H, and S-H, as well as from stretchingbending combination involving these groups, 13,14 so it can reect the composition and structural information of organic substances in the sample. When near-infrared light is irradiated onto the coal, photons of different wavelengths will be selectively absorbed.…”

New Insight into Temperature Effects on Low-Rank Coal Flotation Using Diesel as a Collector

“…As a low-grade resource, the processing of low-rank coal (LRC) has been paid more and more attention. − Efficient and full utilization of LRC is of great significance to understand green and low-carbon cycle development. − Flotation plays an important role in the recovery of fine-grained LRC. − However, the flotation efficiency still needs to be improved, and there is an urgent need to find more factors restricting flotation and solve it. − …”