Thermal behaviors of a porous calcium silicate material prepared from coal-bearing strata kaolinite
The thermal behaviors of a porous calcium silicate (PCS) material prepared from coal-bearing strata kaolinite were investigated by thermogravimetry and derivative thermogravimetry (TG–DTG), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy, and Brunauer–Emmett–Teller method. The XRD results showed that the PCS was determined as calcium silicate hydrates (C–S–H) and a small amount of CaCO3, which transformed to an orderly crystal structure of wollastonite approximately at 700 °C. The TG–DTG results indicated that the dehydration was observed until 300 °C and the dehydroxylation presented at 728 °C. The PCS exhibited a large number of pores with a fibrous flake network structure, which disappeared at 800 °C. The BET data showed that the specific surface area of material decreased as the temperature increased. The high-temperature phase transformation of PCS underwent the following transformation: active calcium silicate → dehydrated calcium silicate → dehydroxylated calcium silicate → wollastonite.
KeywordsCoal-bearing strata kaolinite Active calcium silicate Phase transition Wollastonite
The authors gratefully acknowledge the financial support provided by the Natural Science Foundation Project of Inner Mongolia Autonomous Region (Grant No. 2015MS0205), Natural Science Foundation Project of Inner Mongolia Autonomous Region (Grant No. 2018MS05061), and Inner Mongolia Educational committee (Grant No. NJZY089).
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