Abstract
The course of thermal behavior of a fresh bituminous high-volatile coal during carbonization and pyrolysis was compared to that of this coal thawed after storage. The research was carried out using the following techniques: X-raying, thermogravimetry/Fourier transform-infrared spectroscopy (TG/FT-IR), extraction, Diffuse Reflectance Infrared Fourier Transform Spectroscopes (DRIFT), Attenuated Total Reflectance (ATR), and SEM. The increase in range of the viscous-liquid state and a decrease in temperature of its appearance were stated along with the formation of a more compact residue at the re-solidification stagtablee for the thawed coal during its carbonization. There is a fourfold reduction in the charge volume. The leakage of bitumen that contains 87 At % of C atoms from swollen grains and a fourfold increase in the yield of the material extracted from these grains are the proof of a greater plasticization of thawed coal. During the pyrolysis of thawed coal, the yield in volatile products of pyrolysis increases, and the composition of these products changes. The contribution ratio of saturated and unsaturated hydrocarbons, CO2, alcohols, and phenols decreases in the composition of volatile products of thawed coal. It is suggested that the use of freezing during the storage of a freshly mined coal that has a poorer caking ability can improve its plasticization during carbonization.
Highlights
Some changes in the technological properties of different rank coals take place under the influence of oxidation during their storage [1,2,3]
The aforementioned gives reasons to presents the curves of mass mass loss rate of fresh and thawed samples suggestFigure that 1the changes in shape of loss the and thermogravimetric analysis (TGA)
The results of the experiment conducted under laboratory conditions proved that the freezing of freshly prepared commercial sample of a highly volatile bituminous coal improves its plasticization degree during carbonization
Summary
Some changes in the technological properties of different rank coals take place under the influence of oxidation during their storage [1,2,3]. The investigations on changes in technological properties of coals in different seasons conducted by Miroshnichenko et al [4] suggest that a seasonal decrease in the temperature of coal before coking positively affects the changes in thickness of the plastic layer and coke quality. This gives a reason to suppose that the freezing of coal in winter can improve its technological properties. Tao and Xiong-Gang [7] noticed that the uniaxial compressive strength and the elastic modulus of coal increase when the temperature of freezing drops. Qin et al [8] determined the changes of the physical pore and fracture structure of coal and uniaxial compressive strengths, acoustic emissions, and ultrasonic wave velocities
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