Dielectric heating in mixtures containing coal and pyrite

Fanslow, G.E.; Bluhm, D.; Nelson, Stuart O.

doi:10.2172/5391651

Cited by 2 publications

(2 citation statements)

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“…25,26 It was found that the ε″ of pyrite in coal was much larger than that of pure coal (excluding minerals), and the heating rate of the former was about 9 times of the latter. 27,28 The desulfurization of coal by microwave irradiation at the frequency of 915 MHz was better than 2450 MHz. 29 Variable frequency microwave heating, 2450 MHz initially and 915 MHz thereafter, contributed to the large-scale coal processing.…”

Section: Introductionmentioning

confidence: 99%

“…Researches in this field were mainly concentrated on optimizing the parameters of desulfurization conditions, determining the variation of the sulfur forms in the desulfurization process − and the dielectric properties of coal. Their results showed that the removal of organic sulfur was more difficult than that of inorganic sulfur in coal by microwave. , Model sulfur compounds studies revealed that the desulfurization process was effective with aliphatic type of compounds by electron-transfer process, while thiophene and condensed thiophene-type compounds remained unaffected due to their higher stability. , It was found that the ε″ of pyrite in coal was much larger than that of pure coal (excluding minerals), and the heating rate of the former was about 9 times of the latter. , The desulfurization of coal by microwave irradiation at the frequency of 915 MHz was better than 2450 MHz . Variable frequency microwave heating, 2450 MHz initially and 915 MHz thereafter, contributed to the large-scale coal processing .…”

Section: Introductionmentioning

confidence: 99%

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Exploration of the Combined Action Mechanism of Desulfurization and Ash Removal in the Process of Coal Desulfurization by Microwave with Peroxyacetic Acid

Tang

Wang

et al. 2017

Energy Fuels

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The combined effect of desulfurization and ash removal in the process of coal desulfurization by microwave with peroxyacetic acid was determined by evaluating variations in minerals and sulfur forms using X-ray diffraction and X-ray photoelectron spectroscopy. Dielectric properties of minerals or organic sulfur functional groups in coal were studied utilizing a vector network analyzer in the 100 MHz−6.5 GHz frequency range. Results showed that the trend of ash reduction was similar to that of desulfurization with the treatment time. The main minerals removed were kaolin, montmorillonite, and pyrite under microwave with peroxyacetic acid. The influences of minerals on the dielectric properties of pure coal were higher than those of organic sulfur containing groups. Peak values of the complex permittivity imaginary part (ε″) and magnetic loss tangent (tan δ) for pyrite or montmorillonite were significantly higher than those of the other model materials. In addition, it is found that the dielectric property curves of the mixed samples contained the characteristic peaks of the corresponding minerals or organic sulfur compounds. Thus, the sulfur-containing substances of coal could be selectively removed with heating selectivity under the microwave of a particular frequency. These findings confirmed that the cause of the combined effect was the difference of dielectric properties between minerals and organic sulfur-containing groups.

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