Frequency Dependence of the Dielectric Properties of Coal

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

doi:10.1080/16070658.1980.11689212

Cited by 32 publications

(3 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Ergun and Bean (1968) found that conversion of only 0.5% of pyrite (FeS2) to pyrrhotite would be sufficient to produce an apparent magnetic susceptibility of 10 or more (Ergun and Bean, 1968). They also proposed that high-frequency heating of coal might achieve selective absorption by pyrite and partial conversion Nelson et al (1981) noticed that the dielectric loss factor of a dense pyrite bearing portion separated from coal with high sulfur content increases with microwave frequency (Nelson et al, 1981). Bluhm et al (1986) investigated the variation of apparent magnetic susceptibility during the microwave heating.…”

Section: mentioning

confidence: 99%

Dielectric Properites of Iron Sulfide in Coal by Microwave Irradiation

Kim¹,

박종력²,

Lee³

2013

ksmer

View full text Add to dashboard Cite

This study focuss on a dielectric and transformation properties of iron sulfide including pyrite, pyrrhotite, and troilite by microwave heation. The relative magnetic loss factors of pyrite at both 915 MHz and 2.45 GHz are between 0.2 and 0.4. This shows that pyrite is not a strong magnetic substance. Also, the decrease of the relative magnetic constant of pyrite is caused by the increase of electrical conductivity of sample, as indicated by the variation of permittivity. The large dielectric constant and loss factor of pyrrhotite at temperatures below 200°C suggest that this phase has good microwave absorption capability at microwave frequency. The dielectric constant and loss factor of troilite are found to be highly temperature and frequency dependent.

show abstract

Section: mentioning

confidence: 99%

Dielectric Properites of Iron Sulfide in Coal by Microwave Irradiation

Kim¹,

박종력²,

Lee³

2013

ksmer

View full text Add to dashboard Cite

show abstract

“…Dielectric properties of cereal grains, seed, and powdered or pulverized material have been determined with various microwave measurement systems assembled for such measurements. Twenty-one-mm, 50-Ω coaxialline systems were used for these measurements at frequencies from 1 to 5.5 GHz (Nelson, 1973b;Nelson et al, 1980. A 54-mm, 50-Ω coaxial sample holder, designed for minimal reflections from the transition, was used with this same system for measurements on largerkernel cereals such as corn (Nelson, 1978(Nelson, , 1979b.…”

Section: Definitions and Principlesmentioning

confidence: 99%

Dielectric Properties Measurement Techniques and Applications

Nelson¹

1999

Transactions of the ASAE

View full text Add to dashboard Cite

The reasons for interest in the dielectric properties of materials are discussed. Terms are defined and principles involving dielectric properties of materials are summarized. Measurement techniques for determining dielectric properties of agricultural materials in the radio-frequency (RF) and microwave ranges are identified with reference citations given for detailed information. Finally, a few new potential applications for dielectric properties of materials are discussed and a few precautions are given for reliable determination of such properties by RF and microwave measurements.

show abstract

“…It has to be able to measure the phase shift and the attenuation of a microwave signal that is transmitted through coal on a conveyor belt, as well as the mass per unit area of that coa1[11, 12,13].…”

Section: Introductionmentioning

confidence: 99%

Continuous measurement of moisture in nonconducting materials

Vermeulen¹,

Hancke²

[1992] Conference Record IEEE Instrumentation and Measurement Technology Conference

View full text Add to dashboard Cite

The capacitive method is based on the high permittivity of water compared with most of the dry materials. It was found A microwave based system has been developed for the that capacitive measurements are also influenced strongly by continuous measurement of the moisture in non conducting the electrolyte content similar to the conductive methods. materials. The system was implemented on conveyor belts carrying coarse cod. To obtain a reliable mxisurement for this The infrared reflection technique, based on the characteristic application, several other factors that influence the microwave absorption by water, is applicable for moisture determination measurement technique had to be investigated. These factors of black coal in spite of its high absorbance. However, the are among others: the mass per unit area, the ash-content and influence of particle size is an order of magnitude greater the temperature. The measurement of these factors make , . ompared with the microwave method. It is also possible the general characterization of the coal, which is disadvantageous that only a small part of the material stream important for optimizing the utilization of the cod in many is sampled. different applications.

show abstract

Frequency Dependence of the Dielectric Properties of Coal

Cited by 32 publications

References 7 publications

Dielectric Properites of Iron Sulfide in Coal by Microwave Irradiation

Dielectric Properites of Iron Sulfide in Coal by Microwave Irradiation

Dielectric Properties Measurement Techniques and Applications

Continuous measurement of moisture in nonconducting materials

Contact Info

Product

Resources

About