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Journal of Microwave Power and Electromagnetic Energy, 47 (3), 2013, pp. 199-209.
A Publication of the International Microwave Power Institute
Temperature and Moisture Dependence
of the Dielectric Properties of Silica Sand
Chenhui Liu1,2,3, Libo Zhang1,2,3, Jinhui Peng1,2,3, Chandrasekar Srinivasakannan4,
Bingguo Liu1,2,3, Hongying Xia1,2,3, Junwen Zhou1,2,3, and Lei Xu1,2,3
1
Key Laboratory of Unconventional Metallurgy, Ministry of Education,Kunming University
of Science and Technology, Kunming 650093, China
2
Faculty of Metallurgical and Energy Engineering, Kunming University of Science and
Technology, Kunming 650093, China
3
Engineering Laboratory of Microwave Application and Equipment Technology, Yunnan
Province, Kunming 650093, China
4
Chemical Engineering Program, The Petroleum Institute, P.O. Box 2533, Abu Dhabi,
United Arab Emirates
Received: January 7, 2013
Accepted: June 3, 2013
ABSTRACT
The major objective of this work was to investigate the effects of temperature and
moisture content on the dielectric properties of silica sand. The dielectric properties of moist
silica sand at five temperatures between 20 to 100 ºC, covering different moisture content
levels at a frequency of 2.45 GHz, were measured with an open-ended coaxial probe dielectric
measurement system. The wave penetration depth was calculated based on the measured
dielectric data. The results show moisture content to be the major influencing factor for the
variation of dielectric properties. Dielectric constant, loss factor and loss tangent all increase
linearly with increasing moisture content. Three predictive empirical models were developed
to relate the dielectric constant, loss factor, loss tangent of silica sand as a linear function
of moisture content. An increase in temperature between 20 to 100 ºC was found to increase
the dielectric constant and loss factor. The penetration depth decreased with increase in
moisture content and temperature. Variation in penetration depth was found to vary linearly
with decrease in moisture content. An predictive empirical model was developed to calculate
penetration depth for silica sand.
This study offers useful information on dielectric properties of silica sand for developing
microwave drying applications in mineral processing towards designing better microwave
sensors for measuring silica sand moisture content.
KEYWORDS: Dielectric Properties; Penetration Depth; Silica Sand; Moisture Content; Temperature
increase; Microwave drying; Temperature dependence.
INTRODUCTION
Silica sand is one of the silicate minerals. It is hard, anti-friction and less reactive, with
the major mineral component being SiO2. High purity quartz sand is the main raw material
to manufacture silica film, quartz glass, semiconductor silicon, fiber optics and metallurgical
fluxes [Mostaghel and Samuelsson, 2010]. The fine silica sand is commonly obtained from
mineral dressing processes such as scrubbing, magnetic separation and flotation. Silica sand
International Microwave Power Institute
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