Microwave technology has a potential application in the extraction of zinc from sulphide\nores, knowledge of the dielectric properties of these ores plays a major role in the microwave\ndesign and simulation for any process. The dielectric properties of zinc sulfide concentrate for two\ndifferent apparent densitiesââ?¬â?1.54 and 1.63 g/cm3ââ?¬â?have been measured by using the resonance cavity\nperturbation technique at 915 and 2450 MHz during the roasting process for the temperature ranging\nfrom room temperature to 850 ââ??¦C. The variations of dielectric constant, the dielectric loss factor,\nthe dielectric loss tangent and the penetration depth with the temperature, frequency and apparent\ndensity have been investigated numerically. The results indicate that the dielectric constant increases\nas the temperature increases and temperature has a pivotal effect on the dielectric constant, while the\ndielectric loss factor has a complicated change and all of the temperature, frequency and apparent\ndensity have a significant impact to dielectric loss factor. Zinc sulfide concentrate is high loss material\nfrom 450 to 800 ââ??¦C on the basis of theoretical analyses of dielectric loss tangent and penetration depth,\nits ability of absorbing microwave energy would be enhanced by increasing the apparent density as\nwell. The experimental results also have proved that zinc sulfide concentrate is easy to be heated by\nmicrowave energy from 450 to 800 ââ??¦C. In addition, the experimental date of dielectric constant and\nloss factor can be fitted perfectly by Boltzmann model and Gauss model, respectively.
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