Dielectric Properties of Zinc Oxide Leach Residues Relevant to Microwave Drying

This paper presents the first study on dielectric properties of zinc oxide leach residues (ZOLR) relating to microwave drying. Dielectric properties of ZOLR were measured by cylindrical cavity perturbation method. The three-dimensional response surface plots show that both the dielectric constant and the loss factor of ZOLR tend to decline while the penetration depth of the microwave energy in ZOLR increases in the process of microwave drying. The largest penetration depth of microwave energy in ZOLR is 50 mm. The results obtained from the experiments are useful not only in developing large-scale industrial microwave drying system but also in numerical simulating of the distribution of the temperature field of ZOLR.