Temperature, frequency and compositional dependencies of the permittivities of hydroxide minerals
| Autor: | C.A. Pickles, D. Boucher, Erin R. Bobicki, O. Marzoughi, R. Hutcheon, J. Forster |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
Thermogravimetric analysis
Materials science Magnesium Mechanical Engineering chemistry.chemical_element Thermodynamics 02 engineering and technology General Chemistry Extractive metallurgy 010502 geochemistry & geophysics 021001 nanoscience & nanotechnology Geotechnical Engineering and Engineering Geology 01 natural sciences chemistry.chemical_compound chemistry Control and Systems Engineering Aluminosilicate Hydroxide 0210 nano-technology Energy source Microwave 0105 earth and related environmental sciences Hydroxyl ion |
| Zdroj: | Minerals Engineering. 174:107244 |
| ISSN: | 0892-6875 |
| DOI: | 10.1016/j.mineng.2021.107244 |
| Popis: | In the last few decades there has been increasing interest in the application of microwaves as an energy source in extractive metallurgy for the treatment of ores and concentrates. The fundamental parameters required for the design of industrial systems are the real and the imaginary permittivities, which are both frequency and temperature dependent. However, there is a dearth of data on the permittivities, of not only the ores and the concentrates, but also the minerals that comprise the ores. In the present research, the permittivities of selected hydroxide minerals were determined using the cavity perturbation technique as a function of both temperature and frequency. The behaviours of the permittivities were interpreted using both thermogravimetric analysis (TGA) and thermodynamic modelling. The water in these minerals, in its various forms, makes a significant contribution to the permittivities. Also, generally, the higher iron-bearing hydroxides have higher permittivities than the magnesium silicates or aluminosilicates. It is shown that the permittivities of the hydroxide minerals are low, but the hydroxyl ion makes a significant contribution. The effect of frequency is more pronounced both during dehydroxylation and at high temperatures and, in both cases, is attributed to increases in the ac conductivity. |
| Databáze: | OpenAIRE |
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