Modeling of microwave heating of andesite and minerals

Lovás, Michal; Kováčová, Milota; Dimitrakis, Georgios; Čuvanová, S.; Znamenáčková, Ingrid; Jakabský, Štefan

doi:10.1016/j.ijheatmasstransfer.2010.03.012

Cited by 51 publications

(18 citation statements)

References 9 publications

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“…In microwave assisted solid-liquid extraction, the extraction is accelerated due to the changes in cell anatomy caused by the impact of microwave radiation. The accelerated extraction may be attributed to synergistic action of temperature and concentration gradients operating in the same direction [3,4]. It is pertinent to note that in microwave assisted solid-liquid extraction, the heat is dissipated directly within the moisture-laden solid matrix causing the sudden disruption of the same [5].…”

Section: Introductionmentioning

confidence: 99%

Microwave assisted extraction of flavonoids from Terminalia bellerica: Study of kinetics and thermodynamics

Krishnan

Rajan

2016

Separation and Purification Technology

119

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Section: Introductionmentioning

confidence: 99%

Microwave assisted extraction of flavonoids from Terminalia bellerica: Study of kinetics and thermodynamics

Krishnan

Rajan

2016

Separation and Purification Technology

119

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“…Similarly, the permittivity of quartz and feldspar powders are indistinguishable using the standard deviation obtained (0.381) from the factorial experiment. The measured dielectric properties of chalcopyrite fit within ranges in scholarly literature which start at  = 8.4,  = 0.2 for chalcopyrite powders (Lovás et al 2010) and reach  = 77.5 (Holderfield & Salsman 1992). Lovás et al (2010) also published values for a pyrite powder (  = 8,  = 0.2), showing similar values to the chalcopyrite powder; which is echoed in the measured properties.…”

Section: Mineral Dielectric Propertiessupporting

confidence: 81%

“…The measured dielectric properties of chalcopyrite fit within ranges in scholarly literature which start at  = 8.4,  = 0.2 for chalcopyrite powders (Lovás et al 2010) and reach  = 77.5 (Holderfield & Salsman 1992). Lovás et al (2010) also published values for a pyrite powder (  = 8,  = 0.2), showing similar values to the chalcopyrite powder; which is echoed in the measured properties. Although no dielectric property data could be found, molybdenite is known to heat rapidly in a microwave field (Ford & Pei 1967) and this supports the measured dielectric properties.…”

Section: Mineral Dielectric Propertiessupporting

confidence: 81%

Novel techniques in ore characterisation and sorting

Genn¹

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Ore sorting is becoming increasingly important to the minerals industry but is a difficult technology to apply effectively to many ore types. Microwave excitation and infrared detection (MW/IR) is a potential new sensor technology for sorting copper sulphide ores.This technology utilises the high dielectric permittivity of copper sulphide minerals and relatively low dielectric properties of gangue minerals to selectively heat copper rich particles and thereby gauge particle grade from temperature. To date, the dielectric properties of minerals and the role of mineral structures within particles are not fully understood and can vary significantly from deposit to deposit due to differences in geochemistry and genesis.These variations in mineralogy and dielectric properties can mean that some ores are unsuitable for sorting. The aim of this thesis is to develop a characterisation methodology to assess the suitability of ores for MW/IR based sorting from small sets of particles.The microwave heating of six different ores, chosen to represent a range of minerals and mineral textures, was characterised using randomly split particles, a domestic microwave oven and thermal imaging. The dielectric properties of core and powder subsamples of particles from four ores were then measured using a resonant cavity perturbation experiments at The University of Nottingham. Three effects were identified that may influence the observed relationship between microwave heating and dielectric properties: strong interaction with the magnetic field, mineral structures and sulphide heterogeneity in samples. These effects were investigated using radiofrequency magnetic permeability measurements, rotation of rock cylinders in a rectangular waveguide resonant cavity and automated scanning electron microscopy (MLA). The modal mineralogy of ore samples was measured using MLA while geochemistry was investigated using electron probe microscopy. The dielectric properties of mineral groups were then calculated using systems of linear equations based on the LandauLifschitz-Looyenga mixture equation as well as modal mineralogy and dielectric property data. Finally, numerical simulations of microwave heating were performed using data on mineralogy, mineral dielectric properties and variability in particle heating to determine to assess the potential of rocks types for sorting.ii MW/IR characterisation showed that quartzite, monzonite and skarn ores have distinct particle temperature distributions and that variation in the pixel temperatures of individual particle surfaces might be useful in distinguishing particle petrology. A power law was found to describe the relationship between microwave heating and dielectric loss tangent (R 2 = 79%) although a good fit could be achieved with a linear relationship (R 2 = 89%) when specific, termed anomalous, particles were excluded. Magnetic permeability measurements indicated that there was no significant difference in permeability between normal and anomalously heating particles. Changes in cavity per...

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“…The authors concluded that these cracks were due to thermal stress, generated because of the different microwave interaction strengths of gangue minerals (weak effect) and of Ilmenite (strong eExperimental microwave processing and its modeling requires knowing the dielectric properties of the MUT as a function of temperature. In that sense, this article presents the main experimental results with some samples that can be compared against the data found by Lovás et al [13]. They dealt with the influence of temperature on the dielectric properties of Pyrite, Galena, Chalcopyrite, Magnesite, Siderite, and Andesite, taken from different parts of the Slovak Republic.…”

Section: Introductionmentioning

confidence: 95%

Microwave enhanced roasting for pyrite ore samples with dielectric properties strongly dependent on temperature

Díaz

Amaya

Correa

2015

I&U

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<p>This article shows the main experimental results related to the measurement of dielectric properties of Pyrite ore mineral samples as a function of temperature, and their effect on the heating behavior of the samples. It was found that the sample’s dielectric properties strongly depend on temperature. The best model for and that fitted the experimental data, was a Gaussian model. Besides, and under certain conditions, it was possible to roast the mineral even better than with an electric furnace, while requiring less processing time and with lower electrical energy consumption. Additional exploratory tests revealed that microwaves can be used to smelt a roasted mineral ore with time reductions of about 90%, while keeping recovery margins above 95%. Thus, we conclude that, as a next stage, the process should be directed to using a single mode applicator, for processing higher volumes of mineral at pilot plant scale.</p>

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Modeling of microwave heating of andesite and minerals

Cited by 51 publications

References 9 publications

Microwave assisted extraction of flavonoids from Terminalia bellerica: Study of kinetics and thermodynamics

Microwave assisted extraction of flavonoids from Terminalia bellerica: Study of kinetics and thermodynamics

Novel techniques in ore characterisation and sorting

Microwave enhanced roasting for pyrite ore samples with dielectric properties strongly dependent on temperature

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