The Effects of Power Level on the Microwave Heating of Selected Chemicals and Minerals

McGill, S. L.; Walkiewicz, J. W.; Smyres, G. A.

doi:10.1557/proc-124-247

Cited by 80 publications

(45 citation statements)

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“…Studies by McGill et al (1988) and Kingman et al (2000b) also demonstrated that higher microwave power levels resulted in faster heating rates of many microwave-absorbing minerals. Subsequent experimental studies by Kingman et al (2000a), Kingman et al (2004a), Kingman et al (2004b) and Sahyoun et al (2005) revealed that high power density treatments (typically >3kW in single mode cavities) allowed for a similar degree of microwaveassisted breakage at significantly lower energy inputs than treatments at low power density (typically <3kW in multimode cavities) due to the significantly higher heating rates attained.…”

Section: Microwave Treatment Of Oresmentioning

confidence: 95%

Deriving the ideal ore texture for microwave treatment of metalliferous ores

Jones

Plint

Kingman

2015

Minerals Engineering

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A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. Highlights The influence of mineralogy on microwave-induced fracture in ores is investigated  Microwave-heating phase and matrix thermo-mechanical properties are both important  Hard microwave-heating phases constrained by a hard matrix gave the best results  ~2-20%wt heating phase abundance with grain size d50 >500µm gave the best results  Ore textural consistency is required for high average strength reductions AbstractHigh power density microwave treatments on metalliferous ores have historically been shown to reduce ore competency prior to beneficiation at economically feasible energy inputs. However, the relationship between mineralogical textural features and the extent of the microwave-induced fracturing had previously been limited to qualitative descriptions or simplistic two-phase numerical models, which could not account for the complex mineral assemblages in real ores. In this paper, mineralogy, grain size, dissemination, textural consistency and mineral associations were determined for 13 commercially exploited nickel, copper and lead-zinc ores using a Mineral Liberation Analyser (MLA). The ores were subjected to high power density microwave treatments at up to 25kW in a single mode cavity with microwave energy inputs of approximately 0.5-10kWh/t, and the subsequent reductions in ore competency were measured by the Point Load Test. The ores that demonstrated the greatest reductions in strength typically contained between approximately 2%wt to 20%wt of highly microwave-absorbing minerals, with a native grain size d50 greater than approximately 500µm, constrained by hard matrix minerals such as quartz and feldspar. Texturally consistent ores with a high proportion of amenable textures also demonstrated the highest average reductions in strength. These findings support the qualitative descriptions and numerical modelling results available in the literature and provide a baseline for selecting likely candidate ores for microwave treatments in the future. Minerals Engineering 84 (2015) 116-1292 http://dx

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Section: Microwave Treatment Of Oresmentioning

confidence: 95%

Deriving the ideal ore texture for microwave treatment of metalliferous ores

Jones

Plint

Kingman

2015

Minerals Engineering

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“…In particular, when the SMCA was heated for 180 s, the increase in temperature was approximately 130˚C, higher than that of the OCA. This may be due to the effective heating of iron oxide [17], which was mixed in the SMCP as a dielectric material, as shown in Figure 11.…”

Section: Experiments Overview and Methodsmentioning

confidence: 99%

Using Microwave Heating to Completely Recycle Concrete

Choi¹,

Lim²,

Choi³

et al. 2014

JEP

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The aim of this study was to develop a technique for the complete recycling of concrete based on microwave heating of surface modification coarse aggregate (SMCA) with only inorganic materials such as cement and pozzolanic materials (silica fume, fly ash). The mechanical properties of SMCA, which was produced using original coarse aggregate (OCA) and inorganic admixtures, as well as its separation from the cement matrix and recovery performance were quantitatively assessed. The experimental results showed that micro structural reinforcement of the interfacial transition zone, which is a weak part of concrete, by coating the surface of the OCA with cement and admixtures such as pozzolanic materials can help suppress the occurrence of micro-cracks and improve the mechanical performance of the OCA. Microwave heating was observed to cause micro-cracking and hydrate decomposition. Increasing the void volume and weakening the hydrated cement paste led to the effective recovery of recycled coarse aggregate.

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“…This is further illustrated with the work of McGill et al, [26]. The heating rates of various pure materials; including some components of cement clinker raw meal, were investigated by using a variable power microwave applicator (500 -2000W, 2.45GHz).…”

Section: Production Of Cement Clinkermentioning

confidence: 97%

Microwave processing of cement and concrete materials – towards an industrial reality?

Buttress

Jones

Kingman

2015

Cement and Concrete Research

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Each year a substantial body of literature is published on the use of microwaves to process cement and concrete materials. Yet to date, very few if any have lead the realisation of a commercial scale industrial system and is the context under which this review has been undertaken.The state-of the-art is evaluated for opportunities, and the key barriers to the development of new microwave-based processing techniques to enhance production, processing and recycling of cement and concrete materials. Applications reviewed include pyro-processing of cement clinker; accelerated curing, non-destructive testing and evaluation (NDT&E), and end-of-life processing including radionuclide decontamination.

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The Effects of Power Level on the Microwave Heating of Selected Chemicals and Minerals

Cited by 80 publications

References 1 publication

Deriving the ideal ore texture for microwave treatment of metalliferous ores

Deriving the ideal ore texture for microwave treatment of metalliferous ores

Using Microwave Heating to Completely Recycle Concrete

Microwave processing of cement and concrete materials – towards an industrial reality?

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