The effect of microwave heating on ore sorting

Rizmanoski, Vladimir (2012). The effect of microwave heating on ore sorting PhD Thesis, Sustainable Minerals Institute, Julius Kruttschnitt Mineral Research Centre, The University of Queensland. doi:10.14264/uql.2015.915

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Author Rizmanoski, Vladimir
Thesis Title The effect of microwave heating on ore sorting
School, Centre or Institute Sustainable Minerals Institute, Julius Kruttschnitt Mineral Research Centre
Institution The University of Queensland
DOI 10.14264/uql.2015.915
Publication date 2012-01-20
Thesis type PhD Thesis
Supervisor Nenad Djordjevic
Rob Morrison
Sam Kingman
Total pages 417
Language eng
Subjects 0914 Resources Engineering and Extractive Metallurgy
0912 Materials Engineering
0904 Chemical Engineering
Abstract/Summary Today the Mining industry is being challenged to develop methodologies and technology to process the lower grade and mineralogically complex ore types using ore sorting. The potential of microwave driven selective heating as an excitation tool to underpin sorting is possibly not well known in the mining and mineral industries due to very few applications and lack of awareness of the potential users. This thesis investigates the conditions under which this process is technically effective and can be utilised. A detailed investigation was conducted to understand the reasons for selective heating of specific mineral phases and how infrared sensing can be used as an identification technique to discriminate certain particles from others. This thesis also quantifies the impact of other important factors on the sorting process including; particle shape and size, mineral composition and most importantly the textures of the mineral bearing particles which have a tendency to heat quickly when exposed to microwave energy. An extensive assembly of analytical techniques such as optical microscopy, high-resolution X-ray computed tomography and XL Scanning Electron Microscopy (used by the Mineral Liberation Analyser) were utilised to obtain a mineralogical characterisation of the tested ores. The choice of microwave applicators enabled heating to be carried out in multimode and single mode types of cavity. By engineering synthetic samples a more comprehensive investigation was carried out which enabled some focusing questions from the thesis hypothesis to be addressed. The synthetic samples were used to experimentally validate an adopted theoretical approach of investigating the influence of mineral texture upon selective heating. The supplied ore from the Bingham Canyon Mine, USA (operated by Rio Tinto’s Kennecott Utah Copper Corporation) was experimentally tested in two steps of investigations. The first step involved the approach of an “ideal”, theoretical sorter for which rock particles had to be destroyed (necessary to perform assaying analysis). The temperature threshold for economically justifiable sorting was determined from a temperature difference and assayed metal content of heated particles. In the second step, samples were analysed by heating them in two applicators and the temperature threshold was determined as a function of mineral texture which caused selective heating as in contrast to assayed metal content. The results showed from the exposure of synthetic particles (with designed textures of microwave more responsive minerals) that it is advantageous to use both multimode and single mode cavities for better understanding of microwave heating of the ore. It was also shown that the texture of microwave responsive minerals has a significant effect on the formation of the temperature profiles which are used to evaluate selectivity and potential for the separation as opposed to only mineral composition of the ore particles. It was demonstrated that the types of ores studied in this work, will respond to microwave selective heating to the extent that infrared detection can be applied to perform selection between cold and hot particles defined by a set threshold.
Keyword Mining engineering
Microwave energy
Process control
Thermal characterisation
Multimode cavity
Waveguide applicator
Materials engineering
Chemical engineering design
Particle technology

Document type: Thesis
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Created: Wed, 05 Sep 2012, 22:41:32 EST by Vladimir Rizmanoski on behalf of Scholarly Communication and Digitisation Service