Browsing by Author "Kingman, Samuel William"
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- ItemMicrowave processing of materials(Stellenbosch : Stellenbosch University, 2018-03) Kingman, Samuel William; Bradshaw, S. M.; Stellenbosch University. Faculty of Engineering. Dept. of Process Engineering.ENGLISH SUMMARY: The world is under increasing pressure to develop new, more energy-efficient technologies that enable the production of less waste and are more sustainable. Material processing through microwave energy has received academic attention in the past few years for potentially delivering environmental benefits for a number of different applications including, food, fine and bulk chemicals, oil and gas, minerals and metals extraction. Despite the potential to deliver a step change in overall process efficiency across a diverse range of sectors, the true economic value of microwave technology has generally not being realised. My work in microwave processing commenced in 1996 with my PhD at the University of Birmingham where I began investigations into the interaction of microwave energy with metal ores in order to reduce grinding energy and improve liberation of valuable minerals. Even at this early stage it became apparent that despite a strong body of literature reporting laboratory studies there was very little knowledge supporting the scale up of microwave technologies for application in industrial processing. Further investigation into other potential application areas such as chemistry, materials processing, drying and food processing demonstrated that similar barriers existed with few if any commercial implementations of basic research realised. I have sought to identify the reasons why scale up of microwave heating is a challenge, to identify solutions to some of the major technical barriers and to develop generic methodologies which can be applied to different material systems across multiple industries. Such barriers relate to a lack of understanding of the interaction of microwaves with materials at a molecular level, lack of a multi-disciplinary approach to scale up, poorly understood value propositions for the use of microwave technology, and a lack of a trained workforce to support technology implementation in industry. Ultimately, it is also true that due to the high capital cost of microwave technology the ability to identify process benefits that can only be delivered through microwave heating alone, rather through cheaper conventional heating technologies is critical for successful commercialisation. Addressing these barriers has led me to develop, in collaboration with colleagues from across the globe, methodologies for the scale up of microwave technology. Identification of the interaction mechanism with the material to be processed, be it bulk or selective heating exemplified through the use of dielectric property measurements at both extremes of temperature and pressure has been reported as has modelling of the impact of rapid heating on material matrices. Studies which have proven the mechanism by which microwaves deliver value through multiple interactions have been reported for numerous different material classes and systems often at the highest power inputs ever reported. Scale up of systems through collaboration with experts in microwave design, materials handling and chemical reaction engineering have been reported for different applications, each providing a basis for the scale up of the technology. In several cases including rock fracture and sorting, oil and drilling waste processing and vermiculite exfoliation this has led to the development of unique microwave technologies. In the case of mineral sorting and fracture this work has directly underpinned the highest throughput microwave processing systems ever built.