Highlights Pilot scale (150t/h) microwave-induced fracture of ores is investigated on three ore types  Microwave treatment energies in the range 0.3-3kWh/t were tested at up to 200kW power input  Equivalent liberation could be achieved at a 40-70µm coarser grind  Specific comminution energy could be reduced by up to 9% at nominal plant grinds  Throughput could be increased by up to 10% at nominal plant grinds Abstract A pilot scale microwave treatment system capable of treating 10-150t/h of material at 10-200kW was designed, constructed and commissioned in order to understand the engineering challenges of microwave-induced fracture of ores at scale and generate large metallurgical test samples of material treated at approximately 0.3-3kWh/t. It was demonstrated that exposing more of the ore to a region of high power density by improving treatment homogeneity with two single mode applicators in series yielded equivalent or better metallurgical performance with up to half the power and one third the energy requirement of that used with a single applicator. Comminution testing indicated that A*b values may be reduced by up to 7-14% and that the Bond Ball Mill Work Index may be reduced by up to 3-9% depending on the ore type under investigation. Liberation analysis of the microwave-treated ore indicated that equivalent liberation may be achievable for a grind size approximately 40-70µm coarser than untreated ore, which is in agreement with laboratory scale investigations reported in the literature at similar or higher doses. Flow sheet simulations further indicated that reduced ore competency following microwave treatment could potentially yield up to a 9% reduction in specific comminution energy (ECS) at a nominal plant grind of P80 190µm, or up to 24% reduction at a grind of P80 290µm, for a microwave energy input of 0.7-1.3kWh/t. Throughput could also be increased by up to approximately 30% depending on grind size, ore type and equipment constraints. To date, approximately 900t of material has been processed through the pilot plant, approximately 300t of which was under microwave power. Metallurgical testing has demonstrated that comminution and liberation benefits are achievable at doses lower than that previously reported in the literature, which allow high throughputs to be sustained with low installed power requirements providing a pathway to further scale-up of microwave treatment of ores.

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.

Highlights A pilot scale system for microwave treatment of ores is presented  Materials handling concepts and justification for packed bed mass flow are discussed  Microwave applicator and choke modelling is validated against real ores  Control of material flow and presentation is discussed  The operating microwave treatment system performance is described AbstractDespite over thirty years of work, microwave pre-treatment processes for beneficiation of ores have not progressed much further than laboratory testing. In this paper we present a scaleable pilot-scale system for the microwave treatment of ores capable of operating at throughputs of up to 150tph. This has been achieved by confining the electric field produced from two 100kW generators operating at 896MHz in a gravity fed vertical flow system using circular choking structures yielding power densities of at least 6x10 8 W/m 3 in the heated mineral phases. Measured S11 scattering parameters for a quartzite ore (-3.69±0.4dB) in the as-built applicator correlated well with the simulation (-3.25dB), thereby validating our design approach. We then show that by fully integrating the applicator with a materials handling system based on the concept of mass flow, we achieve a reliable, continuous process. The system was used to treat a range of porphyry copper ores. Minerals Engineering 109 (2017) 169-832 http://doi.org/10.1016/j.mineng.2017.03.006 IntroductionMicrowave treatment of metalliferous ores has long been investigated as a means to enhance the recovery of valuable minerals and reduce the comminution resistance of ores (Chen et al., 1984;Walkiewicz et al., 1988;Walkiewicz et al., 1989). The underpinning mechanism and textural characteristics of amenable ores has been described by Batchelor et al. (2015). Selective heating of microwave-absorbent sulphides and metal oxides deported in a microwave-transparent gangue matrix results in differential thermal expansion of the heated phase, yielding micro-fracture around grain margins Jones et al., 2005Jones et al., , 2007Kingman et al., 2004a;Kingman et al., 2004b;Kingman et al., 2000a). Subsequent downstream processing may then yield higher recovery of valuable mineral sulphides and/or lower specific comminution energy, compared to non-microwave treated ore.While the mechanistic principles are well established, the scientific and engineering challenges of developing a commercial scale system are immense. Typical throughputs of a large copper mine can be in excess of 5,000 tph of milled ore (Brininstool, 2015) and a microwave based treatment system would need to handle equivalent throughputs. This is at least an order of magnitude higher than any other microwave process ever built.The following paper details the design, commissioning and operation of a system which was the culmination of over fifteen years of research and development activity. This resulted in a high power microwave treatment process, capable of operating continuously at throughputs of up to 150tph, but crucially, scaleable up to several th...

A continuous conveyor-belt processing concept using microwave heating was developed and evaluated. Four hydrocarbon-contaminated soils were used as model feedstocks, and the degree of organic removal was assessed against the power and energy input to the process. The findings of this study at scale (150kg/h) are in direct agreement with data obtained in batch laboratory scale experiments, and show that microwave heating processes are fundamentally scalable. It is shown that there is a trade-off between the efficiency of organic removal and the power distribution, and applying the power in a single stage was found to be 20-30% more energy efficient but the overall degree of organic removal is limited to 60%. 75% removal was possible using two processing steps in series, but the organic removal is ultimately limited by the amount of power that can be safely and reliably delivered to the process material. The concept presented in this work is feasible when 75% organic removal is sufficient, and could form a viable industrial-scale process based on the findings of this study.

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