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京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第17956号 / 工博第3804号 / 新制||工||1582(附属図書館) / 30786 / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 辻 伸泰, 教授 松原 英一郎, 教授 安田 秀幸 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18986号 / 工博第4028号 / 新制||工||1620(附属図書館) / 31937 / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 辻 伸泰, 教授 田中 功, 教授 乾 晴行 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18987号 / 工博第4029号 / 新制||工||1620(附属図書館) / 31938 / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 辻 伸泰, 教授 白井 泰治, 教授 松原 英一郎 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19308号 / 工博第4105号 / 新制||工||1633(附属図書館) / 32310 / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 辻 伸泰, 教授 白井 泰治, 教授 乾 晴行 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

No description available.

Froth flotation has long been regarded as the best available technology for ultrafine particles separation. However, froth flotation has extreme deficiencies for recovering ultrafine particles that are less than 30-50 μm in size for coal and 10-20 μm for minerals. Furthermore, dewatering of flotation products is difficult and costly using currently available technologies. Due to these problems, coal and mineral fines are either lost to tailings streams inadvertently or discarded purposely prior to flotation. In light of this, researchers at Virginia Tech have developed a process called hydrophobic-hydrophilic separation (HHS), which is based originally on a concept known as dewatering by displacement (DbD). The process uses non-polar solvents (usually short-chain alkanes) to selectively displace water from particle surfaces and to agglomerate fine coal particles. The resulting agglomerates are subsequently broken (or destabilized) mechanically in the next stage of the process, whereby hydrophobic particles are dispersed in the oil phase and water droplets entrapped within the agglomerates coalesce and exit by gravity along with the hydrophilic particles dispersed in them. In the present work, further laboratory-scale tests have been conducted on various coal samples with the objective of commercial deployment of the HHS process. Test work has also been conducted to explore the possibility of using this process for the recovery of ultrafine minerals such as copper and rare earth minerals. Ultrafine streams produced less than 10% ash and moisture consistently, while coarse coal feed had no observable degradation to the HHS process. Middling coal samples were upgraded to high-value coal products when micronized by grinding. All coal samples performed better with the HHS process than with flotation in terms of separation efficiency. High-grade rare earth mineral concentrates were produced with the HHS process ranging from 600-2100 ppm of total rare earth elements, depending on the method and reagent. Additionally, the HHS process produced copper concentrates assaying greater than 30% Cu for both artificial and real feed samples, as well as, between 10-20% Cu for waste samples, which all performed better than flotation. / Master of Science / Froth flotation has long been regarded as the best available technology for separating fine particles. Due to limitations in particle size with froth flotation, and high downstream dewatering costs, a new process has been developed called the hydrophobic-hydrophilic separation (HHS) process. This process was originally based on a concept known as dewatering by displacement (DbD) which was developed by researchers at Virginia Tech in 1995. The process uses hydrocarbon oils, like pentane or heptane, to selectively collect hydrophobic particles, such as coal, for which it was originally developed. In coal preparation plants, a common practice is to purposefully discard the ultrafine stream that flotation cannot recover and has an increased dewatering cost. The HHS process can effectively recovery this waste stream and produce highgrade salable product, with significantly reduced cost of dewatering. In the work presented, laboratory-scale tests have been conducted on various coal samples with the objective of commercial deployment of the HHS process. In this respect, several varying plant streams have been tested apart from the traditional discard stream. Additionally, test work has expanded into mineral commodities such as copper and rare earth minerals. In this work, salable high-value coal products were achievable with the HHS process. Ultrafine streams consistently produced less than 10% ash and moisture. Coarse coal feeds had no observable degradation to the HHS process and were able to produce single digit ash and moisture values. Middling coal samples were upgraded to high-value coal products when micronized by grinding. All coal samples performed better with the HHS process than with flotation in terms of separation efficiency. High-grade rare earth mineral concentrates were produced with the HHS process ranging from 600- 2100 ppm of total rare earth elements depending on the method and reagent. Additionally, the HHS process produced copper concentrates assaying greater than 30% Cu for an artificial and feed samples, as well as, between 10-20% Cu for waste samples, which all performed better than flotation.

A simple thermodynamic analysis suggests that oil can spontaneously displace water from coal's surface if the coal particle has a water contact angle greater than 90°. However, the clean coal products obtained from laboratory-scale dewatering-by-displacement (DbD) test work assayed moistures substantially higher than expected. These high moisture contents were attributed to the formation of water-in-oil emulsions stabilized by coal particles. Four different approaches were taken to overcome this problem and obtain low-moisture agglomeration products. These included separating the water droplets by screening, breaking emulsions with ultrasonic energy, breaking agglomerates with ultrasonic energy, and breaking agglomerates using vibrating mesh plates. On the basis of the laboratory test work, a semi-continuous test circuit was built and tested using an ultrasonic vibrator to break the water-in-oil emulsions. The most promising results were obtained agglomerates were broken using the ultrasonic probe and the vibrating mesh plates. Tests conducted on flotation feed from the Kingston coal preparation plant gave a clean coal product containing 1% by weigh of moisture with a 94% combustible recovery. The separation efficiency of 93% is substantially higher than results achievable using froth flotation. When agglomerates formed from thermal coal from the Bailey coal preparation plant were broken using either ultrasonic energy or vibrating mesh plates, the obtained results were very similar: clean coal products assayed less than 5% moisture with separation efficiencies of 86% in average. / Master of Science

No description available.

Fine particle separation is a grand challenge in the mining and mineral processing industry. The industry standard process, froth flotation, is extremely robust and adaptable; however, it is inefficient for particles less than 20 microns. Owing to this limitation, some mining sectors, such as coal, opt to discard the ultrafine particles to waste impoundments as the costs to recover and dewater these materials are prohibitive. The Hydrophilic Hydrophobic Process (HHS) is one alternative to flotation that uses a recyclable solvent, rather than air bubbles, to selectively recover fine hydrophobic particles. Prior laboratory, proof-of-concept, and demonstration-scale testing has shown that the HHS process is extremely efficient, having no effective size limitation. The purpose of this research was to continue the development and improvement of the HHS process, through the design, construction, and testing of a mobile pilot plant. The pilot plant would in turn be used to demonstrate the robustness of the HHS process through a systemic study of multiple coal sources and ranks. In addition, the pilot plant would serve as a testbed for inquiry-based process intensification, the development and evaluation of design criteria for the various unit operation. Through the course of this research, a 50 lb./hr. (product rate) pilot plant was constructed and commissioned. Initial investigations focused on the shakedown and design of key unit operations, including the agglomeration and de-emulsification (i.e. Morganizing) steps. Studies showed that the initial design of these units, namely pump induced mixing in agglomeration and packed bed emulsification in the Morganizer, were not adequate to meet production demands, and as such, these stages were redesigned after appropriate fundamental evaluations. After implementing the design changes, the pilot plant was successfully operated over a 7-month period, routinely producing bituminous products with less than6% ash and less than 10% moisture as well as anthracite products with less than 3% ash and less than 4% moisture. This study also evaluated a new approach to de-emulsification using a jig based Morganizer in place of the standard oscillating column Morganizer. The jig utilizes a pulsing mechanism to move liquid to break up agglomerates versus the mechanical disk stack. Preliminary results showed that the jig Morganizer was comparable to the oscillating unit at more than half the size. This new design provides a pathway for reduced cost, footprint, and improved scalability. Lastly, this study evaluated both the HHS process and dual-scan X-ray based particle sorting as means of increasing the REE content of coal-based materials. Data from a pilot-scale x-ray sorter showed the unit was capable of preconcentrating REEs to over 300 ppm, while data from the HHS similarly showed the process was capable of REE recoveries of 85-90% and of preconcentrating REEs above 300 ppm. Altogether, these results indicate That both of these technologies are capable of efficiently and cost effectively preconcentrate REEs from wastes streams at operating coal preparation plants. / Doctor of Philosophy / The mining sector has traditionally been a large producer of waste, with the vast majority of this waste being ultrafine particles that are unable to be recovered using conventional technologies. These particles are often disposed of in large surface impoundments, which are an environmental and social liability in many mining districts. This study has evaluated a novel method of fine particle separation, the hydrophobic-hydrophilic separation (HHS) process. The HHS process uses a recyclable oil to selectively agglomerate fine particles, which are subsequently dispersed and recovered. The oil is then filtered and recycled within the process creating an approach that is both efficient and environmentally friendly. In this study, a mobile pilot HHS plant was constructed and tested, with the results showing that the HHS can effectively recover fine carbon from waste coals, thus turning an environmental liability into a potential value stream for high-end applications. In addition, the study showed that the process can be further improved to reduce costs while improving overall efficiency. Overall, this study has provided the data needed to further commercialize the HHS process. If widely deployed, the HHS process has the potential to both reduce the current amount of waste fines being generated and reclaim the existing impoundments.