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Novel thermomicroscopy techniques applied to metal recovery from waste electrical and electronic equipment and metal catalyst

  • Adam Watson

Student thesis: Master's Thesis

Abstract

Novel thermal analytical instrumentations were used to explore the use of high frequency heating in thermal analysis. Microwave differential thermal analysis (MW-DTA) was adapted to allow for thermomicroscopy allowing for microwave differential temperature analysis thermomicroscopy (MW-DTA-TM) and the development of a newer induction heating thermal microscope (ITHM). Calibration on these instruments was carried out, determination of limits of the instrumentation and a basic comparative study on metal complexes. Heating limits were observed on the new IHTM as a result of the use of a graphite susceptor compared to the iron susceptor used in the original model. MW-DTA-TM was used to explore the effect of ceramic and quartz crucibles and was found that whilst quartz crucibles could cause slight visual difference as a result of its reflectiveness it was determined to be the better crucible choice as it removed the temperature lag from the furnace to the sample observed with the ceramic crucible. It was also observed the difference in temperature throughout the quartz crucible as it was observed some samples recrystalising on the top ridge of the crucible. The difference between using the onsets of the RGB count plot and the differential temperature plot for calibration was also explored and determination of using differential temperature was the best for calibration. Microwave thermogravimetric analysis (MW-TGA) was explored and the heating ability of graphite compared to ceramic and silicon carbide assisted ceramic crucibles. It was observed that whilst graphite crucible was able to heat the sample at a constant rate much like the silicone carbide assisted it required slightly more energy to do so and was also observed the ceramic crucible was unable to maintain a constant heating rate profile. Whilst initial studies in the susceptibility of heating of the graphite it was observed a limitation in the way the pyrometer was calculating the temperature of the samples by taking a cone which with smaller sample or crucible sizes resulted in a lower onset temperature . The original IHTM system was used for a comparative study to convention thermogravimetric analysis (TGA) in the decomposition and reduction of a series of different metal complexes. The system utilised the use of Red, Green, Blue (RGB) pixel count as a function of the temperature to determine onset temperatures of decomposition and reduction steps. It was observed that the RGB count plots gave comparable onsets temperatures however a limitation of the technique was discovered in determining the onsets of events of samples that are in liquid form as the production of decomposition gases causes disturbance on the liquids surface and makes the technique used to determine onset temperatures. Metal oxalates and benzoates were explored in the study as possible alternative products for the recovery of metals from waste electronics and electrical equipment (WEEE). They were chosen as a result of their decomposition producing metal oxides, carbon dioxide and carbon monoxide as products offering an alternative carbon friendly technique compared to current methods of metal recovery. Successful separation of Cobalt-Copper, Lithium-Cobalt, Indium-Tin simulations of WEEE waste. The technique was also explored into the use of recovering metals from spent and poisoned metal based catalysed and an Alumina-Copper-Zinc catalyst selected and successfully recovering the copper and zinc oxalates from it.
Date of Award11 Nov 2025
Original languageEnglish
SupervisorGage Ashton (Main Supervisor) & Gareth Parkes (Co-Supervisor)

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