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This dissertation, Phase Transformations and Leaching Behavior of Hazardous Zinc Stabilized in Aluminum-based Ceramic Products by Xiuqing, Lu, 卢秀清, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled Phase Transformations and Leaching Behavior of Hazardous Zinc Stabilized in Aluminum-Based Ceramic Products Submitted by LU XIUQING For the degree of Doctor of Philosophy at The University of Hong Kong in May 2015 During the production and applications of zinc, large amounts of waste are produced and require appropriate treatments. An environmentally friendly and economical strategy is to utilize the hazardous zinc-laden waste as a material resource and then convert it into ceramic products. This study focuses on building a fundamental understanding of zinc transformations during the thermal reactions between zinc waste and ceramic precursors and the stabilities of the generated ceramic-based products. The simulated zinc waste, ZnO, can react with kaolinite, the mixture of mullite and cristobalite, the mixture of gamma alumina and quartz, to generate both ZnAl O and Zn SiO . The ZnAl O spinel with a stronger acidic resistance than ZnO 2 4 2 4 2 4 i and Zn SiO is a favorite zinc-hosting phase. To effectively convert the zinc into 2 4 ZnAl O structure rather than Zn SiO, kaolinite/alumina precursors at a treatment 2 4 2 4 over 950 C for hours, or mullite precursor at a treatment at the higher temperature is required. The generation of ZnFe O spinel from ZnO and Fe O is more efficient than 2 4 2 3 that of ZnAl O spinel from ZnO and -Al O within 1250 C. ZnAl Fe O spinel 2 4 2 3 x 2-x 4 solid solution can be obtained from the reaction among ZnO, Fe O and -Al O . The 2 3 2 3 leachability of ZnAl O is the lowest compared with that of ZnFe O and ZnAlFeO, 2 4 2 4 4 but all the spinel products are much more acidic resistant than ZnO. Therefore, stabilizing the zinc into ZnAl Fe O spinel solid solution by the sintered sewage x 2-x 4 sludge is an environmentally beneficial strategy. The highly acidic resistant ZnAl O becomes a promising phase in the immobilization 2 4 of zinc waste with rich Al, such as Zn-laden zeolite. Zeolite is an inexpensive but effective adsorbent for hazardous metals removal. Under thermal treatments, the Zn-laden zeolite successfully transformed into glass ceramic products mainly composed of zinc spinel. The sintered glass ceramic product only released little Zn in the alkaline solution, weak or strong acidic solutions, DI water and the simulated seawater, while much more Zn in the unsintered Zn-laden zeolite was extracted by near neutral and acidic leachants. Furthermore, if Zn was simultaneously adsorbed with Ni and Cu by zeolite 4A, the Zn can also be effectively thermally immobilized. In the Ni-laden zeolite, the adsorbed Ni transformed into NiO after the decomposition of zeolite structure and then incorporated into a spinel structure when the temperature was further increased. Zn also probably incorporated into a spinel structure in the sintered Zn-Ni-Cu-laden zeolite. However, in ii both the sintered Cu-laden and Zn-Ni-Cu-laden zeolites, the incorporation of copper into a spinel structure was hindered, and other copper phases together with spinel were detected during the thermal treatments. For these zeolites, the thermal treatments failed to stabilize the hazardous copper effectively but enhanced the stability of Ni and Zn significantly. The simultaneous loading of Ni and Cu has no negative impact on the thermal stabilizati

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