Incorporating Simulated Zinc Ash by Kaolinite- and Sludge-based Ceramics: Phase Transformation and Product Leachability

详细信息    查看全文

• 作者：Kaimin SHIH ; Yuanyuan TANG
• 关键词：municipal solid waste incineration ; spinel ; willemite ; zinc ; sludge ; stabilization
• 刊名：Chinese Journal of Chemical Engineering
• 出版年：2012
• 出版时间：June, 2012
• 年：2012
• 卷：20
• 期：3
• 页码：411-416
• 全文大小：216 K

文摘

Zinc is one of the hazardous metals commonly found in municipal solid waste incineration (MSWI) ash, and this study reveals the stabilization mechanisms when sintering zinc-laden ash and ceramic precursors as a waste-to-resource strategy. Using ZnO to simulate the zinc-laden ash and sintering with kaolinite and mullite ceramic precursors, both zinc aluminate spinel (ZnAl₂O₄) and willemite (Zn₂SiO₄) phases were found in the products under the tested thermal conditions. The results also indicate that kaolinite and mullite precursors exhibit different incorporation behavior, and ZnAl₂O₄ and Zn₂SiO₄ were found to be competitive as the Zn-hosting phases in the system. A prolonged leaching test was used to evaluate the leachability of potential product phases in the system. The concentrations of zinc in ZnO and Zn₂SiO₄ leachates were about two orders of magnitude higher than that in ZnAl₂O₄ leachate, indicating the preference of forming ZnAl₂O₄ for zinc stabilization. Furthermore, the aluminum-rich sludge generated from waterworks could be beneficially used as a material resource to stabilize zinc in this study. The X-ray diffraction (XRD) pattern collected from the 1150 ¡ãC and 3-h sintered sample shows the success of incorporating zinc into the ZnAl₂O₄ spinel structure with waterworks sludge precursor. The formation of ZnAl₂O₄ indicates a strong potential for employing aluminum- and silicon-based materials to thermally immobilize zinc and achieve the beneficial use of metal-laden MSWI ash.