Industrial activities discharge heavy metal-laden wastes; and copper is one of these metals that can be stabilized after ceramic sintering by Al- or Fe-containing precursors. Besides traditional precursors, Al- and Fe-containing solid wastes (e.g., sewage sludge incineration ash, coal fly ash) were found equally capable of copper stabilization when they were adopted in the reaction matrices. However, the effect of CaO and SiO₂, the predominant components in most of the inorganic solid wastes, on metal transformation and stabilization has not been addressed. Therefore, a CaO-SiO₂-CuO-Al₂O₃-Fe₂O₃ reaction matrix was proposed in this study, focusing on the effect of CaO and SiO₂ on copper transformation and immobilization. Results showed that a single-phase CuAl_xFe_2-xO₄ spinel solution was developed in the system without CaO and SiO₂, whereas the addition of CaO led to the generation of two separate spinel phases: CuAl₂O₄ and CuFe₂O₄. Compared with CaO, the existence of SiO₂ showed less impact on the phase transformation. The effect of sintering temperature and additive dosage was also illustrated in this study and the results provided useful guidance for the optimization of reaction systems to achieve beneficial utilization of solid wastes for heavy metal stabilization.

中文翻译：

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微晶玻璃中的铜稳定性：CaO 和 SiO2 对 CuAlxFe2-xO4 形成的影响

工业活动排放含重金属的废物；铜是这些金属中的一种，在陶瓷烧结后可以通过含铝或含铁的前体进行稳定。除了传统的前体，含铝和含铁的固体废物（例如，污水污泥焚烧灰、煤飞灰）被发现在反应基质中采用时同样能够稳定铜。然而，大多数无机固体废物中的主要成分 CaO 和 SiO ₂对金属转化和稳定化的影响尚未得到解决。因此，本研究提出了CaO-SiO ₂ -CuO-Al ₂ O ₃ -Fe ₂ O ₃反应基质，重点研究了CaO和SiO的影响。₂关于铜的转化和固定化。结果表明，在不含 CaO 和 SiO ₂的体系中形成单相 CuAl _x Fe _{2- x} O ₄尖晶石溶液，而添加 CaO 导致产生两个独立的尖晶石相：CuAl ₂ O ₄和CuFe ₂ Ø ₄。与CaO相比，SiO _2的存在对相变的影响较小。本研究还说明了烧结温度和添加剂用量的影响，结果为优化反应系统以实现固体废物的有益利用以稳定重金属提供了有益的指导。