The potential leaching risk poses a concern for the large-scale recycling of hazardous waste as lightweight aggregates (LWAs). This paper investigated the combination state of heavy metals in target immobilized phases of LWA through both theoretical calculations and experimental verification. Results reveal that Pb can enter the feldspar crystal cell to form stable interstitial solid solutions, while Cu, Cr, and Ni can replace specific ions in spinel to form replacement solid solutions. The addition of target immobilized phases generally weakened the physical performance of LWAs, while reducing the leaching risk. The appropriate amount of the spinel phase favored the immobilization of Cu, Cr, and Ni, whereas albite contributed to the immobilization of Pb with low leaching values. Due to the lower melting temperature, albite could facilitate the introduction of a high-temperature liquid phase, enhancing the migration of Pb²⁺ for better immobilization in glassy phase. In contrast, anorthite exhibited a higher viscosity at 1100 °C, leading to ineffective physical encapsulation of heavy metal ions by the liquid phase. Heavy metal ions react with additional spinel phase at high temperatures to form stable solid solution phases. This study provides a novel method for regulating heavy metal leaching in hazardous waste-based LWA.

中文翻译：

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针对危险废物基轻骨料中重金属的固定相


潜在的浸出风险使危险废物作为轻质骨料 （LWA） 的大规模回收引起了人们的担忧。本文通过理论计算和实验验证，研究了LWA目标固定相中重金属的结合状态。结果表明，Pb 可以进入长石晶胞形成稳定的间隙固溶体，而 Cu、Cr 和 Ni 可以取代尖晶石中的特定离子以形成替代固溶体。添加目标固定相通常会削弱 LWA 的物理性能，同时降低浸出风险。适量的尖晶石相有利于 Cu、Cr 和 Ni 的固定化，而钠长石有助于低浸出值的 Pb 的固定化。由于熔融温度较低，钠长石可以促进高温液相的引入，增强 Pb²⁺ 的迁移，从而更好地固定在玻璃相中。相比之下，钙长石在 1100 °C 时表现出更高的粘度，导致液相无法有效地物理封装重金属离子。重金属离子在高温下与额外的尖晶石相反应，形成稳定的固溶相。本研究为调控基于危险废物的 LWA 中重金属浸出提供了一种新方法。