Secondary alumina dross (SAD) has emerged as an alternative to bauxite in the production of flash setting admixtures (FSA), a critical admixture in shotcrete. However, the presence of hazardous components has hampered its large-scale adoption. This study conducted field tests at an FSA factory, utilizing SAD as the primary raw material, to evaluate the feasibility and environmental risks. The results confirmed that SAD can effectively replace bauxite in FSA production without compromising quality, as it closely resembled the chemical properties of bauxite. Emissions of fluorides, heavy metals, dioxins in flue gases during production met the relevant Chinese standards. The analysis of hazardous component distribution revealed that more than 50% of volatile components, such as Cl, Cd, Pb, and Zn, were directed into fly ash, exhibiting a significant internal accumulation pattern. In contrast, more than 95% of low-volatility components, including Cu, Cr, Mn, and F, were transferred to the FSA, and the introduction of CaCO was confirmed to effectively immobilize F. Moreover, the leaching risk of heavy metals and fluorides in FSA applications slightly increased but remained minimal and within acceptable limits. This technology provides an environmentally sound solution for the disposal of SAD.

中文翻译：

---

经过现场检验的创新：可持续利用再生氧化铝渣生产闪凝外加剂

二次氧化铝浮渣 (SAD) 已成为生产闪凝外加剂 (FSA)（喷浆混凝土中的关键外加剂）时铝土矿的替代品。然而，危险成分的存在阻碍了其大规模采用。本研究以SAD为主要原材料，在FSA工厂进行了现场测试，以评估可行性和环境风险。结果证实，SAD 可以有效替代 FSA 生产中的铝土矿，且不会影响质量，因为它的化学性质与铝土矿非常相似。生产过程中烟气中氟化物、重金属、二恶英等污染物排放均符合国家相关标准。有害成分分布分析表明，50%以上的Cl、Cd、Pb、Zn等挥发性成分直接进入飞灰，呈现出明显的内部积累模式。相比之下，超过 95% 的低挥发性成分（包括 Cu、Cr、Mn 和 F）被转移到 FSA，并且 CaCO 的引入被证实可以有效固定 F。此外，重金属和 F 的浸出风险也降低了。 FSA 应用中的氟化物略有增加，但仍保持在可接受的限度内。该技术为 SAD 的处理提供了一种环保的解决方案。