Environmental Science Research Institute, School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China; School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
Environmental Science Research Institute, School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
Environ Int. 2020 Feb;135:105406. doi: 10.1016/j.envint.2019.105406. Epub 2019 Dec 19.
Arsenic-alkali residue (AAR) from antimony smelting is highly hazardous due to its ready leachability of As, seeking for proper disposal such as stabilization treatment. However, As stabilization in AAR would be challenging due to the high content of coexisting soluble carbonate. This study conducted the stabilization treatments of AAR by ferrous sulfate and lime, respectively, and revealed the significant influence of coexisting carbonate. It was found that ferrous sulfate was more efficient than lime, which required only one-tenth of dosages of lime to reduce the As leaching concentration from 915 mg/L to a level below 2.5 mg/L to meet the Chinese regulatory limit. The combining qualitative and quantitative analyses based on XRD, SEM-EDS, and thermodynamic modeling suggested that the formation of insoluble arsenate minerals, ferrous arsenate or calcium arsenate, was the predominant mechanism for As stabilization in the two treatment systems, and their efficiency difference was primarily attributed to the coexisting carbonate, which had a slight effect on ferrous arsenate but severely obstructed calcium arsenate formation. Moreover, the examination of As leaching concentrations in 1-year-cured samples indicated that the long-term stability of ferrous sulfate treatment was far superior to that of lime treatment. This study provides ferrous salts as a promising and green scheme for stabilization treatment of AAR as well as other similar As-bearing solid wastes with coexisting soluble carbonate.
砷碱渣（AAR）来自于锑冶炼，由于其砷的易浸出性，具有高度的危害性，因此需要进行适当的处理，如稳定化处理。然而，由于共存的可溶性碳酸盐含量高，AAR 中的砷稳定化处理具有挑战性。本研究分别采用硫酸亚铁和石灰对 AAR 进行了稳定化处理，揭示了共存碳酸盐的显著影响。结果表明，硫酸亚铁比石灰更有效，只需石灰十分之一的剂量就可以将砷的浸出浓度从 915mg/L 降低到低于 2.5mg/L，达到中国的监管限值。基于 XRD、SEM-EDS 和热力学建模的定性和定量分析表明，在两种处理系统中，形成不溶性砷酸盐矿物（亚铁砷酸盐或钙砷酸盐）是砷稳定化的主要机制，其效率差异主要归因于共存的碳酸盐，它对亚铁砷酸盐的影响较小，但严重阻碍了钙砷酸盐的形成。此外，对 1 年养护样品中砷浸出浓度的检测表明，硫酸亚铁处理的长期稳定性远远优于石灰处理。本研究为 AAR 及其他类似含有共存可溶性碳酸盐的含砷固体废物的稳定化处理提供了一种有前景的绿色方案。
