Chen Weifang, Wang Yegui, Sun Yimo, Fang Guilin, Li Yonglun
School of Environment and Architecture, University of Shanghai for Science and Technology, 516 Jun Gong Road, Shanghai, 200093, China.
School of Environment and Architecture, University of Shanghai for Science and Technology, 516 Jun Gong Road, Shanghai, 200093, China.
Chemosphere. 2022 Nov;307(Pt 2):135860. doi: 10.1016/j.chemosphere.2022.135860. Epub 2022 Aug 6.
Two municipal solid waste incineration fly ashes were selected for washing by deionized water and NaCO solution for comparison. Results showed that the benefits of washing were two folds: (1) Washing was able to reduce the contents of Cl and SO while increased the contents of CaO, SiO, AlO etc.; (2) Washing by NaCO solution showed increased stability of heavy metals (Cr, Ni, Cd, Cu, Zn and Pb) and fly ash was safe for later reuse. Release of Cl was high at more than 90% regardless of washing solution. SO and Ca removal was highly dependent on the dissolution and precipitation equilibriums. NaCO washing promoted the formation of CaCO. Thus SO was washed off instead of precipitating as CaSO and retained in fly ash solid. SO removal was raised to more than 80% by NaCO washing as compared with about 30% by deionized water. At the same time, Ca removal by NaCO dropped to 1-2%. In addition, the basicity of fly ash was important as high basicity helped SO removal. Overall, washing by NaCO appears to be a promising option for fly ash treatment.
选取了两种城市固体废弃物焚烧飞灰，分别用去离子水和碳酸钠溶液进行洗涤以作比较。结果表明，洗涤的益处有两方面：（1）洗涤能够降低氯和硫的含量，同时提高氧化钙、二氧化硅、氧化铝等的含量；（2）用碳酸钠溶液洗涤显示出重金属（铬、镍、镉、铜、锌和铅）的稳定性增强，且飞灰后续再利用是安全的。无论使用何种洗涤溶液，氯的释放率都很高，超过90%。硫和钙的去除高度依赖于溶解和沉淀平衡。碳酸钠洗涤促进了碳酸钙的形成。因此，硫被洗脱而不是以硫酸钙的形式沉淀并保留在飞灰固体中。与去离子水洗涤约30%的去除率相比，碳酸钠洗涤使硫的去除率提高到80%以上。同时，碳酸钠洗涤使钙的去除率降至1%-2%。此外，飞灰的碱度很重要，因为高碱度有助于硫的去除。总体而言，碳酸钠洗涤似乎是飞灰处理的一个有前景的选择。
