Xia Yi, He Pinjing, Shao Liming, Zhang Hua
State Key Laboratory of Pollution Control & Resource Reuse, Tongji University, Shanghai 200092, China; Institute of Waste Treatment and Reclamation, Tongji University, Shanghai 200092, China.
Institute of Waste Treatment and Reclamation, Tongji University, Shanghai 200092, China; Center for the Technology Research and Training on Household Waste in Small Towns & Rural Area, Ministry of Housing and Urban-Rural Development of China (MOHURD), Shanghai 200092, China.
J Environ Sci (China). 2017 Feb;52:178-189. doi: 10.1016/j.jes.2016.04.016. Epub 2016 May 21.
Bottom ash is the major by-product of municipal solid waste incineration (MSWI), and is often reused as an engineering material, such as road-base aggregate. However, some metals (especially aluminum) in bottom ash can react with water and generate gas that could cause expansion and failure of products containing the ash; these metals must be removed before the ash is utilized. The size distribution and the chemical speciation of metals in the bottom ash from two Chinese MSWI plants were examined in this study, and the recovery potential of metals from the ash was evaluated. The metal concentrations in these bottom ashes were lower than that generated in other developed countries. Specifically, the contents of Al, Fe, Cu and Zn were 18.9-29.2, 25.5-32.3, 0.7-1.0 and 1.6-2.5g/kg, respectively. Moreover, 44.9-57.0wt.% of Al and 55.6-75.4wt.% of Fe were distributed in bottom ash particles smaller than 5mm. Similarly, 46.6-79.7wt.% of Cu and 42.9-74.2wt.% of Zn were concentrated in particles smaller than 3mm. The Fe in the bottom ash mainly existed as hematite, and its chemical speciation was considered to limit the recovery efficiency of magnetic separation.
底灰是城市固体废弃物焚烧（MSWI）的主要副产品，常被再用作工程材料，如道路基层集料。然而，底灰中的一些金属（尤其是铝）会与水发生反应并产生气体，这可能导致含有该灰的产品膨胀和失效；在利用该灰之前必须去除这些金属。本研究考察了中国两家MSWI工厂底灰中金属的粒度分布和化学形态，并评估了从该灰中回收金属的潜力。这些底灰中的金属浓度低于其他发达国家产生的底灰。具体而言，铝、铁、铜和锌的含量分别为18.9 - 29.2、25.5 - 32.3、0.7 - 1.0和1.6 - 2.5g/kg。此外，44.9 - 57.0wt.%的铝和55.6 - 75.4wt.%的铁分布在粒径小于5mm的底灰颗粒中。同样，46.6 - 79.7wt.%的铜和42.9 - 74.2wt.%的锌集中在粒径小于3mm的颗粒中。底灰中的铁主要以赤铁矿形式存在，其化学形态被认为限制了磁选的回收效率。
