Recycling of Waste Incineration Bottom Ash and Heavy Metal Immobilization by Geopolymer Production
Recycling of Waste Incineration Bottom Ash and Heavy Metal Immobilization by Geopolymer Production
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DOI：
10.3151/jact.19.259
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发表时间：
2021-04-01
影响因子：
2
通讯作者：
Ikeda, Ko
中科院分区：
文献类型：
--
作者：
Li, Zhuguo;Kondo, Ryusei;Ikeda, Ko
城市垃圾焚烧灰中含有重金属，其处置和再利用的安全性是一个重要问题。在本研究中，我们利用地质聚合物（GP）优异的重金属固定特性，讨论了底灰（BA）的安全回收技术。首先，研究了不同月份排放的BAs的化学成分、物理性质和重金属含量的差异。接下来，检查了 BA 和碱活化剂 (AA) 溶液的混合物的反应产物和强度，以阐明 AA 溶液中 BA 的反应性。以高炉矿渣粉（BFS）和粉煤灰（CFA）为前驱体，BA为细骨料，研究了BA的排放时间、AA溶液的配料、养护方式和BFS的混合比例对GP砂浆的凝结时间、强度和重金属固定能力的影响，并讨论了GP砂浆的反应产物和微观结构。主要结果如下： 1）BA中含有少量非晶相。使用 BA 和 AA 溶液硬化的 GP 整体材料不致密且强度非常低。 2）以BA为细骨料的BFS/CFA基GP砂浆，以硅酸钠溶液（WG）为AA溶液时，比添加氢氧化钠或完全使用氢氧化钠时具有更高的强度和更长的凝结时间。使用温暖季节排放的BA的GP砂浆具有较长的凝结时间和较高的强度。 GP砂浆与WG溶液和BA的反应产物主要是C-A-S-H凝胶。随着渗滤液碱度的降低，GP砂浆中重金属元素（HME）的浸出量增加，但本研究未发现BA排放季节的影响。非酸性水环境中GP砂浆的HME浸出浓度低于直接与水接触的再生建筑材料规定的HME浸出限值，因此带有BA的GP材料可以在干燥或非酸性水环境中使用。但在酸性水环境中使用时，应降低GP材料中的BA含量。
Municipal waste incineration ash contains heavy metals, and the safety of its disposal and reuse is an important issue. In this study, we discussed a safe recycling technology for bottom ash (BA) by utilizing the excellent heavy metal immobilization feature of geopolymer (GP). First, the differences in chemical compositions, physical properties, and heavy metal contents of BAs discharged in different months were investigated. Next, the reaction products and strength of the mixture of BA and alkali-activator (AA) solution were examined to clarify the reactivity of BA in the AA solution. We also investigated the effects of the discharge time of BA, ingredients of AA solution, curing method and mixing ratio of BFS on the setting time, strength and heavy metal immobilization capacity of GP mortar using ground granulated blast furnace slag (BFS) and coal fly ash (CFA) as precursors, and BA as fine aggregate, and discussed reaction products and micro-structure of the GP mortar. The main results are as follows: 1) BA contained a small amount of amorphous phase. Hardened GP monolith using BA and AA solution was not dense and had a very low strength. 2) The BFS/CFA-based GP mortar with BA as fine aggregate had a higher strength and a longer setting time when sodium silicate solution (WG) was used as AA solution than when sodium hydroxide was added or used entirely. The GP mortars using the BAs discharged in the warm season had longer setting time and higher strength. The reaction products of the GP mortar with WG solution and BA were mainly C-A-S-H gels. The leaching of heavy metal elements (HME) from the GP mortars increased with decreasing the alkalinity of leachate, but the effect of BA's discharge season was not found in this study. The HME leaching concentrations from the GP mortars in non-acidic water environment were less than the HME leaching limits specified for recycled construction materials directly contacting with water, thus the GP materials with BA can be used in dry or non-acidic water environment. However, when used in acidic water environment, the BA content in the GP materials should be reduced.