重构矿渣在线双重固化垃圾焚烧飞灰重金属及其安全消纳

The municipal solid waste incineration （MSWI） fly ash have low residual activity and potential threat from residual dioxin and toxic heavy metals, which make it difficult to be used in the field of building materials for large amount of safety consumption. Firstly, aiming at this technical difficulty and key scientific problem, molten slag composite of MSWI fly ash at high temperature followed by reconstructing with water quenching, and the reconstructed slag is added into cement hydration process to achieve the toxic heavy metals' dual solidification. Secondly, the interaction between MSWI fly ash and molten slag, the occurrence state and the mechanism of degradation and solidification will be studied. Based on the above research, the parameter designing method and principle in high-temperature composited process will be developed through laboratory simulated molten mode. Thirdly, the optimal point will be studied, which may meet the requirements of heavy metals solidification state stability and improve the reconstructed slag in cement composite system's largest amount consumption, and the heavy metals' existence state and second solidification mechanism is studied during this process. At last, though severe erosion environment of actual application safety assessment to ascertain the reconstructed slag's application threshold and control method. Eventually, the safe disposal theory system for different industry will be formed to further promote the overall development of industrial economy low carbonization process.

本主要课题针对垃圾焚烧飞灰活性偏低，残余二噁英及有毒重金属潜在威胁极大，难以在建材领域大掺量安全消纳的技术难点和关键科学问题，重点研究熔融矿渣复合垃圾焚烧飞灰重构水淬成渣，再大掺量复合水泥水化对垃圾焚烧飞灰中有毒重金属进行双重固化技术。研究垃圾焚烧飞灰与熔融矿渣之间的交互作用及其重构水淬渣体中典型重金属的赋存状态和降解固化机理。在此理论基础上，通过实验室模拟煅烧熔融的方式完善高温复合过程中的工艺参数设计方法与原则。根据重构水淬渣粉磨细度-水化活性-重金属浸出率之间的关系探明既满足重金属固化状态的稳定性又提高重构水淬渣在水泥复合体系中的最大消纳量的最佳平衡点，探明重构水淬渣与水泥复合水化过程中重金属的赋存状态与二次固化机理。并通过严苛侵蚀环境下的实际应用安全性评估确定重构水淬渣的应用阈值及控制方法。最终形成通过行业联动协同处置垃圾焚烧飞灰的理论体系，进一步推动整体工业经济发展低碳化进程。

以国家自然科学基金项目-“重构水淬渣在线双重固化垃圾焚烧飞灰重金属及其安全消纳”（51202222）为研究背景。主要针对采用焚烧法处置城市生活垃圾而产生的垃圾焚烧飞灰活性偏低，残余二噁英及有毒重金属潜在威胁极大，难以在建材领域大掺量安全消纳的技术难点和关键科学问题，重点研究借助熔融矿渣闲置高温载体高温复合城市垃圾焚烧飞灰重构水淬成渣，再大掺量复合水泥水化对垃圾焚烧飞灰中有毒重金属进行双重固化技术。研究工作取得如下主要成果： .1. 进行了矿渣高温复合垃圾焚烧飞灰重构及其重金属一重固化研究。重构水淬渣呈现长程无序的玻璃态特征，XRD、SEM及IR分析表明重构水淬渣的化学组成及矿物组成与原状矿渣相似。经29Si NMR分析发现含超危垃圾焚烧飞灰重构水淬渣相比于原状矿渣的Q1(-77.1ppm)和Q4(-118.0ppm)两种聚合态峰值明显宽化且减弱，且由Q0转移至Q1说明其聚合度增加而活性降低。相对于原状矿渣，重构水淬渣的强峰线位移朝负值方向移动，呈现出由低场的集中向高场的转移趋势，亦说明其网络结构聚合度增加，说明重构水淬渣相比于原状矿渣其活性有明显的降低。重构水淬渣的重金属浸出毒性满足环境排放要求，实现超危垃圾焚烧飞灰中重金属的一重固化目标。.2. 进行了重构水淬渣复合水泥常规性能及其重金属二重固化研究。首次提出利用高温载体（熔融高炉矿渣）熔融重构垃圾焚烧飞灰水淬成渣，再常温状态大掺量复合水泥水化进行双重固化有毒重金属的新理念。其中Ⅲ过程中的重金属固化主要分为两个部分：一部分是Ⅱ过程中未实现有效固化部分游离重金属，在复合水泥水化初期即随重构水淬渣参与反应并固结于水泥复合体系水化产物中；另一部分是Ⅱ过程中已实现有效固化的重金属，因为重构水淬渣在参与水化反应过程中产物和结构发生变化，此部分原已有效固化的重金属失去保护而微量释放。而释放的重金属瞬间被重构水淬渣与水泥复合体系的水化产物及时固结包裹，重归稳定固化状态。.3．进行了严苛侵蚀环境下双重固化体系的安全性分析。根据该环境条件下砂浆外观破坏及强度损失等宏观性能变化及化学组分变化。经过不同破坏循环各试件4种典型重金属的浸出浓度均明显低于国标最高允许浓度