随着我国经济发展和城市化进程的加快，生活垃圾的产生量持续增长。焚烧作为一种处理垃圾的有效手段，得到了越来越广泛的应用，由此也产生了相当数量的焚烧飞灰。飞灰中含有重金属等有毒有害物质，是一种危险废物，当其与水溶液反应时，重金属会被释放到溶液中，带来潜在的环境风险。垃圾焚烧飞灰含有大量的碱性物质，因此具有很高的酸中和容量（acid neutralizing Capacity， ANC），具有缓冲酸性溶液的能力，这对重金属的浸出有抑制作用。但是当采用填埋等土地方式处置飞灰时，其中的碱性物质会在降雨等长期作用下被逐渐消耗，从而造成重金属的持续浸出。本文旨在研究飞灰与酸性溶液之间中和反应的发生过程，以及重金属的浸出行为，从而为飞灰的处理处置提供理论和技术支持。采用定pH值滴定的实验方法，研究了飞灰在不同pH值下的浸出过程，发现飞灰的浸出经历了不同的阶段，在初期消耗酸量迅速增加，元素快速释放，随着反应的进行，酸消耗量以及元素浸出的速率都趋缓。飞灰中各种组分反应活性和溶解速度的差异，使得元素的释放表现出不同的行为。采用连续过流实验的方法，研究了溶液更新条件下，飞灰的中和以及重金属浸出的过程。发现由于飞灰ANC的消耗和水流的传质作用，在系统中形成了一个pH值的锋面，重金属在锋面上得到富集。随着反应的进行，系统中飞灰的酸中和容量不断被消耗，pH值锋面向系统后方移动，富集的重金属由于浸出液pH值的下降，重新溶解到液相中，随水流向下游迁移，当整个系统飞灰的酸中和容量被耗尽的时候，pH值锋面会消失，而锋面上富集的重金属也会释放到环境中。借助地球化学模型PHREEQC，对过流实验中飞灰的浸出过程，进行了模拟，并与实验结果进行了对照，发现二者较吻合。借助地球化学软件，可以对飞灰浸出的长期过程做出预测与评价。

In China, rapid development of economic and urbanization brings a sharp increase of the production of municipal solid waste (MSW). Incineration is an effective technology for MSW treatment, which will generate a large amount of fly ash. The municipal solid waste incineration (MSWI) fly ash is considered as hazardous waste for the presence of heavy metals and other toxic substances. Alkaline substances take a large proportion of the fly ash composition, which bring a high acid neutralizing capacity (ANC) to buffer the acid solution. In real disposal environment such as the landfill, the ANC will be consumed by neutralizing process. With the loss of ANC, the heavy meals will be released to environment. This study focuses on the neutralizing process between fly ash and acid and the leaching behavior of heavy metals. This will provide theoretics for developing treatment technology. The consumption of ANC and heavy metals leaching as a function of pH value and time was studied using a pHstat titration test. The pH value of the system was kept constant during titration. The result indicates that in the initial time of the titration, the amount of consumed acid increases rapidly. As the accumulation of the ions in the solution, the rate of the fly ash dissolution gets an inflection point. With the fall of the controlled pH values, the proton buffering capacity of fly ash increases correspondingly. Elements represent different types of leaching behavior during the titration. A serial-batch leaching experiment was used to simulate the leaching process of fly ash in a flow-through system. The pH front formed in the system because of the mass transport effect and neutralizing process. The heavy metals were accumulated near the pH front zone. Some species dissolved upstream of the pH front and then precipitated downstream to form a secondary mineral enrichment zone which limited the heavy metals leaching. When the whole ANC of fly ash is exhausted by acid, the heavy metals will release to solution suddenly. The leaching process of fly ash in the flow-through system was simulated using geochemical modeling software PHREEQC. The result shows that PHREEQC can successfully simulate the leaching process under the chemical transport condition. However, the complexity of chemical composition and reaction during leaching bring some deviation for simulation. To get a better insight of the neutralizing process and heavy metals leaching behavior, further research should focus on fly ash composition and the leaching mechanism.