Abstract:

In order to explore the optimal solid-liquid separation method and process parameters, six air pollution control (APC) residues from waste incinerators were washed with water at a liquid to solid ratio of 3 L·kg^-1. Three methods of solid-liquid separation were adopted for the APC residues suspension, i.e., gravity sedimentation, centrifugal sedimentation and suction filtration. Their effects were evaluated based on the turbidity and total solids (TS) concentration of the supernatant/filtrate, the moisture content and capillary suction time of the mud cake. The results showed that gravity sedimentation was suitable for separating the APC residues with concentrated particle size distribution, and the best settling time should be set at the inflection point of the gravity sedimentation curve (20—70 min). The optimal centrifugal sedimentation parameters were 3000 r·min^-1, and 5 min. Suction filtration had the best effect on reducing supernatant/filtrate turbidity and mud cake moisture content, and was suitable for separating the APC residues with a wide range of particle size distribution. The results of this study can provide a theoretical basis for the engineering application of solid-liquid separation of washed APC residues, and the appropriate solid-liquid separation method can be selected according to the particle size distribution of APC residues, treatment capacity and site requirements.

Key words: air pollution control residues, gravity sedimentation, centrifugal sedimentation, suction filtration, particle size distribution, separation

摘要：

为探究垃圾焚烧飞灰水洗后的最佳固液分离方式和工艺参数，将6种飞灰样品以3 L·kg^-1液固比水洗后，分别采用重力沉降、离心沉降和抽滤3种方式固液分离，依据上清液/滤液浊度和总固体(TS)浓度、泥饼含水率和毛细吸水时间等指标，评价不同固液分离方式的效果。结果表明，重力沉降适用于分离粒度分布集中的飞灰，最佳的沉降时间应设在重力沉降曲线的拐点处(20~70 min)。最佳的离心沉降参数为转速3000 r·min^-1、时间5 min。抽滤降低上清液/滤液浊度和泥饼含水率的效果最好，适用于分离粒度分布范围较广的飞灰。研究结果可为水洗后飞灰固液分离的工程化应用提供理论依据，应用时可根据飞灰的粒度分布、处理规模和场地需求选用合适的固液分离方式。

关键词: 飞灰, 重力沉降, 离心沉降, 抽滤, 粒度分布, 分离