干湿交替中碳酸化对废物水泥窑共处置产品中重金属浸出的影响

摘要

通过比较连续浸出、碳酸化保存间歇浸出和密封保存间歇浸出3种浸出条件下,废物水泥窑共处置产品--混凝土中Cr、Ni、As、Cd和Pb的浸出量,研究了干湿交替的环境中碳酸化对混凝土中重金属浸出的影响.结果表明,不同的漫出条件对混凝土中重金属的浸出产生了一定的影响.间歇浸出过程降低了重金属在混凝土固相与孔隙水(液相)中的浓度梯度,连续浸出条件更有利于混凝七中重金属的浸出;碳酸化保存过程中发生的碳酸化作用使混凝士中孔隙水的pH比密封保存条件下的低,碳酸化保存间歇浸出与密封保存问歇浸出相比,减小了Cr的浸出量,增加了Ni、As、Cd和Pb的浸出量;用基于连续浸出的实验方法或评价模型去预测和评价干湿交替环境中废物水泥窑共处置产品的重金属浸出可能导致错误的结果,应该建立一种混合干化、碳酸化的实验方法和评价模型.%Dynamic leaching tests on concrete, a co-processed cement product, were carried out in 3 modes of continuously leaching, intermittent drying-wetting leaching with and without carbonation. The quantity of Cr, Ni,As, Cd and Pb leaching from concrete was investigated to determine the influence of carbonation on heavy metals leaching characteristics. The results showed that leaching mode had certain impact on heavy mental releasing. The constituent concentration gradient in the liquid and solid phase was decreased during the intermittent carbonation leaching process, and heavy metals were more easily released from concrete under continuously leaching conditions. The carbonation could decreased the pH of leaching solutions and Cr leaching quantity, but increased the Ni, As, Cd and Pb leaching quantity. It was unfeasible to apply the evaluation mode, which established base on continuously leaching experiment for predicting the heavy metal releasing from co-processed cement product, so a new model should be established which take intermittent drying-wetting condition and carbonation into consideration.