废物水泥窑共处置产品中重金属释放模型研究——混凝土路面场景

Model of heavy metals releasing in cement produced from co-processing waste in cement kiln——ased on concrete pavement scenario

通过模拟煅烧试验制取水泥熟料,并制得混凝土样品。在混凝土路面场景分析的基础上,参照欧盟固体中无机组分有效量测试方法(EA NEN7371),以pH=3.2的HNO3/H2SO4溶液(质量比为1∶2)为浸取液,在液固比为20 L/kg条件下,对混凝土样品进行模拟浸出实验;参照欧盟块状材料中无机组分的扩散实验方法(EA NEN7375)测定混凝土样品中重金属的有效释放量。模拟浸出实验结果表明,Cr、Ni和Cd在浸出过程中扩散控制是其释放的主要因素。在此基础上建立了重金属在混凝土路面中的释放模型。实验室实测累积释放量(实测值)与模型预测累积释放量(预测值)的拟合检验结果表明,实测值与预测值之间差异不显著,释放模型能较好地预测混凝土路面中重金属的长期累积释放量。

Cement clinker was prepared by simulating cement calcination, and the obtained clinker was used to produce concrete samples. On the basis of concrete pavement scenario analysis, the simulated leaching test of concrete samples which refers to EA NEN7371 was conducted to study the heavy metal releasing model. In the simulated leaching test, a blend of thick HNO3 and H2SO4 （weight ratio of 1 ： 2, pH of 3.2） applied as extraction solvent and liquid to solid ratio was 20 to 1, the maximum release amount of heavy metals from concrete was determined according to EA NEN7375. Result showed that diffusion control was the major release mechanism of the Cr, Ni and Cd, and the leaching model of heavy metals in concrete pavement was built on that basis. The independent t-test of the predicted results and the measured ones showed that the no significant difference was found between the measured values and predictive values, they were fitting very well. The release model could forecast the cumulative release amount of heavy metals in concrete excellently.