废物水泥窑共处置产品中重金属的释放特性

选用欧盟固体中无机组分有效量测试方法(EA NEN7371)和块状材料中无机组分的扩散实验方法(EA NEN7375),研究了模拟混凝土样品中重金属(Cr、Ni、As、Cd和Pb)的释放特性.结果表明,混凝土中重金属的有效释放量低于总量;不同重金属的有效释放量与总量比值差异较大.扩散控制是混凝土中Cr、Ni和Cd释放的主要机理,释放曲线与斜率为0.5的直线拟合较佳,且不同区间浸出量曲线的斜率均在0.35~0.65范围内;As在释放前期有延滞现象,但中后期仍以扩散控制为主;Pb的释放为溶解控制,受浸取液的pH值影响较大.重金属扩散系数负对数值按Pb

Release characteristics of heavy metals in cement product from co-processing waste in cement kiln

Clinker used in this experiment was produced by simulating cement calcination test, and concrete samples were prepared from the clinker. The release characteristics of heavy metals in concrete was studied by using two leaching methods, EA NEN 7371 and EA NEN7375. Availabilities of the heavy metals were lower than the total amounts in concrete. Ratios of availability to total amount were of great difference among each heavy metal and the ratio of Ni(64.6%) was the biggest among five heavy metals(Cr, Ni, As, Cd, Pb). The major release mechanism of the Cr, Ni, and Cd was diffusion control and the release curves fitted the standard line well with a slope of 0.5 and that of different increments were all between 0.35 and 0.65. Leaching of As appeared delayed-stagnant phenomena initially, but diffusion control was still the major mechanism in middle and later leaching period. Release of Pb was controlled by solution and influenced significantly by eluates pH. The negative logarithm of diffusion coefficient of each heavy metals changed as the following order: Pb