脱硫废水水泥化固定产物重金属浸出特性实验研究

Experimental Study on Leaching Properties of Heavy Metals in Cement-based Products by FGD Wastewater Solidification

提出一种新型的脱硫废水烟气浓缩和水泥固化/稳定化的技术路线,将固化体固化As5+和Se4+的能力作为考察重金属水泥固化/稳定化效果的依据,以探究重金属的浸出特性。首先利用脱硫废水与水泥、粉煤灰和河砂拌合制得固化体,将其养护至特定龄期后,对As5+和Se4+的浸出率进行检测,再研究水胶比、泥灰比和河砂量对固化体固化As5+和Se4+能力的影响。结果表明:As5+和Se4+的浸出率均随胶凝材料掺入量的增大而大幅增大;泥灰比对As5+的固化/稳定化效果的影响更为显著,当泥灰比为3.2∶1时,固化体中水泥与粉煤灰的水化反应达到最佳。

A new technical route was proposed for the flue gas concentrating and cement-based solidification/stabilization of desulfurization wastewater, in which, the ability of the solidifying object to fix arsenic ions and selenium ions was taken as the basis for predictive analysis of the cement-based heavy metal solidification/stabilization effects, so as to study the leaching properties of the heavy metals. The specific way is to mix the desulfurization wastewater with cement, fly ash and fluvial sand to obtain a solidifying object. After curing to a certain time for the solidifying object, the leaching rates of the arsenic ions and selenium ions were tested. Finally, the effects of the following factors on the solidifying ability to the arsenic ions and selenium ions were analyzed, such as the water-cement ratio, cement-coal fly ash(CFA) ratio and the sand amount, etc. Results show that the leaching rates of arsenic ions and selenium ions increase significantly with the rise of the amount of cementitious materials;the effects of water-cement ratio on the solidification/stabilization of arsenic ions are more significant. When the mass ratio of cement to CFA is 3.2∶1, the hydration reaction of cement and CFA in the solidifying object reaches the optimal state.