养护条件对二次铝灰-垃圾飞灰基地聚物中重金属稳固化的影响

以添加SiO2粉末后的二次铝灰和垃圾焚烧飞灰为原料，经过碱激发制备地聚物固化体。将制备好的地聚物固化体样品分别放在30、35、40、45和50 ℃，相对湿度为80%的恒温恒湿培养箱内养护，探究不同养护条件对固化体中重金属浸出特性的影响，并考察生活垃圾焚烧飞灰处理前后重金属化学形态、晶体结构和微观形貌的改变。结果表明：重金属Cr的相对浸出率在30～45 ℃下降明显，45～50 ℃内趋于平缓；而Cd和Pb的相对浸出率在30～40 ℃略微上升，40～50 ℃呈下降趋势，并且Pb的相对浸出率在40～45 ℃下降明显；Zn的相对浸出率随着养护温度的升高缓慢下降。重金属Cr、Cd、Zn和Pb的相对浸出率在前10 d内下降较大，10～14 d下降缓慢。当养护温度为50 ℃时，地聚物中重金属Cr、Cd、Zn和Pb的浸出浓度分别降到0.172、0.072、0.218和3.803 mg·L-1,满足《生活垃圾填埋场控制标准》（GB 16889-2008）的浸出要求。

Effects of curing condition on the stabilization of heavy metals in geopolymer of secondary aluminum ash - MSWI fly ash

The secondary aluminum ash added with silica fume and the municipal solid waste incineration fly ash (MSWI FA) were used as raw materials to prepare solidified geopolymer through the alkali activation process. The samples were placed in a constant temperature and humidity incubator with the humidity of 80% and the temperatures of 30, 35, 40, 45 and 50 °C to investigate effects of different curing conditions on the leaching characteristics of heavy metals. The chemical forms, crystal structures and microscopic features were also analyzed. The results show that the relative leaching rate of heavy metal Cr decreases obviously when the curing temperature rises from 30 to 45 °C and tends to be leveling off within 45 to 50 °C. The relative leaching rates of heavy metal Cd and Pb increase slightly when the curing temperature rises from 30 to 40 °C and then decrease from 40 to 50 °C, the relative leaching rate of heavy metal Pb declines significantly within 40 to 45 °C. The relative leaching rate of heavy metal Zn decreases slowly with the increase of curing temperature. The relative leaching rates of Cr, Cd, Zn and Pb in heavy metals decrease greatly within the first 10 days and descend slowly in 10 to 14 days. When the curing temperature is 50 °C, the leaching concentrations of heavy metals Cr, Cd, Zn and Pb in geopolymer decrease to 0.172, 0.072, 0.218 and 3.803 mg·L-1 ,respectively, which meets the leaching requirements of Standard for Pollution Control on the Landfill Site of Municipal Solid Waste (GB 16889-2008).