高炉矿渣-粉煤灰地聚合物胶凝材料固化砷钙渣

Solidification/stabilization of calcium arsenate waste with blast furnace slag and fly ash geopolymer materials

以高炉矿渣、粉煤灰为地聚合物胶凝材料原料,配合复合化学激发剂固化砷钙渣,并采用X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)和扫描电子显微镜(SEM)探究固砷机理。研究结果表明,固化体优选质量配比为高炉矿渣粉∶粉煤灰∶砷钙渣=4∶2∶4,配合1.5%~2.0%的NaOH和工业水玻璃复合化学激发剂,固化体砷浸出浓度0.5~0.9mg/L,低于危险废物浸出毒性鉴别标准限值(5mg/L)。XRD、FTIR和SEM结果表明,砷钙渣经高炉矿渣-粉煤灰地聚合物胶凝材料固化,反应体系液相环境pH>13,促使砷钙渣中的含砷矿物CaHAsO_4·3H_2O向更加稳定的Ca_5(AsO_4)_3OH及类质同象物Ca_5(AsO_4)_3(OH,F)转变。同时地聚合物胶凝材料水化产生的网络状水化凝胶可把砷钙渣中的各组分胶结在一起有效抑制固化体中砷的溶出。可见,高炉矿渣-粉煤灰地聚合物胶凝材料可作为固化含砷渣的一种潜在固结剂。

Blast furnace slag and fly ash were utilized as raw materials for the preparation ofgeopolymer from industrial wastes.After that,calcium arsenate waste was solidified/immobilized withblast furnace slag and fly ash geopolymer materials as well as addition of compound chemicalactivators.Moreover,the mechanism for the solidification/stabilization of calcium arsenate waste withblast furnace slag and fly ash geopolymer materials by exploring the cementitious matrices using X-raypowder diffraction(XRD),Fourier transform infrared spectroscopy(FTIR)and scanning electronmicroscopy(SEM).The results showed that the optimum combination of the solidified sample was themass ratio of blast furnace slag,fly ash and calcium arsenate waste=4∶2∶4as well as addition ofcompound chemical activators(NaOH and industrial water-glass mixture)1.5%-2.0%.The arsenicconcentration of the leachate from the solidified forms was lower(0.5-0.9mg/L)than the national standard(i.e.,5mg/L).The results of XRD,FTIR and SEM showed that the sparingly solubleCaHAsO4·3H2O transformed into more stable Ca5(AsO4)3OH or the isomorphous Ca5(AsO4)3(OH,F)compounds at the pH of cementitious system over13when calcium arsenate waste solidified with blastfurnace slag and fly ash geopolymer materials.Meanwhile,the hydration products of blast furnace slagand fly ash geopolymer materials consolidated with other components in the solidified body to form astable whole,decreasing eventually the arsenic leachability of the solidified sample.Based on theseresults the blast furnace slag and fly ash geopolymer materials may be considered as a potentialmaterial to solidify arsenic-containing wastes.