危险废物焚烧飞灰玻璃化产物危险特性

《国家危险废物名录》中HW18焚烧处置残渣明确规定，"危险废物等离子体、高温熔融等处置过程产生的非玻璃态物质和飞灰"判定为危险废物.为降低危险废物焚烧飞灰的生态环境危害，并期望对其进行更好的资源化利用，采用国际前沿的玻璃化技术对危险废物焚烧飞灰进行处置，制备得到玻璃态物质，即玻璃体.结果表明:①焚烧飞灰掺杂不同比例的高岭土、SiO₂、CaO后，可形成符合玻璃体烧制条件的CaO-Al₂O₃-SiO₂系统，经过2 h 1 400℃高温熔融，几种不同配料比的玻璃体均可形成无定型的、微观表面平滑的结构.②玻璃体对Zn、Cr、Pb、Cd和As等重金属均有不同程度的固化作用，采用HJ/T 300-2007《固体废物浸出毒性浸出方法醋酸缓冲溶液法》测得的重金属浸出浓度均低于焚烧飞灰.③采用Hakanson公式中潜在生态危害模型对焚烧飞灰及玻璃体进行风险评价显示，几种玻璃体的RI（潜在生态危害风险指数）均在50~100范围内，呈中等风险，低于焚烧飞灰（299.34）.④效果最优的玻璃体的碱度（CaO/SiO₂，质量分数）为0.3，呈现浅绿色且质地透明的外观形貌，它对Zn、Cr的浸出浓度分别为0.12、0.05 mg/L，但均未检出Pb、Cd、As，远低于焚烧飞灰浸出浓度及GB 16889-2008《生活垃圾填埋场控制标准》中生活垃圾焚烧飞灰和医疗废物焚烧残渣浸出限值（Zn、Cr、Pb、Cd、As浸出浓度限值依次为100、4.5、0.25、0.15、0.3 mg/L），该玻璃体的RI为60.05，远低于焚烧飞灰的299.34.研究显示，采用玻璃化技术对焚烧飞灰进行处置后，焚烧飞灰可形成无定型的玻璃态结构，碱度为0.3时，玻璃体的重金属浸出浓度最低，且潜在生态风险最低，为最适用于焚烧飞灰玻璃化技术的调控比例. 

Fly Ash from Hazardous Waste Incineration: Vitrification and Hazardous Characteristics

The HW18 in National Hazardous Waste List clearly indicates that 'non-glassy materials and fly ash generated by hazardous waste during plasma vitrification and high temperature melting processes' are regarded as hazardous waste. In order to reduce the damage to ecology and create better resource utilization, the advanced vitrification technology is adopted to dispose of the fly ash from the incineration process of hazardous waste and obtain a vitrified sample. The results showed that, firstly, the mixing fly ash with different proportions of kaolin, SiO₂ and CaO, suitable vitrification conditions of 'CaO-Al₂O₃-SiO₂' system could be reached. After two hours' melting at 1400℃, several vitrified samples with different ingredients ratio could form an amorphous structure with a smooth microscopic surface. Secondly, the vitrified samples have a fine capacity to fix some heavy metals, such as Zn, Cr, Pb, Cd and As. According to Solid Waste-Extraction Procedure for Leaching Toxicity-Acetic Acid Buffer Solution Method (HJ/T 300-2007), the toxic substances in vitrified samples were lower than that in incineration fly ash. In addition, the potential ecological risk model put forward by Hakanson was used to evaluate the ecological risk of both fly ash and vitrified samples. The results showed that all the potential ecological risk indices of vitrified samples ranged from 50 to 100, with moderate risk, while incineration fly ash was 299.34, with comparatively high risk. At last, the most effective vitrified sample was BLT-0.3, which the basicity was 0.3, and with a light green, transparent appearance. The BLT-0.3's leaching concentration of Zn, Cr was detected as 0.12, 0.05 mg/L, respectively, and for Pb, Cd, As was not detectable, much lower than that of original fly ash of 261.60, 0.25, 2.02, 0.23, 0.18 mg/L, and less than the limit of Chinese standard for pollution control on the landfill site of municipal solid waste of 100.00, 4.50, 0.25, 0.15 and 0.30 mg/L, respectively. Moreover, the potential ecological risk index of BLT-0.3 was 60.05, far below the original fly ash index of 299.34 as well. They showed, after disposed by vitrification technology, that the fly ash from the incineration process would form an amorphous structure and obtain a vitrified sample. With a basicity of 0.3, the vitrified sample has the lowest concentration of heavy metal leaching and the lowest potential ecological risk, which is the most suitable proportion of vitrification technology for fly ash.