利用热等离子体熔融垃圾焚烧飞灰

为了评价垃圾焚烧飞灰的热等离子体熔融处理效果, 研究SiO2和CaO对重金属固化效果和重金属毒性浸出特性的影响. 在飞灰中添加一定比例的SiO2和CaO, 配置成不同的配灰样品, 利用纯氩热等离子体在1 400～1 500 ℃下, 对飞灰及配灰进行熔融玻璃化的实验研究, 分别利用X射线能量色散谱仪(EDX)、场发射扫描电子显微镜(FSEM)、X射线衍射仪(XRD)和毒性浸出方法(TCLP)分析飞灰和熔渣的化学组成、微观结构、晶相组成和重金属毒性浸出特性. 结果表明, 热等离子体熔融所得熔渣为无定形的玻璃体, 重金属浸出质量浓度均远低于毒性标准. SiO2和CaO的添加都可以改善重金属固化效果, CaO比SiO2对Cu、Zn、Cd和Pb挥发的抑制效果更好. SiO2的添加可以改善熔渣中重金属的浸出特性, 而CaO的作用与之相反.

Vitrification of MSWI fly ash using direct current double arc plasma

The effects of additives SiO2 and CaO on heavy metal residual fraction and leaching toxicity were analyzed in order to evaluate the plasma treatment process and treatment effect of municipal solid waste incinerator (MSWI) fly ash vitrification. Fly ash samples with additives SiO2 and CaO were vitrified by thermal argon plasma arc at 1 400~1 500 ℃. The chemical compositions, microstructures, crystalline phases and leaching toxicity of the fly ash and produced slag were determined by energy dispersion X ray spectrometer analyzer (EDX), scanning electron microscopy (FSEM), X-ray diffractometry (XRD), and toxicity characteristic leaching procedure (TCLP), respectively. Results show that the slag is amorphous and plassy after thermal plasma vitrification,  and the mass concentration of heavy metal leaching from slags is much lower than the standards. Both the additions of SiO2 and CaO can keep heavy metals volatilizing from fly ash through vitrification, and CaO is more effective than SiO2 to prevent the volatilization of heavy metal. The additive SiO2 can reduce the leaching toxicity of slags, while CaO has opposite effects.