垃圾焚烧飞灰的酸处理及其固化效果研究

Study on Acid Treatment of Waste Incineration Ash and Its Solidification Effect

以苏州城市垃圾焚烧灰为主要研究对象,采用磷酸、醋酸分别对其进行先陈化后酸浸的预处理,并控制酸处理飞灰的碱度p H值不低于8.0。采用水泥对其进行固化,按规范测定体系的凝结时间、无侧限抗压强度及膨胀性,结果表明:与原样飞灰水泥固化体系相比,酸处理飞灰水泥固化体系的凝结时间缩短,无侧限抗压强度接近1 MPa,对P2酸处理飞灰固化的水泥掺量达到22%后,体系无侧限抗压强度达到稳定土填埋标准(1.5 MPa);经过酸处理的飞灰胶砂体系的膨胀率明显小于原样飞灰胶砂体系。在10%水泥对酸处理飞灰固化的体系中,随着粉煤灰对酸处理飞灰替代量达到30%时,固化体系的无侧限抗压强度达到稳定土填埋标准。固化体系中Cu、Mn、Pb、Cd、Cr、Zn等重金属浸出质量浓度均远低于危险标准值。

Suzhou municipal solid waste incineration（MSWI） ash is mainly studied. MSWI ash was pretreated by phosphate or acetic acid through firstly aging and then acid leaching. Alkalinity p H value of acid treated MSWI may be controlled at over 8.0. Then acid pretreated MSWI ash was solidified by cement. According to specification setting time, unconfined compressive strength and expansion of each system were measured. The results showed that： compared with solidification system with raw MSWI ash and cement, in acid pretreated MSWI ash solidification system setting time may be shortened and unconfined compressive strength may be close to 1 MPa. After P2 acid pretreated MSWI ash was replaced by 22% cement, unconfined compressive strength of solidification system can meet stabilized soil landfill standard（1.5 MPa）. The expansion of acid-treated MSWI ash mortar system was significantly less than that of raw ash mortar system. In solidification system with acid-treated MSWI ash and 10% cement, when the replacement percentage of fly ash for acid-treated MSWI ash was 30%, unconfined compressive strength of system may reach stabilized soil landfill standard. Leaching concentration of heavy metals such as Cu, Mn, Pb, Cd, Cr, Zn can be far less than national standard of the risk of toxic concentrations.