复合助熔剂对垃圾焚烧飞灰熔融温度与物相的影响

Effect of Composite Fluxing Agent on Melting Temperature and Phase of Fly Ash from Waste Incineration

高温熔融玻璃化是危险废物垃圾焚烧飞灰最安全的无害化处置技术。以高钙飞灰为研究对象,引入SiO_(2)、H_(3)BO_(3)和CaF_(2)助熔剂进行飞灰低温熔融处置,采用X射线衍射仪、灰熔点测定仪及电感耦合等离子体原子发射光谱仪表征飞灰熔融温度、物相变化及重金属浸出。结果表明,利用SiO_(2)(27.9%,质量分数)将飞灰碱度调整至1.10时,形成低熔点的CaSiO_(3)矿物,飞灰熔点由1400℃以上降至1300℃。引入H_(3)BO_(3)(4.5%,质量分数)、CaF_(2)(7.0%,质量分数)作为助熔剂时,可进一步将熔融温度降至1200℃,但导致SiO_(2)超掺;经优化,复合助熔剂配方为SiO_(2)(20.0%,质量分数)、H_(3)BO_(3)(4.5%,质量分数)与CaF_(2)(7.0%,质量分数)时,飞灰最低熔融温度为1124℃,熔融产物玻璃体含量达到87%(质量分数),酸浸出有害物质低于限值,满足GB/T 41015—2021标准对玻璃化处理产物的技术要求。

High temperature melting vitrification is the safest and harmless disposal technology for fly ash from hazardous waste incineration.Fly ash with high calcium content was used as the research object to melt fly ash with low temperature by introducing SiO_(2),H_(3)BO_(3)and CaF_(2)fluxing agents.The melting temperature,phase change and heavy metal leaching of fly ash were characterized by X-ray diffractometer,ash melting point analyzer and inductively coupled plasma atomic emission spectrometer.The results show that when the alkalinity of fly ash is adjusted to 1.10 by SiO_(2)(27.9%,mass fraction),CaSiO_(3)minerals with low melting point are formed,and the melting point of fly ash decreases from above 1400℃to 1300℃.H_(3)BO_(3)(4.5%,mass fraction)and CaF_(2)(7.0%,mass fraction)are introduced as fluxing agents,and the melting temperature is further reduced to 1200℃,but SiO_(2)is overdoped.After optimization,the composite fluxing agent formula is SiO_(2)(20.0%,mass fraction),H_(3)BO_(3)(4.5%,mass fraction)and CaF(2)(7.0%,mass fraction),and the minimum melting temperature of fly ash is 1124℃,the vitreous content of the melt product reaches 87%(mass fraction),and the harmful substances of acid leaching are lower than the limit value,meeting the technical requirements of GB/T 41015—2021 standard for vitrification products.