The disposal of municipal solid waste incineration fly ash (MSWI FA), as one of hazardous wastes, is restricted by the energy consumption in the melting process. Coal ashes are suitable additives to lower the melting temperature thanks to the enrichment of Si, Al and the low costs. Herein, MSWI FA was added with three representative coal ashes at varying ratios to uncover the co-melting mechanism. The three types of coal ashes contain high Ca (SMca), high Si (CPca) and medium Ca, Si (SEHca), respectively. Ash fusibility temperature (AFT) test, heating and water quenching, X-ray diffraction, scanning electron microscopy and FactSage analysis were conducted. Results show that both CPca and SEHca can decrease the flow temperature of FA. After the blending with 40% CPca or SEHca, the flow temperature of FA dropped from 1460 to 1240 and 1280 °C respectively. However, only CPca-40% led to the formation of uniform vitreous bodies at 1300 °C. SMca did not considerably impact the melting temperature. As the Si/Ca ratio increased from 0.19 to 0.62, main minerals in the mixtures were transformed at 1300 °C as follows: Ca₂SiO₄+Ca₃Al₂O₆+Ca₁₂Al₁₄O₃₃→Ca₁₂Al₁₄O₃₃+ Ca₂SiO₄→Ca₂Al₂SiO₇ (glass phase). FactSage calculation revealed that when nepheline was formed, the coal ash content was just enough for reducing FA melting temperature below 1300 °C. To control the melting temperature below 1300 °C, we suggest the composition in coal ashes to be: 43.75%–87.50% SiO₂, 12.50%–25.00% Al₂O₃, and as little CaO as possible.

作为危险废物之一，城市固体废物焚烧飞灰（MSWI FA）的处置受到熔化过程中能耗的限制。由于硅，铝的富集和低成本，煤灰是降低熔融温度的合适添加剂。在本文中，MSWI FA以不同的比例添加了三种代表性的煤灰，以揭示共熔机理。三种类型的煤灰分别包含高Ca（SMca），高Si（CPca）和中等Ca，Si（SEHca）。进行了灰烬易熔温度（AFT）测试，加热和水淬，X射线衍射，扫描电子显微镜和FactSage分析。结果表明，CPca和SEHca均可降低FA的流动温度。与40％CPca或SEHca混合后，FA的流动温度分别从1460降至1240和1280°C。但是，只有CPca-40％导致在1300°C形成均匀的玻璃体。SMca不会显着影响熔融温度。随着Si / Ca比值从0.19增至0.62，混合物中的主要矿物质在1300°C下的转化如下：Ca₂ SiO ₄ + Ca ₃ Al ₂ O ₆ + Ca ₁₂ Al ₁₄ O ₃₃ →Ca ₁₂ Al ₁₄ O ₃₃ + Ca ₂ SiO ₄ →Ca ₂ Al ₂ SiO ₇（玻璃相）。FactSage计算显示，当形成霞石时，煤灰含​​量足以将FA熔化温度降低至1300°C以下。为了控制低于1300℃的熔化温度，我们建议在煤灰组合物为：43.75％-87.50％的SiO ₂，12.50％-25.00％的Al ₂ ö ₃，并尽可能减少CaO。