焚烧发电是我国生活垃圾处理的主流技术，相应地，富集重金属和二噁英的危险废物——垃圾焚烧飞灰大量产生。由于成分复杂多变、具有高氯高碱特性，飞灰的安全处置和利用是固体废物领域的难点问题。飞灰高温熔融技术是国内外固废资源化利用技术的重点发展方向之一，但存在能耗高、需水洗脱氯、资源化利用价值低等问题。本研究基于炉排炉飞灰与流化床飞灰的化学组分互补及高活性炭残留特性，提出炉排炉飞灰与流化床飞灰共还原熔融技术，在实现飞灰免水洗无添加低熔点玻璃化的同时，为飞灰的分相清洁资源化利用奠定技术基础。基于两种飞灰组分互补特性，均衡混合飞灰体系Si-Ca-Al三相比例可有效降低共还原体系熔点。炉排炉飞灰为高钙、低硅和低铝体系，流化床飞灰为低钙、高硅和高铝体系。在免水洗、不添加任何助熔剂的情况下，将两者按照适宜配比混合后进行熔融共还原，熔融温度从1600℃以上降低至1300℃以下。优选出共还原熔融最佳工艺条件：炉排炉飞灰与流化床飞灰质量比为3:7，共还原温度为1300℃，保温时间2.5 h，玻璃体含量可达98.8%。确定了生成玻璃体的混合飞灰体系的工艺参数：Ca为23.2-39.7%，Si为4.3-10.4%和Al为1.9-7.3%。通过对飞灰共还原熔融体系主要物质进行热力学反应模拟，揭示金属化合物碳热共还原机理和重金属在玻璃体相、铁合金相、二次飞灰相中的形态转化规律。飞灰熔融经历未熔融、快速熔融、熔融渐增三个阶段，铁氧化物的碳热还原主要路径为Fe2O3-Fe3O4-FeO-Fe。飞灰中的C、Cl、Fe促进了重金属在高温下从玻璃体相向铁合金相和二次飞灰相的迁移。基于上述共还原熔融机理，定向调控不同特性重金属在熔融过程中的迁移转化，实现飞灰的分相清洁资源化利用。还原气氛下亲铁重金属Cu、Cr、Ni与Fe伴生形成铁合金，进一步磁选回收利用。高氯条件下，Zn、Cd、Pb等易挥发性重金属挥发进入二次飞灰，可作为进一步回收金属的原料。玻璃体中重金属含量极低，可以安全利用。对最佳工艺条件下的铁合金产品进行分析，铁合金中Fe的回收率达到83.67%，品位达到92.18%。玻璃体粉末具有胶凝性能，可替代水泥用作飞灰固化稳定化材料，在养护时间仅为6天时，固化体抗压强度及浸出毒性即可满足填埋场入场标准。

Incineration for power generation is the mainstream technology for municipal solid waste treatment in China. Correspondingly, large quantities of hazardous waste—fly ash, enriched with heavy metals and dioxins—are produced. Due to its complex and variable composition, and characteristics of high chlorine and high alkali content, the safe disposal and utilization of fly ash is a challenging issue in the field of solid waste management. High-temperature melting technology for fly ash is one of the key development directions for the resource utilization of solid waste both domestically and internationally. However, it faces issues such as high energy consumption, the need for water washing to remove chlorine, and low resource utilization value. This study proposed a co-reduction melting technology for grate furnace fly ash and fluidized bed fly ash based on their complementary chemical compositions and high residual active carbon content. This technology achieved low-melting-point vitrification without water washing or additives, while also realizing clean and segregated resource utilization of fly ash.Based on the complementary characteristics of the two types of fly ash, a balanced mixture of the fly ash systems in the Si-Ca-Al ternary phase can effectively lower the melting point of the co-reduction system. Grate furnace fly ash was characterized by high calcium, low silicon, and low aluminum content, while fluidized bed fly ash was characterized by low calcium, high silicon, and high aluminum content. Without water washing and any flux addition, a suitable proportion of the two ashes was mixed and subjected to co-reduction melting, reducing the melting temperature from above 1600°C to below 1300°C. The optimal process conditions for co-reduction melting were identified as a grate furnace fly ash and fluidized bed fly ash mass ratio of 3:7, a co-reduction temperature of 1300°C, and a holding time of 2.5 h, and the vitreous content can reach 98.8%. The process parameters for generating a vitreous mixture of fly ash were determined to be: Ca 23.2-39.7%, Si 4.3-10.4%, and Al 1.9-7.3%.Thermodynamic reaction simulations of the main substances in the co-reduction melting system revealed the carbothermal co-reduction mechanism of metal compounds and the transformation patterns of heavy metals in the vitreous phase, ferroalloy phase, and secondary fly ash phase. The melting process of fly ash underwent three stages: unmelted, rapid melting, and gradual melting. The primary pathway for the carbothermal reduction of iron oxides was Fe2O3-Fe3O4-FeO-Fe. Elements such as C, Cl, and Fe in the fly ash promoted the migration of heavy metals from the vitreous phase to the ferroalloy phase and secondary fly ash phase at high temperatures.Based on the aforementioned co-reduction melting mechanism, the directional control of the migration and transformation of different characteristic heavy metals during the melting process was achieved, enabling clean and segregated resource utilization of fly ash. Under reducing conditions, iron-affinitive heavy metals such as Cu, Cr, and Ni associated with Fe to form ferroalloy, which can be further recovered through magnetic separation. Under high chlorine conditions, volatile heavy metals such as Zn, Cd, and Pb vaporized into secondary fly ash, which can be used as raw materials for further metal recovery. The vitreous phase contained very low levels of heavy metals and can be safely utilized.Analysis of the ferroalloy products under optimal process conditions showed an Fe recovery rate of 83.67% and a grade of 92.18%. The vitreous powder exhibited cementitious properties, which can replace cement as a material for the solidification and stabilization of fly ash. After only 6 days of curing, the compressive strength and leaching toxicity of the solidified body met the landfill entry standards.