School of Chemistry and Chemical Engineering of North University of China
Institute of Resources and Environmental Engineering of Shanxi University, State Environmental Protection Key Laboratory on Efficient Resource-utilization Techniques of Coal Waste
School of Materials Science and Engineering of North University of China

利用粉煤灰制备高强度无机纤维是实现其高值化利用的重要路径，由于粉煤灰硅铝含量较高，可通过添加钙铁助剂降低均质化过程中原料熔融温度，避免降温拉丝过程中结晶行为。本工作研究了空气气氛下不同含量及比例钙铁助剂对煤灰熔融性及结晶行为的影响机理。结果表明，空气气氛下氧化钙（CaO）与氧化铁（Fe2O3）不存在协同助熔效果，CaO的助熔效果优于Fe2O3。高温下Fe2O3未与硅铝组分生成低熔点矿物，而添加CaO有利于将难熔的莫来石转化为钙长石，使得粉煤灰熔点大幅度降低；然而，当CaO添加量超过30%时，生成了大量的钙黄长石，使得粉煤灰熔点迅速升高。降温过程中，铁元素以赤铁矿形式析出，析晶温度相对较低；而钙元素以钙长石形式析出，析晶温度相对较高，不利于无机纤维制备过程中纺丝操作。当CaO含量为32.46%时，粉煤灰熔点最低，且降温过程中无晶体析出，因此，在粉煤灰基无机纤维制备过程中应选择钙基助剂调控熔融性和结晶行为。

The preparation of high-strength inorganic fibers by coal fly ash is an important method to achieve its high-value utilization. Due to high content of SiO2 and Al2O3 in coal fly ash, it is necessary that Ca-Fe flux should be added to decrease melting temperature of coal fly ash during homogenization of slag and avoid crystallization behavior during preparation of fibers. In this paper, the influence mechanism of Ca-Fe flux on the fusibility and crystallization behavior of coal fly ash under air atmosphere was investigated. The results show that calcium oxide (CaO) and iron oxide (Fe2O3) does not show synergistic fluxing effect on fusibility of coal fly ash under air atmosphere, moreover, the fluxing effect of CaO on fusibility is more obvious than that of Fe2O3. At high temperature, Fe2O3 cannot react with silicon-aluminum components to form low melting point minerals, while CaO is beneficial to transform refractory mullite into anorthite, which greatly reduces the melting point of fly ash. However, excess CaO (>30%) leads to formation of calcium feldspar, which increases melting point of fly ash obviously. During the cooling process, iron precipitates in the form of hematite while calcium precipitates in the form of anorthite, and the crystallization temperature of hematite is lower than that of anorthite. When content of CaO is 32.46%, the melting point of coal fly ash is the lowest, and there is no crystallization during the cooling process. Therefore, CaO is suitable to adjust fusibility and crystallization behavior of coal fly ash during preparation of inorganic fiber.

山西省基础研究计划青年项目（ 202203021212135），国家自然科学基金（ 22078181），山西省重点研发计划（ 202102090301004，202102090301024，202102090301025），山西省研究生创新项目（2022Y131）资助

王冀, 郭航昊, 路广军, 渠永平, 马志斌. 钙铁助剂对粉煤灰熔融性和结晶行为的影响机理[J]. 燃料化学学报（中英文）, 2024, 52(1): 1-8.

WANG Ji, GUO Hanghao, LU Guangjun, QU Yongping, MA Zhibin. Influence mechanism of Ca-Fe flux on fusibility and crystallization behavior of coal fly ash[J]. Journal of Fuel Chemistry and Technology, 2024, 52(1): 1-8.