Abstract:

In this study, the Wucaiwan high-alkali coal (WCW) from Zhundong was used as the raw material. SiO₂, Al₂O₃, Fe₂O₃, Na₂CO₃ and CaCO₃/CaSO₄ were used to prepare the synthetic ash. The samples were burned in the furnace. The ashes after burning were screened and analyzed by XRD and FTIR to explore the influence of calcium species on the sintering characteristics of high-alkali coal ash. The results show that the initial sintering temperature of the synthetic ash prepared by CaCO₃ (RR-1-Cal) is lower than that of prepared by CaSO₄ (RR-1-An), but the sintering tendency of RR-1-An is stronger than that of RR-1-Cal. The influence of CaCO₃ in ash on liquid phase sintering is because Na-Si-Al reacts to form albite, and after CaO reacts with Si/Al to form calcium-containing aluminosilicate, albite and calcium-containing aluminosilicate undergo low-temperature eutectic. Without the low-temperature eutectic between calcium aluminosilicates and albite, CaSO₄ contained in the ash add the sulfate radicals into the reaction, which make the silicon-aluminum structure more unstable at high temperatures and leads to the melting and sintering phenomenon easier to occur. During the solid-phase sintering process, CaCO₃ first destroys and then polymerizes the silicon structure of coal ash, while CaSO₄ promotes the polymerization of coal ash at lower temperatures.

Key words: coal combustion, sintering, reaction, polymerization

摘要：

以准东五彩湾高碱煤（WCW）为实验对象及模型进行合成灰配比，选用SiO₂、Al₂O₃、Fe₂O₃、Na₂CO₃和CaCO₃/CaSO₄为原料进行合成灰制备。对样品进行燃烧实验，对所得灰样进行筛分、XRD和FTIR检测，以探究不同钙对高碱煤灰烧结特性的影响。结果表明，使用CaCO₃制备的合成灰（RR-1-Cal）初始烧结温度低于使用CaSO₄制备的合成灰（RR-1-An），RR-1-An烧结倾向强于RR-1-Cal。灰中CaCO₃对液相烧结的影响路径是因为Na-Si-Al之间反应生成钠长石，CaO与Si/Al反应生成含钙硅铝酸盐后，钠长石与含钙硅铝酸盐发生低温共熔。除此之外，硫酸根的加入会使得硅铝结构在高温下更不稳定，更易出现熔融烧结现象。在固相烧结过程中，CaCO₃对煤灰硅结构先破坏后聚合，CaSO₄则促进煤灰在更低温度下发生聚合。

关键词: 煤燃烧, 烧结, 反应, 聚合