鸟粪石添加剂对准东煤燃烧过程中钠、钙矿物转化和释放的影响

Understanding effect of struvite additive on mineral transformations and release of Na and Ca during Zhundong coal combustion

准东煤作为优质动力煤,高含量的Na和Ca导致沾污结渣成为制约其大范围工业应用的因素。选取准东五彩湾煤作为研究对象,使用富磷鸟粪石作为添加剂,分别对500℃下处理后的原煤灰和混合煤灰(掺入质量分数为5%的鸟粪石)进行同步热分析;在管式炉中以空气气氛对原煤和混合煤在不同温度下进行燃烧实验;通过X射线荧光光谱分析仪(XRF)、X射线衍射分析仪(XRD)、电感耦合等离子体发射光谱仪(ICP-OES)对收集灰分进行分析;并通过热力学软件FactSage对实验结果加以验证。结果表明:鸟粪石添加剂对Na和Ca的释放规律影响较大,大量的Na和Ca在燃烧过程中以磷酸复盐的形式聚集在混合煤灰中,Ca的低温共熔物未能生成;在1000℃之前鸟粪石添加剂对Na和Ca的捕集效果较好,温度上升后有所下降。

Zhundong coal is a kind of high-quality power coals.However,the high content of Na and Ca in Zhundong coal causes contamination and slag which restrict the large-scale industrial application.In this paper,Zhundong Wucaiwan coal was selected,and the phosphorus-rich mineral struvite was used as an additive.The simultaneous thermal analysis(STA)was performed on raw coal ash and coal ash(doped with 5% struvite)treated at 500℃.Combustion experiments of raw coal and treated coal were performed at different temperatures in a tube furnace under air atmosphere.The ash samples were analyzed by XRF,XRD,and ICP-OES.Supporting evidence for the chemical transformations occurring was obtained from FactSage.The results showed that struvite additives had an obvious effect on the release of Na and Ca.A large amount of Na and Ca were accumulated in the form of phosphate complex salt in the treated coal ash during combustion.The struvite additive had a better trapping effect on Na and Ca before 1000℃,but the capture effect weakened after the temperature continues to rise.