燃煤固体产物中含钙矿物的迁移与多相反应

TRANSPORTATION AND HETEROGENEOUS REACTIONS OF CALCIUM CONTAINING MINERALS IN COAL COMBUSTION SOLID RESIDUES

燃煤灰渣中含钙矿物的组成和多相反应与灰渣活性密切相关。该文对SBF试验台上煤粉与添加剂混烧后的灰样进行XRD分析,并采用F*A*C*T软件包对煤和添加剂组成的多组分系统进行热力学计算,探讨了不同条件下灰渣中含钙矿物的组成特性。结果表明,燃煤灰渣中含钙矿物主要参与固相反应和固硫反应,固相反应生成的含钙矿物主要包括CaO-SiO2、CaO-Al2O3、CaO-Fe2O3以及CaO-SiO2-Al2O3类矿物。随着CaO含量的增加,灰渣中生成的最主要矿物从莫来石→钙长石→钙黄长石→硅酸二钙过渡。在CaSO4稳定存在的温度范围内,固硫反应比固相反应更易进行;随着温度的升高,CaSO4发生分解或者进一步反应生成硫铝酸钙或硫硅酸钙从而使得钙向硅酸盐矿物迁移。

Activity of coal combustion solid residues is relevant closely to calcic minerals composition and reactions. In this paper, the solid residues were analyzed by X-ray powder diffraction when firing coal and additives in a single burner furnace, moreover, the computer package F*A*C*T was used to predict the products composition of the multi-component system containing coal and additives. The mineral composition of solid residues under different conditions has been well investigated. The results indicate that there are two types of reactions with respect to calcic minerals: desulfurization and solid state reaction. The calcic minerals generating from solid state reactions include CaO-SiO2, CaO-Al2O3, CaO-Fe2O3 and CaO-SiO2-Al2O3 group minerals. When increasing CaO content in ash, the primary mineral in the products varied following the route of mullite→anorthite→gehlenite→dicalcium silicate. Desulfurization is prior to solid state reaction when CaSO4 is stable. Due to the decomposition or further reactions of CaSO4 at high temperature, most calcium enters in silicate minerals and complicated S-containing minerals such as calcium aluminosulfate and calcium silicosulfate can be obtained.