高硅煤中Si-Al-Fe-Ca四元体系碳热反应研究

研究了不同温度条件下高硅煤中矿物组成比例下的Si-Al-Fe-Ca多元体系的碳热反应以及其影响因素。通过XRD和FESEM-EDS技术对各还原产物进行分析。结果表明,Fe_2O_3对含硅矿物的碳热反应起促进作用,Fe可以有效提高Si反应活性。CaO在较低温度时与灰中的Al_2O_3和SiO_2反应形成致密的Ca-Al-Si相共熔体CaAl_2Si_2O_8,阻碍含硅矿物碳热反应的进行。随着温度的升高,继续反应生成SiC、CaAl_4O_7和CaSiO_3。热力学模拟计算与实验结果基本吻合。

Carbothermal reduction of Si-Al-Fe-Ca quaternary system in a high-silica coal

During coal pyrolysis and gasification, the minerals in coal undergo various transformations, which affects coal conversion and characteristics of coal ash obviously. Carbothermal reduction of Si-Al-Fe-Ca quaternary system in high-silica coal under different temperature was investigated. Composition of products obtained was analyzed by X-ray diffraction (XRD) and field emission scanning electron microscope-energy dispersive spectrometer (FESEM-EDS) technology. The results show that Fe₂O₃ plays a positive role in carbothermal reaction of silicon-bearing minerals, which could effectively improve activity of Si. On the contrary, CaO reacts with Al₂O₃ and SiO₂ to form dense Ca-Al-Si eutectic, mainly CaAl₂Si₂O₈, at lower temperature, covering surface of the reactant, which hinders the carbothermal reaction of silicon-containing minerals. With increasing temperature, CaAl₂Si₂O₈ reacts with graphite to generate SiC, CaAl₄O₇ and CaSiO₃. The related thermodynamic calculations are in accordance with the experiment results.