铝杂质强化固相碳热还原氟磷灰石过程分析

Enhanced Effect of Aluminum Impurity on Solid State Carbonthermal Reduction of Fluorapatite

在氮气保护下的管式炉中对比考察了Al2O3的添加对碳热还原氟磷灰石体系的反应的影响,结果发现添加5%Al2O3的反应体系的磷矿转化率及反应速率要高于没有添加的体系。固相产物的XRD分析结果与热力学分析一致。含5%Al2O3的反应体系中出现的Al2Si O5、Al PO4和Ca Al2Si2O8等产物增加了反应体系的液相,促进了碳热还原反应的进行。在Si O2、Al2O3作用下的固相碳热还原氟磷灰石反应本质上是一个气液固反应,符合由反应扩散产物层生长理论推导的动力学模型。添加Al2O3的强化碳热还原反应的作用主要表现在相对低温区和反应初期。

Two reaction systems of carbonthermal reduction of fluorapatite were investigated in the tube furnace with protecting nitrogen,one of which contained 5% Al2O3,and the other didn't contain any Al2O3. The results showed that the conversion fraction and the conversion rate of fluorapatite with 5% Al2O3 are both higher. The analysis of XRD for the compositions of solid state products is consistent with the analysis of thermodynamics. The products of Al2 Si O5,Al PO4 and Ca Al2Si2O8 in 5% Al2O3 reaction system cause the amount of liquid phase the increase of and then enhance the carbonthermal reduction. The solid state carbothermal reduction reaction of fluorapatite in the present of Si O2 and Al2O3belongs to gas-liquid-solid reaction and the reaction process meets the kinetic equation which was derived from the theory of layer growth based on reaction-diffusion. And more,the enhanced effect of adding Al2O3 is more prominent at relative lower temperature or at the initial reaction stage especially.