富钾正长岩水热分解生成沸石反应热力学

以安徽某地富钾正长岩粉体为原料，研究其水热碱法分解生成沸石化合物的反应热力学。采用“聚合多面体模型”计算了几种沸石的热力学参数，结合矿物端员组分热力学数据及“混合电解质模型”，构建了富钾正长岩-NaOH-H₂O水热体系平衡热力学模型。反应Gibbs自由能计算结果表明，在160-300 ℃范围内，由富钾正长岩水热分解生成羟钙霞石、方沸石、P型、A型等沸石的反应可自发进行；通过OLI Analyzer 9.3软件对该体系不同条件下的相平衡进行模拟，预测了富钾正长岩水热碱法分解生成羟钙霞石、方沸石的反应条件。通过实验验证，生成的方沸石呈规则的四角三八面体晶型，粒径约50 μm；羟钙霞石呈柱状，长约20 μm，截面尺寸约500 nm-1 μm，K₂O溶出率97%以上。

Thermodynamics of the Hydrothermal Decomposition Reaction of Potassic Syenite with Zeolite Formation

The thermodynamics of hydrothermal decomposition reaction of potassic syenite, collected from Anhui province, China, with the formation of zeolites was studied in this work.The phase equilibrium model of the potassic syenite-NaOH-H₂O hydrothermal system was constructed by the combination of "mixed solvent electrolyte model" and thermodynamic data of mineral end-members, as well as zeolites species, which was calculated from the"polymer model".According to the Gibbs free energy of reaction, the decomposition of potassic syenite into hydroxycancrinite, analcime, zeolite P, and zeolite A occurs spontaneously within the temperature range of 160-300℃.The formation conditions of hydroxycancrinite and analcime were predicted from the simulation of phase equilibrium by OLI Analyzer 9.3 software.After experimental verification, analcime (regular tetragonal trisoctahedron, ~50 μm) and hydroxycancrinite (columnar crystals, ~20 μm in length, 500 nm-1 μm in diameters) were respectively obtained with >97% K₂O leaching.