水热分解锆英石的物理化学研究  

STUDY ON PHYSICAL CHEMISTRY OF HYDROTHERMAL DECOMPOSITION OF ZIRCON

作　　者：殷澍[1] 毛铭华[1] 

机构地区：[1]中国科学院化工冶金研究所,北京100080

出　　处：《化工冶金》1992年第3期238-243,共6页

基　　金：国家自然科学基金

摘　　要：本文对水热法分解锆英石制备超细ZrO_2粉末过程进行了物理化学方面的研究,重点考察了锆英石的水热分解过程,选择了一个最佳的水热分解体系,讨论了温度、搅拌速度、碱浓度、反应物粒度以及液固比对水热分解速率的影响,对其分解机理和动力学进行了讨论,初步探讨了超细ZrO_2粉末的制备过程,提出了一个由锆英石制备超细ZrO_2粉末的建议流程.The physico-chemical aspects of hydrothermal decomposition of zircon have been studied. It is found that NaOH is the efficient reagent for decomposition of zircon. Under the optimum conditions, above 99% of zircon can be decomposed. The effects of various reaction conditions such as temperature, concentration of alkali, solid/liquid ratio, particle size, stirring rate on the decomposition rate are investigated in detail, and rational operation conditions for decomposition have also been given in this paper. The results show that the hydrothermal decomposition reaction ZrSiO_4+2NaOH=Na_2ZrSiO_5+H_2O is a diffusion-controlled, non-catalytical, solid/liquid reaction. The apparent activation energy is found to be 37.65 kcal/mol. The rate equation may be written as 1-2/3·α-(1-α)^(2/3)=3.975×10~7·A^(2.164)·C^(1.425)·e^(-18950/T)·t. The reaction mechanism consisting of the following sequence of steps has beeen proposed: (1) Diffusion of NaOH in the solution, (2) Diffusion of NaOH through the solid product layer Na_2ZrSiO_5, (3) Chemical reaction on the surface of zircon, Step (2) is the rate-controlling step. Based on the experimental data a flow diagram of preparation of ultrafine ZrO_2 powders from zircon by hydrothermal reaction method has been suggested. Ultrafine ZrO_2 powders with d～0.01μm can be obtained.

关 键 词：锆英石 水热分解 物理化学 

分 类 号：TF841.401[冶金工程—有色金属冶金]