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Phase Equilibrium of the V2O5–Na2O System
Metallurgical and Materials Transactions B ( IF 3 ) Pub Date : 2022-05-27 , DOI: 10.1007/s11663-022-02560-z
Xuewei Lv , Guishang Pei , Dapeng Zhong , Lilian Yang , Junyi Xiang , Qingyun Huang

Knowledge of the equilibrium phase relationship in the V2O5–Na2O system is critical and essential for the sodium salts roasting process of slag-bearing vanadium, and those fundamental studies can be used to accelerate industrial optimization and update the process. Therefore, phase equilibrium and quenching and thermal analysis experiments on the V2O5–Na2O binary system were carried out in the present work under pO2 of 10−3.5 atm. The V2O5–Na2O system has 7 primary phase fields including two simple oxides (V2O5 and Na2O), and 5 binary compounds (Na2V12O31, Na10V24O65, NaVO3, Na4V2O7, and Na3VO4). The existence of Na2V12O31 and Na10V24O65 was experimentally confirmed and then characterized by EPMA, no extensive compounds or solid solutions were detected in the present study. The liquidus lines were experimentally determined in most of the primary phase fields in the temperature range from 500 °C to 800 °C. The temperatures and components of some invariant reactions, including Liq → V2O5 + Na2V12O31 (640 °C, 53 mol pct Na2O), Liq → Na10V24O65 + NaVO3 (504 °C, 40.2 mol pct Na2O), Liq → NaVO3 + Na4V2O7 (540 °C, 59.0 mol pct Na2O), and a new peritectic reaction at 570 °C with 32 mol pct Na2O were rechecked, and Liq + Na2V12O31 → Na10V24O65 was also reconstructed. The large amount of new phase equilibrium data proposed in this work will serve as reliable input for future thermodynamic reassessments of the V2O5–Na2O system within the CALPHAD framework to extensively improve the current V2O5-based thermodynamic databases.

Graphical Abstract



中文翻译:

V2O5-Na2O 体系的相平衡

了解 V 2 O 5 -Na 2 O 体系中的平衡相关系对于含渣钒的钠盐焙烧工艺至关重要,这些基础研究可用于加速工业优化和工艺更新。因此,本工作在10 -3.5 atm的pO 2下进行了V 2 O 5 -Na 2 O二元体系的相平衡和淬火及热分析实验。V 2 O 5 –Na 2 O 系统有 7 个初级相场,包括两种简单的氧化物(V 2 O 5和Na 2 O),以及5种二元化合物(Na 2 V 12 O 31、Na 10 V 24 O 65、NaVO 3、Na 4 V 2 O 7和Na 3 VO 4 )。Na 2 V 12 O 31和 Na 10 V 24 O 65的存在经实验证实,然后通过 EPMA 表征,在本研究中未检测到广泛的化合物或固溶体。在 500 °C 至 800 °C 的温度范围内的大多数初级相场中,通过实验确定了液相线。一些不变反应的温度和组分,包括 Liq → V 2 O 5 + Na 2 V 12 O 31 (640 °C, 53 mol pct Na 2 O), Liq → Na 10 V 24 O 65 + NaVO 3 (504 ° C, 40.2 mol pct Na 2 O), Liq → NaVO 3 + Na 4 V 2 O 7(540 °C,59.0 mol pct Na 2 O)和在 570 °C 下与 32 mol pct Na 2 O 的新包晶反应进行了重新检查,Liq + Na 2 V 12 O 31 → Na 10 V 24 O 65重建。这项工作中提出的大量新相平衡数据将为未来在 CALPHAD 框架内重新评估 V 2 O 5 -Na 2 O 系统提供可靠的输入,以广泛改进当前基于 V 2 O 5的热力学数据库。

图形概要

更新日期:2022-05-27
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