In-Situ Separation and Structure Characterization of V-Cr Spinel in High-Chromium Vanadium Slag

The crystal structure of minerals plays a pivotal role in their applications. The V-Cr spinel is the main crystalline phase of high-chromium vanadium slag, and its crystal structure is crucial for the extraction of V and Cr resources. In this study, the phase equilibrium experiments were first conducted on vanadium slag with Cr 2 O 3 contents ranging from 0 to 15 wt.% at 1400°C. The results demonstrated that almost all V and Cr elements crystallized as V-Cr spinel, and the increase in Cr 2 O 3 content promoted the crystallization of V-Cr spinel. Subsequently, three types of V-Cr spinel crystals were obtained via in-situ super-gravity separation at 1400°C, and the corresponding crystal structures were determined based on structural characterization as (Fe 2+ )(Fe 3+ 0.085 ,V 3+ 0.77 ,Cr 3+ 0.145 ) 2 O 4 , (Fe 2+ )(Fe 3+ 0.01 ,V 3+ 0.625 ,Cr 3+ 0.365 ) 2 O 4 and (Fe 2+ )(Fe 3+ 0.005 ,V 3+ 0.475 , Cr 3+ 0.52 ) 2 O 4 , respectively. On this basis, it was found that Cr 3+ ion migrated into V-Cr spinel by replacing Fe 3+ and V 3+ ions, thereby enhancing the stability of the V-Cr spinel and serving as the fundamental reason for the promotion of its crystallization. This study provides additional crystal parameters for V-Cr spinel, which facilitates an understanding of the physicochemical properties of V-Cr spinel and is of great significance for the efficient extraction of V and Cr resources from high-chromium vanadium slag.