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

Abstract

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 Cr₂O₃ 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 Cr₂O₃ 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 (Fe²⁺)(Fe³⁺_0.085,V³⁺_0.77,Cr³⁺_0.145)₂O₄, (Fe²⁺)(Fe³⁺_0.01,V³⁺_0.625,Cr³⁺_0.365)₂O₄ and (Fe²⁺)(Fe³⁺_0.005,V³⁺_0.475, Cr³⁺_0.52)₂O₄, respectively. On this basis, it was found that Cr³⁺ ion migrated into V-Cr spinel by replacing Fe³⁺ and V³⁺ 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.