Oxidative leaching of V-Cr–bearing reducing slag via a Cr(III) induced Fenton-like reaction in concentrated alkaline solutions

Abstract

V-Cr–bearing reducing slag (VCRS) is considered a hazardous waste that can create ecosystem disasters if handled improperly. It consists of a considerable amount of heavy metals, such as vanadium (V) and chromium (Cr). In this study, we propose a novel process featuring a VCRS self-induced Cr(III)-Fenton-like reaction to efficiently recover V and Cr from hazardous VCRS. The generation of hydroxyl radicals (·OH) and determination of their effect on V and Cr oxidation were examined via electron spin resonance detection, free radical quenching, and terephthalic acid fluorescence probe methods. The V and Cr oxidative leaching processes were directly controlled by the amount of added H2O2 and generated·OH from the Cr(III)-Fenton-like reaction, which in turn was dependent on the amount of dissolved Cr(OH)4-. In a single oxidative leaching process, the leaching efficiencies of V and Cr reached 97.5 ± 0.6 % and 85.2 ± 0.8 %, respectively, and reached 99.4 ± 0.5 % and 94.6 ± 0.9 %, respectively, from circular leaching owing to a continuous supply of dissolved Cr(OH)4- from fresh VCRS. This study identifies a novel approach to discovering deep oxidation of the VCRS while minimizing environmental contamination via a waste control strategy and can be considered an attractive alternative approach for the green treatment of VCRS.