Recovery of vanadium and cesium from spent sulfuric acid catalysts by a hydrometallurgical process

Abstract

Vanadium and cesium were recovered from spent sulfuric acid catalysts, generated during a sulfuric acid manufacturing process, by an environmentally friendly hydrometallurgical process. This process consisted of water leaching to recover valuable metals, a solvent extraction process to recover vanadium selectively, and a precipitation process to recover cesium selectively. More than 99% of vanadium was leached from the spent sulfuric acid catalysts using water only at room temperature. The leachate obtained was employed in the solvent extraction process to recover vanadium selectively. The solvent extraction experiments were conducted by varying the concentration of the extractant, the equilibrium pH, the organic/aqueous (O/A) phase ratio, and the saponification ratio using di-2-ethylhexyl phosphoric acid (D2EHPA). As a result, more than 99% of the vanadium was separated from cesium in the leachate in three stages of counter-current extraction at an O/A ratio of 1.5. However, impurities such as iron and titanium were found to be present in the loaded organic phase. Therefore, vanadium was stripped selectively from the latter using an alkaline solution. The concentration of the alkaline solution and the O/A phase ratio affected emulsion formation during the stripping process. Cesium present in the raffinate was precipitated as a cesium alum by adding aluminum sulfate, with a precipitation efficiency of more than 98% and with greater than 99% purity. The process developed in this study provides an efficient method for recovering vanadium and cesium from spent sulfuric acid catalysts using an eco-friendly and economical metallurgical process.