Reduction of Cr (VI) in sulfuric acid solutions by iron with the use of steel cuttings

Characteristic features of the chemical process in the system of chromium anhydride - sulfuric acid - steel wool with the aim of hexavalent chromium recycling were studied. The presence of periodical concentration oscillation of Cr(VI) and Cr(III) in the solution during reduction of Cr(VI) by steel cuttings was established. The influence of reaction mixture composition and temperature on the kinetic curves for the reduction of Cr(VI) was shown. The morphology, structure and composition of the resulting precipitates were studied at various initial concentrations of Cr(VI) in the solution. With increasing initial concentration of Cr(VI) the change in the phase composition of precipitates occurs, from simple oxyhydrate forms to formation of iron-chromium-containing hydroxide sulfates. On the basis of elemental composition of precipitates the possibility of their practical application in metallurgical production was estimated.