Recovery and Separation of Vanadium and Chromium by Two-Step Alkaline Leaching Enhanced with an Electric Field and H₂O₂

Abstract

This paper focused on the treatment of vanadium−chromium reducing residue with a two-step alkaline leaching process: electro-oxidation leaching of vanadium and H 2 O 2 as well as oxidation leaching of chromium in an alkaline medium. The effects of experimental parameters on the leaching performance of vanadium and chromium were investigated. The experimental data showed that in the first alkaline leaching in stage I, the leaching efficiency of vanadium reached up to 95.32% under optimal conditions, while most of the chromium could not leach out (about 4% of chromium was leached out). Chromium was easily oxidized to high valence (CrO 4 2− ) with H 2 O 2 in the second alkaline leaching stage II. Under optimal conditions, 96.24% chromium was leached out.

Reduction behavior of chromium(VI) with oxalic acid in aqueous solution

“…3 c that the reduction efficiency of Cr(VI) could up to 100% at all reaction temperatures with enough reaction time, and it was easily achieved at a higher reaction temperature in low reaction time, which was partially consistent with a recent study. Higher temperature could increase the activity of atoms and molecules, enforced the reaction intensity, and promoted the reduction process of Cr(VI) 12 , 13 , 33 . Meanwhile, high reaction temperature could destroy the stable complex compound and release oxalate, which facilitated the reduction of Cr(VI), thus, the reduction efficiency of Cr(VI) was increased with the increase of reaction temperature.…”

Leaching Kinetics of Vanadium from Calcium-Roasting High-Chromium Vanadium Slag Enhanced by Electric Field

“…Increasing the reaction temperature could increase the activity of atoms and molecules, enforce the reaction intensity, and promote the reactions and thus was beneficial for leaching out vanadium. 40 Higher reaction temperature did not lead to a high leaching efficiency of vanadium. Therefore, the reaction temperature of 90 °C was chosen as the optimal condition for further experiments.…”

“…During the electro-oxidation leaching process, two kinds of “reactive oxygen” (hydroxyl radical chemisorbed oxygen atom) adhered on the anode surface (seen in eqs 1 , 2 and Figure 4 ) within the electric field. 32 , 36 , 38 − 40 The vanadium in low valence could be oxidized resulting in a high leaching efficiency ( eqs 3 and 4 ). Nearly 92.14% vanadium could leach out at a current density of 750 A/m 2 , which was much lower than 1000 A/m 2 for vanadium leaching with sodium-roasting alkaline leaching process.…”

Process Optimization and Experimental Study on the Alkaline Production Process of Potassium Isopropoxide

“…The production process of alkali metal alkoxides includes metal process, alkaline production process, electrolysis process and so on [6]. Alkali process has the advantages of safe and simple operation and low production cost, so the alkali process has been used in an industrial process [7][8][9][10]. The production process of potassium isopropoxide has not been reported in literature.…”