Stability of the interfacial crud produced during the extraction of vanadium and chromium

The stability of the interfacial crud produced during the extraction and separation of vanadium and chromium was studied in this paper. Thermodynamic stability, particle size distribution, setting time and clarifying curve of the emulsion droplet were investigated. From the results, the percentage of the crud produced decreases with the increasing setting time and after 30 min it shows less change. The coalescence rate is relatively smaller than the rising rate, and the phase separation time is determined by the coalescence behavior of the droplet. The crud is considered to have thermodynamic instability, kinetic stability. The demulsifying mechanism was also put forward. New extraction system using n-hexane instead of kerosene as diluent with larger surface energy can prevent the emulsion formation. (C) 2013 Elsevier B.V. All rights reserved.