Transport of Au(CN)2 − by Mixtures of Amine Primene JMT and Phosphine Oxide Cyanex 923 Using the Pseudo-Emulsion Based Hollow-Fiber Strip Dispersion Technology

Abstract

The transport of Au(CN)2 − between alkaline aqueous solutions and organic phases consisting of a mixture of the amine Primene JMT and the phosphine oxide Cyanex 923 in xylene was studied using the pseudo-emulsion based hollow-fiber strip dispersion (PEHFSD) technology. The feed phase was passed through the lumen side, and the pseudo-emulsions of the extractant mixtures and NaOH were passed through the shell side in a countercurrent mode using a single hollow-fiber contactor for extraction and stripping. In this membrane technology, the strippant (NaOH solution) is dispersed in the organic (Primene JMT + Cyanex 923 in xylene) membrane solution in a tank with an impeller stirrer adequate to form strip dispersion. The pseudo-emulsion phase is circulated from the reservoir tank to the membrane contactor to provide a constant supply of the organic solution to the membrane fibers. Furthermore, this technology allows a direct contact between the organic and strip solutions, providing a greater area for stripping and facilitating the metal recovery from the strip solution once both phases are separated. Various hydrodynamic and chemical parameters, such as flow of feed phase, extractant mixtures and gold concentrations, organic diluents, variation in feed pH, and the selectivity of the system with respect to the transport of different metal-cyano complexes, were investigated. Aqueous and membrane mass transfer coefficients were estimated for the present system.