A novel solvent extraction process with bottom gas injection without moving parts

Abstract

A novel solvent extraction process in which the emulsion is generated by bottom gas injection rather than mechanical stirring has been developed. This process has a number of advantages over the mixer–settler unit or the spray column in terms of simple equipment configuration and the ease of cleaning and process control, while providing a sufficiently large interfacial area for mass transfer. The equipment consists of a horizontal cylindrical vessel in which the two immiscible liquids flow countercurrently. High-strength gas jets are injected from the bottom at certain intervals along the length of the vessel. The gas jet creates a plume zone consisting of an emulsion of the two liquids which contains a large interfacial area for rapid mass transfer. The two liquids then disengage and flow in the opposite directions before entering another plume zone. Thus, the process combines the simplicity of a cylindrical vessel, having no moving parts, with the contacting efficiency of a mixer–settler. The gas can be recycled in a closed loop, thus eliminating mist and other emission problems. By using an inert gas, the oxidation degradation of the extractants and/or solutes can be prevented.