Supercritical fluid extraction of cobalt

Cosolvated supercritical fluid carbon dioxide has been investigated for its potential for the kinetically controlled extraction of coordinated cobalt ions with 2-ethyl hexyl 2-ethyl hexyl phosphonic acid as the complexing agent. Hexamine has been used as the coordinating agent and heptane as the cosolvent. A mixture of cobaltous chloride and he)(amine with a small quantity of water was made to react dynamically with the complexing agent in heptane in the medium of supercritical fluid carbon dioxide (SCF CO2). Extraction efficiencies have been found as a function of time and the optimum pressure-temperature regime established. The study has implications for the end purification of cobalt from nickel and may serve as a role model for the refining and purification of one rare earth element from its other rare earth impurities.