Abstract
With the purpose of extracting rhenium from molybdenum concentrate, electrolysis of slurry, prepared by mixing molybdenum sulfide concentrate and 10 mass% NaCl aqueous solution, was carried out at 1 A, 313 K. The slurry was continuously circulated into a vertical type 10 stack bipolar electrolytic cell consisted of carbon electrode disks, and the concentrate was dissolved by electrochemically generated oxidizers. The current efficiency for molybdenum dissolution was 73 % after 10 hours electrolysis, and the leach solution was found to contain 0.2 mol / l of molybdenum and 4×10-5 mol / l rhenium. This result shows the dissolution speed is more than 8 times faster than that obtained using a single cell at applied current of 1 A. Prior to rhenium separation from the leach solution, preliminary experiments for rhenium extraction by MEK (Methyl-ethyl-keton) were carried out using synthesized test solutions having similar composition. The behavior of molybdenum, rhenium, and sulfur was investigated for examining the extraction conditions and efficiency. The leach solution obtained by electro-oxidation was then subjected to a solvent extraction experiment, and rhenium present at several tens of mass ppm in the concentrate was enriched to more than 1,000 times, and recovered as sulfides. After rhenium separation, molybdenum was recovered by precipitation after changing pH of the solution.
