Recovery of rhenium from a molybdenite roaster fume as high purity ammonium perrhenate

• Rhenium was selectively recovered from a fume produced by a Mo sulphide roaster.
• Scrubbing produced a strip liquor containing 260–280 mg/L Re and 80–90 mg/L Mo.
• The concentrated liquor produced from solvent extraction contains 29.9 g/L Re and 5.63 g/L Mo.
• Selective precipitation recovered > 85% available Re as 99.8% pure ammonium perrhenate.

Rhenium (Re) was recovered as high purity ammonium perrhenate (APR) from a scrub liquor produced by a pilot plant treating 2000 m3/h of a fume discharged from a molybdenite roaster. The hydrometallurgical process adopted incorporates first a neutralisation stage using lime to remove most of Mo, all Cu, As and other minor contaminants to produce a liquor containing 260–280 mg/L Re and 80–90 mg/L Mo. Solvent extraction was subsequently used to first load the Re and Mo into a 10 v/v.% tertiary amine (Alamine 304–1), 10 v/v.% Isodecanol in 80% Anysol-150. The organic phase which contained typically 6.2 g/L Re and 1.29 g/L Mo was stripped with 30% ammonium hydroxide to yield a liquor containing 29.9 g/L Re and 5.63 g/L Mo. High purity APR (> 99.8% purity) was recovered from this liquor by adding sulphuric acid to pH 6.8. The whole process would provide an efficient method to recover at least 85% of Re produced from the roaster, with some loss probably incurred due to the re-condensation and/or re-crystallisation of gaseous Re oxide in the cool part of the fume extraction circuit.

Process for recovering rhenium from molybdenite roaster fumes.Figure optionsDownload as PowerPoint slide