I. V. Tananaev Institute of Chemistry and Technology of Rare Elements and Mineral Raw Materials, Kola Scientific Centre, Russian Academy of Sciences

A. M. Petrova, Junior Researcher
A. G. Kasikov, Head of Hydrometallurgy Department
P. B. Gromov, Deputy Director of Scientific Work, Head of Laboratory
V. T. Kalinnikov, Director of the Institute

The paper deals with the development of rhenium recycling technology from the waste of nickel-based heat-resistant alloys which is an urgent problem because of rising demand for the rare metal from catalysts and superalloys producers. An overview of rhenium recovery methods from heat-resistant alloys scrap is presented. The advantage of the hydrometallurgy methods for metal isolation and purification during processing of multicomponent alloys wastes was shown. The authors propose two new flowsheets of rhenium recycle technology from nickelbased heat-resistant alloys. The first flowsheet involves leaching of the nickel-base of heat-resistant alloys by mineral acid including rhenium pre-concentration in the residue, followed by rhenium high-temperature distillation as Re₂O₇. After dissolution and hydrometallurgical purification of sublimate, a technical-grade ammonium perrhenate was obtained. In the second variant, the waste acidic leaching occurred under oxidizing conditions, with more than 95% of rhenium transferred to solution. Rhenium was selectively recovered by solvent extraction with high-molecular secondary aliphatic alcohol. By washing with water and stripping using ammonia of the extragent, a pure ammonium perrhenate solution was obtained from which a pure technical-grade rhenium salt was precipitated. The proposed flowsheets have been tested on an laboratory pilot scale. The scope of the inventions is processing of nickel-base heat-resistant alloys wastes.

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