Satbayev University, JSC “Institute of metallurgy and ore benefication”, Almaty, Kazakhstan:

L. Y. Agapova, Associated Professor, Chief Scientific Officer, e-mail: rm.303.imo@mail.ru
S. K. Kilibayeva, PhD, Senior Researcher, e-mail: k_salikha@mail.ru
Z. S. Abisheva, Professor, Academician NAS RK
A. S. Sharipova, PhD, Senior Researcher, e-mail: a_sharipova@mail.ru

Corresponding author: Z. S. Abisheva, e-mail: abisheva_z@mail.ru

The complex electrochemical processing in sulfuric acid solutions of technogenic wastes of renium-containing heatresistant nickel alloys (HRNA) in the form of rather large scrap pieces of turbine blades has been studied. It was found that anodic dissolution of large waste pieces of rhenium-containing HRNA can be successfully carried out in sulfuric acid solutions (100 g/dm³) with addition of nitric acid (20 g/dm³) under direct current with a current density of 500–1000 A/m² and a temperature of 30–40 ^oC without preliminary preparation. As much as 80–90% of rhenium, 90–95% of nickel, cobalt, chromium and aluminum pass into solution under these conditions. Almost all refractory rare metals (tungsten, tantalum, hafnium) pass into the anode slime almost completely. Rhenium, nickel and cobalt remaining in the anode slime were converted into solution by chemical slime treatment in a 2 M sulfuric acid solution with the nitric acid additives. Rhenium in the form of crude ammonium perrhenate, where rhenium content is not less than 68.9 wt.%, has been recovered from the combined solution after anodic treatment of alloy wastes and chemical dissolution of anode slimes by a known solvent extraction method. The cake, remaining after chemical treatment of anode slimes, is a concentrate of refractory rare metals containing, wt.%: up to 39–42 W; 15–18 Ta; 3–4 Hf. According to X-ray fluorescence (XRF) analysis, the cake base is tungsten trioxide. Following rhenium extraction, the sulphate raffinate, containing significant amounts of nickel, cobalt, chromium, aluminum and some other metals, has been neutralized with alkali which allowed to precipitate hydroxides of these metals into a nickel-cobalt concentrate which aincludes 37.55% Ni and 4.48% Co. Roasting of nickel-cobalt concentrates obtained from the products of the HRNA waste electrochemical treatment at a temperatures of up to 400 ^oC will allow one to converte all nonferrous metal hydroxides into oxides, reduce the mass of concentrates by 15–20%. The process flowsheet of complex processing of large-scale waste of renium-containing HRNA is proposed. The technology was successfully tested within the pilot project at the enterprise of RSE “Zhezkazganredmet”, which is an internationally known manufacturer of ammonium perrhenate.
The work was carried out with the financial support of the Committee of Science of the Ministry of Education and Science of the Republic of Kazakhstan under the Target financing program (project No. BR05236406).

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