Single-stage synthesis of nickel concentrate in processing of rhenium-containing heat-resistant alloy

Abstract

The paper outlines the results of electrochemical processing of HAS32-VI heat-resistant alloy in nitric acid solutions. The main technological idea is based on running an electrochemical process at a controlled anodic potential value, thus providing for a preferential transition into nickel solution with nickel as basis metal, and synthesis of a cathodic product – metal nickel with purity of at least 95 %. Experiments in electrochemical dissolution of the said alloy were conducted using a nitric acid solution with concentration of 100 g/l at different values of anodic potential. It was determined that at Еa = 1,05 V cathodic product contains, %: Ni – 94,9, Re – 0,2, Co – 4,7, Cr – 0,1. The study determines that introduction of chloride ion (20 g/l) into the nitric acid electrolyte has no significant effect on the process parameters: the amount of nickel in anodic slime is reduced from 2,4 to 1,6 % with no significant increase of nickel content in the cathodic product. An exception is a considerable increase in the transition speed of rhenium into electrolyte: after a 10-hour process, rhenium concentration in a nitric acid electrolyte was 1,26 g/l; in a nitric acid electrolyte with addition of chloride ion – 8,90 g/l. The study demonstrates that the process of electrochemical dissolution of Re-containing heat-resistant nickel-based alloys at a controlled anodic potential Еa = 1,05 V in nitric acid electrolytes provides for a one-stage synthesis of nickel concentrate with a purity of not less than 95 % and allows to concentrate rhenium in anodic slime.