Rhenium-molybdenum separation in an alkaline leaching solution of a waste superalloy by N263 extraction

The recovery of rhenium from waste superalloys has always been a research focus. This study focuses on the performance of extraction of rhenium and its separation with molybdenum in alkali leaching solution of waste superalloy by methyl trioctylammonium chloride (N263). Minitab 17 Statistical Software (Trial version, Techmax, USA) was used to create a four-factor (N263 concentration, sec-octyl alcohols concentration, extraction time and organic to aqueous ratio (O/A ratio)) two-level orthogonal experiment table. According to the orthogonal experiment results of rhenium extraction and rhenium molybdenum separation coefficient, rhenium extraction model, rhenium molybdenum separation coefficient model and the corresponding regression equation were established. The rhenium extraction performance of N263 was investigated by the rhenium equilibrium curve and NaSCN concentration. It was found that the N263 concentration was the main factor affecting rhenium extraction, and the regression equation of rhenium extraction was Re extraction/% = 0.672 + 9.880 [N263]. Moreover, N263 concentration and O/A ratio are the main factors affecting rhenium molybdenum separation coefficient. The regression equation of rhenium molybdenum separation coefficient is β Re/Mo = 37.5 + 116.88* [N263] −24.3 *(O/A ratio) −20.62 [N263]*(O/A ratio). At the same concentration of the rhenium stripping agent, the rhenium stripping efficiency is perchloric acid > nitric acid > sodium thiocyanate. However, the strong oxidability of perchloric acid and nitric acid destroys the organic phase, making the organic phase produce visible destruction. The rhenium stripping was about 75.8 % with 40 times the theoretical amount of sodium thiocyanate. The results showed that Re was easy to be extracted in the alkali solution, but it was not easy to be stripped from the loaded N263 phase.