Sorption of Rhenium from Cobalt–Nickel Mother Liquors Formed in Complex Processing of Rhenium-Containing Superalloy Waste

Abstract

The possibility of the rhenium recovery by sorption onto a fluoroplastic-containing composite from the mother (process) liquor after precipitation of the cobalt–nickel concentrate obtained by complex processing of nickel-based rhenium-containing superalloy waste was examined in batch experiments. The isotherms of the rhenium sorption from a model solution and the mother liquor were obtained by the variable-volume method. The Henry constant in rhenium sorption from the mother liquor was 2100 ± 600 mL g^–1. The rhenium sorption kinetics was studied in batch experiments. Mathematical processing of the data of the integral kinetic curves using the kinetic and diffusion models showed that the highest coefficient of determination (R² = 0.999) was observed when using the pseudo-second-order model formally confirming certain contribution of the chemical reaction to the process. The rate constants calculated using the pseudo-second-order model were (1.7–2.8) × 10^–3 g mg^–1 min^–1. Analysis by the external and internal diffusion models showed that the rhenium sorption onto the fluoroplastic-containing carbon composite occurred by the mixed-diffusion mechanism, with the contribution of the internal diffusion increasing with an increase in the concentration of ReO₄^– ions on the composite pore surface. The sorption properties of the carbon composite were stable in three cycles of rhenium sorption–desorption from the mother (process) liquor.