Recovery of Tantalum from a Semi-Product of the Comprehensive Processing of Waste from a Rhenium-Containing Nickel-Based Superalloy

To address pressing resource and environmental challenges, this study investigates the tantalum recovery from a Ta-W semi-product generated during the processing of grinding waste from the ZhS32 VI rhenium-nickel superalloy.

The Ta-W semi-product was sintered with NaOH (700–1000 °C) to oxidize TaC into insoluble sodium tantalates (NaTaO₃/Na₅TaO₅), with an optimal ratio (semi-product: NaOH) and temperature determined. The sintered residue underwent acid leaching (HF/H₂SO₄ mixture, room temperature), where leaching parameters (time, phase ratio) were optimized; the kinetics was studied, and K₂TaF₇ was precipitated from the leachate using KCl.

Minimum Ta extraction into solution during sodium hydroxide sinter leaching, along with complete transfer of W and Mo to the aqueous phase, is achieved at 700°C and a 1:3 (g/g) ratio. Subsequent leaching of the solid residue with an HF-H₂SO₄ mixture (1 g: 1 mL: 1 mL) enables complete Ta recovery (>99.99%) within 30 minutes. The kinetics of tantalum acid leaching from the residue indicates a shift in the rate-limiting step from diffusion to chemical reaction. Through precipitation from the sulfate-fluoride solution using a KCl solution, Ta was obtained as K₂TaF₇ (~52.64% Ta).

The presented process allows for the selective separation of tantalum from tungsten and molybdenum. The kinetics show a transition from diffusion to reaction, which enables efficient extraction at room temperature. Controlling impurities in K₂TaF₇ requires further refinement.

An effective two-stage hydrometallurgical process (alkaline sintering + acid leaching) enables high-yield tantalum recovery from superalloy grinding waste while facilitating valuable component recycling from heat-resistant alloy residues.