Utilizing Recyclable Task-Specific Ionic Liquid for Selective Leaching and Refining of Scandium from Bauxite Residue

Area of Science:

• Extractive metallurgy
• Materials science
• Chemical engineering

Background:

• Ionic liquids (ILs) offer low-temperature leaching with selectivity and recyclability.
• Aqueous-IL systems face challenges with IL dissolution, leading to losses and increased costs.
• Scandium (Sc) recovery from bauxite residue (BR) is crucial for various industrial applications.

Purpose of the Study:

• To optimize the stripping process for enhanced scandium recovery from ionic liquid leachates.
• To minimize co-extraction of impurities and ionic liquid losses during metal stripping.
• To develop a selective, cost-effective method for scandium extraction from bauxite residue.

Main Methods:

• Leaching of bauxite residue using betainium bistriflimide ([Hbet][Tf2N])-water mixture.
• Preparation of ionic liquid leachate (IL-PLS).
• Optimization of hydrochloric acid stripping experiments to enhance Sc concentration and minimize IL losses.

Main Results:

• A two-step stripping process selectively increased Sc concentration by 8 times.
• Metal cation extraction was found to be dependent on acidic solution stoichiometry.
• Adjusting volume ratio and acid concentration minimized ionic liquid dissolution in the aqueous phase.

Conclusions:

• The developed two-step stripping method significantly enhances scandium concentration.
• The process effectively minimizes ionic liquid losses, improving economic viability.
• This advancement offers a selective and efficient route for scandium recovery from bauxite residue.