Scandium Recovery Methods from Mining, Metallurgical Extractive Industries, and Industrial Wastes

Abstract

The recovery of scandium (Sc) from wastes and various resources using solvent extraction (SX) was discussed in detail. Moreover, the metallurgical extractive procedures for Sc recovery were presented. Acidic and neutral organophosphorus (OPCs) extractants are the most extensively used in industrial activities, considering that they provide the highest extraction efficiency of any of the valuable components. Due to the chemical and physical similarities of the rare earth metals, the separation and purification processes of Sc are difficult tasks. Sc has also been extracted from acidic solutions using carboxylic acids, amines, and acidic β-diketone, among other solvents and chemicals. For improving the extraction efficiencies, the development of mixed extractants or synergistic systems for the SX of Sc has been carried out in recent years. Different operational parameters play an important role in the extraction process, such as the type of the aqueous phase and its acidity, the aqueous (A) to organic (O) and solid (S) to liquid (L) phase ratios, as well as the type of the diluents. Sc recovery is now implemented in industrial production using a combination of hydrometallurgical and pyrometallurgical techniques, such as ore pre-treatment, leaching, SX, precipitation, and calcination. The hydrometallurgical methods (acid leaching and SX) were effective for Sc recovery. Furthermore, the OPCs bis(2-ethylhexyl) phosphoric acid (D2EHPA/P204) and tributyl phosphate (TBP) showed interesting potential taking into consideration some co-extracted metals such as Fe(III) and Ti(IV).

Nanofiltration-Enhanced Solvent Extraction of Scandium from TiO2 Acid Waste

“…Solvent extraction (SX) is the most commonly used technique to separate and concentrate Sc from aqueous solutions. ,− The commonest extractants are organophosphorus compounds, such as di-(2-ethylhexyl)­phosphoric acid (D2EHPA). ,− Nevertheless, extraction of trace Sc from complex aqueous media remains technically challenging, requiring high aqueous to organic phase ratios, with the higher costs and emissions associated with large process volumes. In addition, coextraction of impurities (e.g., Fe, Ti, Zr, Th, U, etc.)…”

A comprehensive review on modelling the adsorption process for heavy metal removal from waste water using artificial neural network technique

“…Researchers have been driven to investigate and create effective and clean water treatment methods by the ongoing flow of new inorganic pollutants into natural aquatic systems [ [1] , [2] , [3] ]. These wastewaters contain a variety of contaminants, each with unique characteristics and concentrations depending on where they came from.…”

One-pot in situ construction of amido and hydroxyl co-modified layered double hydroxides for selective scandium adsorption

“…3d. However, according to the literature, 43,44 –NH 3 + also has extraction ability for Sc 3+ . This may explain why the material can still have good adsorption capacity under acidic conditions.…”