Tantalum Recycling by Solvent Extraction: Chloride Is Better than Fluoride

Abstract

The recycling of tantalum (Ta) is becoming increasingly important due to the criticality of its supply from a conflict mineral. It is used extensively in modern electronics, such as in capacitors, and so electronic waste is a potentially valuable secondary source of this metal. However, the recycling of Ta is difficult, not least because of the challenges of its leaching and subsequent separation from other metals. In this work, we show that Ta(V) halides, such as TaCl5 and TaF5, which can potentially be accessed from Ta metal upon acid halide leaching, can be recovered by solvent extraction using a simple primary amide reagent. The need for high halide concentrations in the aqueous phase implies the formation of the hexahalide salts [TaX6]− (X = F, Cl) and that an anion-swing mechanism operates. While extraction of the fluorides is poor (up to 45%), excellent extraction under chloride conditions is found (>99%) and presents an alternative route to Ta recycling.

Recovery of niobium and tantalum by solvent extraction from Sn–Ta–Nb mining tailings

“…9,10 For example, Ta could be recovered by using a simple primary amide reagent. 11 Niobium and tantalum are two transition metals almost always paired together in nature, with similar physical and chemical properties. Niobium has a high melting point, relatively low density, and important magnetic and superconducting properties.…”

Simple Amides and Amines for the Synergistic Recovery of Rhodium from Hydrochloric Acid by Solvent Extraction

“…This latter aspect is likely due to the difficulty in forming the chloridometalates of these metals, which requires high HCl concentrations at which competition for extraction of chloride arises. Other metals such as gold [14] and tantalum [15] are also extracted from HCl solutions by amide L 1 alone. Thus overall, the combination of L 1 and L A is not particularly selective for rhodium.…”

Dismantling of Printed Circuit Boards Enabling Electronic Components Sorting and Their Subsequent Treatment Open Improved Elemental Sustainability Opportunities

“…To reach higher grades, one needs to include either: (i) a fairly classical halogenation purification step [139,140], with some possible innovation to avoid the toxicity of halide gases [141], for example by using CCl 4 [139], or FeCl 2 as a chlorination agent [142,143]; or (ii) additional hydrometallurgy and reduction steps. For the latter case, most published works proposed alternative approaches that avoid the use of hydrofluoric acid for the Ta lixiviation step [144].…”