Hydrometallurgical Process for Tantalum Recovery from Epoxy-Coated Solid Electrolyte Tantalum Capacitors

Abstract

Tantalum is a critical metal that is widely used in electronic products. The demand for tantalum is increasing, but the supply is limited. As tantalum waste products have increased in Taiwan in recent years, the treatment of spent tantalum capacitors has become necessary and important. The recycling of tantalum from tantalum capacitors will not only decrease pollution from waste, but will also conserve tantalum resources. The tantalum content in epoxy-coated solid electrolyte tantalum capacitors (EcSETCs) is over 40 wt.%. Here, we designed a recycling process that includes pre-treatment, leaching, and solvent extraction to recover tantalum. In the pre-treatment process, epoxy resin and wires were removed. During hydrometallurgical process, pressure leaching by hydrofluoric acid was used to leach tantalum and manganese from solid electrolyte tantalum capacitors (SETCs). During our testing of this proposed process, the acid concentration, reaction time, temperature, and solid–liquid ratio were examined for leaching. After the leaching process, Alamine 336 was used to extract tantalum from the leaching solution. The pH value, extractant concentration, extraction time, and aqueous–organic ratio were investigated. Then, tantalum was stripped using HNO3, and the HNO3 concentration, stripping time, and organic–aqueous ratio were analyzed in detail. Under optimal conditions, the recovery efficiency of tantalum reached over 98%, and a final product of tantalum pentoxide with 99.9% purity was obtained after chemical precipitation and calcination.

Recycling Strategies for Ceramic All-Solid-State Batteries—Part I: Study on Possible Treatments in Contrast to Li-Ion Battery Recycling

“…Chen et al report a low Ta leaching efficiencies in HCl, H2SO4 and HNO3 [74]. When applying hydrogen fluoride (HF) based pressure leaching, at 23 bar, 180 °C for 3 h, a leaching efficiency of 99% could be obtained [74]. Regarding Ta-recovery from the solution by solvent extraction, an extraction efficiency of 99.5% could be reached at pH = 1 (see Figure 10).…”

“…Deblonde et al report on a combination process consisting of alkaline leaching and pH-value However, a literature research gives more information on the dissolution and precipitation of Ta-compounds dependent on the pH-value. Chen et al report a low Ta leaching efficiencies in HCl, H2SO4 and HNO3 [74]. When applying hydrogen fluoride (HF) based pressure leaching, at 23 bar, 180 °C for 3 h, a leaching efficiency of 99% could be obtained [74].…”

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]. Hence, in 2005, Mineta and Okabe published a complete process (Figure 6), including hydrometallurgy and a magnesiothermic reduction step of the intrinsic capacitor TaOx dielectric, which enabled the recovery of 99 w% pure Ta with an overall 90-92% recovery efficiency [145].…”

Optimization of Selective Hydrometallurgical Tantalum Recovery from E-Waste Using Zeolites

“…However, research has already been conducted on the recycling and recovery of tantalum capacitors. Various methods have been explored to remove components from PCBs, including chemical dissolution, manual and automated mechanical picking, and laser integration into automated processes to melt component solders. − For the removal of the resin part of capacitors extracted from PCBs and the exposure of tantalum cores, mechanical treatment, pyrolysis, − and supercritical water treatment have been applied. In tantalum refining, various organic solvents such as MIBK (methyl isobutyl ketone) and TBP (tributyl phosphate) have been used, but the use of TSILs (task-specific ionic liquids) has been proposed as an environmentally friendly alternative. − Current studies involving tantalum recovery from e-waste using ion exchange resins or similar materials such as zeolites seem very scarce or close to nonexistent based on literature search.…”