Value extraction from semiconductor industry tantalum scrap through understanding the thermodynamics and chemistry

The electrode in the waste capacitor and capacitor producing semiconductor industry produces a significant amount of tantalum-bearing e-wastes. The lack of proficient technology poses a significant challenge for valorization and the circular economy of tantalum-bearing waste. Currently, we are developing a process for the purification and recovery of metal values from such waste through a combination of hydrometallurgy and pyrometallurgy techniques. In our present investigation, the initiative for the study includes an understanding of rudimentary thermochemistry and thermal characterization of semiconductor industry tantalum scrap for possible pretreatment. Also includes identification of suitable pretreatment conditions for feasible oxidation of semiconductor industry tantalum scrap to generate leachable tantalum oxide. Followed by the possibility for leaching has been investigated through the Pourbaix diagram and selected case studies. Our leaching investigation reasonably indicated that tantalum nitride in the semiconductor industry tantalum scrap can efficiently be oxidized using Na2CO3 (1:1 weight ratio) at 500 degrees C and roasting time of 3 h. Then Ta leaching using concentrated HF and H2SO4 at 50:50 wt% ratio as a lixiviant can be achieved efficiently. As the roasting and leaching process is feasible and scalable, Ta can be successfully extracted from the semiconductor industry tantalum scrap on an industrial scale.

Automated summary

The study has successfully developed a method for extracting and recovering metal values from semiconductor industry tantalum scrap through a combination of hydrometallurgy and pyrometallurgy techniques, including understanding of thermochemistry, determination of suitable oxidation conditions, and effective leaching methods.