Recovery of Noble Metals (Au, Pt, Ir, and Ta) from Spent Single-Use Medical-Technological Products

Due to their unique properties, i.e., fluoroscopy response and inertness, noble metals and alloys are present in several widespread medical-technological products, such as catheters, guide-wires, and stents. Despite their value, these products serve as single-use consumables, following a fate of solid waste disposal and loss of their valuable metals. This work studies the development of a treatment methodology to recover noble metals such as Pt, Ir, Au, and Ta from certain commercial products commonly used for medical practices. In particular, a sequence of preliminary pyrolysis, aiming at polymer elimination, as well as an acid digestion step for selective metals dissolution, is suggested. Pyrolysis was capable of enriching samples with the targeted metals, though a small change in their oxidation states was observed. Still, acid digestion was fully able to successfully separate Au using a 50% v/v aqua regia solution for 30 min at room temperature and the Pt/Ir using concentrated aqua regia for 72 h under heating. Dissolution of Ta required a different leaching solution, i.e., a 50% v/v HF/H2SO4 mixture for 10 h under heating. According to the developed method, selective extraction of such noble metals in a concentrated slurry provides a high potential for the complete recovery and valorization of otherwise disposed medical wastes.