The disclosure provides to a PDC element protective system including a mask configured to protect a non-leached portion of a leached polycrystalline diamond compact (PDC) element during a leaching process. The mask may be formed from or coated with polytetrafluoroethylene (PTFE). The disclosure also provides a leaching system containing such a mask and a leaching vessel as well as methods of using the protective and leaching systems. The disclosure further provides a Lewis acid-based leaching agent and methods of its use. Finally, the disclosure provides a method of recycling a PDC or carbide element using a Lewis acid-based leaching agent.