Fig. 3: Leaching efficiency improvement of precious metals by the flash Joule heating (FJH) process.
a Schematic of the pressurized setup for FJH. b Gas flow simulation under different pressures. The inner pressure (P0) during the FJH was calculated to be ~5 atm. Pout of 0 atm, 1 atm, and 4 atm correspond to the FJH under vacuum, atmospheric pressure, and 3 atm of positive pressure. c Concentration of precious metals and improvement of recovery yield by FJH. Y0 and Y mean the recovery yield by leaching printed circuit board (PCB) and PCB-Flash, respectively. The dashed line denotes Y/Y0 = 1. The error bars denote the standard deviation where n = 3. d Concentration of precious metals and improvement of recovery yield by FJH and calcination. Y0 and Y mean the recovery yield by leaching PCB and PCB-Flash-Calcination, respectively. The dashed line denotes Y/Y0 = 1. The error bars denote the standard deviation where n = 3. e Improvement of recovery yield varied with FJH voltages under atmospheric pressure. The highlighted region is the approximate optimal voltage for all metal recovery. f Improvement of recovery yield varied with pressure. For e and f, the recovery yields of Rh, Pd, and Ag are calculated from PCB-Flash, and the recovery yield of Au is calculated from PCB-Flash-Calcination.
