Full definition
Hydrometallurgical process that dissolves valuable metals from crushed or run-of-mine ore stacked on lined pads. Acid sulfuric solution irrigates copper ore (SX-EW route); cyanide solution is used for gold/silver (Merrill-Crowe or carbon-adsorption). Typical conditions: pH 0.5–2 (Cu), pH 10–11 (Au). Lower capital cost than agitated tank leaching; recoveries: 60–80% Cu, 70–90% Au. Pregnant Leach Solution (PLS) feeds electrowinning.