In general, cross-flow and counter-current leaching methods are achieved in percolation-slot leaching, while cocurrent-flow is always used in continuous-stirring leaching. And solid-liquid separation in each grade of leaching equipment must be achieved. Percolation-slot leaching can get clear lixivium directly while stirring leaching need solid-liquid separation to get clear lixivium.
For higher leaching rate and lower solvent cost, 2-stage leaching process is always choosed:
1. Leach hard-leaching and easy-leaching materials respectively, which is to say, leach hard-leaching materials in first stage and reuse solvent to leach easy-leaching materials in the second stage.
2. Leach easy-leaching ingredients in the first stage in low-acid condition; lixivium from solid-liquid separation is sent to further processing while solid leaching material is resent to the second leaching stage to leach hard-leaching materials in high-acid condition.
