Pregnant leach solution

Alkaline conditions must be used to prevent the decomposition of thiosulfate. The resulting pregnant leach solutions also contain the monothiosulfato complex, [Au(S203)] .49... 

The copper electrowinning process requires concentrated solutions to improve mass transport and increase the solution conductivity. The pregnant leach solutions from leaching are too dilute and too impure for the direct production of high-purity cathodes. Electrowinning from these solutions would give impure, dendritic deposits. Solvent extraction provides the means for producing pure,... 

Although the overall processes have evolved for specific metals, and leachants, there are principally only two leaching techniques that provide the pregnant leach solution for metal recovery percolation leaching and agitated tank leaching. 

Pregnant leach solution containing copper, cobalt and nickel, is pumped from the PLS storage tank through heat exchangers to the extraction trains. The PLS minimum temperature is 15 °C and maximum 50 °C when entering into solvent extraction. The extraction train contains DOP unit, spirok unit and mixer-settlers. After the last mixer settler, the aqueous phase is directed to raffinate after settler. From the after settler the solution is pumped to raffinate filter and to cobalt solvent extraction. 

Organic reagent removes impurities/metals from the pregnant leach solution according to reaction 7. RH is aldoxime or ketoxime (or a mixture). 

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