Processes for recovering metals from aqueous solutions

A solvent extraction process for recovering a metal present at low concentration from an acidic aqueous solution, the process comprising:

• a) contacting in a mixer the acidic aqueous solution with an organic phase solution comprising a phosphinic acid compound represented by:
• wherein each of R1 and R2 is independently chosen from an optionally substituted radical selected from the group consisting of C1-C30 alkyl, C3-C30 cycloalkyl, C3-C30 alkoxyalkyl, C4-C30 alkylcyclo, C7-C30 alkylaryl, C7-C30 aralkyl, and C8-C30 cycloalkylaryl, thereby extracting at least part of the metal from the acidic aqueous phase;
• increasing or maintaining the concentration of metal in the organic phase solution by recycling from 50-100% by volume of the organic phase solution containing the metal and contacting the organic phase with an acidic aqueous solution containing the metal until the concentration ranges from 0.3 g/L to 25 g/L;
• b) contacting the organic phase solution containing metal with an aqueous phase strip solution comprising an inorganic compound that back-extracts the metal, thereby stripping at least part of the metal from the organic phase solution to the aqueous phase strip solution;
• and
• c) separating the metal from the aqueous phase strip solution, thereby recovering the metal,
• with the proviso that the metal present at low concentration is not molybdenum.