PURPOSE: To improve the Ni extraction efficiency from an aq. ammoniacal soln. by recovering the nickel values from the stripping aq. ammonical soln. contg. the Ni values with an oxime extractant in a specified manner.

CONSTITUTION: An aq. ammoniacal soln. contg. Ni values is brought into contact with an org. solvent soln. contg. a water-insoluble oxime extractant dissolved in a water-immiscible org. solvent and an equilibrium modifier to obtain an Ni-rich org. layer and an Ni-free aq. layer. The aq. layer is separated from the org. layer. A stripping aq. soln. is separated from the org. layer. The objective Ni values are recovered from the stripping aq. solution. The oxime extractant is an hydroxyaryl ketone oxime shown by the formula (R and R' are each a 1-25C saturated aliphatic group, etc., (n) is 0 or 1 to 4, and (a) and (b) are each 0 or 1 to 4). The equilibrium modifier is a 6-20C aliphatic alcohol, a 6-20C alkylphenol, etc.