by volume of an organic stage consisting of 20 by volume of di 2 ethylhexyl phosphoric acid and 80 by volume of kerosene one part by volume of an aqueous solution containing 5 6 g ni l 43 g na l 45 g cl l and 31 g so 4 l is added four times in succession at the same time soda lye is added with mixing at room temperature until a constant ph value of 5 5 is obtained each extraction process was finished in approximately five minutes four portions of refined products were obtained with increasing ni concentrations of 0 7 2 8 5 3 and 5 6 respectively the subsequent re extraction with 20 hydrochloric acid resulted in a strip eluate containing 74 g ni l and 25 g na l to 1 part by volume of an organic stage consisting of 14 volume of naphthenic acid neutralization no 220 and 86 by volume of kerosene two parts by volume of an aqueous stage are added containing 6 g ni l 57 g nacl l and 139 g na 2 so 4 l a 32 solution of naoh was added dropwise with mixing at room temperature and in such a manner that the ph value did not exceed 7 5 the naoh was added until this ph value remained constant the course and the speed of the extraction were observed on a ph recording instrument more than 90 minutes had elapsed until the completion of the extraction after separating the aqueous stage whose nickel content was 0 05 g l 1 2 part by volume of the aqueous initial solution was again mixed into the charged organic stage as a result the ph value of the emulsion dropped to 7 0 the strip eluate subsequently obtained by.