Recovery of Lead and Zinc from a Citric Leach Solution of a Non-sulfide Type Ore Flotation Tailing via Precipitation Followed by Solvent Extraction

The recovery of zinc (Zn) and lead (Pb) from a citric leach solution of a non sulfide type ore flotation tailing was examined utilizing sulfuric acid precipitation followed by solvent extraction using di(2-ethylhexyl) phosphoric acid (D2EHPA) as the extractant. Following lead precipitation (98.9%) with sulfuric acid, the pregnant leach solution was sent to solvent extraction stage with D2EHPA for the separation of zinc from the other impurities such as Ca, Mg and Fe. The best solvent extraction conditions were determined to be a concentration of 20% D2EHPA, temperature of 25 degrees C, contact time of 10 min and phase ratio of unity. Under the optimum conditions, 98.3% Zn was extracted into the organic phase in a single contact at a pH of 3.6, along with a significant amount of Ca (79%) and minor amounts of Mg (14.7%) and Fe (8.6%). At pH 4.5, the loaded organic solution was carried to the scrubbing stage, where 20 g/L zinc solution was used to remove approximately 91% Ca and 34% Mg from the organic solution. At a pH of 0.25, the loaded organic solution was almost completely stripped of zinc and 27% of calcium in two steps.