A considerable quantity of metal-containing waste oxide is generated by the primary metal industry, and under increased environmental regulation, treatment of these wastes has become viable. Hydrometallurgical processing is often appropriate and one potential treatment process for zinc oxide wastes involves leaching the oxide with an acid, purifying by a solvent extraction operation, and recovering metallic zinc by electrowinning the purified leach solution. The purification stage is frequently critical and the introduction of a solvent extraction organic reagent into the flowsheet can be detrimental to downstream processes. The object of this study was to determine the effect of organics, entrained during solution purification, on the zinc electrowinning efficiency. Zinc solvent extraction / electrowinning studies were made using di-2-ethylhexyl phosphoric acid (D2EHPA), diluted with kerosene, as the organic extractant. The stripping of the zinc from the organic phase was achieved using spent electrolyte solution. Multiple stages of zinc solvent extraction tests were performed to produce a strong acid electrolyte suitable for electrowinning tests. The entrainment of the organic extractant, from the solvent extraction stage, in the loaded spent electrolyte was found to significantly affect the current efficiency, and to change the zinc deposit morphology and orientation with concurrent modifications to the polarization behavior of the system being noted. Purification of the contaminated electrolyte with activated carbon improved the current efficiency and deposit morphology and decreased the polarization to acceptable levels. The conclusions are that the detrimental effects of entrained organic can be eliminated, and that solvent extraction processing is a viable method for the treatment of zinc containing waste oxides. © 1992.


Materials Science and Engineering


U.S. Environmental Protection Agency, Grant R-815709

Keywords and Phrases

electrowinning; organic entrainment; Solvent extraction; waste zinc oxides

International Standard Serial Number (ISSN)


Document Type

Article - Journal

Document Version


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© 2023 Elsevier, All rights reserved.

Publication Date

01 Jan 1992

Included in

Metallurgy Commons