Masters Theses

Author

Wenyuan Cui

Keywords and Phrases

Chloride; Copper; Electrowinning; Organic additives

Abstract

"This thesis is to understand and compare the effects and interactions of modified polysaccharide (HydroStar), polyacrylamide (Cyquest N-900) and chloride ion on copper electrowinning. A study of the nucleation and growth was conducted in a synthetic electrolyte (40 g/L Cu, 160 g/L H₂SO₄, 20 mg/L Cl-) with the addition of HydroStar or Cyquest N-900 using potential step measurements. The current responses generated were compared to theoretical models of nucleation and growth mechanisms. The nucleation and growth mechanism changed as function of potential and the presence of organic additives. The nucleation and growth mechanisms were confirmed using scanning electron microscopy (SEM). At low overpotentials, electrodeposition from the electrolyte without additives proceeded by progressive nucleation with three-dimensional (3-D) growth. The addition of HydroStar produced smaller nuclei and changed the mechanism to progressive nucleation and 2-D growth. Cyquest N-900 used there appeared to be progressive nucleation with 2-D growth and polarize the cathodes. In addition, instantaneous nucleation under diffusion control occurred at high overpotentials.

Chloride ion and its interaction with HydroStar and Cyquest N-900 were further characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The trends observed from Nyquist plots and equivalent circuit models were consistent with the CV results. Chloride, on its own, depolarized copper electrodeposition, while chloride ion associated with Cyquest N-900 inhibited the reaction. It is proposed that Cl- acted as a bridging ligand between copper and Cyquest N-900. The addition of HydroStar depolarized copper deposition, but it did not interact with"--Abstract, page iv.

Advisor(s)

Moats, Michael S.

Committee Member(s)

Fahrenholtz, William
OKeefe, Matt

Department(s)

Materials Science and Engineering

Degree Name

M.S. in Materials Science and Engineering

Publisher

Missouri University of Science and Technology

Publication Date

Summer 2014

Journal article titles appearing in thesis/dissertation

  • Effect of commercial electrowinning additives on the nucleation and growth of copper on stainless steel
  • Chloride ion and its interaction with commercial additives in copper electrowinning

Pagination

x, 71 pages

Note about bibliography

Includes bibliographic references.

Rights

© 2014 Wenyuan Cui, All rights reserved.

Document Type

Thesis - Open Access

File Type

text

Language

English

Library of Congress Subject Headings

Copper -- Electrometallurgy
Copper -- Additives
Polysaccharides
Polyacrylamide

Thesis Number

T 10507

Electronic OCLC #

894578504

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