To Polarize or Not to Polarize: Practical
Advice on How to Control Zinc
Electrodeposition
Michael Moats and Timothy Hymer
Abstract The interaction of impurities and additives on zinc electrodeposition in
electrowinning cellhouses are well documented, but generally not well understood.
Operators attempt to maximize current efficiency by promoting zinc deposition, while
simultaneously inhibiting hydrogen evolution. However, the impacts of impurities
and additives are often difficult to understand and predict. Thus, plant personnel are
left to ponder whether to polarize (add more gelatin) or not to polarize (add less
gelatin). This joint paper by an industrial practitioner and academic scholar attempts
to describe the interactions between impurities and additives in simple terms and to
offer practical advice on how to control cellhouse operations.
Keywords Zinc · Electrowinning · Polarization · Impurities · Microstructure ·
Current efficiency
Introduction
This paper is dedicated to the lasting memory of Professor Thomas J. O’Keefe. The
authors were privileged to learn from Tom in class and one-on-one as our graduate
advisor. In the spring of 1991, Prof. O’Keefe told our metal deposition class that
if we understood polarization and how it could be applied to the electrodeposition
of metals that we would be far ahead of many people. As students will do, we did
not really believe our professor. After all, the concepts of electrochemical reaction
polarization were not that difficult to grasp in a classroom setting.
Many years later, we have come to understand the truth that many operators do not
really understand polarization. We have also learned that we were a bit naïve to think
polarization was easily understood. This is especially true for zinc electrodeposition
and the competing hydrogen evolution reaction that occurs in zinc electrowinning.
M. Moats (B)
Materials Research Center, Missouri University of Science and Technology, Rolla, MO, USA
e-mail: moatsm@mst.edu
T. Hymer
The Doe Run Company, Viburnum, MO, USA
© The Minerals, Metals & Materials Society 2020
A. Siegmund et al. (eds.), PbZn 2020: 9th International Symposium
on Lead and Zinc Processing, The Minerals, Metals & Materials Series,
https://doi.org/10.1007/978-3-030-37070-1_10
111
Advice on How to Control Zinc
Electrodeposition
Michael Moats and Timothy Hymer
Abstract The interaction of impurities and additives on zinc electrodeposition in
electrowinning cellhouses are well documented, but generally not well understood.
Operators attempt to maximize current efficiency by promoting zinc deposition, while
simultaneously inhibiting hydrogen evolution. However, the impacts of impurities
and additives are often difficult to understand and predict. Thus, plant personnel are
left to ponder whether to polarize (add more gelatin) or not to polarize (add less
gelatin). This joint paper by an industrial practitioner and academic scholar attempts
to describe the interactions between impurities and additives in simple terms and to
offer practical advice on how to control cellhouse operations.
Keywords Zinc · Electrowinning · Polarization · Impurities · Microstructure ·
Current efficiency
Introduction
This paper is dedicated to the lasting memory of Professor Thomas J. O’Keefe. The
authors were privileged to learn from Tom in class and one-on-one as our graduate
advisor. In the spring of 1991, Prof. O’Keefe told our metal deposition class that
if we understood polarization and how it could be applied to the electrodeposition
of metals that we would be far ahead of many people. As students will do, we did
not really believe our professor. After all, the concepts of electrochemical reaction
polarization were not that difficult to grasp in a classroom setting.
Many years later, we have come to understand the truth that many operators do not
really understand polarization. We have also learned that we were a bit naïve to think
polarization was easily understood. This is especially true for zinc electrodeposition
and the competing hydrogen evolution reaction that occurs in zinc electrowinning.
M. Moats (B)
Materials Research Center, Missouri University of Science and Technology, Rolla, MO, USA
e-mail: moatsm@mst.edu
T. Hymer
The Doe Run Company, Viburnum, MO, USA
© The Minerals, Metals & Materials Society 2020
A. Siegmund et al. (eds.), PbZn 2020: 9th International Symposium
on Lead and Zinc Processing, The Minerals, Metals & Materials Series,
https://doi.org/10.1007/978-3-030-37070-1_10
111