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Overview Copper Electrodeposition
The development of the CollaMat glue measuring system started at Norddeutsche Affinerie (NA) in 1986. Since 1989, CollaMat has been used for continuous glue measuring in NA's copper tankhouse. In addition, the system is used under license worldwide in ten tankhouses. This paper provides an overview of basic CollaMat investigations in the laboratory as well as NA experiences in the production plant.
INTRODUCTION
While the process of electrolytic refining of copper has not changed significantly for more than 100 years, its efficiency has been improved significantly by, inter alia, increasing current density and improving spacetime yield.
The improvement in the geometry of the electrodes resulted from the changeover to stainless-steel cathodes and the use of anode-preparation machines to optimize the hanging behavior of the anodes. This development went hand-in-hand with demands for refined copper with high purity levels. A normal "Grade A" cathode today is, at best, only average. The refining process must produce a cathode that is as smooth as possible, without inclusions of electrolyte and without nodules/dendrites that encourage the adherence of anode slimes. Great importance is attached to the optimal dosing of additives.
While, 20 years ago, operators had to rely more or less on empirical experience, today, various methods are available for measuring the concentrations of glue or thiourea in consistent copper electrolyte.1
With the aid of the CollaMat system, which has been developed at Norddeutsche Affinerie (NA), basic questions can be answered about the impact of different glue qualities as well as their degradation rates in relation to acid concentration and temperature. When these parameters are better understood, glue can be dosed more exactly and evenly, while the outline conditions for copper deposit can be improved.
The results of the tests on the behavior of glue and their consequences for daily production will be discussed in this article.
COLLAMAT PROCESS
Norddeutsche Affinerie's philosophy-and that of most other operators of copper tankhouses-is to check as many parameters as possible during the electrolysis process and, if an optimum is found regarding quality and efficiency, to keep them constant. For additives, which play a central role in the electrolytic copper deposition, this was only possible to a limited extent. While chloride and thiourea are clearly defined chemical substances...