Bernd Böttcher, Dr. Franz Martin Knoop
The use of lead anodes has a long history in the metal winning industry. In the past, most smelters
produced the lead anodes on their own in a simple casting process. The quality of these anodes basically
satisfied the requirements of the electrolysis process, especially with the exclusive use of concentrates.
Driven by the need to reduce costs, improving quality and using a wider range of raw materials,
more and more smelters have gone through internal make or buy decisions with the result to
focus on their core business and to buy from specialized anode producers. These manufacturers have
emerged from the lead processing industry and are well established in the market today. Initially these
anode producers have been seen only as an extended workbench of the smelters, but with growing
experiences and ongoing partnership and cooperation, smelters and operators of electrolytic plants
are taking advantage of possible cost reductions and quality improvements.
In a first step, a development from the cast anode towards a two-component anode with a rolled anode
sheet took place. Manufacturing of the anode heads is still focused on a moulding process; however, other
methods at appropriate process conditions are available. Tinning of the Cu bars as a further measure to
improve the bonding has been established and provides a decisive contribution to the performance of the
anode. Rolling of the anode sheets instead of casting already brought a significant performance increase;
further improvements can be achieved by using different rolling processes and selected temperature
ranges which are optimized and tailor-made to the process conditions of each individual electrolysis. This
is also possible for the alloys used in anode design. Anode alloys can be fundamentally selected and
optimized to guarantee the best economic and metallurgical performance combined with excellent mechanical
and chemical properties, which are adjusted to the load conditions in different areas of the anode.
This presentation describes new production routes, alternative rolling and treatment conditions and
microstructures as well as state of the art technologies for anode production (e.g., automatic tinning,
lead welding by robots) and completely new design ideas for advanced anodes. By leaving the historic
production routes and treading completely new paths today, existing electrolytic plants and operators
can take advantage of the described developments which will further enhance their performance and
cost situation and finally improve their competitiveness in the global markets significantly.