Söderberg electrode
The Söderberg electrode is a self-burning, electrical permanent electrode. It was invented by Carl Wilhelm Söderberg at Elektrokemisk A / S (today Elkem ) Oslo and is used for the electrochemical melting of aluminum , silicon and calcium carbide .
history
In 1920 the first Söderberg electrodes were introduced in Germany at the Knapsack Chemical Park .
Basic structure and function
The Söderberg electrode essentially consists of several ring-shaped sheet metal jackets welded to one another, which are filled with an electrode compound.
The cylindrical sheet metal jacket serves on the one hand as a shaping, mechanically solid casing for the loose electrode mass and as a conductor.
The 1–2 mm thick sheet metal jacket is provided with barbs or ribs on the inside to absorb the weight of the unbaked electrode material. During operation, the electrode burns continuously due to the oxygen compounds that have been released from the ores, which is why the electrode tip in the furnace is tracked via an adjustment device. To compensate for the electrode, which is getting shorter and shorter due to burn-off, a new sheet metal jacket is regularly welded to the upper end of the electrode during operation.
The filled and then compacted anode mass consists of anthracite powder , petroleum coke and hard coal pitch . The heat of the melt bakes this mass into electrically conductive graphite . Since the unbaked raw material is practically non-conductive, the sheet metal jacket is also used to supply electricity.
Application in aluminum production
Since the 1970s, Söderberg cells in aluminum production using the Hall-Héroult process have increasingly been replaced by cells with pre-baked electrodes, as these are more powerful. The reasonably priced Söderberg technology still plays an important role in the region today, with over 80% of Russian aluminum production using Söderberg electrodes.
Individual evidence
- ^ A b Walter Freilang: Söderberg electrodes . In: R. Durrer and G. Volkert (eds.): The metallurgy of ferroalloys . Springer-Verlag, 1953, ISBN 978-3-662-00209-4 , p. 177-190 .
- ↑ chemiepark-knapsack.de: History 1920–1929
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↑ Details on the binding agent:
LF King, WD Robertson: Coal tar and petroleum pitches as binders for Soderberg electrodes . In: ACS Fuels . tape 18 , no. 4 , 1973, p. 145-154 ( PDF ). - ↑ Franz Pawlek: metallurgy . Walter de Gruyter, 1982, ISBN 978-3-11-090318-8 , p. 363.
- ^ Analyzing of Soderberg Cell Technology Performances and Possibilities
- ↑ RUSAL: Aluminum Technology & Production in Russia
- ↑ aluminum-production.com prebake and Soderberg