What is a soderberg electrode?

A soderberg electrode is a type of electrode used in the production of aluminum. It is named after its inventor, Norwegian engineer and metallurgist Harald Soderberg.

In the aluminum production process, alumina is dissolved in a molten cryolite bath in a large carbon-lined vessel called a cell. Electric current is then passed through the bath, causing the alumina to break down into aluminum and oxygen. The electric current is provided by a series of electrodes, which are essentially large carbon rods that are inserted into the bath from above.

However, the electrodes are consumed over time due to the extreme heat and chemical reactions within the bath. To maintain a constant supply of electricity, the electrodes must be continuously replaced. This is where soderberg electrodes come in.

Unlike traditional pre-baked electrodes, which are made offsite and then installed into the cell, soderberg electrodes are made in situ. Carbon paste is packed into a steel casing that is lowered into the cell from above. As the paste is heated by the bath, it gradually solidifies into an electrode.

The advantage of soderberg electrodes is that they can be continuously replenished as they are consumed, without the need to shut down the cell and replace the electrodes. This results in a more efficient and cost-effective production process.

However, soderberg electrodes also have some disadvantages. Because they are made in situ, the quality of the electrode can be difficult to control. In addition, the process of making the electrode can release large amounts of greenhouse gases, which contribute to climate change.

Despite these drawbacks, soderberg electrodes are still widely used in the aluminum industry today. They remain an important innovation that has helped make aluminum production more efficient and cost-effective.