potline

A potline is a series of electrolytic cells, known as pots, used in the Hall-Héroult process for the primary production of aluminum. These cells are arranged in a long row, hence the term "potline." Each pot is a large steel shell lined with refractory material and carbon blocks, which serve as the cathode. Inside the pot, a molten electrolyte consisting primarily of cryolite and aluminum fluoride is maintained at a temperature around 950-980 degrees Celsius. Carbon anodes, typically made of petroleum coke and coal tar pitch, are suspended in the electrolyte.

During the electrolysis, a direct electric current is passed through the electrolyte. Aluminum oxide, dissolved in the molten cryolite, is decomposed. Aluminum ions are reduced at the cathode, forming molten aluminum metal, which collects at the bottom of the pot. Oxygen ions react with the carbon anodes, forming carbon dioxide and carbon monoxide, which are released as gases. The molten aluminum is periodically tapped from the pots and cast into ingots or other forms.

Potlines are the core of an aluminum smelter, and their operation requires significant electrical energy. The efficiency and design of the potline are crucial factors in the economic viability of aluminum production. Modern potlines are highly automated and incorporate advanced control systems to optimize performance and minimize environmental impact. The length of a potline can vary significantly, from a few dozen pots to several hundred, depending on the capacity of the smelter.