In the course of the smelting process already produced aluminum is lost. The reasons are discussed. The reaction of aluminum with
the anode gas is the primary reason for current efficiency losses. The mechanism of this reoxidation reaction is described.
Current efficiency is determined industrially by weighing the amount of produced metal. To obtain current efficiency values
for short time periods the aluminum inventory is tracked by following the content of tracer elements in the metal pad or by
analyzing by analyzing the composition of the anode gas.