
186 Control for Aluminum Production
Variability patterns within an alumina feeding cycle can be used for
detection and diagnosis of faults in the aluminum smelting process and
prediction of future consequences.
3
As seen in the industrial example, nine overfeed–underfeed cycles
over a period of 11 hours were observed from a cell in an aluminum
smelter, where each observation had an average duration of ve minutes.
The ninth cycle relates to an anode effect. A change in rate of increase
in cell resistance was observed in the ninth cycle. This change has
triggered earlier overfeeding (shorter underfeeding) than previously,
and it is also possible ...