Aluminium electrolysis problem

The thermo-electric design of an aluminum reduction cell has the most influence on the cell power consumption against aluminum yield, thus affecting the bottom line profitability of smelters operation. It is also one of the key elements affecting the cell lining life, because the thermal balance of the cell is often the limiting factor which prevents smelters to increase production by increasing line amperage. Smelters retrofitting should also tend to minimum cost.

So, improving the cell thermo-electric design has clearly the potential of bringing the fastest return of investment in continuous improvement projects of most smelters.

Conventional Hall-Haroult aluminum electrolysis process is very complex as it involves many interacting physical and chemical phenomena, few of them completely understood. This means on one hand, that improvement of smelters design by trial-and-error method is not a practical solution, and, on the other hand, that developing of reliable models for theoretical analysis is not easy. Figure 1 performs this process schematically; the bubbles mark chemical reaction.

Fig.1 Schematic draft of Hall-Haroult aluminum electrolysis process

Stresses originated from temperature factor should be take into account for predicting lifetime of bottom blocks, anode and bath(cell).

The structure of this section is as follows.

• First, we formulate rigorous statement of the problems the model is based on. Both differential and weak statements are given.
• Second, the FEM approximations are discussed.
• Third part of the study is dedicated to the details of full simulation algorithm.
• And at last, numerical test results for two geometric structures are displayed.