Method for regulating an electrolysis cell

Regulation method for an electrolytic cell (1) for the production of aluminium by means of electrolytic reduction of alumina dissolved in an electrolyte bath (13) based on cryolite, said cell (1) comprising a pot (20), anodes (7) and. cathode components (5, 6) capable of circulating a so-called electrolytic current in said bath, the aluminium produced by means of said reduction forming a pad referred to as a “liquid metal pad” (12) on said cathode components (5, 6), said method comprising the supply of said cell with alumina in said bath and being characterised in that it comprises:

• the set-up of a regulation sequence comprising a series of time intervals p of a duration Lp referred to as “periods”;
• the determination of a mean temperature T(p) of the electrolyte bath, from at least one measurement of the temperature of said bath made during the last period or at least one of the last Nt periods;
• the determination of a so-called “equivalent” quantity Qc1(p) of AlF3 contained in the alumina added to the cell during the period p;
• the determination of a value Qm(p) of the total equivalent AlF3 supplies per period during the last period or during the last N periods;
• the determination of a quantity Q(p) of aluminium trifluoride (AlF3) to be added during the period p, referred to as “determined quantity Q(p)”, using the formula:
• Q(p)=Qint(p)−Qc1(p)+Qt(p), where
• Qint(p)=α×Qm(p)+(1−α)×Qint(p−1),
• α is a smoothing coefficient,
• Qt(p) is a determined function of the difference between said temperature T(p) and a set-point temperature To,
• the addition in said electrolyte bath, during the period p, of an effective quantity of aluminium fluoride (AlF3) equal to said determined quantity Q(p).