Patent ID: 8961773
Filing Date: 2015-02-24
Classification: C25C

Abstract:
1. Method of producing aluminium in an electrolysis cell, said cell comprising a pot, a plurality of anodes and at least one alumina feeder device capable of delivering amounts of alumina powder in said cell, said cell containing an electrolytic bath comprising alumina dissolved therein, said anodes and electrolytic bath being covered with a protecting layer made from a powdery material containing alumina, said method including: circulating an electrical current having intensity I through said cell, so as to reduce said alumina and thereby produce liquid aluminium, performing tending operations on said cell, selecting an electrical parameter EP for said cell that is sensitive to the alumina concentration in said electrolytic bath, setting up a succession of control periods of duration T, measuring said electrical parameter EP during each control period, determining a rate of variation P(k) of said electrical parameter EP during at least one previous control period k, selecting at least a slow feed rate B determining a regulation feed rate B(k′) for a subsequent control period k′ by setting said regulation feed rate B(k′) equal to said fast feed rate B adding alumina at a specified feed rate SR(k′) during said subsequent control period k′, wherein said method further includes: identifying perturbative tending operations on said cell that can introduce superfluous alumina in said electrolytic bath, noting the control periods k setting said specified feed rate SR(k′) equal to M(k′)×B(k′), where M(k′) is a predetermined modulation factor that modulates said regulation feed rate B(k′) so as to take into account a reduction of the needs of said cell induced by said superfluous alumina.