Method of regulating the aluminium oxide concentration in an aluminium-producing electrolytic cell

摘要

Methods of regulating the Al2O3 concentration in an Al-producing electrolytic cell consists of adding Al2O3 (containing material) through holes in the electrolyte crust. A resistance difference (DR), a parameter (k) where 0k1, a basic dosing interval t0 and an addition time (T11) are predetermined. From the basic dosing interval t0 the overdosing (1-k) t0 and underdosing (1+k) t0 intervals are determined during which equal amounts of raw material are added. During the addition time (T11) overdosing followed by underdosing steps are carried out with the resistance being monitored. The time lapse (T1) from when (T11) starts is noted when the resistance change (DR) is greater than a min. value (R) and at this point a new basic dosing interval (t0') is calculated from t0' = t0x f (x) with x=T11/T1 where f(x) is a function with the value f(0.5)=1. This new value replaces the old value (t0) and the addition time is restarted.