Lead electro refining using current inversions

In lead electrorefining using current inversions with a period duration of 7-30 secs, a reverse pulse relative duration of 2-8% of the current inversion period and a normal current pulse current density of 100-500 A/sqm. the basic stage of the process is preceded by a preparatory stage, in which the electrodes are fed with active current pulses of different polarity with equal width and intensity, and an initial stage, in which electrorefining is effected with current inversions of reduced current density. the density of the normal current in the initial stage is half that necessary for normal process yield, the density of the reverse current in the initial and basic stages is 0.5-8 times that of the normal current during the same stage, the pulse width during the preparatory stage is 5-15 secs, the preparatory stage direction is 600-900 secs and the initial stage duration is 2-3 hrs. Appts for carrying out the process is also claimed.