The process and the apparatus described hereinbefore are applied to {HEAD ~ the series} of tanks intended for the production of aluminium by the electrolysis of alumina dissolved in {TAIL ~ molten cryolite base baths} and more particularly to the situation where the bath comprises: 
The process and the apparatus described hereinbefore are applied to { HEAD ~ the series } of tanks intended for the production of aluminium by the electrolysis of alumina dissolved in { TAIL ~ molten cryolite base baths } and more particularly to the situation where the bath comprises :
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