Aluminium Pechiney

Aluminum Pechiney

Benoit Sulmont

Bernard Langon

Pierre Homsi

Jean-Luc Basquin

George Duprat

Olivier Granacher

Alain Paternoga

A method for measuring temperature and electrolyte level of a molten electrolysis bath in a cell for production of aluminum by electrolysis of alumina includes the steps of: (a) piercing the crust of a solidified bath with a crust breaker and immersing into the electrolyte, an extremity of a temperature probe to a sufficient depth until an initial temperature reading of at least 850.degree. C. is measured, then maintaining the immersion of the probe, in said electrolyte for a length of time which is less than the time taken to establish the thermal equilibrium of the probe in the electrolyte, (b) withdrawing the probe and determining a temperature of the electrolyte by extrapolation of the temperature values measured by the probe, (c) measurement of the level of electrolyte in the cell by moving the lower extremity of the probe into contact with the electrolyte while recording potential signals between the cathodic substrate and the probe, and recording position signals corresponding to the position of the probe, and (d) determining the level of the electrolyte by comparison of recorded potential and position signals.

Method and device for measuring the temperature and the level of the

The invention relates to a process for regulating the acidity of the electrolytic bath by recycling fluorinated effluents emitted by the Hall-Heroult electrolytic cells for the production of aluminum, in which said fluorinated effluents are collected, by the dry route, on the alumina. It comprises the following stages:

Process for regulating the acidity of all-Heelectrolytic cells

Process and apparatus for controlling solid electrolyte additions to electrolytic cells for aluminum production. The invention relates to a process for controlling solid electrolyte additions to a cell for producing aluminum by the electrolysis of alumina dissolved in a molten cryolitic bath according to the Hall-Heroult process. According to this process a nominal value HBC is fixed for the bath height, the level of the bath in the cell is periodically determined on the basis of a fixed dimension point PF known relative to the carbon-containing cathode substrate, from it is deduced the total height HT of the electrolytic bath layer HB and the liquid aluminum layer HM, the thickness HM of the liquid aluminum layer on the cathode substrate is determined, from it is deduced the bath layer height HB, HB=HT-HM and Hb is compared with the nominal value HBC. If this comparison reveals a bath deficiency, a ground bath addition is initiated from a storage means through at least one opening made in the solidified electrolyte crust normally covering the cell. If this comparison reveals a bath excess, an alarm is triggered in order to bring about a bath tapping operation.

Process and apparatus for controlling solid electrolyte additions to

A process for automatically going into the mode for increased suction extraction of the gases emitted by the tanks of series for the production of aluminium by igneous electrolysis using the Hall-Heroult process, each tank being closed around its periphery by a plurality of removable covers which are disposed in substantially sealed relationship with each other and between each thereof and their support means on the periphery of the tank, the gases being collected over each tank by at least one duct connected to a centralized suction extraction system. The temperature of the gases in the duct is continuously measured. Opening of at least one cover gives rise to an abrupt drop in temperature, which makes it possible to put the system into the increased suction extraction mode, which will be automatically stopped when, all the covers being closed again, the temperature of the gases will substantially resume its initial value. The power required for the suction system is thus substantially reduced.

Growing community of inventors

St Jean de Maurienne, France

Benoit Sulmont