The different effects of fluoride in electrolytic aluminum process.

The effect of different fluoride salts in electrolytic aluminum smelting is different, generally it is to reduce the initial temperature of the electrolyte and optimize the electrolyte composition.
For example, magnesium fluoride can be used to separate carbon residue and improve electrolyte conductivity.
When the molecular ratio is high, the addition of aluminum fluoride is adjusted.
When the molecular ratio is low, sodium fluoride or soda can be added to adjust.
Aluminum fluoride added methods: aluminum fluoride should be added in the middle of the alumina surface shell parts, after the first to add a layer of alumina after processing, the aluminium fluoride evenly sprinkled on thin shell, and then with insulation material.
Next time processing, can not pick material, fluoride with the shell into the tank.
Precautions for adding aluminum fluoride:
(1) aluminum fluoride cannot be added to the electrolyte surface, nor should it be placed near the fire eye and anode.
(2) it is not suitable to process aluminum fluoride before aluminum production.
(3) in order to reduce the loss of aluminium fluoride, aluminum fluoride can be mixed with cryolite, aluminum fluoride in electrolytic cell after the aluminum processing add it is best for the first time, at ordinary times can be added in the electrolytic cell little head processing.
The role of cryolite:
Firstly, it can dissolve the alumina well, and the melt can be electrolyzed under the melting point of pure cryolite.
And the liquidity is good.
Second, under the electrolytic temperature, cryolite, aluminum oxide liquid density is 10% smaller than aluminum liquid density, so the liquid aluminum electrolytic out can be deposited on the cathode electrolyte, which can reduce the oxidation of aluminum loss, and greatly simplifies the structure of the aluminum electrolytic cell;
Third, cryolite has good conductivity;
Fourth, the crystal stone contains no metal impurities that can correct the electrical properties of aluminum, which can guarantee the quality of aluminum products.
At present, cryolite is the most ideal flux in aluminum electrolysis production.

The chemical composition of cryolite used in general aluminum electrolysis should meet the requirements of national level 2.