Fluorine-contg. gas emission prevention in Al fusion electrolysis - by admixing fluoride with the alumina replenishments

摘要

Emission of fluorine, AlF3 and Na tetrafluoraluminate gases usually formed when replenishing the fluoride content of Al salt baths during electrolysis, is eliminated by bringing the fluoride into contact with Al oxide contg. =40% oxide, either directly after the addn. or when adding these substances. Fluoride is pref. cryolite, Al fluoride, and/or Na fluoride and is either mixed together with Al oxide before addn. to the electrolyte or the surface of the intermixture gate is coated with the fluoride and the fluoride immediately with Al oxide.