Reduction of sodium sulfate to sodium sulfide

摘要

Methods and apparatus pertaining to reduction of sodium sulfate to sodium sulfide include the feeding of sodium sulfate into a combustion chamber in which the sodium sulfate is exposed to a reducing atmosphere while at the same time being exposed also to a temperature above the melting point of sodium sulfide. Thus, a liquid accumulates at the bottom of the combustion chamber and this liquid will of course contain a considerable amount of sodium sulfide reduced from the sodium sulfate. The exhaust gases of the combustion chamber are utilized in a steam generator the exhaust gases of which may in turn be returned to the combustion chamber where these exhaust gases from the steam generator serve as an inert gas which is directed through the collected liquid to increase the turbulence thereof while at the same time additional reducing agents may be introduced into the liquid, in some cases with additional sodium sulfate, for improving the purity of the collected liquid as well as for decreasing the amount of non-reduced sodium sulfate in the liquid. Secondary air is supplied to the steam generator for burning therein the exhaust gases from the combustion chamber.