FIELD: gas treatment. SUBSTANCE: purification of gas from hot electrolytic aluminum production process includes at least two stages. Aluminum oxide particles pass through the two adsorption process stages in countercurrent to gas. Thus, gas is partially cleaned with exhausted adsorbent in the first dry adsorption stage, after which adsorbent particles are separated from gas downstream to the first adsorption stage. Part of separated adsorbent particles are removed from the adsorption process to recover and return adsorbed fluorine-containing substances into electrolytic process. The rest of separated adsorbent is recycled to optimize adsorption of fluorine- containing substances and desorption of sulfur dioxide in the first stage. Simultaneously, gas moves to the second adsorption stage, where it is cleaned by essentially fresh chemically active aluminum oxide so that any gaseous fluorine compound remaining in gas is very efficiently adsorbed as well as a very important part of sulfur dioxide still present in gas. The latter part of aluminum oxide particles are separated from gas downstream to the second adsorption stage and cleaned gas is released into atmosphere. Separated adsorbent moves to the first adsorption stage optionally being subjected to intermediate desorption wherein adsorbed sulfur dioxide is removed and thereby sulfur dioxide emission from aluminum production reduced. Separation of sulfur dioxide in the second stage is therefore facilitated. EFFECT: enhanced sulfur dioxide separation efficiency. 5 cl, 1 dwg
