METHOD OF PURIFYING HOT GASES FROM THERMAL PROCESSES, MEANS FOR IMPLEMENTATION OF THE METHOD, AND METHOD FOR PREPARATION THEREOF Russian patent published in 1996 - IPC

FIELD: gas purification. SUBSTANCE: invention relates to purifying hot gases to remove acidic ingredients, heavy metals (Hg, As, Cd, Tl, Sb, Pb, etc. ) and/or injurious organics occurring in the processes of burning fuel, household wastes, and in metallurgy. Into hot gases withdrawn from thermal processes at 150-400 C, a finely divided calcium hydroxide-containing means is added. Solid purification products are separated mostly on textile filters. The added means, along with calcium hydroxide, additionally contains 0.01-5 wt % of water-soluble sulfur-containing salt belonging to group of alkali metal sulfides, polysulfides, thiosulfates, and mercaptides. In another version, this salt may be mixed with or applied to activated carbon, brown coal hearth coke, or alumina, their content being 0.5-10 wt %. In a third version, the means contains calcium hydroxide and 0.5-5 wt % of sulfur powder, which is mixed with or applied to activated carbon, brown coal hearth coke, or alumina, their content being 0.5-10 wt %. Calcium hydroxide largely consists of grains less than 200 mcm in size and contains 0.1-5 wt % water. When purifying gases, sulfur-containing salts to heavy metal (mainly mercury) weight ratio is (1-1000):1, preferably (25-500):1. Sulfur to heavy metal weight ratio is (5-200):1, preferably (25- 500):1. The means is prepared by slaking lime, while to the lime before slaking and/or to slaking water during the slaking, and/or to calcium hydroxide after slaking, the following substances are added: water-soluble sulfur-containing salt or activated carbon, brown coal hearth coke or alumina together with a water-soluble sulfur-containing salt, or sulfur alone, or sulfur applied onto indicated high-porous materials. EFFECT: enhanced efficiency of purification process. 12 cl, 5 tbl