METHOD AND APPARATUS FOR HEAT TREATING FINELY GRANULAR SUBSTANCE, PARTICULARLY BURNING CEMENT RAW MATERIAL GRAIN

In a process of thermally treating fine-grained solids, the latter are preheated in a plurality of heat exchange stages by means of exhaust gases flowing in two parallel exhaust gas lines and are subsequently heated only by exhaust gases from a furnace and are then fed to the reaction vessel and subsequently to the furnace. The two exhaust gas streams are supplied with a mixture of exhaust gases from the furnace and exhaust gases from the reaction vessel. To permit different condition in the heat exchange stages associated with the two exhaust gas lines to be taken into account, two partial streams of exhaust gases are withdrawn from the reaction vessel and supplied to respective ones of the exhaust gas lines. Two partial streams of exhaust gases from the furnace are admixed to respective ones of said partial exhaust gas streams from the reaction vessel.