The invention relates to a process and a two-shaft stepped multiple-hearth kiln for burning piece-form or fine-grained bulk materials, such as limestone, dolomite or other carbonate rocks, in which, by regenerative material heating, the thermal economics of this system can be considerably improved, i.e. decrease of the specific heat consumption per unit weight. The object of the invention is to change the fuel path in the known multiple-hearth kiln according to Patent Application P 4300235.8 in such a manner that the fuel gases are not run directly into the combustion compartment, but are first conducted into one of the two preheating shafts, from there through the combustion compartment with subsequent flow through the charge bed, impinge the second preheating shaft in the multiple-hearth area, are extracted by means of a fan and gas flows through the preheating shafts alternately in countercurrent and cocurrent flow in a preset cycle. IMAGE
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