Rotary kiln and method for burning carbonate-containing material, in particular limestone or dolomite

A rotary kiln for burning carbonate-containing material, the rotary kiln comprising a rotary tube having an inlet end for feeding in the material to be burned and an outlet end for discharging the burned material, and a calciner unit which is arranged in the region of the outlet end, the rotary tube having an inlet zone at the inlet end and having an outlet zone at the outlet end, with a preheating zone and a burning zone being arranged between the inlet zone and the outlet zone in a transport direction of the material,

• wherein a plurality of projections are arranged in the preheating zone of the rotary tube,
• the plurality of projections are arranged in groups with each group comprising a plurality of projections arranged one behind the other in a longitudinal direction of the rotary tube,
• each of the groups in the preheating zone is substantially parallel to the longitudinal axis of the rotary tube,
• projections of adjacent groups in the preheating zone in a circumferential direction of the rotary tube are offset relative to one another in the longitudinal direction of the rotary tube such that spiral transport paths for the material to be burned are formed in the preheating zone, and
• in the circumferential direction, each group in the preheating zone is spaced apart from adjacent groups, and
• wherein a plurality of further projections is provided in the inlet zone of the rotary tube, each of the plurality of further projections has at least one sliding surface inclined to the longitudinal axis of the rotary tube for conveying the material to be burned from the inlet zone into the preheating zone, and
• the plurality of further projections are arranged in groups such that the respective sliding surfaces of the plurality of further projections in each group of further projections form a common sliding surface for the material to be burned.