method and ringschachtofen for burning and sintering of limestone or dolomite, recovered as a valuable material, as in several brennzonen

摘要

Lumpy material such as limestone or dolomite is calcined in a ring shaft kiln arranged with its longitudinal axis substantially vertical, descending through a preheating zone, a first countercurrent calcination zone, a second countercurrent calcination zone, a third countercurrent calcination zone and a countercurrent cooling zone. Cooling air flows through the cooling zone in countercurrent, is extracted and is introduced into the column of material with or without an admixture of fuel and air at the bottom end of the first and/or second calcination zone. Fuel feed to the gases which flow through the first and/or second countercurrent calcination zone maybe controlled and/or regulated so that the first and second countercurrent calcination zones can be operated with different excesses or deficits of air and at correspondingly different temperatures from one another. IMAGE