Abstract: A method for burning lumpy combustion material, in particular limestone, dolomite and magnesite, in a regenerative shaft furnace comprising at least two shafts (1, 2) comprised of a preheating zone (A) as well as a combustion zone (B). The shafts are connected below a cooling zone (C) by a transfer channel (3). The combustion air is charged at the head of one shaft (1), heated by hot combustion material as it flows through the preheating zone (A), and brought into contact with fuel before it enters the combustion zone (B). The combustion zone (B) is flowed through by combustion gas produced in the combustion of the fuel. Cooling air is admitted at the lower end of the shaft (1) and, as it flows through the cooling zone (C), heated by hot combustion material exiting from the combustion zone.

Abstract: A method and apparatus is disclosed for burning and sintering alkaline materials such as limestone and dolomite in a shaft furnace wherein the alkaline material travels successively through a preheating, burning and cooling area. At the upper end of the cooling area the cooling air traversing the shaft from bottom to top is aspirated into a recuperator wherein fresh combustion air is preheated by the cooling air and then supplied to the burner which heats the burning area. Part of the aspirated cooling air may also be directed past the recuperator through a bypass conduit to heat a dryer which dries the materials to be processed by the shaft furnace.