Stirrer of a reactor for gasifying solid fuels

In a reactor for gasifying granular fuels, particularly coal, under a pressure of 5 to 150 bars by a treatment with gasifying agents which contain free oxygen, steam and/or carbon dioxide, wherein the fuel forms in the reactor a descendable fixed bed, means for introducing the gasifying agents into the fixed bed from below, means for withdrawing the incombustible mineral constituents of the fuel below the fixed bed as solid ash or liquid slag, and at least one stirring arm in the fixed bed which is rotatable about a vertical axis and is approximately triangular in cross-section and has a knife edge penetrating through the fixed bed and a rear crushing edge, which is the top rear edge, the improvement wherein each of the knife edge and the crushing edge of the stirring arm is provided with a replaceable armoring, the armoring at the knife edge comprises a plurality of armoring elements, which are substantially V-shaped in cross-section and arranged one beside the other so as to define an expansion joint, and the armoring at the crushing edge comprises a plurality of wedge-shaped armoring plates arranged one beside the other, said armoring elements and said armoring plates being mounted on the stirring arm so as to be movable at ambient temperature and said armoring elements and said armoring plates having a width of 5 to 50 cm measured in the direction which is parallel to the radial extent of the arm.