Method for the treatment of finely grained material, particularly for the precalcining of cement

Claim 1

A structure for thermally treating material such as for the calcining of cement, comprising in combination: a rotary kiln, at least one cyclone separator heat exchanger having a solids discharge and an inlet gas conduit, a standpipe connecting said rotary kiln to the solids discharge of said cyclone separator, means for directing a controlled amount of fuel and oxidizing gas into said standpipe to provide a spatially limited preoxidation zone therein, means in said standpipe providing an admixing zone immediately above said preoxidation zone, feed means for injecting raw material directly into said admixing zone for admixture with the partially oxidized gas emanating from said preoxidation zone, means in said standpipe providing a precalcining zone between said admixing zone and the inlet gas conduit of said cyclone separator, movable deflector means between said preoxidation zone and said precalcining zone, said deflector means being sufficiently porous to adjustably permit partially oxidized gases to flow from said preoxidation zone into said precalcining zone but preventing heavy particles from falling from said feed means into said preoxidation zone, and means for discharging precalcined particles from said cyclone separator into said rotary kiln.