PROCESS OF PRODUCING CEMENT CLINKER

摘要

In a process of producing cement clinker comprising preheating the raw cement powder in a suspension-type heat exchanger, de-acidifying the so-preheated raw cement powder in a fluidized bed, clinkering the so de-acidified material in a rotary kiln and subsequently cooling the clinker, the improvement comprising: de-acidifying said raw cement powder at a temperature above 850.degree.C to a degree of at least 95 % in a deacidification circulation system comprising a de-acidification fluidized bed reactor, a cyclone separator and a recycling duct; feeding at least 65 % relative to the total heat requirement, of the fuel required for the calcining and clinkering processes to the de-acidifying fluidized bed reactor and at least 10 %, relative to the total heat requirement, to the rotary kiln. Then, near stoichiometrically burning the fuel supplied to the de-acidifying fluidized bed reactor in at least two combustion stages with at least two partial streams of oxygen-containing gas, one of said streams being supplied as fluidizing gas and the other being supplied on a higher level as secondary gas, the ratio of the rates and volumes of fluidizing gas to second ary gas being maintained in the range from 1:1 to 1:10 so that a mean suspension density of 100 to 300 kg/m3 is maintained in the zone between the inlet for fluidizing gas and the inlet for secondary gas; and maintaining a mean suspension density of 5 to 30 kg/m3 above the inlet for secondary gas.