Method and device for the calcination of finely grained to dust-form material, particularly of comminuted raw material to be used in the manufacture of cement

A mechanism for heat treating a comminuted raw material for cement comprising in combination:

• a preheating means for preheating all of the raw material;
• means defining a first reaction zone connected to receive all of the preheated material;
• a first fuel supply connected to the first reaction zone for supplying a first fuel which is a solid fuel having a first heat content for supplying thernal energy for carrying out a first partial calcination reaction of all of the pre-heated material in the first reaction zone;
• a first separation means connected to the first reaction zone for separating the partly calcined material from the hot gases received from the first reaction zone;
• means defining a second reaction zone remote from said first reaction zone and connected to successively receive all of the separated material as well as any unburnt solid portion of said first fuel from the separation means;
• a second fuel supply connected to the second reaction zone for supplying a second fuel having a second heat content to said second reaction zone to supply thermal energy for carrying out a second calcination reaction for completing calcination of all of the partly calcined material in the second reaction zone;
• a second separation means connected to the second reaction zone for separating material from the hot gases;
• a sintering kiln remote from said first and second reaction zones and having an input connected for receiving all of the discharge of completely calcined material from said second reaction zone for sintering the completely calcined material and for producing hot exhaust gases;
• and
• means for passing hot exhaust gases from said kiln sequentially through said second reaction zone and then said first reaction zone.