Installation and process for calcining a mineral load containing a carbonate in order to produce a hydraulic binder

The installation (11;

• 211;
• 311;
• 411) as claimed in any one of the preceding claims, characterized in that the combustion means (55) successively comprise, between the means (51) for forming the fluidized bed and the means (57) for introducing a gas having a controlled carbon dioxide content:
• fuel supply means (73) ;
• then
• means (75) for injecting the oxidizing gas for combustion coming from the cooler (31) into the chamber (15).

The installation (411) as claimed in any one of the preceding claims, characterized in that the combustion means (55) comprise a secondary combustion chamber (413) having:

• secondary means (417) for introducing some of the mineral load coming from the preheater (27);
• and
• means (419, 421) for injecting an oxidizing gas for combustion coming from the cooler (31) into the secondary chamber (413);
• the secondary chamber (413) being connected to the combustion chamber (15) by an outlet duct (415) opening between the means (53) for introducing the mineral load and the additional means (57) for introducing the treatment gas.

A process for calcining a mineral load containing a carbonate in order to produce a hydraulic binder, of the type comprising at least one calcining phase, the process successively comprising a phase for preheating the mineral load in a preheater (27), at least one phase for calcining the preheated mineral load in a combustion chamber (15) and a phase for cooling the calcined mineral load in a cooler (31);

• the calcining phase comprising the steps of:
• introduction of the mineral load coming from the preheater (31) into the chamber (15);
• combustion of a fuel in order to maintain the chamber (15) at a temperature between 700° C. and 900° C., the combustion step comprising the introduction of an oxidizing gas for combustion coming from a cooler (31) into the chamber (15);
• introduction of a treatment gas having a controlled carbon dioxide content into the chamber (15), in order to oppose the dissociation of the carbonate in the chamber (15) ;
• and
• removal of the calcined mineral load in order to introduce it into the cooler (31);
• the process comprising a phase of discharging the flue gases produced during the or each calcining phase into the atmosphere;
• characterized in that the calcining phase comprises a step of forming a fluidized bed in the chamber (15), and in that the step of introducing a treatment gas comprises at least partially bypassing some of the flue gases discharged during the gas discharge phase and supplying the chamber (15) with said bypassed flue gases.