Process for making cement, especially for the reduction of NOx-emissions

摘要

Production of a cement incorporating a firing stage, using a cement furnace flame, for a raw dust previously preheated, then possibly pre-calcined using a pre-calcination flame, includes the injection of a metal oxide having a catalytic effect in the reduction of nitrogen oxides into the cement furnace flame and/or into the pre-calcination flame when a pre-calcination stage is included. The metal oxide is chosen from a group made up of CuO, Co3O4, Mn3O4, Fe2O3, SnO2, NiO, ZnO, V2O5 and TiO2. The metal oxide is preferably ferric oxide. The metal oxide can be pre-mixed and pre-ground with the solid fuel feeding the cement furnace burners (claimed). An independent claim is given for a process for reduction of NOx generated in a cement manufacturing installation comprising a preheating zone upstream of the cement furnace, and optionally a pre-calcination zone in front of the cement furnace. A metal oxide selected from the above metal oxides is injected into the cement furnace flame and/or into the pre-calcination flame, in order to obtain at least a 20% reduction in NOx content.