6 - Vicat

6BUSINESS OVERVIEW6.3. DESCRIPTION OF THE BUSINESSES AND INTRODUCTION TO THE MARKETS• The kiln system includes a heat exchanger cyclonetower, where the raw meal is introduced after beingheated by the exhaust fumes of the revolving kiln(precalcination phase). The raw meal undergoescomplex chemical reactions during this firing : first,limestone is decarbonated under the action of heatat a temperature bordering 900°C and is convertedinto lime, while clays are broken down into silicatesand aluminates. The unit then recombines these at atemperature of approximately 1,450°C into lime silicatesand aluminates. This chemical process createsa semi-finished product called clinker, which has theproperties of a hydraulic binder. This firing takesplace in tilted revolving kilns lined with refractorybricks.There is a large global trade in clinker, the semi-finishedproduct. As this product is easier to transportand store, clinker transfers from areas with excesscapacity to areas with under-capacity or to areas nothaving the mineral resources necessary for cementmanufacture have been developing over the past fewyears. This reduces the volume of the transportedproduct compared to cement thereby lowering logisticscosts. Once it has reached the consumptionmarket, clinker is delivered to grinding plants, whichcomplete the cement manufacturing process up topackaging and distribution. This method is used inItaly in particular, as discussed below.36 VICAT - 2009 registration document