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Exhibit D <br />Quarried limestone will be processed through a crusher that will grind this material down <br />to a five-inch size and smaller. Afrer crushing. the limestone will be combined with other <br />raw materials such as iron and alumina (an aluminum bearing mineral) and processed <br />through a milling operation. The milling operation will grind the raw materials into a <br />fine powder in preparation for processing these materials through the preheater and kiln <br />system: <br />After milling, the raw materials will be processed Chrough a five-stage preheater and <br />calcining vessel. A preheater is designed to heat the raw- materials using waste heat from <br />hot combustion gases vented from the rotary kiln .and calcining vessel. A calcining <br />vessel is designed to further heat the raw materials to the point where calcination of the <br />material is started. Calcination, where limestone is converted to lime, is the first of <br />several material changes that occur within a kiln/calciner system during the manufacture <br />of portland cement. Of the total fuel consumed in a kiln/calciner system, 60 percent is <br />consumed in the calciner vessel. Afrer preheating and calcining, the raw materials are <br />introduced into the kiln. <br />The rotary kiln will heat the raw materials to an ultimate temperature of around 2,800 °F. <br />Additional heating of raw materials in the rotary kiln initiates a series of changes that <br />result in the formation of clinker, which is an intermediate product. In physical <br />appearance, the clinker looks roughly like walnut-sized nodules that are dark gray in <br />color. Coal will be used as a source of fuel for supplying the necessary heat required in <br />the rotary kiln to convert raw materials to clinker. Natural gas will be used as a back-up <br />fuel. A coal stockpile will be maintained in an enclosed covered storage area. <br />Clinker is discharged from the kiln at about 2,200 °F. This material needs to be cooled <br />prior to the next processing step, which is achieved by passing the clinker through <br />equipment known as a clinker cooler. The clinker cooler blows large volumes of air from <br />under the clinker to quickly cool it. This serves two purposes: cooling the clinker in <br />preparation for the next processing step and flash-freezing the desirable chemical and <br />physical properties of this material. <br />The final step in the manufacture of portland cement is the addition of about 5 percent <br />gypsum to the clinker. This mixture is then ground to a very fine powder in a process <br />known as finish milling. The product from the finish mill process is portland cement. <br />Most of the portland cement produced at the facility will be shipped out by railcar. Some <br />of the annual production will be shipped out by truck. The portland cement will be <br />shipped to either distribution terminals or directly to customers. <br />• <br />APPPxhibitsA-T-APPp 180)Rev8gmuary 17, 2002 D-6 <br />