Pressure-sealing feeder improves coal delivery in cement plant
A cement company replaces its triple-flap gate with a pressure-sealing feeder for smooth coal feeding in clinker processing.
In Cape Girardeau, Mo., Lone Star Industries produces 1.4 million tons of cement annually. The company extracts limestone from an open pit mine adjacent to the plant. The limestone, sometimes in chunks as large as a piano, is crushed to softball-sized pieces and delivered to the plant for processing into various cement products such as Portland type 1, type 2, low heat, and masonry. Additives such as aluminum ore, diaspore, silica, fly ash, tripoli, and iron ore are added to the limestone prior to being ground up in a roller mill. The roller mill grinds the limestone and additives into a material called raw meal. The raw meal enters a four-stage preheater tower and begins to preheat. From here, the raw meal enters the precalciner, where 88 to 90 percent of the raw meal's chemical transformation into clinker takes place. The precalciner is a furnace that rapidly elevates the raw meal's temperature to 1,600°F. Next, the raw meal enters a rotary kiln.