Cement company puts the screws to blending air problems
When a rotary vane compressor requires excessive maintenance and contaminates blending air with oil, a cement company switches to a rotary screw compressor.
Medusa Cement, Clinchfield, Ga., manufactures various types of cement. For production, the cement company mines limestone, fuller's earth, and clay. Bulldozers, front-end loaders, and trucks remove stripped overburden before workers drill, shoot, and blast materials from the mine pit. Front-end loaders and trucks move the materials to a rotating crusher in the pit, and a belt conveyor moves the crushed materials about 4 miles to a hammermill near the cement plant. The materials are stored in feed bins, and cranes move the materials to rotary feed tables that proportion the materials to achieve certain chemical properties in the finished cement. A belt conveyor then moves the materials to a rotary dryer that reduces the moisture content from 20 percent to 9 percent. After initial drying, the materials pass through a roller mill system that further dries, crushes, and pulverizes the materials to powders sized 78 percent to 80 percent smaller than 200 mesh.