Analysis and Verification of Design Concepts for a 7000-hp Ring Gear Driven Mill - Part I

The choice of one 7000-hp (5220-kW) finish grinding mill versus two smaller units for the Martin Marietta Cement plant in Davenport, IA is discussed. Design considerations of the mill-drive system are covered, with emphasis on the composite mechanical- electrical drive and the need to avoid damaging torsional frequency conditions in it. The mathematical torsional analysis of the mill-drive system is presented, and conclusions of that design activity are given.