Bulk cement ship and barge unloading systems, which system is best?

During the 1990s, economic circumstances have encouraged the development of new water based bulk material terminals in many parts of the world. This has become increasingly the case in the USA during the latter part of the 1990s, when cement shortages have caused bulk cement to become one of the major import commodities for many bulk terminals. Because of the physical nature of cement, the process of unloading it from ships or barges can present a major hurdle in the path of the implementation of a cement unloading terminal. The purpose of this paper is to analyze the advantages and disadvantages of the four unloading systems that are available (mechanical screw unloader, pneumatic unloader, self discharging ships, and grab bucket and hopper unloaders), and to help the reader to better understand which system may work best for their specific application.