Improved screening of coal and other difficult to screen bulk materials by means of LIWELL^® screens

Abstract

Typically bulk materials such as coal and others like ore, coke, sand and gravel show significant worse screening properties in case of higher moistures and/or smaller required cut sizes. The surface moisture causes adhesive powers resulting in massive chokings of installed screen media. Consequences are loss of capacity / efficiency, fluctuation of product qualities and negative influences on other connected process steps. To enable a sufficient classification even with smaller cut sizes and/or higher surface moistures the screening machine must provide higher accelerations to avoid choking of perforation up to the physical limits. The special design of LIWELL^® screens provide much higher amplitudes and accelerations compared to standard machines. To achieve higher amplitudes/accelerations of the installed screen panels the machine consists of 2 screen cases powered by an eccentric shaft. The eccentric shaft allows a 100 % defined movement independent of influences like load, granulometry, speed and others. Typical applications are classification of coal for improved next processing (jig), production of fine coal for fluidized bed boiler, removal of fines for coal gasification processes. Furthermore many other applications exist, for example, improvement of ore qualities by removal of fines, recycling applications and production of sinter coke.