Page 207 - Materials Chemistry, Second Edition
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                       178                       Waste Management Practices: Municipal, Hazardous, and Industrial













































                                                                         FIGURE 7.6 Base of a conveyor
                                                                         belt showing rollers: (a) schematic
                                                                         (reproduced with kind permission of
                                                                         CEMA, 1995); (b) photo.

                       the range of 1220 of 1520 m/min (4000–5000 ft/min) and the materials to air ratio is about 0.045
                       kg (0.1 lb) material to 0.45 kg (1 lb) air (Vesilind and Rimer, 1981; Tchobanoglous et al., 1993).
                          The utilization of conveyors for MSW transport has not been without its share of problems.
                       Wastes which are too heavy or extremely sharp can be dropped on the belt, thus damaging the belt,
                       pulleys, or other components; wastes may fall off the belts at transfer points, i.e., where one belt
                       empties onto another (Figure 7.7); and wires and string within the wastes can become tangled
                       around pulleys and other equipment.

                       7.2.8 SCALES
                       Scales are included inside the MRF. These are typically small models and are used to weigh objects
                       such as bales of metal or paper, or cages of materials (Figure 7.8).

                       7.3 MATERIALS RECOVERY AT MRF UNIT OPERATIONS

                       In a hypothetical situation where one material is to be segregated from a mixture, the separation
                       process is termed binary, as two outputs result from the operation. A binary separator receiving a
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