Bulk materials loaders and unloaders are used to fill and remove
powders, granular substances and other bulk solids from bags,
bins, boxes, carts, drums, hoppers, railcars, trucks, and silos.
They often include solids feeders and can break down clumps or
arches to allow for more uniform distribution of bulk materials.
Some bulk materials loaders and unloaders are designed to handle
abrasives or ceramics, chemicals or fertilizers, cosmetics or
pharmaceuticals, construction materials or cement, food
products, metals or minerals, and paints or pigments. Others are
designed to handle pulp and paper, wood chips, polymers,
adhesives, molding, coal, or wastewater sludge. Dry or free-
flowing devices can handle a variety of dry materials. Wet or
bridging devices can handle moist materials, slurries and
dispersions; flakes and fibers; and other bridged materials with
high aspect ratios.   There are many types of bulk materials
loaders and unloaders. Belt or apron feeders dispense material
from a serrated or smooth belt