Sand making is important for
the construction industry, foundry, and other applications. Sand is produced by
a sand making plant that is a complex structure with crushers for crushing
materials to the desired size. The sand size produced will be dependent upon
the sand application.
The most widespread sand
ingredient is silica, also called SiO2 or silicon dioxide. It is generally in a
quartz form that is resistant to weather effects due to its inertness and
hardness. Sand structure is extremely inconsistent and is dependent upon the
rocks used and its condition. The brilliant white sand obtained from the
subtropical and tropical regions are worn limestone, containing fragments of
shell and coral. Several sands include chlorite and magnetite. The color of sands that have heavy contents of magnetite
is normally black. Some sands contain iron impurities in the quartz crystals,
producing a yellow color.
Sand is normally a main
element of the aggregate that is used for the concrete preparation. Foundry
sand, also called molding sand, is
moisturized and subsequently formed into molds for
the sand casting. This kind of sand is dependent upon the silicon dioxide
structure. It should be able to endure high pressure and temperature, permit
gases to flee, and have a small grain size. Sand is used as an additive for the
manufacture of bricks. Sand is also used extensively in landscaping. The raw
materials for sand making are crushed by an impact crusher or jaw crusher.
The major components of a sand
making plant are a vibrating feeder, impact crusher, jaw crusher, vibrating
screen, mechanism for washing sand, conveyor
belts, and a control system. The raw material is regularly fed to the first
crushing machine by vibrating feeder for necessary crushing to required
dimensions. The elementary products are transferred by the conveyor belt to the
second crushing machine for additional crushing. The products are separated
according to the requirements by vibrating screen, and those requiring
additional crushing are fed back to the impact crusher. The sand produced is
washed, and the size of sand produced is in accordance with the requirements of
the customer. The impact plate fixed in the machine body is normally produced
from chromium cast steel, and is highly resistant to abrasion. An air cycling
device is included in the system that produces wind to minimize the dust, and
ensure its discharge to the atmosphere. It should be ensured that a sand making
machine should be environmentally friendly, with low noise and dust.
A jaw crusher is comprised of
a pair of vertical jaws. One jaw is fixed, while the other jaw moves back and
forth by a pitman mechanism or a cam. The jaws are more spread at the top
compared to the bottom position, developing a tapering shaft. Thus, the
materials are increasingly crushed to a small size as they move downwards. When
the desired size is reached, the materials will be released through the opening
at the bottom. The jaw movement is small, and the entire crushing process is
not completed in a single stroke. The inertia necessary for crushing is
imparted by a heavy flywheel that creates an eccentric movement. The jaw
crushers are formed of fabricated frames that are reinforced by ribs. The
crusher elements have a high strength to endure the stresses. Manganese steel
is a suitable material for the jaw crushers.
The vibrating feeder basically
contains a vibrating frame, vibrator, spring, vibrating machine, and motor. The
vibrator consists of two eccentric shafts with meshed gears. The shafts are
rotated by the motor, due to which the feeder is vibrated. Due to the
vibrations, the materials will fall, and move forward. The small parts are
passed through the screen, preventing additional crushing.