Date post: | 16-Jul-2015 |
Category: |
Engineering |
Upload: | rasheedur-rehman |
View: | 187 times |
Download: | 4 times |
26 January 2015 1
INTRODUCTIONWhat Sand Reclamation ?
Sand reclamation, the process of cleaning previouslyused sand so it can be reused.
Why sand reclamation ?
Due to environmental regulations, the disposal ofwaste foundry sand has become one of the mostpressing problems for the foundry.
In recent years because of the high disposal costsencountered and difficulty in finding disposal sites.
26 January 2015 2
Definition for Sand Reclamation
Sand reclamation is the physical, chemical or
thermal treatment of foundry sands so that
they can be safely re-used in place of new
sand in molding and core making mixes.
26 January 2015 3
Function of Sand Reclamation
Reduce all lumps to sand grain size.
The sand grain size distribution of the reclaimed sand
should be the same as that of the new sand as
purchased.
Remove all tramp materials such as metal particles ,
slag, refractory particles, etc...
Remove fines to a acceptable level.
26 January 2015 4
Types of sand Reclamation
Mechanical Reclamation
Thermal Reclamation
Dry Reclamation
Wet Reclamation
26 January 2015 5
Mechanical Reclamation
Mechanical sand reclamation systems remove
accumulated coatings around the sand grains.
As well as dust and other impurities that
would otherwise make the sand unusable.
26 January 2015 6
Steps involved mechanical reclamation
Mold + castings
Shake out gird
Secondary sieve
Compressed air is passed
Sieve for final crush it as fine sand
Automatic discharge of
castings and mud
Removal of
impurities
Sand collection
Reclamation of sand for
next lot
26 January 2015 7
Videos for Mechanical Sand
Reclamation
26 January 2015 8
you can search in youtube
Thermal Reclamation block diagram
26 January 2015 9
Thermal Reclamation
Most thermal reclamation systems are
preceded by mechanical systems.
That preparation the sand for thermal
treatment by removing metallic's and part of
the sand coatings.
Thermal reclamation system uses a unique
fluidized, gas-fired bed design to combust and
remove remaining residual sand coatings.
26 January 2015 10
Thermal Reclamation by process
Thermal Reclamation is the process in which
the sand is heated to a temperature of about
800°C.
The sand grains obtained from the lump
breaker is generally pre-heated .
And fed into the combustor where it is
fluidized by precisely controlled air flow at
desired pressure.
26 January 2015 11
Lump Reducer – It Reduces the de-moulded sand
lump into sand grains in a vibrating unit fitted with
unbalance motor.
Pneumatic Sand Transporter - to deliver the de-
moulded and reduced sand grains to the return sand
storage.
Screw Feeder - It feeds this sand in to sand preheating
unit.
26 January 2015 12
Sand Preheating Unit - fitted at the inlet of
the fluidized bed combustor to preheat the
incoming return sand by using waste heat in
the flue coming out from the combustor.
Air Pre heater - for further extracting waste
heat from flue.
26 January 2015 13
Fluidized Bed Combustor - where the
preheated sand is fed from the sand pre-heater
by a screw feeder and fluidized by preheated
air.
Preheated sand is further heated to about
800°C by heat provided from the Wesman
(company name) combustion system.
26 January 2015 14
Skip Hoist - for transporting hot reclaimed
sand into hot sand silo at the inlet of the cooler
in a particular model.
Fluidized Bed Cooler - where the hot
reclaimed sand is cooled to usable temperature
by means of fluidizing air as well as cooling
coil.
Dust Extraction System - having suction
points at various stages of reclamation for
removing dust as well as for classification of
sand.
26 January 2015 15
Dry Reclamation pictorial view
26 January 2015 16
Dry Reclamation
Dry reclamation processes first crush the lumps to
grain size.
Mechanical abrasion then removes part of the
binder from around the sand grains.
Released fines are separated and removes by dry
classification.
The impact of the sand scrubs off the clay coating
from the surface of the sand grain, and the
resulting fines are removed to a dust collector.
26 January 2015 17
Wet reclamation pictorial view
26 January 2015 18
Wet Reclamation
Wet reclamation technique is wet scrubbing, in
which suspended sand grains are subjected to
vigorous motion and mutual rubbing by water
currents, jets and agitation.
The main use of wet reclamation has been for
sodium silicate bonded sands, where the whole
of the binder residues can be effectively
removed.
26 January 2015 19
Wet reclamation can also be integrated with
hydraulic cleaning and decoring of castings
The same pressures will continue as a
powerful factor in the design.
This would clearly shift the balance from the
situation in which landfill dumping is the sole
alternative to reclamation.
26 January 2015 20
Major drawback on wet reclamation
In addition, capital cost of the equipment is
high .
A large amount of floor space is required.
26 January 2015 21
26 January 2015 22