The document discusses sand preparation and reclamation in foundries, emphasizing the importance of conditioning molding sand for quality castings, with procedures for mixing ingredients and enhancing properties. Sand reclamation is highlighted as an environmentally and economically beneficial practice that restores used sand for reuse, utilizing various techniques such as dry, wet, thermal, and combined methods. The document outlines advantages of reclamation, including cost savings and resource conservation, while detailing processes for achieving optimal sand quality.

1. TOPIC – SAND PREPARATION $
RECLAMATION

2. MOLDING SAND PREPARATION OR CONDITIONING
• Sand preparation means mixing the molding sand ingredients , Such as sand,
binder (clay, cereal), moisture and other additives
• Sand conditioning consists of preparing the mold sand so that it becomes suitable
for molding purposes
• Approximately 90% of all castings produced today are made by the sand molding
process.
• Even the best selected sands and binders would not produce in which good
castings, until they are efficiently and properly mixed and prepared.
• The quality of molding sand depends upon the manner it is prepared.
• Mixing may be carried out manually or by mechanical mixers.

3. Functions of Sand Preparation or Conditioning
(i)To develop optimum properties in molding sands.
(ii) To obtain even distribution of sand grains throughout mold
(iii) To add adequate amount of water to activate clay binder.
(iv) To remove foreign matter from the molding sand.
(v) To deliver sand at the proper temperature.
(vi)The major objective in molding sand preparation is to obtain
a uniform, and homogeneous aggregate of sand grains
completely coated with binder.

4. Step Involved In Sand Preparation
• Fins, nails and other metal pieces may be removed from molding sand with the help
of magnetic separators .
• The sand can then be screened.
• Using a mechanical mixer ie. a MULLER, start the mixing of sand ingredients in dry
condition.
• Continue mixing or mulling action until there is a uniform distribution of the
ingredients (like sand, binder, water and additives) and the optimum properties
develop.
• As the next step the sand is treated by an Aeration Process.
• Aerating separates sand grains into individual particles.
• Aerated sand is fluffy, is easier to handle and use and gives better molding results.
• Aeration results in a sand which flows readily around the pattern and molds itself
easily as per the pattern.
• Sand may be cooled below 100°F to avoid difficulties in mold making .

5. Muller
A mulling action is very much required for mixing sand, binder and moisture, thoroughly.
Mixing can be carried out by hand shovels or mechanical mixers- Mullers.
 Hand mulling, though alright for natural sand mixing, does not work well with synthetic
sands because they can neither readily nor thoroughly be mixed by hand mulling.
A muller stirs the sand by means of revolving wheels or rollers.
Sand mixers or mullers may operate on the following principles of construction
The two wheels along with two plows roll and rotate in a circular path about horizontal
axis.
Wheels either rest on the sand or remain about 5 mm above the base of the rotating
pan.
Wheels may either be attached with a vertical shaft or mounted rigidly with the rotating
pan.
After mixing the sand, it may be taken out from a drop door at the bottom of the muller.

6. SAND MULLER

7. Sand reclamation
Sand reclamation must not be misunderstood as a waste treatment
process; rather, it is an integral part of the foundry sand preparation
system. Today, a major concern of the foundry industry in all highly
industrialized countries is the reclamation of molding sand for
environmental and economic reasons .
Sand reclamation means the full recovery of the sand grade for use as
a direct substitute for new sand.
 Sand reclamation aims at removing all undesirable objects from the
used sand and restores the sand to as nearly its original condition as
possible.

8. Advantages
Sand reclamation offers the economic utilisation of the sand which would otherwise
need to be dumped out to make space for new sand.
legislative regulations ere increasingly restrictive on land fill disposal, making it
accordingly more expensive.
sand is a finite resource of the earth's crust and we should be therefore looking
towards a conservation policy.
reclaimed sand can be of a higher quality than new sand.
Purchasing new sand may not be expensive but freight charges , loading and hauling
make it costlier.
Sand reclamation eliminates the necessity of storing new sand in bulk and thus
reduces inventory size.
Reclaimed sand eliminates the need of using separate facing and backing sands,
because reclaimed sand is just like new sand
 New purchased sand may not be of the required grain shape and size

9. SAND RECLAMATION TECHNIQUES
(a)Dry reclamation (b) Wet reclamation
(c) Thermal reclamation ( d)Combined wet plus thermal reclamation
(a) Dry Reclamation:
In dry reclamation process, fines, spent and free clay, fractured sand grains and iron oxide particles etc, are removed
from the used sand .
Steps Involved
Magnetic separators are employed for removing iron and steel particles
 Sand is screened.
 Sand lumps are either discarded or crushed and then screened.
After passing through the screen, sand goes to a pneumatic sand scrubber unit where sand particles get rubbed
against one another. This partly removes the clay coating from the sand grains.
Reclaimed sand comes out of the pneumatic sand scrubber while fines and dust are separated from the air .
Drawback of dry reclamation process
Since it is not possible, by this process, to remove clay, organic and carbonaceous materials completely from the sand
grains,

10. Wet reclamation :
Wet reclamation process removes fines and foreign matter from the sand.
Removes partly clay coating from the sand grains.
Does not remove completely, carbonaceous and organic materials from the sand grains.
Like dry reclaiming, does not convert the used sand into an original new one.
Steps Involved:
A magnetic separator removes all ferrous matters from the used sand.
Sand passes through the screens.
Sand is mixed with water to form a slurry.
Fines (such as silica flour) are removed
Sand slurry goes to sand scrubber (propeller type) where sand grains are rubbed against
one another and thus the clay adhered to the Sand grains gets partly removed
Sand-water slurry enters another section where fines produced in the cleaning operation
are removed and desired sand grain-size distribution is obtained.
In the end, a filter and drying unit removes moisture from the sand (water slurry)

11. (c) Thermal reclamation
Thermal reclamation process involves heating the sand to 1200-1500°F.
Carbonaceous and organic materials get burnt and are removed.
 This process does not remove clay
This process is very suitable for oil bonded sands which contain no clay.
Thermal Reclamation is preferred in non-ferrous foundries performing all core
molding.
Thermal Reclamation is very effective in reclaiming shell mold sand.
Thermal Reclamation is not recommended for foundries using clay binders .

12. Combined wet reclamation plus thermal reclamation
This process possesses the good points of both wet and thermal reclamation
processes.
It restores the qualities of the original sand.
 The sand reclaims its original shape, size and distribution . However sand grains
get slightly etched and pitted.
The process removes fines, clay, organic and carbonaceous
Thus reclaimed sand produces castings as good as those made by original sand

13. THANK YOU