Collection of used SiO2 SAND:
There are many types of waste sand is disposed in foundry. They are SiO2 sand, resin sand, baking sand, facing sand etc. But in general SiO2 sand is used in large quantity therefore SiO2 sand is collected from the foundry.
HAMMERING AND SIEVING:
Then the lumps are ground by hammering and screened to remove stone and other foreign bodies by sieving to 4.75mm of standard sieve size to maintain proper grain size of the sand.
MIXTURE IN FOUR DIFFERENT RATIOS:
From the journal and discussions four different ratios are selected. Then sieved foundry sand is mixed with red soil in three ratios such as 1:9, 2:8, 3:7 and 4:6. It kneaded without adding water till it get blended well with the red sand.
PUG PIT:
Then it is placed into a pug mill where it was mixed with water to obtain the right consistency for moulding.It was kneaded with the hands and feet to mix all the elements of the clay together. This step was called tempering or pugging. Then it is exposed to air for 48 hours to remove unwanted oxides.
