All over the world foundry industries uses and disposes of over one million tons of foundry sand per year. Indian foundry industry is the 4th largest casting producer in the world. There are more than 5000 foundry units in India, having an installed capacity of approximately 7.5 million tons per annum. The majority (nearly 95%) of the foundry units in India falls under the category of small-scale industry. These foundry units generate approximately 1,710,000tones waste foundry sand per year. There are two types of foundry sand utilized to produce moulds into which metal cast, green sand and chemically bonded sand. The type of sand used is dependent upon factors such as the type and size of casting being produced.
Approximately every three to four months, spent foundry sand must be replaced with new sand to meet casting quality and environmental testing requirements. This sand replacement requirement generates nearly 80 tons of spent foundry sand. Additionally, normal foundry operations generate one to two tons of spent foundry sand per month. The spent foundry sand is collected in roll-off bins and transported by a wasted management to a licensed landfill. It is standard foundry practice to reuse molding and core making sands. Residual sand is routinely screened and returned to the system for reuse. As the sands are repeatedly used, the particles eventually become too fine for the molding process; and, combined with heat degradation from repeated pouring, require periodic replacement of spent foundry sand.
STRUCTURAL FILL: Structural /sub base fills are applications where foundry sand has been beneficially used as structural fill, embankment material, granular backfill, roadway sub-base, and roadway base material.
CONCRETE AND RELATED PRODUCTS: This is an application where foundry sand has been used in the production of concrete bricks, pre-cast concrete such as blocks and construction of pavement.
ASPHALT: This is an application where foundry sand has been used in asphaltic (bituminous) concrete considering of mixture of aggregates bound together by asphalt cement.
SOIL AMENDMENTS: Soil amendments are applications where foundry sand has been used in agriculture soil amendments. These soil mixtures used by the nursery industry are typically sand mixed with peat, fertilizers and topsoil. The presence of clay in the sand is the sand is beneficial because clay increases the capacity of soil retain nutrients and water.
PORTLAND CEMENTS: Portland cement application where foundry sand has been used in the production of Portland cement (concrete), concrete consists of a mixture of 30% sand, 50% gravel, 15% cement and 55% water. Concrete can be cast-in-place or pre-cast into concrete products such as bricks, pipes and blocks.
Brick manufacturing is historic process and it involves more percentage of soft mud is used. Bricks are dried and then fired in chambers at high temperature to get their properties and to form a rigid shape.