Millions of tons of Waste Foundry Sand (WFS) is lost each year due to dumping. Sand mining bans in nearly every state have led to a scarcity of fresh sand, significantly increasing its cost. No technically feasible chemical reclamation method is available, which can reclaim WFS for making cores and thus cater to the need of foundries. Although extensive research has been conducted to utilize waste foundry sand (WFS) in other industries such as construction and ceramics, there has been relatively little effort to reclaim and reuse waste sand within the foundry industry itself.
Complete process diagram for the reclamation of sand
In India, millions of tons of waste foundry sand (WFS) is dumped annually without undergoing any scientific disposal treatment. Due to the lack of a viable techno-commercial solution for treating WFS, its disposal continues to be a significant challenge. This invention has proposed a process for reclaiming waste foundry sand. It involves reacting the waste foundry sand with an acid solution of a predetermined concentration, and then using the reclaimed sand to make cores and molds.
- Produces sand with approximately 99% silica content, making it nearly equivalent to fresh sand and ideally suited for core making
- Generates around 20% fines, which can be utilized for brick or paver block manufacturing
- Produced sand has the following properties: loosely bound clay content of 0.05%, oolitic content of approximately 0.05%, a grain fineness number of 55, a loss on ignition of 1.2%, and an acid demand value of 1.5 ml
- Reclaimed sand suitable for making cores
- Replaces the need for fresh sand with reclaimed sand
- Establishes zero-waste foundries by making them partially or fully independent of sand mining
- Cores made using chemically reclaimed sand (CRS) mixed with different amounts of binder (phenol formaldehyde resins), hardener (polymeric isocyanate) and purge amine gas
The reclaimed sand produced by this method has the following properties: loosely bound clay content of 0.05%, oolitic content of approximately 0.05%, a grain fineness number of 55, a loss on ignition of 1.2%, and an acid demand value of 1.5 ml. These properties make the reclaimed sand suitable for making cores. The castings produced using these cores were found to be of highly satisfactory quality
The invention is currently at the stage of Pilot or full scale system demonstration in operational environment.
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It helps preserve the ecosystem by reducing sand mining and minimizes the environmental footprint by avoiding waste sand disposal. Reclaiming waste foundry sand for core and shell production makes foundry operations economically viable and reduces the dumping of waste sand, which poses environmental and health hazards.
Core-making industry, sand industry
This sand reclamation technique holds tremendous potential for commercialization. It offers a holistic approach to establishing zero-waste foundries, addressing their needs by making them partially or fully independent of sand mining. Additionally, it helps preserve the ecosystem by eliminating the need for sand mining and reducing the environmental footprint associated with waste sand disposal. Core making requires high-quality sand combined with a chemical binder, hardener, and catalyst, which are essential for producing specific castings. However, core sand can only be used once before it must be discarded. The proposed chemical reclamation process transforms waste foundry sand (WFS) into a material suitable for core production, significantly enhancing its value.
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