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now there are 5000 units across the country. During the casting process, molten metal is poured into molds made from foundry sand. Once the casting is done, the mold is broken and the sand loses its capability of being reused (it must be simply dumped). Right from the rise of the foundry business in India, millions of tons of WFS is being dumped every year without any regret or consideration. Since there is no viable techno-commercial solution available for WFS treatment, the disposal of WFS remains a big challenge to date, leaving us with the dumping of sand in water bodies or on land. This dumped sand contains several heavy toxic metals such as lead, zinc, tin, etc., which tend to pollute the air, water, and soil to a large extent. It has affected flora and fauna and also posed a threat to human health. Stringent government regulations and environmental laws now restrict such dumping. Adding to the challenges of the foundry industry, the cost of fresh sand has doubled in the
last 5 years owing to the ban on dredging in most of the states.
After returning from my field trip, I decided to resolve these issues by reclaiming WFS in a way that was cost-effective and scalable, which would make it commercially feasible. I started working on a technology capable of reclaiming WFS economically and meeting the foundries’ requirement, while effectively addressing environmental issues.
In the current study,
a mechanical method, as
opposed to the existing
expensive heat treatment
method (at 700°C), was used
to reclaim WFS. I developed an economical and efficient approach that involved removing the dead clay by employing attrition and a
Mr. Mohd Moiz Khan || 385
sieving unit. This new approach has practically demonstrated an economical way that ensures the reuse of the WFS to make molds in the foundry.
The core idea in sand reclamation is the removal of the dead clay layer deposited over the sand particles. Various methods were explored to mechanically remove the dead clay deposits. Three prototypes were developed, namely, vertical tube unit, horizontal tube unit, and attrition, and sieving unit. I eventually concluded that attrition and sieving was the optimal solution, which I have named as the “two-stage attrition” method. Moreover, I sensibly used removed dead clay for making bricks and paver blocks. Through this technique, complete waste is converted into a valuable product that positively impacts the business bottom line.
Allow me a moment to demonstrate the efficacy of this technique. I found out that the proposed two-stage method reduced the clay content to just 2.2%, the operational cost being INR 550 per ton. This reclamation process results in a whopping 83% saving over buying fresh sand, the cost of which is around INR 3200 per
ton.
Fortunately, I have
commissioned a pilot plant (capacity 1 ton per day) in the Government Polytechnic at Kolhapur, Maharashtra, which is running continuously for more than 2 months with commendable success. Currently, WFS is collected from foundries and reclaimed using this plant. More than
50 tons of sand has been reclaimed to date and tested in the foundries. The results are exceptional. Going forward, a local foundry
The Sand Yatra turned out to be quite fruitful, enlightening my knowledge about foundries. I found out that about 80% of the cast metal objects around us, from bathroom taps to airplane gearboxes, were manufactured in foundries using the casting method. The foundry industry in India started in 1959, and now there are 5000 units across the country.