In the heart of Telangana, India, researchers are tackling a pressing environmental challenge that could reshape the future of the construction and energy sectors. Narlagiri Snehasree, a civil engineering expert from the National Institute of Technology Warangal, is leading a charge to transform coal gangue, a often-overlooked byproduct of coal mining, into a valuable resource for sustainable engineering applications.
Coal gangue, which makes up 10-15% of total coal output, has long been a thorn in the side of the mining industry. Its accumulation leads to significant environmental issues, from land occupation to acid mine drainage and heavy metal leaching. “The challenge lies in the stable and crystalline structure of raw coal gangue, which limits its potential uses,” explains Snehasree. “But what if we could change that?”
Snehasree and her team have been exploring various activation strategies to enhance the properties of coal gangue. Through thermal, mechanical, chemical, microwave, and hybrid methods, they’ve managed to increase the surface area of coal gangue up to 55 m²/g, amorphizing kaolinite to metakaolinite and generating mesoporosity. This enhanced material, known as activated coal gangue, shows promising potential in geotechnical, geoenvironmental, and construction applications.
In geotechnical applications, activated coal gangue can be used for soil stabilization and mine backfill. “We’ve seen that it can replace 50-75% of cementitious binder in backfilling,” says Snehasree, “and it meets the subgrade/base material strength criteria, with a unconfined compressive strength (UCS) of more than 2 MPa.”
In geoenvironmental applications, activated coal gangue has demonstrated remarkable pollutant removal capabilities, with more than 90% efficiency in adsorbing phosphate, dyes, heavy metals, and even CO₂ mineralization. In the construction sector, it can be used as a supplementary cementitious material and in the production of sintered bricks.
The commercial implications of this research are substantial. By transforming a waste product into a valuable resource, mining companies could significantly reduce their environmental footprint and operational costs. Moreover, the construction industry stands to benefit from a new, sustainable material that could revolutionize building practices.
However, Snehasree acknowledges that there are still challenges to overcome. “There are critical knowledge gaps, such as the limited understanding of long-term durability and the inconsistent activation optimization across different coal gangue sources,” she says. “We also need to assess the environmental impacts during large-scale implementation.”
Published in the journal ‘Applied Sciences’ (translated from the original Latin as ‘Scientia Aplicata’), this research provides a roadmap for advancing sustainable coal gangue utilization. It highlights emerging opportunities for cost-effective applications in the mining and construction sectors, paving the way for a more sustainable future.
As the world grapples with the pressing need for sustainable solutions, Snehasree’s work offers a beacon of hope. By turning a problem into an opportunity, she is not only addressing environmental challenges but also driving innovation in the energy and construction sectors. Her research serves as a testament to the power of human ingenuity in the face of adversity, offering a glimpse into a future where waste is not just discarded, but transformed into something valuable.