CFlo's Solution Maximizes Bentonite Recovery & Water Recycling

Tunnelling and underground construction projects are vital for modern infrastructure. However, these projects can generate significant waste, including used bentonite slurry and excavated materials. Fortunately, advancements in tunnel waste recycling technology offer a sustainable solution – closed-loop slurry treatment plants (STPs).


Bentonite slurry plays a crucial role in tunnelling, acting as a stabilizing fluid for tunnel walls. However, traditional methods often result in discarding the used slurry, leading to increased costs and environmental impact. Closed-loop STPs, like those offered by CFlo, address this challenge by maximizing bentonite recovery and water recycling.

Recovering Bentonite for Continued Use

CFlo's STPs utilize hydrocyclone technology with unparalleled cut-point accuracy. This meticulous separation process allows for the efficient recovery of valuable bentonite clay from the used slurry. The recovered bentonite can then be treated and reused in tunnel boring machine (TBM) operations, significantly reducing the need for purchasing virgin bentonite.

Removing Sand and Silt for Optimal Performance

The efficiency of bentonite slurry can be hampered by the presence of sand and silt particles. CFlo's STPs employ high-frequency dewatering technology to effectively remove these contaminants. This ensures the recovered bentonite performs optimally, maximizing its effectiveness in subsequent TBM operations.

Repurposing Excavated Materials

The focus isn't solely on bentonite recovery. Following dewatering, CFlo's STPs allow for the recovered mineral materials (waste rock) to be screened and graded. This opens the door for on-site production of valuable construction materials like sand and aggregates, minimizing the need for virgin materials and reducing transportation costs.

Closing the Loop on Water Usage

Water is another critical resource in tunnelling projects. CFlo's STPs incorporate thickening and sludge management systems. These systems treat the recovered bentonite slurries, enabling an impressive 95% water recirculation for use in TBM operations. This significantly reduces freshwater consumption, promoting environmental sustainability. Furthermore, CFlo's technology boasts zero discharge, eliminating the need for disposal of wastewater, a major advantage in environmentally sensitive projects.

Sustainable Tunnelling Solutions

By implementing closed-loop STPs, tunnelling and underground construction projects can achieve significant environmental and economic benefits. Bentonite recovery minimizes waste and reduces reliance on virgin materials. Water recycling conserves this vital resource. Repurposing excavated materials further reduces environmental impact and lowers project costs.

An added benefit of CFlo's STPs is their portability since these plants require no major foundation for setup. This allows for quick deployment and relocation as tunnelling progresses, maximizing efficiency.

Dr. A. Bandyopadhyay, Chief Technologist at CFlo (CDE Asia Limited), emphasizing the importance of these advancements, says, "CFlo's closed-loop STPs represent a significant leap forward in sustainable tunnelling practices. By maximizing bentonite recovery, recycling water, and repurposing excavated materials, we are helping construction projects achieve their goals while minimizing their environmental footprint."

If you're undertaking a tunnelling project, consider partnering with CFlo to explore the value of closed-loop STPs. Our team of waste recycling experts can help you achieve sustainable and cost-effective solutions for your project.

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