In the heart of Beijing, researchers at the University of Science and Technology Beijing are tackling a pressing issue for the mining industry: the management of sulfur-rich tailings. These waste materials, often a byproduct of metal mining, can generate acid during the filling process, compromising the structural integrity of cementitious backfill and posing environmental risks. Enter Qianru He, a researcher at the State Key Laboratory of High-Efficient Mining and Safety of Metal Mines, who is leading a charge to mitigate these issues.
He and her team have been exploring the use of alkaline agents to stabilize high-sulfide tailings, with promising results. Their study, published in the journal ‘Developments in the Built Environment’ (translated from Chinese as ‘Advances in the Built Environment’), delves into the compressive behavior and microscopic mechanisms of cementitious high-sulfide tailings backfill (CHSTB) under varying pH conditions.
The team prepared samples using different doses of fly ash (FA), sodium bicarbonate (SB), and calcium oxide (CaO) as alkaline agents. They then subjected these samples to unconfined compressive strength (UCS) tests, pH measurements, and scanning electron microscopy (SEM) analysis. The results were enlightening.
Fly ash emerged as a standout performer. “The strength of the CHSTB with fly ash was significantly higher than that of the other materials,” He noted. The optimal dose was found to be 3% fly ash, which achieved the highest UCS of 1.34 MPa. This enhanced strength is crucial for the structural integrity of backfill in mining operations.
The study also revealed that all CHSTBs maintained a strongly alkaline pH (≥ 10.8). However, the pH changes were minimal and dose-independent for fly ash and sodium bicarbonate. In contrast, calcium oxide significantly increased the pH, reaching up to 12.5. This finding is vital for understanding how different alkaline agents affect the chemical environment of the backfill.
SEM analysis provided further insights. CHSTB samples with 3% fly ash and sodium bicarbonate exhibited a denser microstructure, which contributes to their enhanced strength. This microscopic view underscores the importance of material selection and dosage in achieving optimal backfill performance.
The implications of this research are far-reaching. For the energy sector, which often deals with sulfur-rich tailings, these findings offer a pathway to more stable and durable backfill materials. This could lead to safer mining operations, reduced environmental impact, and potentially lower long-term costs.
He’s work also provides a valuable reference for the optimal concentration range of various alkaline agents. This information is crucial for engineers and researchers looking to enhance CHSTB and improve filling technology. As the mining industry continues to evolve, such advancements will be key to sustainable and efficient operations.
The study published in ‘Developments in the Built Environment’ marks a significant step forward in tailings management. It highlights the potential of fly ash and sodium bicarbonate as effective alkaline agents, paving the way for future research and practical applications. As He and her team continue their work, the mining industry watches with keen interest, eager to integrate these findings into their operations. The future of tailings management may well be shaped by these alkaline agents, offering a more stable, durable, and environmentally friendly solution.
