New technology helps prevent tailings dam collapses
Mine tailings, or the material left over after the desired product is separated from an ore, pose a significant challenge to the environment and human health and safety. Not only are tailing materials highly toxic if released, they can also cause erosion and sinkholes and contaminate ground water and soil. Tailings are typically stored in an earth-fill embankment called a tailings dam, which may grow to considerable heights (60+ m). However, such dams are notoriously unstable, both during the mining operation and after the tailing reservoir is dismissed. In fact, over 30 tailings dam failures were recorded between 2000 and 2015, resulting in human fatalities and catastrophic damage to the environment. The key to preventing such failures is to ensure that the dam is stable. For this purpose, Studio Prof Marchetti, an Italian technology company, has developed Medusa DMT, a new automated tool that provides highly accurate soil data, useful in assessing the stability of a tailings dam. “Providing highly accurate geomechanical and geophysical parameters, Medusa DMT helps prevent dam collapses,” says Alessandra Saccomandi, project coordinator of the EU-supported MEDUSA project and partner of Studio Prof Marchetti. Today, thanks to the support of EU funding, the Medusa DMT solution is a step closer to marketisation.
Advancing the industry standard
For over 40 years, the flat dilatometer test (DMT) has been the industry standard for testing and characterising soil stability. Based on pressure-displacement measurements, DMT is an in situ deformation test. This means results are more closely related to soil stiffness than results derived from standard cone penetration tests, which essentially test the soil near failure and are thus strictly related to soil strength. The operative modulus estimated from DMT, on the other hand, provides very accurate predictions of settlements and displacements, which govern geotechnical design. “DMT provides information on stress history, which has a major influence on soil behaviour,” explains Diego Marchetti, owner, Studio Prof Marchetti. “Knowledge of this stress history is fundamental to obtaining realistic predictions on settlements and liquefaction resistance.” Medusa DMT enhances the standard dilatometer by combining it with hydraulic automation and a measuring system. The result is a new solution that autonomously performs DMT testing without the need for a trained operator. Furthermore, the fully automated dilatometer provides repeatable measurements, thus enabling additional measurements that were not possible using traditional pneumatic equipment. “Medusa DMT is an innovative flat plate dilatometer that provides quick, precise, simple and cost-efficient measurements of the most relevant parameters used in geomechanical and geophysical stability analysis,” explains Marchetti. “This allows one to more readily identify potential stability problems, send out alerts and take necessary preventative action.”
Ready for marketisation
With the support of EU funding, Studio Prof Marchetti has been able to test Medusa DMT’s validity and prove its effectiveness. Following several successful tests of a prototype in several European and South American mining operations, the company is now investigating the potential for large-scale production of the device. “From improved simplicity in operation to an impressive increase in accuracy, these tests have proven the many expected advantages of using Medusa DMT,” adds Saccomandi.
Keywords
Medusa, tailings dam, mine tailings, tailing materials, mining, flat dilatometer test, DMT