Mechanical Separation Technology Could Prevent Brazil-Style Dam Breaks

According to a scientist from TU Bergakademie Freiberg, mechanical separation technology could prevent dam failures such as those that have occurred in recent years in Brazil.

"As experts in separation technology, we have developed techniques that can be used to dewater sludges and mine tailings, making it possible to store residual materials in a completely different way," said Prof. Urs Peuker, head of the Institute of Mechanical Process Engineering and Mineral Processing at TU Freiberg.

Until now, the residual materials from ore extraction have been collected in large tailings ponds and stored there. These artificial ponds can cover areas of several square kilometers and contain millions of cubic meters of sludge. The associated retaining dams are then up to 30 meters high. A dam on one such tailings pond failed a number of weeks ago in the Brazilian state of Minas Gerais, costing the lives of over 100 people. Alternative solutions are being researched at TU Bergakademie Freiberg.

Professor vor Flipchart und Maschinen"The concept of so-called 'Dry Tailings Stockage' is more sustainable because, after filtration, the residual substances are no longer suspended in large quantities of water, as the liquid has already been separated and the solid material can be stored on stockpiles in a dry form. This material has the consistency of slightly moist sand," explained Prof. Peuker, who holds several patents for filtration technologies. "Previously, the investment in this processing technology was too expensive for mining companies – it was easier to simply store the sludge. In view of the increasing future costs of securing dam stability over the long term and the potential dangers of dam failure, the filtration techniques have now become cost-effective." Storage of the filtered solid materials requires less space and can be better sealed against environmental influences, so that no pollutants are released into the environment. The first ‘Dry Tailings Stockage’ systems have been installed in recent years. The impetus for this was the recovery of the processing water, as the associated mining operations were operating in very dry areas or had only received limited water rights.

The ‘Mechanical Liquid Separation’ expert group of the Association of German Engineers (VDI), which is coordinated by Prof. Peuker, deals with the separation of dispersed material systems in the size range of 10 nm to 10 mm. Both solid-liquid material systems and liquid-liquid material systems can be separated. The main focus is on both mechanical separation processes – such as e.g. sedimentation, filtration, grading and sorting, with gravity-based and centrifugal-based separation – and separation processes for particle systems using electric or magnetic fields.

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Contact person: Prof. Dr.-Ing. Urs Peuker, Phone +49 3731 / 39-2916