Tailings storage facilities, which hold the residues of mineral processing, can pose major risks to the natural and social environment. Failures of these dams have received significant attention in recent years, following several high- profile disasters. Some countries, such as Brazil, have now mandated increased safety standards, and in some cases, the complete decommissioning of high-risk dams.

At the same time, tailings can also hold interesting opportunities, as valuable materials may still be extracted from these dumps, thanks to more advanced extraction techniques.

Either way, the remining of tailings, whether for dam decharacterisation or reprocessing, has become a prominent part of mining, says minerals processing equipment supplier IHC Mining.

The company, which is part of marine technology supplier Royal IHC, has developed a range of solutions for tailings dewatering and mineral processing. One of its latest innovations is the semi-mobile tailings slurrification unit (TSU) for slurry generation and transport to a destination site.

The starting point for the design of the TSU was to improve the transport capabilities of a tailings rehandling operation, says IHC Mining consultant Stefan Groenheide. “A single TSU and a slurry pipeline can do the same amount of work as about ten mining trucks, thereby reducing the costs of transport per in situ cubic metre tailings enormously. Not only can the TSU replace an entire fleet of mine trucks, but this also positively impacts on the carbon footprint of the operation. Furthermore, the TSU is fully electrical driven.”

At the time of writing, the first TSU test unit was being assembled and tested, before transport of the equipment to a mine site for testing in a live setting.

“We have received a lot of interest, especially from the mining industry in Latin America, where tailings problems are quite pressing. But we have also received interest from other parts of the world, where tailings are relocated and rehandled, which may yield valuable resources,” marketing manager Wendy Heesbeen tells Engineering News & Mining Weekly.

The TSU is capable of transporting 125 m^₃/h to 250 m³/h of in situ tailings. The unit is equipped with one of Royal IHC’s high-pressure, high-efficiency pumps and is suited to work with existing machinery, such as excavators and dozers.

There is a growing awareness of the need for water sustainability within organisations in the mining industry. Optimising and controlling water use is particularly important as many mining sites are facing limits on freshwater intake and discharge qualities. The TSU can use water that is present in mined out pits for dilution. This allows for a closed water loop.

In addition to the positive impact on the carbon footprint, IHC Mining states that the TSU offers several additional benefits: as it is remotely controlled, there is no need for personnel in the dams, resulting in increased operational and personnel safety. Efficiency gains include a lower cost per tonne, compared with truck and shovel and, owing to the automatic pump control system, a minimal downtime and lower risk. The TSU has a modular and therefore easy transportable design.

IHC Mining also has several other slurrification options with transport tailings, offering a more environmentally responsible and efficient method, compared with conventional mining equipment such as truck and excavators. For example, its dry mining slurrification unit – which provides a solution for high-capacity tailings rehandling operations – and a range of TT-Pump dredging units.

IHC Mining understands that tailings management requires a careful approach and integrated solutions in which all aspects relating to rehandling, water management and reprocessing are taken into account in a sustainable way.

Heesbeen states that IHC Mining’s extensive knowledge about soft sediments, slurry transport and rheology has allowed it to develop several unique technologies for water management and the beneficial reuse of tailings to create circular solutions.