African Mining July 2022 | Page 11

GLOBAL NEWS • GLOBAL NEWS •

TAKRAF

DST system under construction for the safe and effective handling of iron ore process tailings recently supplied by TAKRAF Brazil to Mineração Usiminas . with evolving mining conditions , mean that the safe and effective handling and deposit of tailings , whilst also considering the environment , is of ever-greater importance . Challenges include the considerable space requirement when storing tailings in impoundments , while the catastrophic tailings dam failures , which have occurred , resulting in significant loss of life and environmental damage , are a stark reminder of the risks .

Exacerbating the situation are current mining conditions , which utilise advanced mineral processing technologies to allow lower grade ores to be processed . This results in a much larger quantity of tailings that need to be safely stored . This ever-increasing tonnage of generated tailings makes a conventional deposit in dams an increasingly significant burden curtailing the expansion and development of mine operations and further highlights the potential of DST as a viable and beneficial alternative .

TAKRAF

A “ typical ” flowsheet showing an example of TAKRAF ’ s complete DST solution .

A recent case study in Brazil shows that implementing a Dry Stack Tailings ( DST ) solution provides a safe and sustainable alternative to the storage of tailings in impoundments .

The recent commissioning of a Dry Stack Tailings ( DST ) system supplied by TAKRAF to a Brazilian mine offers a complete end-toend solution for safe and environmentally friendly mine waste management .

While the dry stacking concept is not new , with references as early as 1909 in Australia , technological advances have made DST an increasingly important alternative to conventional methods for handling mine waste , enabling mining companies to significantly decrease their risk profile .

Currently , the most widely utilised method of disposing of tailings ( waste material from the mineral extraction process ) is to pump the tailings slurry to a dedicated impoundment area ( pond or dam ) to allow sedimentation to occur and solids to settle out . Part of the water is then recovered and re-used in the process . However , the risks and challenges associated with this method , combined

Advantages of DST With DST , the moisture content in the tailings is reduced by a mechanised and controlled process to the point that it can be safely transported , deposited , and stacked as solid cake-form tailings . This yields several advantages over other surface-tailings storage options , including :

• Significant safety improvement with the risk of catastrophic dam failure and tailings run-out being eliminated .

• Transformation of tailings into a stable landform , and facilitation of rehabilitation and eventual closure .

• Smaller tailings footprint that can be employed in undulating or steep terrain .

• Suitability to areas of high seismic activity and areas where there is limited construction material to develop a conventional retention impoundment .

• Reduced requirements for make-up water in plants , principally achieved by recycling process water , and near elimination of water losses through seepage and / or evaporation .

As tailings processing is complex , a detailed understanding of and expertise in the different steps specific to the commodity and project location are required . All equipment must be designed and / or adapted to specific project requirements and to be integrated seamlessly into the overall system . As a result , TAKRAF adopts a comprehensive and holistic approach to the design of its DST systems , combining its expertise in dewatering ( DELKOR ) and materials handling ( TAKRAF ) with a dedicated team of mining , materials handling , and processing specialists . This two-fold approach – bottom-up , equipment supply , and top-down , planning a long-term sustainable system – enables the company to develop