Breakthrough solution reduces risks and costs in tailings management

As ore grades decline, more water is needed to process more material just to keep up with production rates. This creates more water and tailings to manage. Looking at the two biggest environmental risks, contamination of ground water and tailings dam failures are the biggest environmental risks associated with mining.

Operating in these arid areas with strained water supplies creates the possibility of more regulation, it amplifies the cost of running a mine, and it brings our industry into possible conflict with local communities. The latter can mean reputational risk and negative media exposure, and it increases mining’s difficulty in attaining a social license to operate. 

But is it possible for you to lessen water consumption in the your mine without compromising productivity? The short answer is yes. But it requires creative thinking and challenging the old mining processes to reach that answer. One cost competitive solution consists of EcoTailsTM and our AFP-IV® Colossal™ filtration solution. Together they eliminate the need for a wet tailings dam and allow for reuse of almost all process water. Even on large mining operations.

Dry tailings – less for you to worry about

Tailings dams have been a part of mining operations for decades. However, every year dams will leak, causing environmental damage to the surrounding areas. Furthermore, dams require upkeep and maintenance, leaving mine owners with high continuous costs for management. This incentivises moving towards using dry stacked tailings instead.

While dry stacked tailings do not have the disadvantages of tailings dams, they do require large amounts of space for dewatering equipment that can be difficult to achieve for large-scale mining operations.

For instance, to provide the necessary filters for a mining operation that produces 100,000 dry tonnes of tailings a day, it would require the space of multiple football fields when using old technology. In addition to this, it would also require an unsustainable amount of piping, valves, pumping, conveyance and maintenance. To reduce the number of filters, we decided to develop an economically viable system for dewatering high tonnages of tailings.

Cut costs by reusing up to 95% of your water 

To make it economically viable for large mining operations to use dry stacked tailings, we developed the AFP-IV® Colossal™ filter. This filter can dewater high tonnages to the scale of more than 120,000 tonnes of tailings a day. Not only does this system require significantly less space than old dewatering equipment. It also increases the amount of water returned to the plant for reuse, as well as decreases the amount of water lost to evaporation and seepage.

To prove the operating and financial benefits of their large format tailings dewatering facility, we partnered with a large mining company in Chile and installed a complete tailings filter system to process approximately 10,000 tonnes per day of whole tailings. A full-scale implementation of this technology would allow mines to operate with a water make-up ratio of 0.2 m3/tonne, compared to traditional sand dams with a water ratio of 0.7 m3/tonne.

By enabling mines to reuse between 90-95% of their process water, the filter solution would thus enable mining companies in Chile to reduce their fresh water intake by more than 70%.

“With this breakthrough development in filtration technology, we have made the operating and capital costs of dry stacked tailings competitive with traditional technologies for large scale mines,” says Todd Wisdom, Director of Tailings Solutions in FLSmidth.

Dry stacking resists earthquakes, climate instability

Another solutions with staggering possibilities is EcoTails that we have developed in cooperation with Goldcorp. EcoTails blends filtered tailings with waste rock in transit and creates a geotechnically stable product called GeoWasteTM. When blended properly, GeoWaste is easy to convey and has a high strength when stacked. EcoTails and GeoWaste make dry stacking possible for large scale mining, even in areas with high seismic activity. With climate change and increased weather instability, the risk of dam overflows is significantly higher. The consequences of dam breaches and overflows are disastrous, and it is crucial both from an environmental and economic standpoint to mitigate this risk.

“This is the essence of sustainable productivity improvement: miners are challenged by investors to deliver good returns that are also environmentally and socially responsible. Water management will be the limiting factor for many mines in the coming years. With less risk and more water recovered, EcoTails is competitive on a sustainable and total cost basis – that should be interesting for the industry at large,” says Todd Wisdom.