Weir urges industry to dewater tailings responsibly

Image: Weir Minerals.

Weir Minerals is looking at different methods to improve the management of tailings amid increased pressure in this area.

One vital component of responsible tailings management strategy is de-water tailings, to reduce the water that needs to be transported from a process plant to a tailings storage facility (TSF).

“Dewatering tailings can be a difficult process, however, when undertaken successfully, it can deliver significant benefits to mine operators,” Weir Minerals regional senior product manager Mike Swintak said.

One of the biggest benefits of reduced water content is a decreased volume of tailings slurry, allowing for smaller pipelines and pumping equipment while minimising power requirements.

Thickened tailings and paste can improve TSF stability and lessen their footprint, and in some instances extend mine life for TSF capacities that are limited by regulatory or other environmental considerations.

Weir Minerals stated it was also becoming increasingly common to use thickened tailings for underground mine backfill to increase productivity and reduce mine cycle times, as well as surfacing TSF disposal volumes.

This improves underground mining conditions thanks to decreased water and slimes handling.

Correct tailings containment reduces the risk to people and the environment, and thickened tailings facilities are easier to rehabilitate when decommissioning a mine, according to Weir Minerals.

“When tailings are not properly managed, the results can be lethal,” Swintak said.

“It is vital that mine operators have a clear understanding of key risks and considerations related to this process, in particular, tailings dewatering.”

As every mine site is subject to different environmental, regulatory, capital and operating cost constraints, cost is often a key consideration for operators when establishing a TSF.

For mine sites based in challenging topography, such as mountainous regions or other environmentally sensitive landscapes, TSFs may need to be built further away from the processing plant.

This can result in slurry being transported longer distances or across higher elevations. Dewatering tailings is a suitable option in scenarios like this as it means less slurry needs to be moved, reducing operational costs.

Some operations also produce highly diluted tailings which require extensive dewatering to reach the desired level of thickness, while other slurries contain extremely fine particle solids, which can also be difficult to manage.

Large mine sites or sites with complex ore bodies can produce many types of tailings waste slurries, which may require various methods of treatment.

Across this range of situations, operators must determine all associated costs and assess the level of dewatering required to achieve the most suitable solution for their site.

While some mines are in a position to increase their TSF size, many are not and must establish a viable dewatering process, which can be costly.

Operators may need to develop a suitable strategy for transporting waste material, as tailings that are too thick to be pumped may need to be transported by a conveyor system or truck.

When a mine site reaches the end of its life and operators start the decommissioning phase, TSFs must be dealt with according to regulatory and legal requirements.

Thickened tailings waste is beneficial when operators restore old mine sites to their former state as they can be covered with overburden and re-planted with suitable vegetation.

Swintak said Weir has invested heavily in its tailings management capabilities and assesses every mine site on a case by case basis when providing TSFs.

Weir can also perform intensive pilot plant testing at its Australian technical centre in Clayton, Victoria, to test tailing samples and investigate the best way to process them.

“From developing flow sheets and process requirements to supplying equipment, we provide customers with peace of mind through our tailings solutions,” Swintak said.

Weir believes dewatering tailings has a fundamental role to play in gaining a better understanding of tailings and improving methods of containment and storage.

The company is developing a tailings dewatering solution, which allows operators to pump slurry containing an extremely high percentage of solids. This is scheduled to launch in 2020.

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