The global energy transition is driving an exponential increase in mine waste : the total amount of tailings ever produced by copper, manganese, lithium and nickel is in the order of 200 billion tonnes. The is estimated to increase to 1000 billion tonnes between 2020 and 2050.
At the same time as demand for battery metals is growing, ore grades are declining and the average mine lead time continues to trend upwards, reaching 17.9 years for mines coming online in 2020-2023 compared with 12.7 years for mines that started up 15 years ago, according to S&P Global.
Many existing mines are extending the LOM to cover this supply shortfall, but it comes with significant tailings management challenges. As tailings storage facilities (TSF) reach their capacity, managing the additional tailings burden can ultimately determine whether production can continue.
One common solution is to create additional capacity in the TSF by simply transporting the waste using the truck-and-shovel method to another pond. This is messy, expensive, inefficient and risky.
Weir has developed an alternative solution in which the tailings are pumped by its submersible dredge pump. Specifically developed for tailings applications, the Multiflo® Mudflo® hydraulic submersible slurry pump has a flow range capability of between 150m3/hr – 1,200m3/hr and can be operated by a single operator. Compared with the truck-and-shovel method, it significantly reduces operational costs per cubic metre of mud pumped.
Operational flexibility
One of the main drawbacks of the truck-and-shovel method is its inefficiency: an excavator perches on the dam wall, picking up the material one bucket load at a time, then dumped into a truck and taken away. It’s a slow and complex process with many moving parts that needs to be carefully coordinated, which means not only is it labour intensive, it also involves significant downtime.
In contrast, the Multiflo® Mudflo® pump can be mounted to a barge or, for a less capital-intensive alternative, it can be mounted to an excavator with a quick hitch to enable easy attachment. The operator can then move around the dam wall easily and quickly, targeting mud and sludge removal from the areas of the pit it’s needed most.
One of the challenges when trying to shift the solid or semi-solid tailings is that the viscosity can change within the same TSF. The mess created by the mud sluicing around in the back of the trucks, spilling and damaging the haul roads, all contribute to higher operating costs and increased fuel consumption and carbon emissions.
Pumping the material directly out of the TSF via the excavator-mounted Multiflo® Mudflo® pump eliminates spillage and minimises the risk to the environment. Moreover, if the material is quite viscous it can be diluted by putting a sparge ring on the pump, which essentially adds water to the material to make it more soluble.
Credit: Weir
Pump design
In designing and developing the Multiflo® Mudflo® hydraulic submersible slurry pump, Weir leveraged its full range of WARMAN® material compositions to ensure it’s able to handle whatever product needs to be pumped. The Multiflo® Mudflo® pump features Weir’s Ultrachrome® A05, which contains high chromium white iron and delivers exceptional wear life.
Moreover, the Multiflo® Mudflo® pump features twin hydraulic cutters with ESCO® Ground Engagement Technology (GET), providing industry-leading wear life and impact resistance. Each cutter is also fitted with ESCO® teeth that utilise the two-piece Ultralok® tooth system to prevent premature breakage, avoid tooth loss and protect the integral locking system to ensure continuous operation of the pump.
Unrivalled results
Weir was approached by PT Putra Perkasa Abadi (PPA), a full- service Indonesian mining contractor, to develop a solution for its customer, PT Borneo Indobara (BIB) coal mine, to help maintain of the site’s sedimentation dams.
The customer needed to remove over 25,000m3 of mud from their sedimentation dams. The tonnage of mud at the BIB site presented environmental and production risks as the dams were reaching capacity and were at risk of flooding during seasonal periods of high rainfall. PPA needed to find an alternative solution to the equipment intensive operation – several 30 tonne excavators and multiple Articulated Dump Trucks (ADT) – it had previously employed to remove the mud.
Weir developed a solution that combined the Multiflo® Mudflo® hydraulic submersible slurry pump with the Multiflo® MF-S125HV booster pump to transport the slurry. The Multiflo® pump units ultilise specially adapted Warman® AH® 8/6 pump wet ends driven by a Caterpillar® C18 diesel engine. The slurry had a specific gravity (SG) of 1.3kg/m3, with excursions up to an SG of 1.6 during operation. This required a total of three booster pumps to transport the slurry over two kilometres away into an unused void on the site.
The solution allowed BIB to reduce their mud processing time by 60%, reduce their carbon emissions by 117 tonnes and, compared to the truck-and-shovel method, it was estimated to be up to 13 times more affordable because of the reduced operating costs.
Maintaining a social license to operate
Miners typically require a suite of site-specific solutions to safely and efficiently manage their tailings and, ultimately, maintain their social license to operate.
There are complex, capital intensive solutions to increase TSF capacity, some of which require limiting or stopping production altogether. Weir’s excavator-mounted Multiflo® Mudflo® hydraulic submersible slurry pump sits at the other end of that spectrum; it isn’t capital intensive, it’s easy to deploy, provides operational flexibility and typically replaces a much more operationally intensive solution.
It is, in short, a ready-made solution for a challenge that’s becoming increasing prevalent in the industry all around the world.
