An environmental masterstroke

FLSmidth’s E-Volute feedwell technology has delivered a 27 per cent reduction in flocculant consumption for a copper-gold miner.

When an Australian copper-gold miner approached FLSmidth to replace an ageing feedwell, the original equipment manufacturer (OEM) came up with an inspired solution.

FLSmidth turned to its engineering team to develop a bespoke solution based on the OEM’s E-Volute feedwell technology.

Feedwells support the thickening process, where slurries are separated into two forms: a dense slurry containing most of the solids from the ore, and an overflow of largely clear water.

At this particular mine site, copper and gold are recovered using a conventional single-line grinding and flotation circuit to produce a bulk copper-gold sulphide concentrate. Waste from the process is thickened and deposited in a tailings dam.

The mining company initially wanted a like-for-like solution, but when FLSmidth compared the existing design with what was possible with the OEM’s E-Volute feedwell and E-DUC autodilution mechanism, the latter option was a clear winner.

Testing demonstrated that the newer design would generate significant savings in flocculant consumption, while also increasing underflow density to improve water recovery.

Testing demonstrated the upside of the newer design; however, implementing the solution wasn’t so straight forward.

“The unique design of the traction thickener placed constraints on the design envelope,” FLSmidth project engineer Katie King said. “This posed a challenge when it came to keeping the new feedwell within the allowable space, while still ensuring an adequate radius for optimum functionality.”

Finding the right solution required FLSmidth to overlay the new feedwell design onto 3D modelling of the existing structure.

“The 3D modelling of the existing structure from the original as-built drawings allowed the new feedwell design to be accurately visualised and positioned, utilising the existing support brackets,” King said.

“This also allowed us to ensure the rotating bridge would not impact the feedwell during operation, especially at the mix trough, as its footprint is considerably larger than the original.”

Optimising the feedwell design also required careful positioning of the feed pipe, which is located within the caisson and fed centrally, in contrast to most feedwells which are fed by a pipe hung underneath the bridge.

“The design of the mixing trough and position of the flocculant pipe, feed pipe, and nozzle each had to be specifically designed to generate the necessary conditions for the feedwell to operate efficiently,” King said.

This led to FLSmidth designing, engineering and installing a completely customised feedwell solution for the customer, alongside providing additional on-site technical resources and expertise.

FLSmidth’s promise to deliver an improved feedwell solution was validated by the operational and environmental benefits the miner has enjoyed.

The miner has experienced a 27 per cent reduction in flocculant consumption, a two per cent by-mass increase in underflow density, and a six per cent reduction in water to tailings. This has enabled the company to recoup the value of the feedwell upgrade in 10 months, thanks largely to the reduced flocculant use.

“The results have been phenomenal and the 27 per cent flocculant reduction is huge,” King said. “Reducing flocculant consumption by that much would reduce the cost of the thickener operation significantly.

“It means the feedwell is mixing a lot more efficiently and waste is reduced, leading to a more environmentally-friendly operation. The miner can achieve the same if not higher throughput with less resources.”

FLSmidth’s feedwell solution has delivered significant environmental, social and governance (ESG) benefits, enabling the miner to better optimise its water usage and mitigate business continuity risks around water security.

“The new feedwell has actually overachieved expectations in terms of density due to improved solids distribution in the tank, with more flocculant savings to come,” FLSmidth global product manager – thickening Craig Gilbert said.

“It’s a great example of what our innovative E-Volute feedwell technology can achieve, as well as the design expertise of our engineers in customising solutions to specific application requirements.”

While this is not the only E-Volute feedwell currently operating on an Australian mine site, the uniqueness of the solution demonstrates not only FLSmidth’s design and engineering capability but also the OEM’s ability to work closely with its partners to think outside the box and devise a strategy that can deliver operating and environmental outcomes previously not thought possible.

And FLSmidth has ambitions to further expand its deployment of E-Volute feedwell technology across Australia.

“This is not a standalone success story,” King said. “There are other instances where we have been able to reduce flocculant consumption and increase a mine’s cost savings while improving their ESG footprint.

“Retrofitting older thickeners with the E-Volute design is what we do, and this is a technology that we continue to evolve and promote to our customers.”

This feature appeared in the June 2024 issue of Australian Mining.

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