After experiencing blockages caused by rigid pipework with 90° bends, Cornish Lithium switched to flexible Corroline+ hoses for transferring a mica slurry treated with sulphuric acid at its hard-rock lithium mining demonstration plant near St Austell in Cornwall, England, Aflex Hose, a Watson-Marlow company, has reported.
At the Trelavour lithium project, the first stage of processing to produce lithium hydroxide monohydrate involves crushing, milling and refining granite ore from a former china clay (kaolin) pit to produce a lithium‑rich mica (zinnwaldite) concentrate slurry. This is followed by hydrometallurgical processing, where the mica concentrate undergoes acid leaching using sulphuric acid. Corroline+ hoses play a critical role in this stage, transferring acid slurries to drive the leaching reaction, as well as supporting downstream processes including impurity removal and by-product recovery, according to Watson-Marlow.
After experiencing problems with the flow of mica concentrate slurry due to bends in the plastic piping, Cornish Lithium needed a flexible hose solution that was tough enough to withstand the harshest operating conditions at Trelavour.
Since late 2024, Cornish Lithium has installed 15 Corroline+ hoses, from Aflex Hose, a Watson-Marlow company, to replace sections of rigid pipework across the hydrometallurgy stage. The hose’s smooth bore ensures uninterrupted flow of mica concentrate slurry in a cascade between process tanks. Their flexibility enables a more direct flow path, eliminating problematic bends and reducing the risk of sedimentation and blockage, the company says.
The Corroline+ hoses contribute to Cornish Lithium’s strategy of developing a sustainable mining process that is as efficient as possible.
Dai Moseley, Senior Process Manager for Hard-rock Minerals at Cornish Lithium, said: “We chose this process because its lower energy consumption and it makes preferable by-products. The hoses are allowing us to do this process as efficiently as possible. It’s a slow-moving process, moving from one tank to another in a cascade, so there’s barely enough velocity to keep the slurry solids in suspension. We want the same fall between tanks rather than the slurry settling at a 90° bend and causing us to clear the blockage. The hoses give us a more direct route than the rigid pipework, so it works better for us. When there’s a block, the Corroline+ hoses are easy to take apart and clean out.
“It’s a highly concentrated sulphuric acid at temperatures above 90°C to leach out all the metals from the mica and turn them into metal sulphates. It’s hot, acidic and abrasive so the conditions couldn’t be harsher for the hoses but we haven’t had an Aflex hose fail on us. They are the worst conditions in the plant, but the hoses handle it.”
Lined with polytetrafluorethylene (PTFE), Corroline+ provides excellent chemical and temperature resistance with an internally smooth bore to ensure fast flow, according to Aflex. Corroline’s flexibility also met Cornish Lithium’s process requirements.
The PTFE-lined flanges or Hastelloy BSPT threads of Corroline+ provide superior chemical resistance and reliability compared with convoluted metal hoses, the company says. A stainless helical wire is wound into the external convolutions, which adds to the kink resistance. A secondary helical wire embedded into the black, fire resistant, antistatic EPDM rubber cover, further adds to the kink resistance.
These qualities of Corroline+ have helped Cornish Lithium simplify maintenance and improve reliable long-term performance at its chemical separation stage, Aflex claims.
Chris Clasby, Engineering Manager at Cornish Lithium, said: “The hoses are durable and a solution to sharp bends in our pipework. The pipework was rigid with 90° bends which do not work with our slurry. We have been able to delete the bends with the hoses which are easy to dismantle, inspect and bend. We haven’t had any issues with kinks either.
“From a replacement perspective, the piping has been difficult and we are now in the process of changing to easier to use Corroline+ hoses. The Corroline+ hoses have been reliable. An unreliable hose would mean downtime for us and be potentially hazardous.”
Corroline+ hoses are part of a continuous 24/7 process which concludes with crystallisation and the production of battery grade lithium hydroxide monohydrate, which will be used to manufacture lithium-ion batteries for electric vehicles and consumer electronics.
The Trelavour demonstration plant is a scaled down mimic of the planned full-scale production facility, which Cornish Lithium aims to develop to produce around 10,000 t/y of lithium hydroxide monohydrate for approximately 25 years.