Imerys British Lithium Processing

Imerys British Lithium’s processing engineers have successfully beneficiated Cornish micas using our unique process to produce a lithium concentrate grading in excess of 1.2% Li with a Li recovery over 90%.

Alongside the mineral beneficiation, we have also conducted numerous low-temperature calcination trials to mobilise Li as well as subsequent leaching and precipitation tests to produce battery-grade lithium carbonate.

Metallurgical scoping studies on the 10 – 100kg scale have provided confidence in our process route and identified opportunities for further optimisation. These optimisation routes are now being assessed as part of an Innovate UK grant. A 13t bulk sample, taken in December 2020, was processed by Wardell Armstrong to determine grindability, carry out desliming trials and produce feed samples that are now being processed further at our mineral processing and lithium refinery facilities.

Extensive mineralogical analysis carried out by Petrolab has shown the other major minerals within the granite include quartz, feldspars, other micas and in some areas kaolinite (china clay), topaz and apatite. Also found in our deposit are various iron and titanium oxides as well as, locally, cassiterite and copper minerals.

Crucially, the grain size distribution of Zinnwaldite in our Li deposit is relatively coarse. Mica liberation at a coarse size has many advantages, including lower grinding energy requirements, lower losses of minerals to the ‘slimes’ (<10µm) fraction and a lower environmental impact of tailings. Imerys British Lithium’s process flowsheet is uniquely positioned to take advantage of the coarse liberation size to realise these benefits.

To start building a geometallurgical framework, test work is ongoing to identify the importance of various geological domains within the deposit with regards to process response. We have also identified a number of element relationships that provide indicators of the grindability of ore, beneficiation properties and tailings characteristics. Our standard assay suites have been tailored to determine these relationships and also gain insight into the distribution of penalty elements