Cinovec Lithium

Czech Republic

In 2016, Andrew Smith was appointed project manager by EMH and led a team completing extensive metallurgical testwork and process design that culminated in a successful Preliminary Feasibility Study (PFS) in April 2017. A particular challenge was developing a novel process route to economically extract lithium from zinnwaldite micas, which has never been done commercially. XRD analysis shows that the Cinovec and Cornish lithium micas are the same mineral species.

Cinovec is located in the Krusne Hore Mountains Czech border with Germany, 100 km NW from Prague, within a historic mining region where artisanal tin mining dates back to the 1300s.

The company completed 32 diamond holes averaging 400m depth, successfully validating earlier drilling results and adding lithium grade data to produce a JORC 2012 Mineral Resource Statement. The core samples were also used for metallurgical test work.

Metallurgical test work

At Cinovec, lithium is hosted within a mica called zinnwaldite, comprising a complex suite of elements including K, Fe, Ca, Si02 and fluorine.  Lithium in Cornwall is also hosted in these micas, which are unlike spodumene ores, currently the major mined source of lithium. There is currently no commercial production of lithium from micas, so it was necessary to conduct extensive metallurgical test work to develop a process flow sheet that would reliably and economically concentrate mica and extract battery quality lithium carbonate.

In support of the PFS, the project team, led by Andrew Smith, undertook extensive metallurgical test work at Nagrom and ALS in Australia, Wardell Armstrong in Cornwall and UVR and Anzaplan in Germany. ALS in Tasmania performed lock-cycle gravity analysis for tin recovery. ALS also performed the gravity test work for the Hemerdon tungsten mine in Devon.

Liberation: Initial liberation analysis was supported by Heavy-Liquid Separation (HLS) of minerals from each of the various lithologies. This was followed by detailed liberation, mineralogical and petrographic analysis using QEMSCAN. SAG ability test work was conducted at ALS on the three primary lithologies. Cinovec’s ore was determined to be amenable to single stage SAG milling, which forms part of the comminution design. Wardle Armstrong Cornwall conducted a Starkey SAG ability test along with standard bond ball and bond rod work indexes.

Mica concentration: Variability test work involved direct flotation and magnetic separation to obtain a Zinnwaldite concentrate ahead of roasting. The chosen flow sheet was tested in a lock-cycle test work programme conducted to simulate the gravity and magnetic recovery circuit component.

Lithium carbonate plant test work

Lithium extraction test work was conducted at both Nagrom and Anzaplan, Germany. Extracting the lithium from the concentrated mica involves a high temperature roast with reagents and a flux. The leach slurry is then purified by a complex hydrometallurgy circuit. The leached slurry is filtered to separate the pregnant leach solution from the residue. The leach liquor solution undergoes impurity removal steps to remove calcium, magnesium, fluoride and silica by double salt removal through chilling, purification by reagent addition to precipitate out impurities and adsorption.

Crude lithium carbonate is then precipitated from the pregnant liquor by further evaporation and addition of sodium carbonate. The crude lithium carbonate is re-dissolved to form bicarbonate solution which is filtered and purified by ion exchange before pure lithium carbonate is re-crystallised. The test work programme produced lithium carbonate with a purity of >99.5% (using bicarbonation).

Note: British Lithium has no ongoing involvement with EMH or the Cinovec Project which is owned by European Metals Holdings Limited.