European Metals Holdings Limited (ASX:EMH; AIM: EMH; NASDAQ: ERPNF) has released promising results from locked-cycle testwork (LCT), a metallurgical processing assessment conducted on ore concentrate extracted from the company’s flagship Cinovec Lithium Project.

Such is the significance of these results that the company’s shares surged to a high of $1.39 in morning trading, representing an increase of about 20% compared with the previous day’s close of $1.15.

Unfortunately, as the broader sharemarket shed more than 100 points, some of these gains were lost, but its current price still reflects a significant positive rerating on a tough day for investors.

The Cinovec Project, located on the German border of the Czech Republic, is the largest hard-rock lithium resource in Europe, containing lithium-bearing mica known as zinnwaldite which the company intends to refine using a number of processes initially outlined in a pre-feasibility study (PFS).

92% lithium recovery slightly exceeds PFS flowsheet

The principal objective in terms of commissioning the LCT was to confirm the flowsheet for the processing of zinnwaldite concentrate from Cinovec run-of-mine ore.

The LCTs differ from previous proof of concept and optimisation testwork conducted during the Cinovec PFS.

LCT confirms the effect of recycle streams that carry some lithium and other alkali metals on the overall recovery of lithium from the pregnant leach solution resulting from the water leaching of the roasted zinnwaldite concentrate and the ability to produce battery-grade lithium carbonate.

The LCTs have processed zinnwaldite concentrate from drill core samples taken from the southern part of the Cinovec orebody, representing ore that will be processed in the first five years of the mine plan.

The recovery of up to 92% of the lithium in the concentrate sample compares favourably with the similar recovery in the PFS flowsheet of 91%.

However, this new recovery of up to 92% is before lithium plant DFS/FEED optimisation testwork that will be targeted in specific process areas, and this is expected to increase hydrometallurgical recovery in the lithium plant to more than 92%.

Separate metallurgical testwork on the Front-End Comminution and Beneficiation (FECAB) circuit is underway and is designed to improve upon the lithium recovery of 90% from ore to concentrate.

Cheaper and cleaner workaround for fluoride removal meets EV specs

Ahead of the LCTs, an alternative process to remove fluoride was tested in order to meet the Electric Vehicle grade specification of less than 50 ppm in the lithium carbonate.

The previously announced PFS flowsheet proposed the removal of fluoride by the use of activated alumina, a relatively costly step because the activated alumina was not considered suitable for regeneration.

This step has been replaced by a cheaper and cleaner two-step process involving chemical precipitation and ion-exchange.

This new method of fluoride removal has been proven to be highly effective, easier to implement and is less costly as the ion-exchange resin can easily be regenerated and re-used many times.

In addition to fluoride, the zinnwaldite mica at Cinovec contains alkali metals, including potassium, rubidium and caesium, which are leached into solution and will build up in the plant if not removed from the circuit.

The LCTs have proven conclusively that unwanted alkali metals can be removed preferentially by control of temperature, pH, solution saturation and crystallisation.

It has been confirmed that these alkali metals will not build up due to recycling processes within the plant.

The removal of these deleterious elements within four LCTs with minor loss of lithium is a major step towards confirmation of process plant design.

Discussing the group’s impressive progress in terms of identifying of all processing methods, executive chairman Keith Coughlan said, “In a significant vote of confidence for our Pre-Feasibility Study (PFS), the proposed process methodology has been confirmed by excellent locked-cycle test results which also include new processes involving recycle streams.

"The robustness of the process was further confirmed by the stabilisation of the process streams, enabling the work to stop after only four of the six test cycles were completed.

"The recovery of up to 92% of the lithium in the zinnwaldite concentrate at this early stage of DFS testwork is very promising for increased recoveries during the planned process optimisation work.

"Further, an improved fluoride removal step which is cheaper and cleaner represents only the beginning of further optimisation work which we expect will result in greater lithium recoveries and even stronger economics for the Cinovec Project.’’

From a processing perspective it is also important to note that the current LCTs have been commissioned to confirm the lithium carbonate processing flowsheet.

The Cinovec Project has optionality to either produce a battery-grade lithium carbonate product or to further process the lithium carbonate to produce battery grade lithium hydroxide.

As the Front-End Engineering Design FEED program continues, testwork should be commissioned to confirm the optimal production route for lithium hydroxide and to produce marketing samples for prospective offtake partners and environmental samples to assist in permitting approvals.