The preliminary test work is being undertaken at SGS Lakefield in Ontario, Canada, which has a Re-2Ox pilot plant.

In February this year, Granada Gold said it had intercepted higher-grade gold at the site that could potentially change the economics of the project. The following month, while continuing to explore for gold, it discovered significant amounts of rare earth elements and alkali metals, including scandium, rubidium and caesium. The size of this deposit has not yet been confirmed, but the company may be able to mine these mineralised zones to access the gold-bearing material.

Following the latter discovery, the company made a joint announcement with Canada Silver Cobalt Works that there was potential for these rare earth and alkali metals to be extracted using the Re-2Ox process.

Canada Silver Cobalt Works' proprietary Re-2Ox process uses a hydrometallurgical approach to selectively leach metal. Rubidium is a particular focus of the Re-2Ox test work on the material from the Granada project as it showed particularly high assays. A 10kg sample of drill core is being studied, and so far the results indicate that rubidium is likely in the micas and/or potassium feldspars. The companies noted: "Distinct rubidium minerals do not commonly occur in nature and are almost always associated with feldspars and micas."

There will be two stages to the test work at SGS Lakefield, which will target rubidium: firstly, flotation followed by leaching using the Re-2Ox process, and secondly, straight leaching using the Re-2Ox process.

The companies noted that rubidium has numerous applications; for example, rubidium salts can be used as an electrolyte to improve the efficiency cycle of sodium-ion batteries. Sodium-ion batteries have applications in stationary storage and cost approximately 10-20% less than lithium-ion batteries; they are not used in battery-electric vehicles.

Frank J. Basa, CEO of Canada Silver Cobalt Works, commented: "Granada currently expects that rubidium will be treated as a zero-cost, by-product alkali metal recovery from Granada's gold mineralised resource. The preliminary test programme will evaluate the potential recovery of rubidium mineralisation and the subsequent amenability of the Re-2Ox process for the leaching and production of rubidium salts. Granada Gold intends to review the viability of suppling rubidium salts as a by-product of gold processing for evaluation into the new fast-evolving sodium-ion storage battery market."