Australian mining company A-Cap Resources reports that its ongoing exploration at the Letlhakane uranium project, located south of the Makgadigadi pan, in Botswana, has resulted in the discovery of a new zone of near-surface secondary uranium mineralisation to the west of the Gorgon Prospect.
The Letlhakane project involves the construction of Botswana’s first uranium mine in the area. A previous scoping study conducted on the site has confirmed a resource of 280-million tons, at 158 parts per million uranium oxide (U3O8) for 44 500 t of contained concentrate.
The new zone has now been defined in a 150-m-wide × 500-m-long north-west-trending corridor, which remains open to the east and to the west. Uranium mineralisation starts within 1 m of the surface and goes down to a depth of 8 m.
Although no assay results are available yet, trenching and visual inspection of hollow auger core has confirmed the presence of carnotite in calcretes and fine-grained, strongly weathered sedimentary rock of the Karoo Supergroup.
This discovery is potentially important as consulting company SRK’s 2008 scoping study on the Letlhakane uranium project showed that this style of mineralisation has the highest grades, the best metallurgical recoveries and is close to surface, making it the project’s most attractive ore type.
The study concluded that the shallow-lying ore will be extracted by conventional openpit mining equipment under a typical mining contract, where the contractor assumes responsibility for all earthworks to the point where run-of-mine production is delivered to the crushers.
The crushed ore will then be stacked on a purpose-designed leach pad and, by implementing alkaline heap leaching, solvent extraction and ion exchange will recover the U3O8.
Meanwhile, a hollow auger drill programme is currently under way to define the extent of the new zone and to provide material for assay to quantify the grades. These holes are not probed with a down-hole radiometric logger, as this method of drilling results in disequilibrium issues, preventing an accurate estimate of the grade in the near-surface environment.
A-Cap used the hollow auger drilling technique to estimate the grade of its Mokobaesi secondary resource, which currently hosts a deposit of about 11,3-million tons.
The project’s power will be sourced through a 10-km power line connecting to the Botswana State grid at the switch station in Serule, located between Francis-town and Palapye, and its water will be sourced from a borefield developed into aquifers within the exploration tenement. This has yet to be verified.
A-Cap MD Dr Andrew Tunks states that this is a promising discovery for the company as the near-surface, secondary mineralisation is its most profitable ore owing to its high grades and excellent metallurgical characteristics. “It is an exciting time for A-Cap as we are progressing through the metallurgical testwork programme that forms the backbone of the current feasibility study that is aiming for production of 1 000 t/y of uranium, with additional studies about to start on the primary ore,” he concludes.