Kayelekera is a sandstone-hosted uranium deposit associated with the Permian Karoo sediments and is hosted by the Kayelekera member of the North Rukuru sediments of the Karoo. The mineralisation is associated with seven variable oxidised, course grained arkoses, separated by shales and chocolate coloured mudstones. Uranium mineralisation occurs as lenses primarily within the arkose units and, to a lesser extent, in the mudstone units. The lowest level of known mineralisation currently is at a depth of approximately 160m below surface.

Kayelekera is situated close to a major tectonic boundary between the Ubendian and the Irumide domains. The Ubendian domain consists of medium to high-grade metamorphic rocks and intrusions cut by major NW-SE dextral shear zones and post-tectonic granitoid intrusions dated at 1.86Ga (Lenoir et al., 1995). These shear zones may well have been reactivated during and after deposition of the Karoo sequence, since many major brittle faults that offset the Karoo-aged rocks have the same orientation.

Mineralisation at Kayelekera is hosted in several arkose units where they are adjacent to the Eastern Boundary Fault zone. The mineralisation forms more or less tabular bodies restricted to the arkoses, except adjacent to the NS strand of the Eastern Boundary fault at the eastern extremity of the pit. Here, mineralisation also occurs in mudstones in the immediate vicinity of the fault. It can be seen that the highest grades correspond to the intersection of the eastern and Champanji faults. Mineralisation grade and tonnage declines with lateral distance from these faults.

Secondary mineralisation tends to be concentrated in vertical fractures and along the contacts between mudstone and arkose and is restricted to the upper parts of the orebody Primary reduced (i.e. carbon and pyrite-bearing) arkose ore accounts for 40% of the total ore. About 30% of the mineralisation is hosted in oxidised arkose (i.e. lacking carbon and pyrite) and is called oxidised ore. 10% of mineralisation is termed “Mixed Arkose” and exhibits characteristics of both primary and secondary arkose mineralisation types.

Uranium in primary ore is present as coffinite, minor uraninite and a U-Ti mineral, tentatively referred to as brannerite. Modes of occurrence include: disseminated in matrix clay, included in detrital mica grains and intimately intergrown with carbonaceous matter. Individual grains are extremely fine, typically <10µm. Coffinite and uraninite also show an association with a TiO2 phase, possibly rutile after detrital ilmenite. It is possible that uranium deposition was accompanied by leaching of Fe from detrital ilmenite and precipitation of a TiO2 polymorph.

The Kayelekera Mineral Resource area extends over a strike length of 1,600m and includes the 300m vertical interval.

Mining is planned to commence in line with the start-up of the processing plant and will initially utilise the high-grade material that is currently on the run-of-mine (RoM) pad to compliment the plant feed. The mining and pit design is relatively simple with mining limited to ~100m depth and very shallow pit wall angles to account for the layered mudstone materials.

Mining is proposed to be completed by conventional open pit mining practices. The parameters associated with the Whittle pit optimisations and open-cut mine operation are as follows:
- Contractor mining;
- Dilution has been accounted for through the geological model used (multiple indicator kriging);
- Pit slopes – 21deg.

The process used at Kayelekera incorporates high density ion exchange (resin-in-pulp), membrane-based acid recovery and conventional yellow cake and tailings operations. The processing plant operated successfully for five years prior to the asset being placed on care and maintenance. Consequently, the metallurgy of the ore and the performance of the process plant and incorporated process are well understood.

The Study assumes the same processing method will be used and that the operation will be acid constrained, based on the capacity of the acid plant located at the site and hence the ore processing rate used is slightly lower than the processing rate achieved prior to the cessation of operations.

Acid Plant
An acid plant is located on site which has a capacity to produce 240tpd of acid (budget assumes 230tpd). The acid plant was decommissioned for the C&M period and will need to be recommissioned as part of Restart.

In addition to the acid plant ........