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 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. The highest grades correspond to the intersection of the eastern and Champhanji faults. Mineralisation grade and tonnage declines with lateral distance from these faults. The lowest level of known mineralisation is currently 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 (from 8,895,300mN – 8,896,900mN) and includes the 300m vertical interval from 1,000mRL to 700mRL.

Orelogy was commissioned by Lotus to conduct the design and scheduling work for the open pit mining component of the Restart DFS.

The mining operation extends over a 6-year mining period followed by a further 4 years of stockpile rehandle. Mining will be undertaken by an independent mining contractor using a multi-stage approach to focus on value maximisation and minimising waste development in the early years, whilst ensuring ore continuity can be maintained over the life of the project.

Mining Method
Conventional open pit mining has been adopted as the preferred mining method as:
- The ore presents as a series of horizontally stacked arkose layers separated by mudstone layers all of which are close to the surface.
- There is space to construct waste dumps to the west of the open pit development.
- It has already been successfully demonstrated with operations running from 2009 to 2014.
- It is expected, with a high chance of success, to generate the best value.

The operation is currently planned in four stages over the 6-year mine life. Open pit mining will be undertaken using:
- A fleet of 75 t class excavators and 60 t class rigid dump trucks supported by an appropriate ancillary fleet will be used to mine approximately 7 Mtpa. This equipment matches the scale of the operation and the mining environment, characterised by predominantly oxide/transitional materials. Bench heights are 10.0m high and will be mined in 2.0m flitches.
- At the completion of the open pit, stockpiled ore will be rehandled and processed at the end of the mine life.

Pit Optimisation
Uranium price for the pit optimisation has been modelled at $75/lb. A range of different scenarios were run including a suite of sensitivity runs across a range of key parameters including changes to uranium price and the inclusion of the ore sorter with various cut-over grades. All of these scenarios mine to the base of the mineralisation with changes to cut-off grades either increasing or decreasing the ore inventory in very similar shells of 40 to 41Mt in size.

Mine Design
Slope design criteria was provided by the independent geotechnical firm Mine Technics. However, this was also refined in areas in around the Champhanji fault which cuts across the Project. Multiple stages were designed to minimise up front waste movements and to help ensure ore continuity can be maintained over the LOM with the least amount of waste required.

Ramp widths were designed to industry standards and are 25m wide at a gradient of 10%, and where required, minimum mining widths have been set at 40m.

Waste dumps and stockpiles are located in areas outside of the mine design envelope. Clean waste material generated will be used for construction of the wall lifts at the TSF and as part of the closure plan will be used as a capping material at the TSF, open pit and for any mineralised waste dumps. Stockpiles are placed as close to the process facility as possible to minimise stockpile rehandle costs.

Production Scheduling
All scheduling has been completed with Maptek Evolution™ in both a strategic and tactical sense. This ensures value is maximised and is also used to inform the tactical level scheduling scenarios.
The primary objectives included:

- Maintain a safe working height between stages to minimise any geotechnical risk. The current mining strategy focuses on mining Stage 1 to get access to high value ore whilst ensuring subsequent stages are developed with a 20 – 30m vertical lag on a period-byperiod basis which will reduce risk failure and ensure a safe operation.
- Work with the ore sorter concept integrated into the scheduling process to target required mill feed grades (i.e., average feed grade to mill after ore sorting).
- Maximise and maintain steady U3O8 output whilst managing feed constraints by targeting approximately 930ppm U3O8 feed grade for the first 3 years, followed by 900ppm thereafter.
- Process a percentage of marginal ore each period to avoid a build-up of stocks requiring sorting in the latter part of the schedule. These low-grade ores are only economic to process if they are sorted before mill processing and would needlessly prolong the Project life if sorted at the end of the schedule due to the finite sorting capacity per period.
- Process a percentage of mudstone material each period to avoid a build-up of mudstone stocks in the latter part of the schedule.

Total material mined is capped at 7.0 Mtpa for the first three years of the schedule. During this period, all arkose waste sent to TSF1, the existing tailings facility, which is located to the south of the process plant, for construction of the required wall lifts.

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

The Restart DFS assumes the same core processing method will be used, but that the front-end circuit will be modified to include the ore sorting process. The new front-end circuit will therefore consist of conventional crushing, scrubbing (to remove fines) screening (to achieve the required particle feed size for the ore sorters), 2 parallel Steinert ore sorters with the concentrate from these units and any fines from scrubber / screening (<10mm size) fed to the existing mill.
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