The Madaouela deposits exhibit classic characteristics of uranium sandstone deposits common the world over (Cuney, 2009).

The Marianne-Marilyn deposit is a nearly flat tabular body of mineralisation that spans approximately 5 km (N70E direction) by 2 km across in plan, and the deposit thickness varies from 0.2 to over 2 m (average thickness of about 1 m). The mineralisation occurs at depths from about 30 m on the eastern end of Marilyn, to approximately 60 m in depth in the middle of the Marianne-Marilyn deposit, up to 120 m in depths on the west extensions of Marianne; below the relatively flat topographic surface.

The MSNE deposit occurs to the south of Marianne-Marilyn and is approximately 140 m deep. It occurs on the same redox front as Marianne-Marilyn and the deposit is approximately 2.7 km long and 2.3 km.

Maryvonne deposit is located to the north of MSNE deposit and is approximately 100 m deep. The length of the deposit is 1.2 km and the width is 0.75 km Miriam deposit is situated 8 km to the south of MSNE deposit and is dipping from 65 m to 120 m deep. The deposit is 2.4 km in length and 0.8 km wide.

Sandstone-hosted uranium deposits are defined as epigenetic concentrations of uranium minerals occurring as impregnations and replacements primarily in fluvial, lacustrine, and deltaic sandstone formations. They occur in permeable medium- to coarse grained sandstone, usually deposited in continental fluvial or marginal marine sedimentary environments. Impermeable shale or mudstone are inter-bedded in the sedimentary sequence, and often occur above and below the mineralisation.

The main primary uranium minerals are uraninite and coffinite with minor secondary uranium minerals being noted in exposed (weathered) mineralisation.

In Niger, including the Madaouela Uranium Project, the uranium deposits belong to the tabular and roll front deposit types. Deposits are epigenetic

The mineralogy of uranium in the deposit is dominated by pitchblende and coffinite. The overall paragenesis could be divided in three stages: (1) early sulfides; (2) uranium on organic matter such as wood fragments; (3) carbonates and barite.

The Guezouman sandstone at the Guezouman-Talak contact in the primary locus of mineralisation, as controlled by the reducing environment and lesser permeability of the Talak argillites below mineralisation, and the regional paleo-groundwater redox boundary in the Guezouman sandstone, down gradient from outcrops. Other relevant geological controls are the N70E structural, which represent older faults, and edges of paleo-channels. Low-amplitude domal features in the sedimentary units are related to the structural environment and are therefore relevant exploration guides.

The uranium mineralisation is all reduced uranium minerals (U (IV) minerals), uraninite and coffinite. The uranium minerals occur as disseminations in the matrix of the sandstone, with nearly all the mineralisation occurring in one tabular horizon. “Redox front” uranium mineralisation in the Guezouman may occur at several levels, as it is the case in the Miriam deposit. The Akouta “front” was the best example of this type of concentration. In the Miriam case a close relationship with structural features is very likely. Mineralisation can sometimes be present at the contact of the Guezouman and the UA formation, in the Talak, and in the UA where the UA is preserved against a N70E fault; however, that mineralisation is also relatively insignificant to the main basal Guezouman sandstone tabular lens of mineralisation.

Mining schedules have been developed including open pit mining at the Miriam deposit, and room and pillar mining from Marianne-Marilyn, MSNE and Maryvonne deposits.

OPEN PIT MINING
The final designed pit has been divided into four pushbacks each to be developed with independent ramp access and with similar bench-berm configurations.

Miriam final pit design quantities:
- Total Rock 84,758 kt;
- Waste 76,708 kt;
- Stripping Ratio 9.9.

The equipment fleet has been selected based on the outcomes of the LoM schedule, material movement profile, required selectivity of the orebody and mining space within the pit and designs and pushback shells.

12 m3 bucket capacity excavators have been selected as the primary excavator for mining ore and waste, with planned productivity of 8.1 Mtpa per excavator. These will be matched with 91 t capacity haul trucks.

All material above the 400 mRL production drilling will be undertaken on a 5.7 m by 4.9 m spacing on 10 m benches with a 171.5 mm blasthole diameter. All material below the 400 mRL 2.9 m by 2.5 m drill patterns will be used on 5 m benches with an 88.9 mm blasthole drill. Presplit drilling will be undertaken with an 88.9 mm blasthole drill rig. The 171.5 mm drill rig will also be responsible for the infill drilling on a 25 m by 25 m spacing for 10 m bench heights.

The Project schedule is based on four work crews working three 8-hr shifts per day.

UNDERGROUND MINING
Marianne-Marilyn (M&M) and MSNE-Maryvonne deposits are to be mined by room and pillar mining methods.

A common approach to mining has been assumed for all underground deposits to allow the same skills and equipment to be applied across all operations. The modular nature of room and pillar mining in panels allows the inputs to production costs and productivities to remain relatively stable across all operations, simplifying the analysis and ultimate operations.

Due to the shallow depth of mineralisation, which is typically around 100 metres below the surface for the Madaouela deposits, decline access has been adopted. This has the following additional advantages:
• The use of conveyors to bring the mineral ore to surface.
• Simplifies materials handling to bring spare parts and other consumables into the mine.
• Simplifies movement of men during shift change-overs.

As mine access is proposed via a decline for each operation, the need for vertical development is limited to providing ventilation. The proximity of the mine workings to the surface and the generation of radon daughters that require primary ventilation of working areas makes the use of many small diameter raises regularly distributed throughout the orebody a practicable alternative to fewer, more isolated, large diameter raises.

The mine layout has been laid out using a conveyor haulage strategy and consists of a central conveyor network carrying large tonnages to the surface fed by trucks hauling from the panels.

The continued generation of radon and its daughters from the rock presents a hazard to mine workers that is mitigated by well controlled ventilation flows and by barricading mined out panels to prevent any leakage into the fresh air network. SRK has therefore assumed there to be limited underground storage of waste and the conveyor system design is capable of handling all ore and waste production to surface.

There is potential to store waste in mined out areas of active panels, however, this is expected to be an ad-hoc activity by LHD only, as trucks will only be able to travel in the central panel access.

Ore and waste will need conveying to the surface separately to prevent waste being fed into the plant. At the surface, the conveyor sends RoM to a radiometric ore sorter. Sorted ore is delivered to an ore bin, and waste is off-loaded to a temporary stockpile near the portal. A surface trucking fleet will rehandle the waste to nearby waste dumps and haul the sorted ore to the plant located near the Miriam pit.

The production fleet is constrained by the working height of the proposed excavations. As the majority of the mineralisation has a thickness less than the minimum mining height, production mining will be largely by low-profile equipment. In most cases, the minimum mining height will be determined by the equipment selection. Low profile mining equipment was developed for, and is used extensively in, South African platinum and chrome operations. It is specifically designed to reduce the total mining height and reduce waste dilution in low seam environments.

The annual production rate of RoM sent to the radiometric sorting plant is around 1.45 Mtpa, which equates to 4,000 tpd. This rate will vary with the mining height, as the processing plant is designed for 1.0 Mtpa after the radiometric sorter (2,860 tpd) and the waste dilution varies with the thickness of the mineralised zone.

The materials handling fleet comprises a rehandle loader and truck fleet and conveyors to transport RoM from the production face to the processing plant, and the waste from the development face to the surface stockpile.

Processing plant will include crushing and grinding operations.

ROM ore is transported from primary crushing (outside of plant battery limits) to a feed stockpile at a rate on average of 2,750 tpd. The ore is then fed via apron feeders to discharge conveyers and transported to the crushing circuit comprising secondary crushing operated in open circuit to reduce the feed size to 100 mm (P80). The crushed ore is fed to a SAG milling circuit operated in closed loop with cyclone clusters to produce a grind size of 212 µm (P80) which proceeds to the leaching circuit.

Primary crushed ore is received by truck into a feed bin and onto the stockpile feed conveyor. The conveyor transfers the primary crusher product material (F80 -250 mm) to the stockpile at a rate of 134.3 t/hr. The stockpile feed conveyor is fitted with a weightometer to account for mass received.

The ore is reclaimed from the stockpile using three apron type feeders that are located in the stockpile tunnel. Three apron feeders discharge onto a common stockpile discharge conveyor that transfers the ore to the secondary crusher. The stockpile discharge conveyor is fitted with a metal detector, tramp-metal belt magnet and a weightometer.

The stockpile tunnel is fitted with a dust control system, with dust extraction hoods located above discharge of each apron feeder. Two spillage sump pumps and one emergency flooding sump pump are installed in the stockpile tunnel. The recovered spillage and flood water will be transferred to the process water holding facility. Two wash water points are installed in the stockpile tunnel and provided at each spillage sump pump.

A stockpile feed conveyor maintenance hoist and stockpile tunnel hydraulics room that is equipped with a ventilation fan, fire suppression system and hydraulic power pack, are all provided for the ROM receive and reclaim area.

Secondary jaw crusher receives feed from crusher feed conveyor and operates in open circuit. The feed conveyor collects and transfers ROM material from the stockpile. The crusher feed is transferred via a chute to the crusher head opening. The crushed product (-100 mm) is transferred via a chute to the mill feed conveyor. The secondary jaw crusher is fitted with dust extraction hoods that are located above dust generating areas.

The SAG mill receives fresh feed from ball mill feed conveyor and slurry from classifying cyclones underflow. Water is added to the mill from the process water reservoir at a defined liquid to ore ratio to obtain 70 % solids in the mill. The mill is an overflow discharge mill and slurry discharges into a mill discharge sump through a 20 mm aperture opening scats screen.

The mill discharge sump has two pumps that transfer the 40 % solids diluted mill discharge to feed two cyclone clusters. A low head sump recirculation pump is installed on the mill sump to keep solids suspended in the slurry.

The ball mill cyclones are designed to operate with a recirculating load of 250 % to the underflow. The cyclone underflow is gravitated to feed the ball mill.

The cyclones overflow gravitates into a transfer sump and pump, where is pumped to a leaching plant thickener. P80 -212 microns is the design target of cyclones overflow product with 40 % solids density.

The mill balls media is stored in a holding bunker. Mill charging is done by collecting balls from bunker with an electro-magnet. The electro-magnet is fixed to a hoist and adds balls into the mill via a special balls discharge chute.

A traditional flowsheet has been chosen as far as possible for the treatment of ore from the open pit mining operation (Miriam), which is relatively low in gangue acid consumers, comprising of Crushing, Milling, Two-stage Tank Leaching, Molybdenum recovery by Ion Exchange (IX) and Uranium recovery by Solvent Extraction (SX). A flotation section can be added in later years, to reject carbonates and consequently decrease acid consumption, when underground ore is treated.

Design plant feed 134.3 tph.

The two-stage leaching circuit consists of primary and intermediate thickeners in combination with a primary and secondary agitated tank leach system. Tanks are agitated to allow the ore to react with concentrated sulphuric acid allowing dissolution of the contained uranium, while the redox potential is controlled by the addition of hydrogen peroxide. The leaching residue is then filtered with filtered solids residue discarded to the tailings storage facility.