The Khemisset Basin is a sedimentary basin of Triassic age, initiated by the opening of the mid-Atlantic ridge. The sedimentary sequence of the basin is characterised by early continental red bed deposits including iron-rich sandstones. Continued subsidence and extensional faulting in the late Triassic and early Jurassic resulted in the deposition of clay and extensive evaporite sequences, characteristic of a closed marine basin and thought to exceed 1,000m in thickness in some areas. The evaporitic sequence is primarily comprised of halite, gypsum and locally, sylvite and carnallite.

The Khemisset basin was characterised by a continental slope leading into a shallow marine environment with the deposition of carbonate banks and the formation of a carbonate platform with associated dolostone and dolomitic limestone deposits. Around this time Western Morocco also experienced the deposition of extrusive basalts. Subsidence in the Moroccan continental margin continued into the Middle Cretaceous, until a period of uplift in the Late Cretaceous leading to salt diapirism; the intrusion of salt into surrounding host rock to form domes. As the rate of subsidence slowed, the basin became erosive leading to the deposition of a thick Tertiary sedimentary sequence of marls and conglomerates.

The evaporite sequence is equivalent to the Lower Salt Formation observed within the Khemisset basin and represents a regional target for potash exploration.

The following basic design assumptions have been made:
• There is no overlying aquifer and no water occurs in the potash seam;
• No flammable gas occurs in the potash seam;
• Geotechnical design can be based upon general geotechnical parameters derived from existing potash operations;
• The salt beam (Lower Salt Formation) between the potash horizon and overlying Basalt Unit is contiguous with the basalt and can be supported through appropriate room sizing with systematic roof bolting in main roadway developments only;
• The potash horizon floor elevation is relatively planar and does not compromise the mine design in terms of access and mineral recoveries;
• No major faulting occurs across the deposit area;
• Panel room orientation is not affected by in-situ stress fields;
• Selective mining of sylvite is not proposed;
• Backfill is not proposed nor required in Morocco;
• The production target is approximately 6.0 Mtpa ROM which will allow for a 19-year life of mine.

The Company has elected to use contract mining for both production and development.

The mine is proposed to be accessed via twin declines from the surface which will enable ore to be extracted using a conventional room and pillar mining methodology using continuous miners.

The decline will be driven through three key lithologies: minor clay formation (~10m thick); primary massive salt horizon (~320m thick); and an overlying basalt unit (~60m thick). Excavation of both declines will be undertaken concurrently with a proposed cross-sectional area of approximately 28m2, which will allow sufficient airflow to ventilate the underground mine when in full operation. The current proposed decline design comprises:
• A portal constructed at the surface with the excavations supported with shotcrete, mesh and soil nailing as required. A buried steel or concrete liner will protect the entrance to the portal;
• Zone 1: through the soft soil/rock will be lined with shotcrete and mesh, with excavation carried out using conventional tunnelling techniques;
• Zone 2: through the salt horizon, will be supported with patterned bolts;
• Zone 3: through the basalt will be excavated using CMs and supported with patterned bolts and mesh. Minimal water inflows are expected within the basalt strata;
• Zone 4: will be driven laterally with the CMs and supported in a similar manner to Zone 2.

The declines will be driven at a gradient of around 1:7 with a length of approximately 3,200m and will reach the potash horizon at a depth of approximately 450m below surface.

Twin declines will provide the entry to the mine with personnel and machinery using a service decline and extracted material transported via conveyor in the production decline. A pillar of support is provided for between and below the declines, which only enter the mined areas towards the base of the decline.

The main roadways connect the declines with all the areas in the mine and constitute the main developments, which are the mining arterials used for ventilation, services, transport conveyors and general haulage. For the main infrastructure areas, four main headings will be driven to provide additional flexibility with respect to panel production. Haulage of extracted material will be carried out continuously by conveyors (main conveyors), which connect directly to the production panels and to faces via shuttle cars. Shuttle cars will empty ROM ore into feedbreakers controlling the flow of ore onto the panel conveyors, which will then feed the main conveyor system taking product via the decline to the surface ROM storage.

Resource blocks are sub-divided into mining panels with inter-panel barrier pillars between each adjacent panel. Each panel will be sub-divided into mining rooms. Panel room design will comprise 3 headings, with a 6m room width and with 10-20m pillars (depth and thickness dependent) with the central heading equipped with the panel conveyor.

Two additional headings will be developed on the sides to form a 5-heading panel room. Crosscuts will be driven at 60° in an offset chevron pattern, interconnecting the headings on a spacing dependent upon depth and potash thickness. The continuous miner will place swap after each cut to allow roof bolting and service extensions. Panel rooms will be developed side by side to form panels approximately 250m wide, separated from the adjacent panel by an inter-panel barrier pillar with a width equivalent to 16 times the average seam height. Panel length is up to 2,000 metres.

To account for the mixed ore feed, all mixed ore must be crushed through both stages of crushing to a size of 0.4 mm and all ore must be processed through a mixed ore decomposition. The first stage of crushing is open circuit crushing to bring the ore to 12-15 mm before reporting to a second stage of closed circuit crushing to reach the 0.4 mm size requirement. Testing determined the 0.4 mm size requirement for efficient rinneite decomposition. When no Rinneite is present, only the first stage crush is required.

Ore will be processed via hot leaching, cold crystallisation to produce the generic K60 MOP product which is standard in the industry.

The go-forward processing case for the Khemisset project following the options study, therefore, consists of seven major process steps.
1) Two-stage ore crushing to 0.4 mm
a. Size requirement driven by rinneite decomposition
b. Potential to treat sylvite and carnallite through simpler processes
2) Decomposition of rinneite and carnallite to solid KCl (mixed with NaCl), with rejection of a high-Mg, high-Fe brine
3) Hot leaching of KCl from KCl/NaCl solids
4) Crystallisation and de-brining of purified KCl product
5) Drying, compaction, and sizing of KCl product
6) Drying, compaction, and sizing of NaCl byproduct
7) Slurry transport of remaining NaCl tailings to storage

The target deposit at Khemisset contains three types of potash species – sylvite (KCl), carnallite (KMgCl2?(H2O)6), and ........