Deposit Types
Frontier Lithium’s target or deposit model is the highly evolved, granitic, rare-element lithium-cesium-tantalum bearing (LCT) complex type, petalite subtype pegmatite. The Tanco pegmatite situated in the Bird River belt in southeastern Manitoba is the best known and a world-class example of this type of deposit model.

Granitic pegmatites are relatively common and widespread, and have been divided into five classes based on the pressure-temperature conditions that characterize their host rock suites (Cerný and Ercit, 2005). Criteria, including mineral assemblages, geochemical signature and conditions of consolidation or combinations thereof, are used to further divide the classes into sub-classes, types, and subtypes.

Of the five classes, the rare-element class is the group with the most attractive economic potential and can represent economic sources of tantalum, ceramic grade spodumene, rubidium, and the main cesium ore mineral, pollucite.The lithium rich, rare-element pegmatites are not common and comprise <0.1% of the total known pegmatites (Kesler, et al, 2012).

The rare-element class of granitic pegmatites is generated by the differentiation of fertile, S-type granitic plutons. This differentiation process of the parental granite is accompanied by the progressive accumulation of lithophile rare-elements as well as elements such as thallium, tantalum, hafnium, gallium, germanium, boron, fluorine, and phosphorus (Cerný and Ercit, 2005). The pegmatite field results when the lithophile rare-element enriched residual melt is expelled from the fertile granite and assuming suitable channels exist migrates outward and upward away from the granite.A field can be comprised of many pegmatites over a distance of a few kilometres from the source granite. The field itself shows an increasing fractionation moving away from the source granite.

The economic concentrations of the lithophile rare-elements will occur in pegmatites crystalizing from the most highly evolved melts. Some of the lithophile rare-elements may occur in separate zones, which may allow for selective exploitation. Economic tantalum mineralization can be complex and the host mineralogy for rubidium can be different in different zones, but pollucite is the main cesium mineral and according to Kesler et al (2012) spodumene is the most economically important lithium mineral.

Mineralization
Upper Intermediate Zone (UIZ)
Upper Intermediate Zone (UIZ)The Upper Intermediate Zone (“UIZ”) represents the lithium zone within the pegmatite and is dominated by “SQUI” (Spodumene + Quartz Intergrowth), a term used to describe anisochemical reversion resulting in the replacement of primary petalite by oriented spodumene + quartz intergrowth (London, 1984), with lesser grey K feldspar and primary white spodumene in quartz. Phosphate minerals such as montebrasite (Breaks et al., 1999) and apatite, and lithian mica are common accessory minerals.

Central Intermediate Zone (CIZ)
The Central Intermediate Zone (“CIZ”) is located in structurally higher portions of the pegmatite and represents the tantalum and rubidium zone of the pegmatite. The CIZ is in contact with both the Upper Intermediate Zone (UIZ) and Upper Wall Zone, and persists to the southeast edge of the outcrop where it is believed the pegmatite continues under the till cover.To the southeast, the CIZ is intersected by channels CH-1 and CH-7 where it consists of similarly sized fragments of randomly oriented coarse K-feldspar + mica + quartz. Micas appear to alter primary K-feldspar.Blue apatite prisms up to 1 cm wide and several cm’s long accompany the mica-rich zones.In the adjoining area to the northeast of CH-7, the K-feldspars are more or less completely replaced with lithian mica + quartz. In this area veinlets and patches of lepidolite are common. Channel 1 (CH-1) contains the highest tantalum grades found to date in the exposed pegmatite, which persist in the subsurface in drillholes PL13-001 and -006, in addition to high rubidium and elevated cesium grades.To the northwest, channels CH-8 and CH19 intersect the central portion of the exposed CIZ where it consists of predominantly grey K-feldspar with minor lithian mica + quartz alteration. Drillholes PL13-004 and -003 confirm the extension of the CIZ into the subsurface in this area, where it features notable cm-scale blebs of the rare cesium mineral pollucite, and high tantalum and rubidium grades.

Lower Intermediate Zone (LIZ)
The Lower Intermediate Zone (LIZ) comprises the bulk of the exposed pegmatite and is considered an intermediate stage zone with significant lithium, tantalum and rubidium.The zone comprises predominantly K-feldspar, Na-feldspar, SQUI and lithian muscovite. Pollucite also occurs in an intersection of LIZ in drillhole PL13-005. The zone has undergone both ductile and brittle deformation at the apparently structurally lowest portions of the pegmatite. Ductile deformation is manifested as a banded appearance on surface, where seams of oriented mica provide a planar fabric.

Wall Zones
The Wall Zones (upper and lower) of complex LCT type pegmatites are generally characterized by the occurrence of brick-red K-feldspar (perthite) and simple mineralogy (Cerný, 2005, Cerný and Vanstone, 1996). The zone mineralogy is simple, but the brick-red colouration of the K-feldspar is more common in the portion of the pegmatite in close proximity to the metasediments. The same colouration does generally not occur where the pegmatite is in contact with the granite.In this latter case, the sections of Wall Zone display a light to medium grey K-feldspar. It is assumed lower inherent iron levels of the Pakeagama Lake granite, unlike the metasediments, were not sufficient to generate the K-feldspar colour change in the adjoining pegmatite.

The Upper Wall Zone found in the southwest portion of the pegmatite exposure, is in contact with the lithium rich UIZ and is composed of quartz with lesser pale-red coloured K-feldspar, minor phosphates and accessory beryl and lithian mica. The exposure of this zone is limited.

The Lower Wall Zone is mineralogically similar to the Upper Wall Zone.A common feature of the footwall Wall Zone in the more complex LCT-type pegmatites is the presence of bands of sodic aplite (“footwall aplite”). These sodic bands are generally not common in the Upper Wall Zone. The Pakeagama Lake pegmatite is somewhat more complex as bands of what appears to be pre-existing banded sodic aplites are found throughout the pegmatite. The contact with the LIZ is gradational and is defined by the general absence of SQUI within the wall zones and the change in colour of the K feldspars from pale-red to the light grey commonly found throughout the pegmatite. Like the LIZ, this zone has undergone deformation.

Open Pit
It is proposed that the PAK Lithium Project is amenable to be developed as an open pit (OP) mine followed by an underground (UG)mine. The mining method selected for the project will be a conventional open pit, truck and shovel, drill and blast operation. Minimal vegetation, topsoil and overburden will be stripped and stockpiled for future reclamation use. The ore and waste rock will be mined with 10 m high benches, drilled, blasted and loaded into haul trucks with a hydraulic excavator and a loader for back up.

The PAK Lithium Project is designed as a conventional truck-shovel operation assuming 36 nominal tonnes articulated trucks and 5m³shovel. Mining at the PAK open pit is planned to produce a total of 4.1Mt of ore and 18.2Mt of waste for a 1:4.5 overall strip ratio, for a period of 12 years (excluding 2 years of pre-production). The average Lithium grade in the PAK open pitis estimated to be 2.06 Li2O%, containing 848,435tonnes of concentrate of lithium. The current life-of-mine (LOM) plan focuses on achieving consistent ore production rates in the production schedule, as well as balancing grade and strip ratios.

The design parameters include a single ramp width of 10.8 m, road grade of 10%, final bench height of 20 m, targeted mining width average of 120 m, variable slope angles by sector and a minimum mining width of 20 m (pit bottom).

Underground Mining
The ramp portal would be located on the north side of the pit in the wall of the bench 50 metres from the pit bottom. The ramp would be excavated using typical mechanized drifting methods. The proposed ramp would be excavated on the footwall side of the mineralized zones at a size of 5.0mH x 5.0mW, and grade of minus 15%. The remucks would be located a maximum 300metresfrom the advancing face. The ramp would be supported using 1.8 m resin grouted rebar in the back and 1.2 m resin grouted rebar in the walls on a 1.5 m pattern.

All development has been designed to be 5.0mH and 5.0mW and would be developed using electric hydraulic jumbos and diesel LHD equipment. Level development would be supported using the same specifications as the ramp development. All waste development rock would be stored underground where feasible or hauled to surface for possible future backfill material.

Ore extracted from the stopes would be transported by LHD to a remuck on the level it is extracted from. From that point, the ore would be loaded into a 40 tonne underground haulage truck, which would haul the material to just outside of the portal in a designated dump area. From that point, a surface truck would be loaded and the material transported to the mill for processing.

The underground portion of the resource will be mined using longhole mining methods. A top sill used for drilling, and a bottom sill used for mucking are required before mining of the designed stope shape can occur. The stopes will be mined from hangingwall to footwall and will be filled and cured before adjacent stopes can be mined.

Pastefill would be used to fill the longhole stopes. Dependent upon where the stope is, or where it lies in the mining sequence, waste rock could be mixed in with the paste if practicable. The paste plant would be located on surface and piped underground to the various headings where needed.

ROM ore is transported by truck from the open pit and dumped into a hopper prior to the Primary Crusher, where it is reduced to a P80size of 150 mm. The ROM ore top size will be controlled by blast fragmentation to below 400mm minus, thereby avoiding the use of a grizzly section prior to the primary. A 895x660mm feed opening crusher has been selected to handle maximum lump size, which is lightly loaded at closed-side setting of 100mm. The Primary Crusher is a 75HP jaw-type, with a minimum operating capacity of 125 tph. A 12-hour operating day for the crusher is assumed.

From the Primary Crusher, crushed ore drops onto a double-deck screen which classifies undersize to bypass the Secondary Crusher. Deck sizes for the double deck screen have been selected at 25mm and 15mm respectively. The double deck screen is 1.5m wide and 4.8m long, and is in open configuration in order to lower the machine load of the Secondary Crusher. The Secondary Crusher is a 120HP cone type, with a predicted operating capacity of 71 tph at a closed side setting of 25mm. Both undersize from the double-deck screen and product of the Secondary Crusher will report to load-out conveyor that carries the ore through a heated gallery to the Fine Ore Storage bin located prior to the concentrator building.

A belt magnet is located on the load-out conveyor to remove tramp ferrous material entrained in the ore before it leaves the crusher building complex.

A belt weigh scale on the load-out conveyor tracks the production rate of the crushing plant. A baghouse collects dust at the ore transfer points within the Primary Crusher Building, which once collected, will report to the tail end of the load-out conveyor. A sump pit is provided to collect wash-up residue, and is designed to be emptied periodically by vacuum truck.

Ore discharged from the Primary and Secondary Crusher circuit is fed to the Fine Ore Storage bin via the crusher circuit load-out conveyor. The Fine Ore Bin is 6.2m diameter x 7.2m high, which corresponds to a design capacity of 600 tons.

Grinding
The Grinding Circuit is designed to produce feed slurry fine enough for effective Flotation.The Primary and Secondary Ball mills work in concert to particle size of P80= 200 µm for feed to a cyclopak unit prior to Mica Flotation.Design product size was set to a P80= 150 µm as a conservative measure.

As previously mentioned, the Primary Ball Mill is in open-circuit with the discharge of the Tertiary Crusher. The Tertiary crusher is a 120HP cone type, with a predicted operating capacity of 22 tph at a closed side setting of 4mm.

The Primary Ball Mill is a 2.2 m diameter x 3.0 m long unit with a 200 HP installed motor and variable frequency drive. The discharge of the Primary mill reports to the Secondary Ball Mill pumpbox.In order to minimize working capital, both the Primary and Secondary mills will have identical installed motors. However, length of the Secondary mill had to be longer to meet product requirements.

The Secondary Ball Mil is in closed configuration with a doubledeck feed screen, a 1.8m x 3.6m unit which is of similar construction as the Coarse DMS feed screen. The Secondary Ball mill is a 2.2 m diameter x 3.5 m long mill with a 200 HP installed motor with a variable frequency drive.

Product of the Secondary Ball mill will be pumped to a de-sliming cyclone cluster consisting of ten (10) 50mm diameter cyclones. Cyclones overflows are classified slimes (<10µ) and report to the tailings thickener. The underflow will feed a Knelson Gravity separator prior to reporting to aLow Intensity Magnetic Separator (LIMS) and Wet High Intensity Magnetic Separator (WHIMS) prior to further the first stage of (Mica)flotation.

Placement of the LIMS and HIMS within the overall circuit will be confirmed at the next stage of study, which will involve pilot plant testing to predict the most efficient arrangement.In practice, there is pragmatic evidence that the LIMS and WHIMS placement would be after pH depression prior to the Mica Flotation circuit. It is also anticipated that further de-sliming using an additional cyclone cluster prior to the next stage of flotation may be of benefit.

All throughput and mass balance calculations used as the basis of design were based on the average production mill feed of 45 tpd of ore. 31% of mill feed is expected to be rejected as a result of the DMS process, thereby reducing the comminution and flotation throughput down to 30.8 tph on a design basis.

Dense Media Separation
The Dense Media Separation (DMS) circuit has been incorporated at the front end of the concentrator facility as a method to remove barren material from SQUI resulting in a reduction of the comminution energy prior to flotation, and an upgraded mill feed.

A two-stage DMS (Coarse and Fine) has been carried based on testwork and pro-forma calculations which set the DMS Plant design.

The selected coarse modular system includes for a two-stage, 300mm diameter separator, and includes one 1.8m x 3.6m drain/rinse screen with 1.0mm aperture panels, as well as a dense media recovery system. The wet drum magnetic separator will be 0.9 ........