The deposit model at the Eldor Property is the carbonatite-hosted REE-Nb-Ta deposit. Carbonatites are by definition igneous rocks, intrusive and extrusive, that contain more than 50% by volume carbonate minerals such as calcite, dolomite, ankerite, and less often siderite and magnesite.
Intrusive carbonatites occur commonly within alkalic complexes or as isolated intrusions (sills, dikes, breccias, or small plugs) that may not be genetically related to other alkaline intrusions. Carbonatites can also be volcanic related and occur as flow or pyroclastic rocks like the well-known active Oldoinyo Lengai volcano in Tanzania. Carbonatites are generally related to large-scale, intra-plate fractures, grabens, or rifts that correlate with periods of extension, typically Precambrian to recent in age.

Carbonatite-hosted deposits occur almost exclusively in intrusive carbonatite and may be subdivided into magmatic, replacement/veins, and residual sub-type. The Eldor Carbonatite can be classified as a magmatic sub-type, which is the same category as the St-Honore deposit in Quebec, Canada (Niobec niobium mine, Iamgold), the Mountain Pass Deposit in California, U.S.A. (REE), and the Palabora Deposit in South Africa (apatite).

The pipe-like carbonatites typically occur as sub-circular or elliptical shapes and can be up to 3-4 km in diameter. Magmatic mineralization within pipe-like carbonatites is commonly found in crescentshape, steeply dipping zones. As carbonatite magma is typically volatile rich with low viscosity, it may ascend rapidly through the mantle, fracturing the crust on impact, causing a characteristic alternating ring (crescent) structure of carbonatite and wall rock to be formed. Metasomatic mineralization occurs as irregular forms, breccias, or veins.

The Rare earth element mineralization at Ashram is hosted primarily (essentially 100%) by monazite, rare earth fluorocarbonates (bastnäsite, parisite, and lesser synchysite) and lesser xenotime. Rare earth mineralization at Ashram is consistent throughout the deposit with minimal dilution from unmineralized fragments and clasts.

Monazite typically occurs as intergrowths with fluorite or disseminations in dolomite and less commonly as intergrowths with apatite or in association with quartz-rutile assemblages. Bastnäsite typically occurs as fibrous cavity fillings in dolomite, anhedral grains in veins associated with Y-NbTi minerals, or anhedral grains and aggregates in fluorite.

The principal heavy rare earth mineral is xenotime-(Dy) present as anhedral to subhedral crystals in association with nioboaeschynite, niobian rutile, ferrocolumbite, monazite, quartz, and mica. Xenotime is present in either pools of quartz, small veins (mm) in fluorite ferro-carbonatites, or scattered throughout the carbonatite as a trace mineral in association with disseminated monazite and/or bastnäsite.

At least two generations of monazite are present: one associated with fluorite and/or disseminated in dolomite, and a second associated with the xenotime mineral assemblage. The xenotime mineral assemblage represents a distinct (later) mineralization event from that which formed the first generation of monazite.

Grain size of the monazite is typically <10 µm to 25 µm, with bastnäsite slightly coarser at <20 µm to 50 µm. Aggregates of monazite±bastnäsite in the several-hundred micron range are present but not common. Xenotime crystals are relatively coarser grained than monazite, although still commonly less than 50 µm. Parasite-bastnäsite intergrowths, where present (BD-Zone), occur as relatively large crystals and masses ranging typically from 200 µm to 400 µm with some aggregates exceeding a millimetre. Although fine-grained, the rare earth mineralogy of the Ashram Deposit is considered simple because it contains three of the four rare earth minerals that dominate commercially production globally (monazite, bastnäsite, and xenotime). In addition, it has been demonstrated that all three rare earth bearing minerals (monazite, bastnaesite, and xenotime) liberate together and share conventional processing techniques.

The Ashram Deposit can be roughly divided into three main mineralized zones termed ‘A-Zone’, ‘B-Zone’, and ‘BD-Zone’. In general the A-Zone is central to the deposit and is rimmed by the B-Zone and BD-Zone respectively. This relationship is more prevalent along the western margin of the deposit, where the BD-Zone is in contact with an unmineralized albite amphibole phlogopitite unit, which interfingers with and transitions to a calcio-carbonatite unit. A simplified illustration of the typical nature of the western contact is presented in Figure 7-5. Along the eastern margin of the deposit, the B and BD zone relationship is more variable, with unmineralized calcio-carbonatite predominantly marking the contact, with the albite amphibole phlogopitite unit noticeably absent.

Taking into account the proximity of the mineralized zone with the surface topography and the presence of high grades of REEs at shallow depth, the mining method selected to mine the Ashram Deposit is open-pit mining. Conventional mining machinery, such as trucks, loaders, and hydraulic shovels will be used on 5 metre benches

At a rate of 4,000 tonnes of ore per day processed at a CoG of 1.25%, the Ashram Deposit contains enough resource to support an operation for more than 177 years (open pit and underground mining). Therefore, the main purpose of the optimization process was to highlight a section of the deposit providing a sufficient TREO grade (over 1.25% TREO) with a reasonable stripping ratio, rather than determining the optimum pit limit.

The mining operation will be carried out with a mining fleet of two 100 mm blast hole drills, one CAT 988H loader, one CAT 385 shovel and four CAT 773 off the road trucks, supplemented by support equipment such as tracked dozers, graders, water trucks, and emulsion tankers backed by other minor equipment.

The mill process will be conventional with operation relying on operators’ experience and skill supported by electronic monitoring and instrumentation. It is anticipated that the head grade will be 1.81% TREO, the mineral concentrate grade will be a minimum of 10% TREO, while recovery will be in the 70% range. Rare earth mineral concentrating and cracking is proposed in the PEA to be completed on site with a 99.9% pure mixed rare earth carbonate (REC) concentrate to be produced for the market.

The process plant is designed to produce a rare earth mineral concentrate by froth flotation. It will incorporate the following sections: run-of-mine ore storage, a one-stage crushing plant, crushed ore storage, SAG milling with screen classification followed by a single-stage ball milling with cyclone classification, flotation of the rare earth minerals, concentrate thickening and filtering, tailings handling, water and reagents distribution.

Cracking of the mineral concentrates generated by Hazen is currently underway. Although only premliminary results are available, a TREO recovery of 95% is foreseen at the cracking plant based on applicable and well-known cracking techniques. Because the radioactivity of the mill concentrate is not fully quantified at this time (testwork results pending), for the purpose of this report, it is assumed thermal cracking will be done directly at the mine site with any radioactive material remaining on site. A trade-off study will be completed in pre-feasibility level evaluation to determine if it is more practical to complete cracking on site or at a location further south (e.g. near Montreal).

The major components of the Acid Cracking Section include the following units: roasting, leaching, calcium and fluorine removal, thorium and iron precipitation and removal, REE carbonate precipitation, centrifuging and drying of the REE carbonate, free of radioactivity.

A trade-off study will be completed during pre-feasibility work to evaluate conventional sulphuric acid cracking versus caustic cracking techniques. Both techniques are expected to be applicable based on the simple and well-known Ashram mineralogy. Such evaluation will assist in determining if a mixed REO product is more economic/practical than and mixed REC product.