Overview

Deposit type

• Pegmatite

Summary:

The Karibib Lithium Project is located in the southern Central Zone of the northeast-trending Damara Belt, which is a part of the Neoproterozoic Pan-African Damara Orogen. The region hosts numerous late- to post-tectonic (~523–506 Ma) lithium-caesium-tantalum (LCT) type pegmatite deposits and uranium bearing niobium-yttrium-fluorine (NYF) type pegmatitic leucogranites that have been intruded into the tightly folded supracrustal rocks of the Damara Supergroup.

The pegmatites of the Damara Orogen occur in five major belts, including the Karibib Pegmatite Belt, which contains large, zoned lithium-beryllium and gem tourmaline-bearing LCT pegmatites. The Rubicon and Helikon pegmatites are typical examples of highly fractionated, complexly zoned LCT pegmatites.

In broad terms, the Rubicon and Helikon 1 pegmatites are highly fractionated quartz-feldspar-muscovite pegmatites, that typically develop a central lithium-mineralised zone. Three zones of lithium mineralisation are identified, generally surrounding a central barren quartz core, namely, Lep Z (high- grade “massive” lepidolite), Lep Z B (low-grade disseminated lepidolite dominated by pale albite) and Mica Z (often broad zones of coarse-grained quartz-albite pegmatite (marked by distinct clusters of dark lithium-bearing mica).

Lep_Z - High-grade lepidolite zone; dark purple, dark grey; generally fine-grained, often cryptocrystalline; lepidolite content noticeable (>15–20%); usually in contact with quartz core.

Lep_Z_B - Low -grade lepidolite zone; pale; white to pale grey; low lepidolite content, but lepidolite noticeable; often displays flow banding; usually occurs below (i.e. footwall to) Lep_Z.

Mica_Z - Mica zone; patchwork rock comprising clusters of dark grey, black, green mica within a pale/white matrix of quartz-feldspar; mica clusters often as radiating concentration of mica, sometimes recognised as dark purple lepidolite; other times black, possibly zinnwaldite; can contain appreciable schorl (black, Fe-rich tourmaline). Occurs in both hanging wall and footwall zones to the Lep_Z; At Helikon, this mica often occurs with pink K-feldspar in footwall (previously often mis-logged as petalite). At both Rubicon and Helikon, the mica zones also occur adjacent to footwall contact where it is associated w ith garnet.

At Rubicon, a series of stacked sub-parallel pegmatites of variable thickness are intruded into a sequence of diorites and pegmatitic granite. The Rubicon pegmatite is the largest of these and forms a prominent ridge that strikes for a distance of approximately 1,200 m in a west-northwest direction. The pegmatite dips to the northeast, with dips of approximately 45° near surface and flattening to between 18° and 25° at depth. Rubicon is a quartz-feldspar-muscovite pegmatite that is up to 70 m thick and extends down dip for in excess of 400 m. At its thicker portions, the pegmatite is well fractionated and forms ellipsoidal, well zoned, lithium-mineralised bodies developed around central quartz cores. The mineralised zones are 10–30 m thick and extend for most of the length of the pegmatite.

At Rubicon, the lithium mineral is lepidolite with lesser petalite and minor amblygonite. Cookeite occurs as an alteration product of petalite. The petalite, which occurs adjacent to the quartz core, was the focus of historical mining (open pit and underground) and is now essentially depleted. Very little petalite is noted in recent drilling.

The historical Helikon workings expose a series of LCT-type pegmatites (Helikon 1 to 5) that have been intruded along two east-west lines into marbles and calc-silicate schists of the Karibib Formation. Helikon 1, the largest of these five pegmatites, occurs on the southern line. The other four notable pegmatites (Helikon 2 to 5) occur 1 km to the north along a 1.7 km semi-continuous line of pegmatites.

The Helikon group pegmatites have been exploited historically by open pit mining for lithium-bearing minerals (petalite, lepidolite and amblygonite), tantalite and beryl. The Helikon 1 pegmatite has a strike length of 400 m and an average thickness of 65 m, dipping 70° to the north. The pegmatite is strongly fractionated and exhibits distinct mineralogical zonation particularly around a central quartz core that develops in the ticker part of the pegmatite. Helikon 1 is truncated at approximately 60 m depth by a low-angle fault dipping 30° south.

The Helikon 2 to 5 deposits occur along a 1.7 km semicontinuous line of pegmatites, approximately 1 km to the north of the Helikon 1 pegmatite.

The main pegmatite at Helikon 4 is of variable thickness (generally 10-50 m), intruded into a sequence of largely marbles and occasional calc-silicates. The main pegmatite extends for 340 m along strike, and to a depth of up to 120 m from surface. The pegmatite dips to the south, with dips of approximately 65° near surface and flattening to around 40° at depth.

A much smaller pegmatite lode occurs in the west of the deposit in the hangingwall to the main pegmatite, extends for 120 m along strike, and to a depth of up to 40 m from surface. More minor pegmatite dykes exist but were not modelled.

At its thicker portions the pegmatite is moderately but not consistently fractionated, with higher-grade lepidolite rich bands and ellipsoidal shapes developed around generally thin and discontinuous quartz cores.

The lithium mineralogy is largely as lithium-bearing muscovite mica, plus lepidolite mica, with lesser petalite and minor amblygonite. The petalite, which often occurs adjacent to quartz cores (if developed), was the focus of previous open pit mining and underground mining.

Mining Methods

• Truck & Shovel / Loader

Summary:

Opencut mining will be conventional methods using hydraulic excavators and mining trucks. All material mined from the pits will require blasting. There will be areas of narrow benches during the initial months of mining around the existing pits but wider benches will be available after a few months.

For the first half of the mine life required mining rates are relatively low so small sized excavators and trucks can be used. Small machines are well suited to the initial pit development work. Mining rates increase in the second half of the mine life as the final pushback is mined. This pushback will have broad benches many of which will be mostly waste rock. There will be a requirement for more or larger mining machines in this period.

Pit stage designs for Rubicon, Helikon 1 and Helikon 4 accommodate ramp access between stages.

Pit wall slopes for Rubicon and Helikon 1 are based on a Feasibility Study level geotechnical analysis by Pells Sullivan Meynink. Both pits tend to follow the orebody down dip so the highest walls are cut across the dip which will promote stability. No geotechnical assessment has been conducted for Helikon 4 so slopes from Helikon 1 were used. This is considered to be conservative because the Helikon 4 footwall is massive marble. Lepidico plan to conduct a geotechnical assessment of Helikon 4 to see if the pit slopes can be steepened.

The opencut target ore zones are within pegmatite sills formed in granite host rock. Dimensions and orientations of the orebodies are as follows:

Rubicon Pit
Orebody Dip: 20° to 30° NE;
Orebody True Width: 5 to 15 m;
Strike Length Mined: 750 m;
Maximum Depth: 98 m.

Helikon 1 Pit
Orebody Dip: 50° to 60° NNE;
Orebody True Width: 5 to 20 m;
Strike Length Mined: 360 m;
Maximum Depth: 65 m.

Helikon 4 Pit
Orebody Dip: 50° to 70° S;
Orebody True Width: 8 to 35 m;
Strike Length Mined: 300 m;
Maximum Depth: 78 m.

Mining will be by a conventional excavator and truck operation with most of the ore and waste requiring drilling and blasting.

Tailings
Tailings from the former small scale petalite mine at Rubicon are included in the Ore Reserve at a zero cut-off grade on the basis that the entire volume is above the economic cut-off grade and will all be processed.

Stockpiles
The surface stockpiles at Rubicon comprise numerous residual dumps from historical mining (mainly petalite) situated at or near the historical Rubicon mine.

The Rubicon stockpiles comprise four distinct material types, namely:
- Unsorted in-situ historical dumps;
- Screened undersize material (<60 mm);
- Sorted (>60 mm) ‘product’ (upgraded lepidolite-rich); and
- Sorted (>60 mm) ‘waste’ (residue from ‘product’ production).

The in-situ historical dumps have extreme variation in particle size which precludes requisite confidence to classify this material in the Indicated category. However, the ‘product’ stockpiles are consistent enough to allow reliable sampling, assaying, volume and tonnage estimation.

The product stockpiles are included in the Ore Reserve at a zero cut-off grade on the basis that the entire volume is above the economic cut-off grade and will all be processed.

Mining Sequence
Mining rates are based on the tonnage and grade of concentrate produced by flotation as feed stock for the chemical plant. For the first four years mining focuses on high grade massive and disseminated lepidolite.

Shallow high grade ore tonnes allow this to be achieved at low total mining rates of 600 to 800 ktpa ore and waste.

After Year 5 most of the high grade ore is depleted and the proportion of low grade mica and pegmatite increases. These ore types produce a lower lithium grade concentrate at a lower mass recovery.

The life of mine production schedule is currently based on Rubicon and Helikon 1 Pits. Ore from Helikon 4 and the Rubicon tailings and stockpiles will be used to supplement the opencut ore to maintain continuity of feed to the concentrator over the project life.

The Karibib Feasibility Study includes provision of diesel fuel supply, workshops, explosives storage and other facilities required to support the opencut mining operation. For the first nine years mining rates do not exceed 60 kbcm per month so the infrastructure to support the mining operation is minimal. Rates rise through Year 10 and 11.

Comminution

Crushers and Mills

Processing

• Hydrometallurgical plant / circuit
• Acid leach
• Crush & Screen plant
• Desliming
• Sulfuric acid (reagent)
• Purification & crystallization
• Flotation
• Concentrate leach
• Dewatering

Summary:

Ore from the pits, tailings and stockpiles will be beneficiated by flotation on site to produce a lepidolite concentrate. The concentrate will be transported from Karibib to Lepidico’s proposed Phase 1 Lithium Chemical Plant at in the United Arab Emirates (UAE). The Ore Reserve is based on use of the LOHMax® process at the chemical plant to produce battery grade lithium hydroxide monohydrate (LiOH.H2O) with by-products of amorphous silica, sulphate of potash (SOP) and rubidium/caesium brine.

Beneficiation of the ROM ore by crushing, grinding and flotation in a concentrator at the Karibib mine site. The lepidolite concentrate will grade approximately:
* 1.80% lithium from massive lepidolite;
* 1.36% lithium from disseminated lepidolite;
* 1.17% lithium from the mica/pegmatite ore types.

The L-Max® process was developed by Lepidico to extract lithium from lepidolite mica concentrates and then purify the leach solution for production of battery grade lithium chemicals. The LOH-Max® process was developed by Lepidico to produce battery grade LiOH.H2O from the purified leach solution. It has never been applied on a commercial scale.

Chemicals Conversion
A unique aspect of the L-Max® process is the direct leaching of the lithium bearing mineral from the feed without the need for an energy intensive thermal treatment step preceding the leach, which is employed by many other hard rock lithium conversion processes. The leach conditions are such that very little energy is required to keep the process at temperature. Optimising the leaching conditions has been an important part of the development process.

Handling of the leached slurry is a key part of the L-Max® process and the embedded intellectual property. The slurry is filtered at elevated temperature to yield a solution containing the valuable monovalent metals and a silica-rich filter cake. Effective washing of this cake is required to achieve high lithium recovery to the liquor moving downstream.

The filtered leach liquor, which is rich in aluminium, is cooled resulting in the crystallisation of an alum solid. This alum crystallisation step achieves the separation of lithium from the other monovalent cations. The monovalents, potassium, rubidium and caesium all form alums, whereas lithium does not. Filtering the alum slurry results in the potassium, rubidium and caesium, and most of the aluminium reporting to the solids, and a liquor containing the lithium and small amounts of other impurities. The alum solids are further treated to yield potassium, caesium and rubidium products.

The impure lithium-rich liquor is treated through a series of pH controlled precipitation stages, with limestone and lime, to sequentially remove the remaining impurities, namely iron, aluminium, manganese, and magnesium. The resulting lithium sulphate solution is of sufficient quality to allow the recovery of a high specification lithium product.

Production of lithium hydroxide is achieved without the co-production of sodium sulphate, using the proprietary LOH-Max® process. The unique chemistry of this process has been able to directly produce high purity lithium hydroxide monohydrate in a cost effective manner. The process takes the lithium sulphate liquor produced from the L-Max® process as feed and involves hydrometallurgical reactions to produce lithium hydroxide and a gypsum containing residue.

The L-Max®/LOH-Max® processes consist of just five main processing steps for the recovery of lithium hydroxide: feed preparation, leaching, impurity removal, sulphate removal and lithium recovery. A further three processing steps are included for the recovery of SOP, being alum dissolution, aluminium removal and SOP crystallisation. A further three processing steps are included for the recovery of rubidium and caesium products, being rubidium-alum crystallisation and re-pulp, aluminium precipitation and rubidium crystallisation.

Water Supply

Summary:

Water supply will be from an existing borefield.

Production

Operational metrics

Personnel

Job Title	Name	Phone	Email	Profile	Ref. Date
Consultant - Mining	John Wyche	+61 419-299-323	John.wyche@amdad.com.au		Feb 2, 2023
General Manager Operations	Timo Ipangelwa				Feb 4, 2025
General Manager Sustainability	Benedicta Uris				Feb 4, 2025
GM - Project Development & Strategy	Peter Walker				Feb 4, 2025
Managing Director	Joe Walsh	+1 647-272-5347			Feb 4, 2025
Mine Manager	Malakia Iindombo				Feb 4, 2025