Kambale Graphite Project

Plan showing historical and recent drill results and Exploration Target estimate outline
Kambale Cross Section 1,112,200mN
Kambale Cross Section 1,111,450mN

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Kambale is emerging as a credible flagship deposit of quality, dominantly fine-flake graphite justifying the fast-track evaluation adopted by Castle over 2022/23. This is in response to the widely forecast and looming supply deficit expected for this “Critical Mineral” as the World rushes to meet its clean energy ambitions.

Diamond core samples laid out in January 2023 at the Metallurgy Pty Ltd laboratory for inspection and compositing ahead of test work

Project Background

The Kambale graphite deposit was identified in the 1960s by Russian geologists prospecting for manganese. They undertook a program of trenching and drilled 25 holes to a maximum depth of 25m.

The mineralisation consists of north-east trending, sub-parallel zones of meta-sediment which is host to the graphitic schists. The Lower Proterozoic Birimian (~2.2Ma) meta sedimentary rocks, namely phyllites, and quartz–biotite schists, generally trend north-easterly and dip between 50o and 75o to the north west. The schists are hosted mainly in granodiorite.

The genesis of the flake graphite in Kambale is believed to be the result of high-grade metamorphism (amphibolite-granulite facies) which has converted trapped amorphous carbon into the characteristic fine crystalline layers.

Castle reviewed the historical work and a wide-spaced, regional-scale electromagnetic survey dataset inherited from previous licence holder, Newmont Limited. This work outlined a roughly elongate, northsouth orientated, ~10km-long region considered prospective for graphitic schist horizons which may host multiple lenses of graphite mineralisation, similar to what is already outlined from drilling and trenching at Kambale. These lenses or horizons can vary in length and be up to 50m wide, creating substantial deposits of graphite.

Encouraged by firm graphite prices in 2012, Castle undertook three consecutive phases of drilling comprising RAB (251 holes, 5,621m), aircore (89 holes, 2,808m) and reverse circulation (3 holes, 303m). Mapping noted occasional outcrops of manganese and graphitic schist as well as graphite in termite mounds.

In 2012 Castle undertook a very limited program of bench-scale test work on RC chips. Thereafter, little work was undertaken until the more recent improvement in graphite prices prompted a re-evaluation of the Project in early 2021.

In September 2021 Castle’s new management team reported that preliminary test work on sub-optimal near-surface, weathered graphitic schists yielded very encouraging fine flake graphite concentrate grades of up to 96.4% and recoveries of 88%. A conventional multiple grind and flotation concentration flowsheet was used. Three excavated and composited samples provided for the test work graded 12.56%, 16.09% and 17.16% total carbon.

In March 2022, a ground electromagnetic (HLEM) survey demonstrated a strong correlation between drill confirmed graphite mineralisation and zones of high conductivity. Several high conductivity zones extending well outside of the existing Inferred Resource boundary were highlighted indicating the possibility of extensions of the known graphitic schists into sparsely or undrilled areas.

In late 2022 a 52-hole 5,353m RC program was undertaken to test the interpreted steep dipping, shallow conductive plates from the EM survey. The results confirmed that the majority of the plates where due to graphite mineralisation and that the graphite continued to depths of at least 100m and likely beyond.

An Independently estimated JORC 2012 Exploration Target of 16.82 million tonnes to 50.46 million tonnes at a grade between 6.74%TGC and 10.40%TGC (Total Graphitic Carbon) was subsequently reported (refer ASX release 28 November 2022).

The Exploration Target has been prepared and reported in accordance with the 2012 edition of the JORC Code. The potential quantity and grade of the Exploration Target is conceptual in nature. There has been insufficient exploration to estimate a Mineral Resource. It is uncertain if further exploration will result in the estimation of a Mineral Resource.

The Exploration Target confirmed that the Kambale represents a credible graphite deposit and provided added impetus for the accelerated evaluation approach now being taken.

Logistics and infrastructure

The Project is located 6km west of the Upper West region capital of Wa which is 400km north, via good sealed roads, of Kumasi. From Kumasi it is approximately 240km south east by rail or road to the international port of Tema, 30km west of the capital Accra, which provides direct access to global export markets. An alternative international port at Sekondi–Takoradi is located approximately 230km west of Accra.

The Wa region has an excellent infrastructure comprising a commercial airport with daily flights, reliable grid power supplied partly by a hydroelectric dam at Bui, river (Black Volta River) and artesian water and many other useful services.


Ghana has a well-established mining industry including several Tier-1 mining operations. It is now Africa’s largest gold producer and the World’s sixth largest and accordingly has a well-trained and very capable workforce supported by an excellent mining services and supply sector. It is a safe and politically stable jurisdiction based on the Westminster system and has a workable Mining Act and fiscal regime.

Social licence

Castle management has spent over 14 years successfully operating in Ghana and in particular its Upper West region. The Company has established an excellent reputation for its pro-active commitment to community engagement, local employment and training, the promotion of youth and women’s development initiatives, maintaining the highest environmental operating standards and overall operating ethically and sustainably whilst carefully managing community expectations.

Prior to embarking on any specific exploration program the Company’s Ghanaian team conducts comprehensive discussions with all stakeholders to fully inform them as to the Company’s activities and to identify sites of cultural, religious, social and economic sensitivity and to appropriately mitigate any matters of concern. Compensation for access and any disruptions caused is provided at a minimum as per Ghana Mining Act guidelines. All site disturbances are rehabilitated immediately after use and in close consultation with landowners.

Graphite market

The graphite market is diverse across industrial, metallurgical, chemical and specialised areas with each sector requiring graphite concentrates with specific qualities. Deposit type, size and geometry, flake size, flake shape, grade, impurities, capital and operating costs, ability to be refined, proximity to specific markets, supply logistics, jurisdiction, fiscal regime and many other factors all combine to determine the commercial viability of a particular deposit.

The current medium to long term outlook for the broader graphite concentrates market is one of escalating demand and a looming supply deficit driven in particular by its use in the fast-growing EV battery and stationary power storage sectors. At present, there is no viable substitute for graphite.

There is an increasing proportion of natural graphite, over high CO2 generating synthetic graphite, being used in battery anode manufacture which also requires a fine flake graphite as the primary raw material. Hence, prices for fine flake graphite concentrates have shown a steady upwards trend in the past year.

The reader is directed to numerous recent publications, conference proceedings, market research papers and corporate websites of companies engaged in graphite exploration, project development or production for informed commentary and analysis of the graphite market.

Next key steps at Kambale

  1. Deliver a JORC 2012 Mineral Resource estimate by end Q1 2023;
  2. Receive Phase 2 test work results and preliminary process flow sheet design Q2 2023;
  3. Provide a bulk concentrate sample generated by current test work to Germany-based specialist consultants for evaluation of its capability to produce Battery Anode Material (“BAM”);
  4. Appoint a multi-disciplinary advisory team;
  5. Commence ESG benchmarking;
  6. Undertake a high-level project development scoping study;
  7. Secure an end-user offtake / project development partner; and
  8. Close up drilling and upgrade Mineral Resource.

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