The program comprised six diamond drill holes on two 80-metre-spaced cross-sections across the high-conductivity electromagnetic (EM) anomaly that corresponds with the graphitic units.
All six holes intersected graphite mineralisation including an interval of 8.63 metres at 12.1% total graphitic carbon (TGC) within an assay of 10.63 metres at 11.6% TGC.
The results have confirmed Peninsula’s exploration target model for Gapyeong, which is for a shallow plunging synformal structure as indicated by the EM model.
Peninsula managing director Jon Dugdale said the high-grade flake-graphite intersections were very encouraging and confirmed the thickness and 12%-plus grades intersected in previous trenching.
The company has also initiated metallurgical testing on fresh-rock drilling samples to confirm that a greater-than-95% TGC concentrate can be produced from the sulphide-bearing graphitic material.
Previous testing on surface trenching samples produced high-purity concentrate of 95.4%.
Further drilling to define a maiden flake-graphite resource will be planned based on the results of the fresh-rock metallurgy.
Dugdale said: “The next step is to complete confirmatory concentrate metallurgy on fresh rock samples before we continue drilling to target a maiden flake-graphite mineral resource in South Korea.
“The main graphitic unit appears to be thickening closer to the interpreted fold hinge at depth, representing a target for thicker, high-grade, graphite intersections similar to those produced by previous trenching.”
Drill holes on each cross-section of the eastern limb intersected multiple steeply-dipping skarn and marble-hosted graphitic units which are interpreted to be folded into a shallowly north-plunging synformal structure.
Other assay results are:
- 6.55 metres at 7.9% TGC from 39.6 metres, including 2.47 metres at 11.9%;
- 10.56 metres at 7.1% from 70.91 metres, including 5.44 metres at 10% and 1.81 metres at 10.7% from 86.95 metres; and
- 6.45 metres at 4.6% from 15.22 metres and 2.64 metres at 7.7% from 38.13 metres.
The western fold limb hosts lower-grade disseminated flake graphite with associated skarn and calc-silicate alteration and sulphide mineralisation.
On the eastern fold, however, the flake-graphite notably increases in abundance, as does the alteration and sulphide mineralisation.
Additional trenching and channel sampling have also been completed and confirms the graphitic units extend over a 400-metre strike length, corresponding to the southern EM anomaly.
Dugdale added: “The ultimate goal is to develop a high-grade graphite mineral resource and prove the potential to produce high-purity, battery-grade, spherical graphite on the doorstep of the world’s largest lithium-ion battery industry.
“These drilling results are a key step towards achieving these objectives.”
The presence of strong sulphide mineralisation had not been evident in previous channel sampling, most likely being oxidised and leached at surface.
Further metallurgical testing will be conducted to confirm the graphite ore’s amenability to produce high-purity concentrate.
The metallurgical work will look to generate a five-kilogram graphite concentrate sample for spherical graphite test work, with the objective of producing a 99.95% TGC-purity spherical graphite product.
This is to meet the specifications of South Korean lithium-ion battery anode manufacturers and other in-country end-users.
Peninsula has had advanced discussions with end-users in Korea regarding feed for battery manufacture and potentially also large-flake graphite for refractories in the steelmaking industry.