Metallurgical testwork including innovative technologies

Koryx’s metallurgical testwork program is well advanced, building on high-quality work carried out since 1996 and supported by the extensive exploration programs completed by Rio Tinto (1970s) and Teck Resources (2000s).

The program has two core objectives:

1. Confirm the feasibility of a conventional processing route – crushing, grinding, and flotation – to produce a clean, high-quality concentrate from higher-grade Haib material (>0.25% Cu)
2. Evaluate the feasibility of a heap-leach route for lower-grade material (<0.25% Cu).

Historical and current metallurgical testwork results have shown that the Haib mineralisation is largely hosted in a competent porphyritic granodiorite rock. The main economic element present in feed mineralisation is copper, with accessory amounts of molybdenum and gold also present. Copper is mainly present as a sulphide in the form of chalcopyrite with minor amounts of secondary chalcocite and bornite and in oxide form (chrysocolla, plancheite, malachite and azurite).

The Haib copper deposit has a long history of metallurgical testwork and studies undertaken by various parties, where the following have been reviewed for the October 2025 PEA:

• mineralogical investigations dating back to 1975 when RTZ explored the deposit
• historical comminution and flotation tests primarily completed by Mintek in South Africa with support from Amdel Limited in Australia. This programme was completed in 1996 to support the 1997 FS
• a bacterial heap leach study by the University of Witwatersrand (Wits) in South Africa in 1997
• an extensive hydrometallurgical test programme directed by the NCJV in 1997, as a supplement to the minerals processing tests already mentioned, that were used to support the 1997 FS of the Haib project
• bacterial column leach tests by Mintek South Africa in 2003
• bacterial leach tests, liberation assessments and pre-concentration scoping tests commissioned between 2019 and 2020 by METS Engineering (METS) to support a PEA originally published in 2021 and amended in 2024, in which a 20 Mtpa H/L process was considered for the recovery of copper from the deposit
• material characterisation, comminution, bulk mineralised material sorting, CPF and conventional flotation tests undertaken from 2024 to 2025 under the management of technical teams from Koryx and DRA in support of the October 2025 PEA. The majority of the testwork programme was undertaken at Maelgwyn Mineral Services Africa (Maelgwyn) in Johannesburg South Africa, with support from Geolabs in Johannesburg and Metso in Pennsylvania for the comminution testwork scope, Eriez in Johannesburg for the CPF scope, SGS in Johannesburg for mineralogical characterisation and Jameson cell flotation tests, and NextOre in Australia for bulk mineralised material sorting test work
• sequential copper analyses using progressively more intense leach conditions to confirm the copper mineral content of the samples tested which was conducted by both Mintek and Maelgwyn in Johannesburg as part of the 2025 PEA testwork program
• Tomra and Rados in South Africa have undertaken particle and bulk mineralised material sorting testwork programs, SGS South Africa has completed HLS test work to inform DMS preconcentration assessments, and Mintek as well as Ceibo in Chile are conducting further heap leach column testwork. With these companies and approaches, there will be six different lixiviants or leach regimes evaluated. This work is still ongoing.

Laboratory tasks in progress

These tasks were completed in late 2025 or are still in progress, mainly at the Maelgwyn laboratory but in some cases by laboratories mentioned above:

• crushing, milling and high-pressure grinding roll (HPGR) tests to support comminution circuit modelling
• mineralogical examination of ore sorting pre-concentrate and rejects samples, to confirm which gangue minerals were specifically rejected during ore sorting as well as main reasons for copper losses to rejects
• silver content of Haib samples was determined to be un-economic based on the PFS flowsheets
• ore sorting tests of both high- and low-grade ore using laboratory test units employing X-ray transmission (XRT) and X-Ray fluorescence (XRF) techniques to enable simulation and modelling of a potential pre-concentration circuit after secondary crushing
• coarse particle flotation tests with potential to significantly reduce tonnage reporting to conventional flotation by removing gangue minerals
• conventional copper milling and flotation tests of fresh sulphide material and in conjunction with CGR tests across a range of copper grades
• gravity and flotation recovery of gold
• Jameson rougher cell tests as an alternative to conventional copper flotation cells
• molybdenum (Mo) flotation and leaching to recover Mo to a separate marketable concentrate and remove Mo as much as possible from the main copper flotation concentrate
• geochemical column leach tests of low grade, waste rock and filtered tailings to determine the potential for acid generation and acid rock drainage
• twelve-month column leach tests of high grade (>0.28% Cu) and low grade (>0.19% Cu) sulphide samples. Two bacterial leach, three chloride leach and one nitrate-based heap leach technologies were tested
• column leach tests of one sulphuric acid, one bacterial leach process and one chloride leach process to recover copper from oxide/transitional ore in which about 75% of copper was present in silicate minerals, 15% as secondary sulphides and about 10% as primary chalcopyrite