ASX- and JSE-listed Orion Minerals has reported robust assay results from the confirmation diamond drilling program at its Okiep Copper Project (OCP) in South Africa’s Northern Cape. These results build on initial findings reported in April and June, including a significant intersection of 49.34 meters at 5.05% copper at Flat Mine East (FME).
“Following our success in confirming high-grade copper mineralization at FME, the first assay results from Flat Mine South (FMS), located about 3 km southwest of FME, have delivered further outstanding copper intercepts,” said Orion Minerals MD Errol Smart. “These results show that the Flat Mines complex contains very high-grade copper sulfide mineralization within wider zones of moderate-grade intrusive.”
The OCP ground holdings span 641 km², covering most of the area where 105 million tonnes have been mined over the past century. The Flat Mines area and the current drilling program fall within an executed mining right.
The results from the first two of four planned holes at FMS have confirmed historical drilling information from Newmont and Gold Fields in the 1980s and 1990s. This information was used in the mineral resource update, which reported 9.4 million tonnes at 1.3% copper for the Flat Mines, including 3.4 million tonnes at 1.4% copper at FMS.
“Our initial bankable feasibility study (BFS) has focused on JORC-compliant mineral resources from Flat Mine North (FMN), FME, and FMS. However, the potential to expand scale and extend mine life is core to why Orion invested in the Okiep district,” Smart noted. “Our goal is to restore our Okiep properties to their historic production levels of 20,000 to 50,000 tonnes per year of copper production.”
The diamond drilling program, which started in February, includes 11 diamond core drill holes planned at FME, FMS, and FMN, totaling about 5,800 meters. The program is designed to confirm historical drilling information, provide geotechnical data, and deliver additional material for confirmatory metallurgical test work for the BFS mine schedule.
Drill hole OFMSD076 returned 6 meters at 0.9% copper from 454 meters within a broad zone of 32.32 meters at 0.63% copper from 427.68 meters. Historical hole FMS012, located about 20 meters from OFMSD076, intersected 34.8 meters at 0.74% copper from 447.9 meters.
Historical hole FMS046, located about 20 meters from OFMSD076, intersected 31.82 meters at 1.14% copper from 377.18 meters. Drill hole OFMSD077 returned an outstanding intercept of 20.5 meters at 4.99% copper from 549.5 meters within 43 meters at 3.41% copper from 527 meters. This is within a broad zone of 62 meters at 2.51% copper from 508 meters.
Historical hole FMS053D1, located about 10 meters from OFMSD077, intersected 38.98 meters at 2.16% copper from 574.44 meters.
Orion said significant widths of waste granitic material are included within the reported intersection widths, providing opportunities for upgrading material through modern X-ray fluorescence (XRF) ore sorting techniques. This allows optimized metal extraction with larger stopes operated at lower mining costs while limiting concentrator capital and operating costs.
Upon completing the drilling program, the geological and mineralization envelope interpretations will be reviewed and adjusted, followed by an updated mineral resource estimate. New geotechnical information will be used for mine design input.
Planned confirmatory metallurgical test work includes XRF sorting, comminution, flotation optimization, and tailings characterization. Detailed geotechnical assessments will be conducted on all intersections.
Orion said three of the five drilling rigs have been retained on-site to test for an increase in the classification of JORC resource blocks not yet included in the mine plan and to test for extensions of high-grade mineralization beyond the margins of the current JORC resource blocks.
At FMS, historical Gold Fields holes and Orion hole OFMSD077 indicate that high-grade mineralization remains open down-dip for up to 200 meters within an untested area encompassing a strike length of 300 meters.
Confirmatory drilling is also underway at Flat Mine Nababeep (FMNb), where an inferred mineral resource of one million tonnes at 1.4% copper was previously reported. Original drilling over the main zone of mineralization was carried out by the Cape Copper Company in the 1940s, with 141,000 tonnes at 2.72% copper subsequently mined in the 1950s.
Six holes totaling about 480 meters are initially planned to test and confirm the near-surface mineralization at FMNb, Orion said. Highly mineralized intrusive rock, similar to that intersected at FME and FMS, has already been found from 6 meters to 52 meters in the first drill hole at FMNb.
Outcropping exposure and drill intersections indicate that FMNb is likely to have a high internal waste content. This is suitable for bulk extraction with the application of ore sorting to remove the granitic waste before milling the higher-grade mafic intrusive rock fraction.
Source: Mining Weekly
