JOHANNESBURG (miningweekly.com) – Johannesburg- and Sydney-listed Orion Minerals has continued its transition to mine developer and operator at the Prieska copper/zinc mine in South Africa’s Northern Cape.

The diversified base metals company, which is developing three complementary base metal production hubs in the Northern Cape, is prioritising the development of projects capable of meeting the growing demand for key future-facing metals that have strong market fundamentals because of declining global resource inventories, falling grades at major mines and lack of investment in new mines.

Recruiting and onboarding of a skilled operating team, preparation of detailed designs together with execution plans for the trial mining programme and installation of primary infrastructure upgrades all progressing according to plan have formed part of the critical path items.

“We spent the greater part of the September quarter completing essential preparations, such as installing underground refuge chambers, upgrading the hoisting capacity of the emergency escapeway to the surface and sourcing and installing key ventilation equipment in preparation for trial mining,” Orion CEO Errol Smart stated in the September quarterly activities report released to Mining Weekly.

A six-month trial mining contract has been awarded to South African contract mining company Newrak Mining, which will target the near-surface crown pillar deposit using both conventional and alternative underground mining methods.

Initial project development funding of A$13.8-million was drawn down in July from facilities totalling R370-million, made up of a R250-million convertible loan facility from South Africa’s State-owned Industrial Development Corporation and A$10-million from the Triple Flag early funding arrangement.

Primary dewatering of the Prieska mine is expected to begin in the first quarter of next year following commissioning of the primary 15 MW electrical power supply. Meanwhile, the installation of a 178 m rising main dewatering pipe has been completed.

The updated feasibility study on the accelerated development strategy and staged ramp-up at Prieska is on track for completion by the middle of next year, once trial mining has been completed.

A revised geological interpretation has resulted in improved definition of the mineralised zones for the Flat Mines area at the Okiep copper project, together with an increase in the total mineral resource.

“While we are very busy at Prieska, we have not lost sight of the huge opportunity we have at our second emerging production hub, the Okiep copper project, also in the Northern Cape,” said Smart.

Mineral resources at Flat Mine north, east and south now total 9.3-million tonnes at 1.3% copper for 130 000 t of contained copper, including a measured and indicated resource of 7.4-million tonnes at 1.4% copper.

The mineral resource for the entire Okiep copper project has now increased to 12-million tonnes at 1.4% copper for 160 000 t of contained copper.

Orion is engaging with various technical and turnkey process plant service providers for the supply of a 30 000-t- to 60 000-t-a-month modular process plant to treat ore from the trial mining phase at Prieska.

The test work is being undertaken on supergene material as initial feed into the sulphide process plant being designed.

Processing routes developed by Mintek in 2018 include hypogene milling, sequential copper flotation, zinc flotation and ultra-fine grinding. However, opportunities exist to improve on the processing route for the supergene sulphide portions of the deposit.

The plant will be designed to treat the different ore bodies in separate treatment campaigns from surface stockpile material.

Former Anglovaal chief metallurgist Bryan Broekman, who was directly responsible for most of the metallurgical process plant optimisations at Prieska to treat mixed oxide, supergene sulphide and hypogene sulphide ores from 1988 until mine closure in 1991, has been contracted to oversee the two sets of supergene flotation test work currently undertaken by Enprotec and MTEC Engineering.

Orion’s third Northern Cape project, the Jacomynspan nickel, copper, cobalt, and platinum group elements sulphide project, will leverage off modern refining technology specifically directed toward production of metal products that are critical to the energy transition. The metal vapour refining technology currently being tested on metal sulphide concentrates presents an opportunity to maximise metal recovery to high-value products.

The engineering design of the 15 MVA electricity supply point substation extension has been approved by Eskom for construction by Orion. The Prieska mine has partnered with Power Plant Electrical Technologies for electrical specifications and electrical project management.

The 15 MVA upgrade is scheduled to be completed by early 2024. In the meantime, the surface and underground electrical reticulation is being project managed by Power Plant Electrical Technologies in readiness for the delivery of the long-lead items of the 15 MVA upgrade.