Name of the Project
Prieska copper/zinc project.

Location
Northern Cape, South Africa.

Project Owner/s
Diversified metals explorer and developer Orion Minerals.

Project Description
An updated bankable feasibility study- (BFS-) 20 has confirmed the potential of Prieska to underpin a significant near-term, low-cost, copper/zinc development project, with exceptional opportunities for future growth.

The updated BFS on the foundation phase of the project proposes the development of a new 2.4-million-tonne-a-year copper/zinc mining operation at the brownfield project.

Underground and surface mining methods are planned to be used in conjunction with conventional froth-flotation concentration to produce differentiated copper and zinc concentrates for export.

Peak production is estimated at 23 000 t/y of copper and 88 000 t/y of zinc.

The life-of-mine (LoM) has been extended by two years, from 9.7 years to 11.5 years.

Material changes in the updated BFS, compared with the 2019 BFS plan, include:

• reducing the mine dewatering timeline and supplementing the treatment of that water,
• incorporating additional mineral resources into the mining plan that will increase the mine life by two years,
• a more conservative timeline to ramp up to steady-state production,
• prioritising the early mining of high-grade zones in the mining sequencing,
• adopting semiautogenous grinding mills in the processing flowsheet,
• an owner-miner operating philosophy for underground mining,
• using an experienced contractor to operate the processing plan, and
• a change in the key operational infrastructure being supplied by third-party financing and in the supply of select key operational infrastructure.

The mining methods for the project remain unchanged, compared with those stated in the 2019 BFS. Tunnel development remaining from the previous mining operations allows for early access to underground production mining areas. It is planned that a combination of longhole open stoping with fill and drift-and-fill mining methods will be used, supported with paste backfill.

Potential Job Creation
Not stated.

Net Present Value/Internal Rate of Return
The project has a net present value, at an 8% discount rate, of A$779-million, compared with A$574-million in the 2019 BFS, and an internal rate of return of 39%, compared with 38%, in the 2019 BFS. Payback from first production is estimated at 2.4 years, a decrease of five months.

Capital Expenditure
Market intelligence firm S2 Research noted in May 2022 that the peak funding requirement of Orion Minerals’ Prieska project had decreased from R2.4-billion to R2.25-billion. This has reduced the funding risk of the project.

In a prior note, S2 anticipated that Orion would need R2.7-billion to develop and optimise the Prieska mine.

Planned Start/End Date
Orion Minerals is targeting production startup in 2024, market conditions permitting.

Latest Developments
Orion Minerals has taken another key step in its early mining strategy.

This includes the completion of an updated mineral resource estimate (MRE) for the near-surface +105 level crown pillar, comprising indicated and inferred resources of 2.3-million tonnes, grading 1.7% copper and 1.6% zinc, outlining a very attractive early mining opportunity at this fully permitted mine, Orion MD and CEO Errol Smart has said on July 25.

The supergene sulphide, indicated resource, with a grade of 2.6% copper, is “a compelling focus for our early mining strategy”, Smart has said. This resource block is accessed from existing underground development through a short ramp, allowing for trial mining to start in the coming weeks.

The updated mineral resource estimate for this shallow portion of the Prieska deposit represents a robust focus for the trial mining programme scheduled to begin shortly. The updated MRE is based on a successful drilling programme completed in 2022. 

The +105 level crown pillar is located in close proximity to existing underground infrastructure and can be readily accessed, allowing for trial mining activities to start immediately, with all required permits and funding now in place.

This programme will generate key metallurgical and other data that will assist with process plant design, and also feed into an updated BFS for the early production strategy at Prieska.

The updated mineral resource estimate for the +105 level crown pillar brings the total indicated and inferred mineral resource, including the deep sulphide mineral resource, to 31-million tonnes, grading 1.2% copper and 3.6% zinc.

Ore sourced from the trial mining will be used for metallurgical optimisation tests and the detailed design of an initial processing plant at Prieska.

Discussions with metallurgical processing and engineering groups interested in offering processing facilities under build, own, operate and transfer arrangements are also under way.

The trial mining phase, metallurgical process optimisation and a resultant updated bankable feasibility study (BFS) are fully funded, with a total of R370-million, available from Industrial Development Corporation and Triple Flag funding facilities.

A first drawdown call for R167-million has been made from this facility.

An infill drilling programme of about 1 700 m on the oxide resource, to provide a further upgrade in confidence and additional metallurgical information, is planned for the third quarter of 2023.

This is, however, not critical to the current early mining BFS studies. Apart from this infill drilling of the oxide resource, no additional drilling is planned for mining of sulphide ore before the completion of the updated BFS.

Grade control drilling on a closely spaced grid will be executed during the operational phase of mining.

Key Contracts, Suppliers and Consultants
Companies involved in the BFS included A&B Global Mining; ABS Africa; BPDT & Co; Bluhm Burton Engineering & Ventilation Consultants; Beulah Africa; Cart Investments; DRA Projects South Africa; Earth Science Solutions; Endeavour Financial Limited; Falcon and Hume Attorneys Inc; Fraser McGill Mining & Minerals Advisory; Knight Piésold; METC Engineering; Gariep Mining and Exploration Services; Mets Consulting South Africa; Patterson and Cooke; PCDS Consultants; Power Plant Electrical Technologies; Professional Cost Consultants; Promethium Carbon; Shift Innovations; SRK Consulting; Strategy4Good; The MSA Group; Turnkey Civil (International) Group; VBKom Engineering Consultants; Whittle Consulting; and Z Star Mineral Resource Consultants.

Contact Details for Project Information
Orion Minerals, tel +27 11 880 3159 or email info@orionminerals.com.au.