Tag Archives: Orion Minerals

Orion settles on SAG milling and water treatment at Prieska Cu-Zn project

Two significant engineering changes have had a positive impact on the expected returns from Orion Minerals’ Prieska copper-zinc project in the Northern Cape Province of South Africa.

Issuing an updated bankable feasibility study (BFS) for a proposed new 2.4 Mt/y copper and zinc mining operation earlier this week, the company said there had been “numerous improvements” on the previous study completed in June 2019.

This included a 43% increase in post-tax undiscounted free cash flows from the project to A$1.2 billion ($798 million); a 36% increase in after-tax net present value (8% discount rate) to A$552 million; and a five-month reduction in the capital payback period to 2.4 years.

In the plant, the major changes include the use of SAG milling, and removal of secondary crushing, screening and rock conveyors.

The use of a SAG and ball milling circuit followed by differential flotation removes the need for multiple stages of crushing – which was included in the previous study.

The new plan envisages a high steel charged SAG mill operating in an open circuit with a secondary ball mill operated in a closed circuit with a classification cyclone cluster. The SAG mill trommel screen oversize feeds a pebble crushing circuit which returns crushed product to the SAG mill feed conveyor, the company said.

The milling circuit, meanwhile, is fed with (F100) 250 mm primary crushed material from the primary stockpile at a throughput rate of 300 t/h and produces a product size of 70% passing 75 μm, which is fed to the differential flotation circuit.

In a presentation, Orion stated that the processing plant costs from the 2019 study to the latest BFS had dropped 16% to A$91 million.

The next big change was a different de-watering philosophy of the old workings of Prieska, with the BFS including a new water treatment route. This resulted in a 30% decrease in the shaft dewatering timeline, it said.

The Hutchings Shaft and underground workings at Prieska are currently filled with water to a depth of 310 m below surface and contain a volume of 8.6 Mcu.m of water.

Dewatering of the workings via a pumping system to be installed in the Hutchings Shaft is now planned, with water being pumped into a 1 Mcu.m volume dewatering dam on surface, from where mechanical evaporators and a reverse osmosis water treatment plant will be used to dispose of and treat the water for discharge into the environment.

The use of water treatment supplements mechanical evaporation, which allows the pumping schedule to be accelerated by four months, Orion said. “Furthermore, the Department of Human Settlements, Water and Sanitation stipulated as part of the IWUL (Repli Integrated Water Use Licence) application process that provision be made for a portion of the dewatered volume to be made available for social, commercial or agricultural use in the locality.”

Forced evaporation is planned to be used as the primary means to dispose of the water with the water treatment plant (WTP) as the secondary means to treat and then discharge treated water into the environment as irrigation water.

Forced evaporation requires the use of a large evaporation dam, according to Orion, which impacts environmental considerations when compared with the small footprint required by the WTP.

“This is mitigated through the early construction of the tailings storage facility (TSF) which serves a dual purpose for early project phase dewatering and later as a TSF during the operational life of the mine,” the company said.

These actions, in addition to prioritising the extraction of higher grade (and confidence) mineral resources earlier in the mine schedule, helped significantly improve the project return economics, according to Orion.

While the changes also came with a 9% increase in peak funding requirements to A$413 million to cater for the operational improvements, it would also see 20% more payable copper produced – 226,000 t – and 17% more payable zinc produced – 680,000 t – over the 12-year mine life.

Orion’s Managing Director and CEO, Errol Smart, said: “With the Prieska BFS update now complete, the development of the Prieska project is ideally positioned to play a vital role in the local economic recovery plan for the Northern Cape region.

“The project’s low exposure to imported materials and foreign labour reduces construction challenges as the world overcomes and recovers from COVID-19.”

Smart added that the company was targeting a production start-up in 2024 as market conditions permitted.

Byrnecut to dig into Orion’s Prieska copper-zinc underground project

Orion Minerals Limited says it has concluded a memorandum of agreement with mining contractor Byrnecut Offshore envisaging an alliancing agreement for underground mine development and production at the Prieska copper-zinc project in the Northern Cape province of South Africa.

The agreement follows the announcement of the grant of the Mining Right for the Prieska copper – zinc mine and, Orion says, “paves the way for Byrnecut to bring the benefit of its experience to the development and operation of the Prieska project which is intended as a global-best practice mechanised mining operation”.

Orion has achieved several milestones in the 16 months since the submission of the Mining Right application, including the announcement of a black economic empowerment (BEE) partnership, the upgrading of the Prieska mineral resource to 30.49 Mt at 1.2% Cu and 3.7% Zn and the completion of the Prieska Bankable Feasibility Study (BFS).

While the Foundation Phase BFS demonstrated strong project economics with a post-tax net present value (8% discount) of A$408 million ($273 million), Orion says it has already identified numerous opportunities to improve on the mining plan set out in the BFS and has commenced work with post-BFS field trials, optimisation and refinement studies.

Key terms of the agreement with Byrnecut are that the parties will seek to enter an alliancing agreement related to underground mining at the Prieska project, whereby Byrnecut will undertake to provide underground mine development and mine production services; commit to promoting local employment and skills transfer in support of transformation of the industry; and commit to collaborating with local BEE enterprises.

Formalising the agreement is one of the key project development milestones that follow the release of the BFS for the establishment of high margin and long-life underground mining operations at the Prieska project. The planned foundation phase of operations would result in the mining and processing of 2.4 Mt/y of run-of mine feed for 10 years, to sell approximately 21,000 t of copper and 70,000 t of zinc as differentiated concentrates each year.

Other post-BFS workstreams in progress to prepare the project for execution include third-party peer reviews of the BFS in preparation for funding discussions, the value engineering of components of the BFS, mine-to-market business plan optimisation using the Whittle Enterprise Optimisation process, pilot-scale water treatment field trials of the water accumulated in the underground excavations and the expedition of the various ancillary licences required to operate a mine. The company said substantial progress is being made in all areas.

Orion’s Managing Director and CEO, Errol Smart, said: “We are delighted to include Byrnecut into the list of partners we will be working with to establish what will be another world-class mine in the Northern Cape.

“Byrnecut has an impressive reputation on the African continent both in terms of their operational proficiency and their approach to skills transfer and harmonious relations with local communities. Their involvement in developing Prieska will be invaluable.”

Orion Minerals looks at renewable options for Prieska zinc-copper project

Orion Minerals, through its subsidiary, Repli Trading No 27, has entered into a collaboration agreement with juwi Renewable Energies South Africa to investigate renewable energy generation for its Prieska zinc-copper project in the Northern Cape of South Africa.

The preliminary scope is to investigate the feasibility of generating and supplying 35 MW of electricity for Prieska, from a hybrid power system using integrated wind and solar technologies. The renewable energy generation site will be located within 20 km of Prieska, making the establishment of a dedicated feed via an overhead power transmission line possible, Orion said.

juwi is part of the international juwi Group, one of the world’s leading renewable energy companies. Its business is focused on both solar energy and onshore wind energy. To date, juwi South Africa has built five utility-scale solar plants totalling 121 MW and developed the 138 MW Garob Wind Farm, which will soon start construction.

juwi South Africa also participates in the South Africa Government’s Small Independent Power Producer Program and operates and maintains all its solar projects on behalf of their owners.

In Australia, juwi was recently responsible for the project development, design, construction and now operations of a $40 million, 10 MW solar power facility which came into commercial operation in 2016 at Sandfire Resources’ DeGrussa copper-gold mine in Western Australia. Orion said: “This facility has since attracted international attention as the largest off-grid integrated solar and battery storage facility in the world. With close to three years of operational data and 100% uptime, this successful project has established juwi as leaders in hybrid power supply solutions for mines.”

The investigations into renewable energy solutions at Orion’s Prieska project will complement the ongoing bankable feasibility study, with the additional benefit of potentially improving the base case plan of obtaining national grid power directly from the Cuprum sub-station already established on site, Orion said.

“Developing the renewable energy potential of the region is also a strategic goal of local government, as communicated in its Integrated Development Plans,” Orion said.

The Prieska copper mine operated from 1971 to 1991, employing approximately 4,000 people. The mine milled 46.8 Mt, producing more than 430,000 t of copper and more than 1 Mt of zinc in concentrate. Post May 1987, no more than 2 Mt of ore was blasted, with milling of surface stockpiles carried out from 1989. In 1991, the mine was closed and the site rehabilitated. It now has a defined maiden resource under the Orion ownership of 1.1 Mt of contained zinc grading 3.8% Zn and 365,000 t of contained copper grading an average 1.2% Cu. The deposit is regarded as one of the world’s 30 largest VMS orebodies, according to Orion.