HEAP LEACHING
Rio Tinto ’ s nature-based technologies under Nuton can be deployed in greenfield , brownfield and legacy sites , producing a 99 % pure copper cathode on site while delivering leading environmental performance
sites , producing a 99 % pure copper cathode on site while delivering leading environmental performance , it adds .
On top of being mentioned by BHP , Nuton leaching potential has also been attached to several junior mine developments .
One of the more advanced assets – in terms of showcasing Nuton ’ s potential – is Excelsior Mining Corp ’ s Johnson Camp Mine ( JCM ), in Arizona , where first copper production is anticipated in the first half of 2025 .
Following the decision by Nuton to proceed to Stage 2 of a process to restart the JCM mine using Nuton copper heap leaching technologies , Excelsior has completed the bulk of the planning and engineering and has mobilised crews to start construction . Earthworks related to the construction of the new leach pad has commenced , including crushing of the over-liner material .
Robert Winton , SVP Operations and General Manager of JCM , said : “ The opportunity to build and operate Nuton ’ s first demonstration of their state-of-the-art copper leaching technology is a privilege Excelsior and our team is proud to deliver .”
The strategic relationship the two companies have in place sees Excelsior providing the ore , existing plant / infrastructure , permits , people and management ; and Nuton providing the expertise , support , specific equipment and funding . Excelsior , in this case , remains the operator and manager .
The benefit for Nuton is the ability to rapidly deploy its nature-based technologies at an industrial scale , according to Excelsior .
This latest stage of work follows drilling , testing and preliminary design – all of which has been completed . The goal is to keep the solvent extraction-electrowinning ( SX-EW ) plant full for approximately four years prior to looking at a much bigger mine life at JCM that could account for more than 15 years of production .
Rio Tinto and BHP are not the only ones putting their leaching wares out in the market , with Antofagasta Minerals saying it is now in the process of evaluating primary sulphide material from third parties that may benefit from its proprietary chloride-based Cuprochlor ® -T leaching process .
Building on its first iteration of leaching technology for secondary sulphides – Cuprochlor – the Cuprochlor-T process effectively binds together the particles of mineral into a porous but manageable material that can then be heap leached based on variables such as temperature , reagent concentrations and particle size .
The company has proven the solution works during an industrial test of over 40,000 t of primary sulphide material averaging 0.4 % Cu – containing more than 90 % chalcopyrite – that , using the same process , showed consistent recoveries of over 70 %.
In its most recent six-month results presentation , Antofagasta Minerals said the company had progressed in trial test work with samples provided by third-party mine sites , with a view to commercially validating Cuprochlor-T in the market .
“ In parallel , a prefeasibility study based on Cuprochlor-T to extend the life of the Zaldívar mine is currently being finalised , following the heap-leach heating pilot conducted in 2023 ,” it added .
Freeport to up its run rate
Among the new applications , technologies and data analytics Freeport-McMoRan is advancing as part of a plan to improve copper recovery from its leach processes in North and South America is Jetti Resources ’ patented catalytic technology .
Jetti has developed catalytic technology to allow for the efficient and effective heap and stockpile leach extraction of copper . This bolts onto existing SX / EW leaching plants so it can be deployed rapidly with limited capital expenditure . Because it uses no heating or grinding , the technology also comes with low operational costs . In addition , there are huge environmental benefits from using leaching over pyrometallurgy , according to Jetti .
In its June quarter 2024 results , released late last month , Freeport said it believed the leach innovation initiatives it was pursuing provided potential opportunities to produce incremental copper from its large existing leach stockpiles and lower-grade material currently classified as waste .
Incremental copper production from these initiatives totalled 55 MIb in the June quarter of 2024 , compared with 29 MIb a year earlier . In the first six months of 2024 , it generated 106 MIb of copper from this work , compared with 51 MIb for the first six months of 2023 .
“ FCX is pursuing opportunities to apply recent operational enhancements on a larger scale and is testing new innovative technology applications that have the potential for significant increases in recoverable metal beyond the current run rate ,” it added . This is where Jetti ’ s technology has come in . Last year , a Freeport spokesperson confirmed to IM that the company was in a trial of the Jetti technology through “ a commercial installation ” at its Bagdad mine in Arizona , USA . This mine is one of Freeport ’ s major leaching test hubs , with the company targeting over 3 MIb / y of incremental copper cathode production from the open-pit copper mine through this work .
Bagdad has a 77,100 t / d concentrator that produces copper and molybdenum concentrate , an SX / EW plant that can produce approximately 6 MIb / y of copper cathode from solution generated by low-grade stockpile leaching , and a pressure-leach plant to process molybdenum concentrate .
Jetti , last year , also reached an agreement with Sociedad Contractual Minera El Abra and Freeport-McMoRan to deploy its leaching technology at the El Abra copper mine in Chile , majority-owned and operated by Freeport .
Jetti ’ s technology is being deployed on the existing leach stockpiles at El Abra and will target over 20 MIb / y of incremental copper cathode production after an initial ramp-up period . The project will leverage existing El Abra infrastructure including excess tankhouse capacity sufficient to process all production from Jetti ’ s leaching technology .
IM
50 International Mining | NOVEMBER / DECEMBER 2024