Morenci Archives - International Mining

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, the company has confirmed to IM.

In its December quarter and 2022 annual results, released late last month, the leading copper miner 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.

The company has been exploring the potential for incremental low-cost additions to its production and reserve profile for some time, saying in the latest results release that it had identified opportunities to achieve an annual run rate of 200 MIb/y (90,718 t/y) of copper through these initiatives by the end of 2023.

Freeport has a long history of copper leaching production with its Americas division, which includes assets such as Morenci and Cerro Verde, having developed and implemented industry-leading technologies for leaching of oxide ores.

The company has been pursuing internal and external initiatives to expand this leading position, focusing on traditional ores and sulphide orebodies that have been typically considered difficult to leach, like chalcopyrite.

This is where Jetti’s technology comes in.

The Colorado-based company has developed catalytic technology to allow for the efficient and effective heap and stockpile leach extraction of copper. This bolts onto existing solvent extraction/electrowinning (SX/EW) leaching plants so it can be deployed rapidly with limited capital expenditure and, because it uses no heating or grinding, has low operational costs. In addition, there are huge environmental benefits from using leaching over pyrometallurgy, according to Jetti.

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 its 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.

The spokesperson added: “There is potential to expand production via the treatment of additional stockpiles at Bagdad in the future based on results.”

The use of Jetti’s technology is one of several leaching initiatives the company is pursuing – some with outside vendors, some using its own technology and some with joint venture partners.

All of these are focused on not only adding low-cost production to Freeport’s large production base, but also achieving a lower carbon footprint.

Jetti, which Freeport is an investor in, has been conducting a carbon footprint study and Life Cycle Assessment (LCA) of its technology, with the LCA including analyses of typical copper mining operations without Jetti’s technology and a mining operation with Jetti’s technology installed. The LCA is being conducted in conformance with the ISO 14040/44 standard and will be critically reviewed by an independent expert.

*Jetti Resources has developed catalytic technology to allow for the efficient and effective heap and stockpile leach extraction of copper*

Jetti has also committed to starting to track water usage and waste at all its operations and sites, which includes the installation it has at Capstone Copper’s Pinto Valley operation, also in Arizona.

At Capstone’s operation, Jetti technology is being used extensively as part of a plan to recover up to 350 MIb of cathode copper over the next two decades from historic and new mineralised waste piles.

Teck Resources has also taken an interest in Jetti’s technology having signed an agreement for the evaluation of the solution at a number of Teck’s assets with potential copper resources outside of existing mine plans. BHP, through its BHP Ventures arm, is also an investor in Jetti.

As to Freeport’s wider leaching plans, it said it was looking to use data analytics to provide new insights to drive additional value, while new applications to retain the heat in the stockpiles were “yielding results”.

The company has assessed that it has some 38,000 MIb of contained copper in leach stockpiles deemed “unrecoverable” by traditional leach methods. Of this amount, about 50% is from the massive Morenci mine, which already has leaching production capacity of 900 MIb/y of copper.

The design and operating principle of Metso Outotec’s HRC high pressure grinding roll has been well proven since going commercial in 2014.

The elimination of the edge effect with a flange design brings with it high throughput, while the anti-skew assembly means customers find faster machine restarts and no downtime from skewing events.

These benefits have been proven at Freeport McMoRan’s Morenci mine, in Arizona, USA, with the company’s largest unit – a HRC 3000 – having now processed more than 120 Mt of ore at that operation. This HRC 3000 is still going strong.

Yet, there was room for improvement, hence the reason Metso Outotec has just released the HRC™e HPGR.

Christoph Hoetzel, Head of Grinding business line at Metso Outotec, explained the rationale for such an update.

“To enable this flange technology, it was very important to have a simple, mechanical solution that works under any circumstances,” he told IM. “Our solution with the HRC was the arch frame, which was a mechanical fix to keep the rolls parallel at all times.

“This, however, came with a compromise. You had to have access to both sides of the machine and, in general, the units were relatively heavy and tall.”

These attributes meant that, if the customer investigated the total installed cost of the HRC – especially if they were weighing the purchase of more than one unit – the cost sometimes outweighed the benefits.

“This was a case of where the economics did not match the sustainability and efficiency of the unit,” Hoetzel said.

Metso Outotec has listened to customer feedback with the HRCe.

“The enabling factor for the flange technology is a mechanical solution for eliminating skewing on the machine,” Hoetzel said. “We have now achieved this with a much simpler, compact design. This is really where the step change has come from.”

Now, when you look at the specifications of the HRCe, which comes with a large feed size acceptance of 60-120 mm and typical capacities of 1,810-6,930 t/h, the footprint is almost the same as other HPGRs on the market, according to Hoetzel.

“Yet, the unit benefits from the proven and reliable flange design of the original HRC,” he said. “You could, potentially, even use a smaller unit for the same application.”

By reducing the size and associated installation cost that comes with the HRC technology, Metso Outotec is suddenly levelling the HPGR playing field. The advantages the company spelt out back in 2014 when the HRC technology was originally publicised now come with no cost drawbacks.

With more miners looking for not only energy-efficient grinding solutions in their flowsheets, but processing options that reduce their water intake, HPGRs are increasingly being used in tertiary or quaternary crush applications, or in lieu of traditional SAG mills.

In this regard, an updated HPGR is coming to the market at just the right time.

Metso Outotec, cognisant of this trend, has also sought to offer the benefits of its HPGR technology to the wider market.

The mechanical skew control HPGR (High Pressure Grinding Roll) retrofit kit takes the key components responsible for minimising skew from the HRC and makes the technology more accessible without the major investment or need to acquire a new machine, according to the company. The technology can also be incorporated into non-Metso Outotec machines.

These latest product updates are in keeping with Metso Outotec’s defined purpose of “enabling sustainable modern life”, fitting the mineral processing reality that miners face today.

Hoetzel reinforced this message: “Customers should not have to choose between sustainability and lowest total cost of ownership with their machines. At Metso Outotec, we truly want to be the partner for positive change, which means we really need to combine both.

“With the HRCe, we think we have achieved that.”

Freeport furthers its leading copper leaching excellence

Metso Outotec ticks the TCO box with latest HRC HPGR design