Morenci Begins Commissioning Final Vessel of Concentrate Leach Plant Expansion

November 21, 2025 - Almost 300,000-work hours, over 200 contractors, more than four months of work and one goal – realizing Morenci’s true potential.

In October, Freeport’s Morenci, Arizona, operation began commissioning the second and final vessel in its concentrate leach plant expansion, setting the stage as the site – much like the company – begins to reinvent its operations for the future.

The CLP expansion gives Morenci the opportunity to more efficiently use the site’s resources, and it could prove to be an important step in helping achieve critical savings in the face of economic headwinds.

“We approached this as more of a sitewide upgrade,” said Alex Banda, Superintendent Hydromet CLP/EW-Morenci who oversaw the development of the expansion project. “Even though it’s one project, it has the ability to impact the way we run our entire business.”

The CLP relies on a pair of autoclaves to create high-pressure, high-temperature environments, Banda said. For a copper mine like Morenci, that means inducing a chemical reaction capable of extracting copper from concentrate that otherwise would be destined for a smelter and redirecting it to the site’s available electrowinning capacity.

Improvements could increase capacity

Morenci’s CLP has been in use for over a decade, but analysis in more recent years showed process improvements could nearly double throughput to 40 short tons per hour from 24.
As one of only two in the company, traditional CLPs are costly and not without their flaws, but the benefits of the proposed expansion were readily apparent.

Not only does this process pull forward copper that otherwise would be shipped off, but it also means Morenci could offset the purchase of 140,000 tons of acid, a byproduct of the process, said Bobby Pollock, General Manager Administration-Morenci.

Pollock, an early advocate for the project, said the site also could gain savings by reducing thousands of shipments of acid coming in and concentrate going out.

“This was something that made sense for us,” Pollock said. “As a company, Freeport does a good job of leveraging existing resources. That’s what we’re seeing here at the site – people putting in the effort to remove bottlenecks and make sure we aren’t leaving anything on the table.”

Team navigates obstacles

Removing those bottlenecks was not without its challenges, though.

Some hurdles included a limited footprint that meant expanding up rather than out, and timing and logistics running up against rising costs. During commissioning, the team identified unexpected reaction behavior in the vessels and successfully stabilized it by operating at a slightly higher temperature than initially planned.

However, the expansion yielded some surprising successes, as well.

Among them, design improvements appear to be reducing the build-up of scale in the off-gas system, meaning the plant could go longer between downtime. One vessel also has exceeded targeted throughput, meeting one success metric success early in its commissioning.

Equipment availability and recovery rates are other metrics the team will be watching – metrics Banda feels confident they’ll achieve as the site continues to pull together on the project.

“There were lots of paths forward for Morenci,” Banda said. “But we found a common vision and everyone from engineering to operations to contractors came together in an effort to make sure we pulled this off. I know they’ll continue that collaboration. This is a milestone for who we are as a site.”

Photos (top to bottom): With the old concentrate leach plant (top) limited by space, the expansion was forced to go vertical and now consists of seven levels; Alex Banda (second from right) and her colleagues stand in front of the completed concentrate leach plant expansion at Morenci.