Chino Mine Clears the Way for ’Perfect Stockpile’

May 30, 2024 - “This is a big deal.”

While Randy Ellison may not have used a lot of words to start a kickoff meeting earlier this year, the General Manager of Freeport-McMoRan’s New Mexico Operations certainly used the right ones.

In January, the company approved construction of North Lampbright, what some have characterized as the “perfect stockpile.” For Freeport’s Chino mine in New Mexico, the project represents its first new leach stockpile in decades and the ability to see out its current life of mine; for the company, it’s an opportunity to apply decades of incremental improvements and upend longstanding copper recovery rates.

“We call it the ‘perfect stockpile’ because it brings together everything we know and have learned through our leaching efforts into a single new stockpile,” explained Marty Brueggemann, Hydromet Manager-Chino. “Its success could change our approach to leaching not just at Chino, but across the entire company.”

In the simplest terms, that success comes down to heat. Many of the innovations being implemented –covers, air injection, irrigation rates and more – are geared toward the generation and retention of heat. Another key component in that equation is pyrite, which creates heat, produces sulfuric acid and may give Chino an advantage over other sites.

According to Brueggemann, the site’s ore body has some of the highest pyrite concentration in the company’s North America properties, with levels two to three times those achieved in the Morenci, Ariz.-engineered heap, a decades-old project that helped maximize the company’s recovery rates in low-grade ore.

To verify conditions, Brueggemann said, North Lampbright also stands to be the most highly instrumented stockpile in the company’s history, incorporating sensors for temperature, oxygen, oxidation-reduction potential and more – and all from the ground up. By providing data from Day 1, this new stockpile will afford the company new insight into the effectiveness of leaching practices over time.

Project origins

As significant as the stockpile now seems, it did not start out that way.

North Lampbright originally was conceived as a waste stockpile, said David Brence, Project Engineering Manager-New Mexico Operations. As the site investigated the possibility of using it for leaching, the costs became hard to justify under ordinary recovery rates. That’s when the team began to look beyond the ordinary.

Rather than reducing costs, the site added more, incorporating every innovation in the company’s portfolio to create the most ideal leaching conditions and increase recovery estimates from the mid-20 percent range to about 50 percent. Now, the project not only made sense from an economic perspective, it effectively could act as a research and development project as the site worked to prove out those assumptions.

Overcoming financial hurdles do not mark the end of risks for Chino’s new stockpile, as North Lampbright is a significant time investment. From its March groundbreaking, the project is expected to take two years of development before leachable pounds are placed.

“There are a lot of inherent risks in managing a project of this magnitude for this long,” Brence explained. “There could be workforce turnover, cost increases and even changes in mine planning that could all slow us down.”

The project faces several engineering challenges as well. A main cost driver, the project necessitates a dual drainage system between North Lampbright and existing, actively leached stockpiles nearby. The site also will need to avoid disrupting operations as it works to move roads, power lines and other collection systems.

At the end, though, North Lampbright has the potential to change Chino’s trajectory.

“We’ve been blessed with one of the highest-grade ore bodies in Freeport’s North American portfolio, but the challenge has always been its complexity,” Ellison said. “Finding innovative solutions to unlock the value from that are the game changers for Chino.”

Photos (clockwise): As contractors work below, engineers Jose Carrasco (left) and David Brence discuss the progress of North Lampbright; David Brence is overseeing North Lampbright, which is expected to be under construction for at least two years; In addition to North Lambright (foreground), Chino’s hydromet operation also is being repaired (right) and expanded (left).