Automated ‘drip coffee’ system eases copper extraction

As global demand for copper rises alongside the push for renewable energy, mining companies are searching for more efficient and sustainable recovery methods. Interdisciplinary Capstone Team 26017 is tackling that challenge for sponsor Freeport-McMoRan with an automated leaching system.

“Our main objective was to develop a piece of lab equipment that automates a hydrometallurgical system,” said Everett Cota, systems engineering student and team lead. “Freeport wanted us to track flow rates, moisture and temperature while solution runs through ore samples.”

Leaching uses a chemical solution to dissolve copper from crushed rock. In laboratory testing, technicians pack ore into vertical columns and slowly drip solution through them, resulting in a copper-containing liquid.

“The best way to visualize it is like drip coffee,” Cota said. “You have a little bit of liquid dripping slowly through the material over time.”

These column tests can run for months – sometimes up to 180 days – and traditionally require individual pumps for each column to deliver precise amounts of solution. Maintaining those pumps demands frequent calibration and hands-on monitoring.

“It’s very manpower-intensive,” said Joanna Robertson, Freeport-McMoRan’s director of metal recovery and team adviser. “People are constantly checking data, collecting samples and maintaining pumps.”

Robertson challenged the team to automate the system and make testing more efficient. The students proposed a simple approach: replace the pumps entirely.

“We thought, what if we try a gravity-fed system?” Cota said. “We could eliminate their biggest problem and replace it with a sensor and a valve to control the flow.”

The design uses a reservoir positioned above the column so gravity pulls the solution through. A flow meter measures the exact amount of liquid delivered, while a small pinch valve opens and closes in short bursts to regulate the daily dosage.

“It doesn’t change much for them operationally,” Cota said. “But it removes the constant calibration and maintenance of pumps.”

The system also has the potential to scale across large testing facilities. Some research labs run hundreds of column systems simultaneously, meaning a simplified setup could significantly cut costs and labor.

Sponsor helps shape career path

Freeport engineers worked closely with the team, offering technical guidance while giving students freedom to explore creative solutions.

For Cota, the project also aligned with his career interests. He spent the past five years interning with M3, a Tucson-based engineering firm that works extensively with mining operations.

“Working there is what really got me interested in mining,” he said. “When I saw this project, it was my number one choice because of my aligned interests.”

The capstone experience prepares students for industry roles through direct collaboration with sponsors. Students gain practical experience in teamwork, communication and project management.

“They learn how to step into a team of diverse individuals and solve a problem together,” Robertson said. “That makes them incredible future employees.”

As Craig M. Berge Design Day approaches, the team is finalizing a working prototype to display at the May 4 event before delivering it to Freeport.

Robertson said partnerships like these show the value of connecting students with real-world engineering challenges.

“The students are wonderful,” she said. “They give me a lot of hope for the future.”

Watch interdisciplinary capstone teams showcase their work at the Craig M. Berge Design Day on May 4.