By Oscar Martinez, Latin American Editor

CALAMA, Chile (August 14, 2019)—One of the most important milestones in the history of the Chilean mining took place recently in the north of the country. The National Copper Corp. of Chile (Codelco) has officially inaugurated the first level of its new underground mine that will replace Chile’s largest open-pit copper mine. The new mine has already started production, but it will have to go through a long ramp-up process before reaching the expected production of 140,000 metric tons of ore per day (mt/d), which will translate into 366,000 mt/y of copper and more of 18,000 mt/y of molybdenum.

After 104 years, one of the world’s largest open-pit mines will transition to a high-tech underground operation that has been designed to meet stringent safety and environmental standards, extending the mine life span for another 40 years. The company will use a traditional block-cave mining method with a macroblock configuration of approximately 35,000 m2 for each block. Each level of the new mine — three levels in total — will have between 16 to 20 macroblocks. According to Codelco’s estimates, Chuqui UG will have 1.03 billion mt of reserves with a grade of 0.82% copper, which represents more than 60% of what has been mined in the last 90 years.

The northern division of Codelco (División Codelco Norte) invited E&MJ to the official opening ceremony that kickstarted the transfer from open pit to underground mining at the Chuquicamata mine site. The ceremony was attended by numerous regional and national authorities, headed by President Sebastían Piñera, community representatives, industry leaders, trusted suppliers and company employees. “Today is an important day, just a few companies have been able to reinvent themselves as Codelco has. This project will extend the life of this mine by 40 years and required a gigantic effort in design, creativity, and adapting to the new times,” Piñera said.

Also, the Codelco’s chairman, Juan Benavides, emphasized that “a transformation that will maximize the economic value of the company and its contribution to the state in the long term has begun, and we will put all our willingness, talent and commitment to strengthen the skills we need to achieve it.” The executive added that “with better projects and greater development of our resources, we commit ourselves to reposition Codelco among the most competitive, sustainable and profitable copper producers in the world. We are proud of what we have advanced and enthusiastic about the road ahead.”

Codelco’s CEO, Nelson Pizarro, highlighted the enormity of this feat of mining engineering, which began in the mid-1990s with the exploration stage drilling nearly 150,000 m. The project involved an 18-year cycle of investments from the initial engineering and design work that began in 2002. “We developed 145 km of mining works and installed 6,300 tons of structure for the ore handling systems. We also bought and deployed three rotary crushers and 14 km of conveyor belts. Project execution required more than 1 million man-hours for engineering and 30 million man-hours in total,” Pizarro explained. He also highlighted an almost 40% increase in productivity expected in this mining operation. This improvement will allow productivity to reach 61 mt/miner of copper in 2025, compared to Chuqui’s current 44 mt/miner.

Chuqui UG is expected to produce nearly 320,000 mt/y of copper by 2026. The depth of the third level will be 900 meters below the bottom of the current pit and more than 2 km below the Earth’s surface. This underground operation will allow a more modern, efficient and sustainable production, as the division will reduce by 97% the emission of particulate material (PM10). It will not increase water consumption and will annually reduce diesel consumption from 75,000 m3 to a much lower range that goes from 2,000 to 15,000 m3, resulting in at least an 80% fuel savings.