Ausenco first worked with Marcobre S.A.C. in 2015 to complete a pre-feasibility study and definition phase study (2016) for Mina Justa – a green-field copper project located in Peru. After demonstrating value through two successful studies, our relationship extended with an EPCM contract to deliver a full mine-to-port solution.
The Mina Justa project includes two conventional open-pit mines and two processing facilities – a 12 Mt/y oxide plant and 6 Mt/y copper sulfide concentrator. With commissioning complete, full nameplate capacity production will be 96 million tonnes per year of total material.
To improve project economics, the mine plan called for oxide and sulphide ore deposits to be processed simultaneously, allowing high-grade sulphide ore to be targeted earlier in the project cycle. The plan also required the design of two high-pressure grinding roller (HPGR) systems, one for each of the oxide and sulphide ore systems. Adding to the complexity of the project, the full mine-to-port solution needed to be executed safely and on time during a global pandemic, when the entire project workforce was required to demobilize and then re-mobilize under strict Covid protocols.
The Better Way
Ausenco’s role was to develop a full mine-to-port solution for Mina Justa including all onsite infrastructure, overland seawater pipeline, offshore port facility for the importation of sulphuric acid, as well as an oxide and sulphide plant. This included the development of a marine entrance from Marcona and a 40 km buried pipeline to deliver seawater for use in the process plant (after desalination) and for dust suppression.
Committed to finding a better, more efficient, and cost-effective way, the team faced a significant challenge when designing the oxide plant. The original design called for oxide ore to be processed by vat leaching, followed by solvent extraction and electrowinning to produce a copper cathode – a process requiring high levels of acid consumption, which resulted in higher operating costs. Focused on finding the best solution for our client, the team came up with an innovative design using a novel crushing and leaching technology that not only significantly lowered acid consumption, but also optimized operating costs.
The team also designed both processing plants to operate with the use of seawater to limit the use of freshwater and lessen the environmental impact of the project overall.
The Mina Justa project demonstrates Ausenco’s award-winning performance with certainty and safety. Despite a global pandemic and shutdown of the mining industry in Peru for two months, our team found a better way to safely demobilize and then re-mobilize almost 4,000 people to site under strict Covid protocols to deliver a complete mine-to-port solution on time and on budget.
The plant layout and general arrangement achieved substantial reductions in the quantities of bulk materials required and improved overall cost-efficiency.
Today the project is 100% complete and has surpassed 10+ million person-hours without a Lost Time Injury (LTI) – a firm-wide record.
Commissioning tests began in December 2020.