The Group seeks to expand its copper production in Chile and abroad through the development of projects and other potential opportunities. Brownfield development within the Group’s Los Pelambres and Centinela mining districts in Chile remain the primary focus for maximising value while managing risks associated with execution.
- Los Pelambres Incremental Expansion
- Centinela Expansion
- Twin Metals
- Focus remains on cost control and efficiency throughout the operations
- Focus on higher-return, lower-risk brownfield debottlenecking/expansion projects
- Progress greenfield projects steadily for future development
Evaluation, Construction & Strategy
This expansion project is being carried out in two phases in order to simplify the permitting application process and spread the cost over a longer period.
This phase is designed to optimise throughput within the limits of the existing operating, environmental and water extraction permits, with only relatively simple updates required and an EIA for the new desalination plant. During this phase, Los Pelambres will operate at an average throughput of 190,000 tonnes of ore per day, with the addition of a new grinding and flotation circuit to mitigate the impact of the harder ore currently being mined, and a 400 litres per second desalination plant and associated pipeline. Desalinated water will be pumped from the coast to the Mauro tailings storage facility, where it will connect with the recycling circuit returning water to the Los Pelambres concentrator plant.
During 2017 the Group progressed the EIA for the project with the authorities and provided various submissions associated with the permitting process. The EIA was approved in February 2018.
The project’s capital estimate has been updated with current pricing projections, advanced detailed engineering and a project execution plan to a revised estimate of $1.3 billion. This figure includes the concentrator plant expansion and pre-stripping at $780 million and the desalination plant and water pipeline at $520 million. The desalination plant will serve as a back-up water supply for the existing operation in conditions of severe drought and for both Phase and Phase 2 of the expansion. The project is expected to be submitted for approval to the Board during the second half of 2018 once ancillary permits to the approved EIA are in place and the 2021 start-up of the project remains unchanged.
The project will increase Los Pelambres’ production by 55,000 tonnes of copper a year from 2021.
In this phase the Group will seek to increase throughput to 205,000 tonnes of ore per day and to extend the mine’s life by 15 years beyond the currently approved 20 years. As part of this development the Group will submit a new EIA to increase the capacity of the mine’s Mauro tailings storage facility and mine waste dumps. Work on the environmental baseline study for the new EIA started in 2017 and the results will be reviewed in late 2018.
Capital expenditure for this phase was estimated in the pre-feasibility study at approximately $500 million, the majority being on mining equipment, additional crushing and grinding capacity and flotation cells. The conveyors from the primary crusher to the concentrator plant will also have to be repowered to support the additional throughput. Critical studies on tailings and waste storage capacity are underway and should be completed in 2018. However, the project will only proceed following a decision on Phase 1 and will require the submission of extensive permit applications, including the new EIA. First production from this phase would be in 2022 at the earliest and is expected to increase copper production by 35,000 tonnes per year.
At Centinela the expansion of the existing concentrator and using its infrastructure (power lines, pipelines, port and other facilities) is being considered as an alternative to building a new concentrator.
Centinela Second Concentrator
One alternative under consideration for the expansion of Centinela is the construction of a second concentrator some 7 km from Centinela’s current concentrator. It is expected to have an ore throughput capacity of approximately 90,000 tonnes per day, with annual production of approximately 180,000 tonnes of copper equivalent, which includes gold and molybdenum as by-products.
Ore will be sourced initially from the Esperanza Sur deposit and, once mining is completed at Encuentro Oxides, additionally from Encuentro Sulphides.
The EIA for the project was approved in 2016 and the Group has commenced applications for the additional permits required for the project following certain design modifications made during the year. The feasibility study for this $2.7 billion project is due for completion by the end of 2018, when a decision will be made on whether to proceed with this project or the expansion of the existing plant. If approval is given in 2018 first production is expected in 2022.
However, if the expansion of the existing concentrator is approved it is likely that the second concentrator will proceed at a later date. Antofagasta plc 11 There is also scope to increase the plant capacity further once the second concentrator is completed, which could bring throughput capacity to approximately 150,000 tonnes per day and increase the plant’s production to approximately 250,000 tonnes of copper equivalent.
Alternative Development Option
As an alternative to the construction of a second concentrator, the Group is evaluating expanding the existing concentrator and tailings storage facilities as a lower capital expenditure and lower construction and project execution risk alternative. Technical viability, capital cost and financial returns will be assessed before the completion of the feasibility study for the second concentrator. The expansion of the existing concentrator will not preclude the later construction of the second concentrator.
More work will be conducted on both expansion options during 2018 with the intention of the Company being able to select its preferred alternative by the end of the year. If the alternative of expanding the existing concentrator is selected then a full feasibility study would be required before it is taken to the Board for approval. This work would delay the date for final project approval by approximately 18 months.
Twin Metals is a wholly-owned copper, nickel and platinum group metals (PGM) underground mining project in north-eastern Minnesota, US.
During 2017 the Group commenced preparation of the Mine Plan of Operations, a pre-requisite for permitting applications. The Group also undertook further evaluation and optimisation exercises on the prefeasibility study completed in 2014, with the aim of completing an updated pre-feasibility study by the end of 2018.
In December 2017, the US Department of the Interior reaffirmed Twin Metals’ right to renew two federal mineral leases, a right denied in December 2016 by the Bureau of Land Management (BLM) and the US Forest Service (USFS). These mineral leases cover part of the project’s mineral resources.