Darren Pylot Archives - International Mining

An updated Technical Report on Capstone Mining’s Cozamin copper-silver mine in Zacatecas, Mexico, has shown the potential for a mine life extension to 2031, and a plan for dry-stack tailings and underground paste backfill. At the same time, the company says it is studying the use of “innovative mining techniques and enhanced pillar recovery” to make the most of existing reserves and resources.

The updated life of mine plan released outlined average annual copper production of 51.2 MIb (23,224 t) of copper and 1.6 Moz of silver production over 10 years at average C1 costs, including the 50% silver stream, of $1.02/Ib of payable copper. From 2021 to 2027, average annual production is slated to be 58.8 MIb of copper and 1.7 Moz of silver.

The company said a planned ramp-up to 3,780 t/d, or 1.38 Mt/y, by the end of March quarter is on track, with a new section of ramp to open the one-way traffic circuit to debottleneck the mine (pictured) completed in early December 2020, ahead of schedule.

Reserves increased by 39% and now stand at 14.1 Mt, relative to April 30, 2020. Contained copper and silver increased by 37% and 49%, respectively, with around half of this increase due to recovery of high-grade pillars using paste backfill, Capstone said.

The miner said “tailings management transformation” activities were progressing on schedule at site, including feasibility-level design and studies in support of permitting a filtered (dry stack) tailings storage facility.

“This conversion from a slurry tailings impoundment aligns with industry leading socio-environmental best practice for tailings management,” the company said.

Meanwhile, a prefeasibility study (PFS) for an underground paste backfill system was completed in December.

The study indicates a paste backfill system will allow ore extraction containing over 100 MIb of copper and 3.1 Moz of silver between 2023 and 2031, which would have otherwise been left as unmined pillars. The PFS design has a capital cost estimate ranging from $41-$45 million and an increase in operating costs of around $7.50/t of ore mined. Capstone says its management has approved the paste backfill project and work has commenced on procurement of long lead items.

The proposed paste backfill system includes a tailings filter plant, a paste mixing plant, twin boreholes to deliver paste underground and an underground distribution system. The system is expected to be commissioned starting in the December quarter of 2022, with ramp-up completed in the March quarter of 2023.

PFS design of these facilities was completed by Paterson & Cooke in December 2020 and a feasibility study is underway with completion expected in April 2021. Mine planning was completed by Cozamin, with design support provided by a geotechnical consultant, and paste backfill operational guidance provided by AMC Consultants.

Within the latest release, Capstone also flagged the initiation of its “Impact23 Growth” project, which has identified areas of exploration excellence, innovative mining techniques and enhanced pillar recovery at Cozamin.

“By 2023, the goal is to further extend mine life, increase environmental and safety standards, and improve operational efficiencies at Cozamin, utilising mineral resources already discovered in addition to testing new targets,” the company explained.

Included among the options are the innovative mining techniques for resource to reserve conversion flagged at the start of this story.

Capstone says a study will be initiated this year to assess alternative mining techniques with the objective of lowering costs and dilution to convert resources to reserves from the indicated resource base. The current mining methods are longitudinal longhole open stoping and AVOCA, with possible alternatives to be studied including cut-and-fill, drift-and-fill and longhole open stoping with ore sorting technology.

Brad Mercer, Capstone’s SVP and Chief Operating Officer, said: “The life of mine plan announced today maximises extraction of the orebody’s high-grade core by deferring stoping in this area until the paste backfill plant is in operation in 2023. Projected production averages nearly 60 MIb of copper per year for seven years at first quartile costs.

“The Impact23 Growth project that we are kickstarting today is aiming to demonstrate in a 2023 technical report how Cozamin can sustain these levels of performance well into the 2030s.”

Darren Pylot, Capstone’s President and CEO, added: “After 14 years in operation, the best years of Cozamin are ahead. The mine is world class with sustainable low costs and leading safety and environmental performance entrenched throughout the organisation. The growth initiatives are supported by an entrepreneurial fabric at Capstone, as we embrace innovation and technology to create high impact value for our shareholders.”

Capstone Mining’s 70%-owned subsidiary Minera Santo Domingo (MSD) has entered into an agreement that could see it slash some $400 million off the capital cost for building its Santo Domingo copper-iron-gold project, in Chile’s Region III, by offloading the port and concentrate transport infrastructure development to another company.

The Memorandum of Understanding (MoU) with Puerto Abierto SA (PASA), a wholly owned subsidiary of Puerto Ventanas SA (also a subsidiary of Sigdo Koppers SA) will see both MSD and PASA, over a 90-day period, explore mutual synergies and regional benefits for the proposed port component of the Santo Domingo project, Puerto Santo Domingo.

The port, which is fully permitted and located 100 km from the Santo Domingo project site, will be one of only two capesize vessel ports in the region, making it an attractive site for bulk shipments and a key asset allowing for broad resource development in Region III, Capstone says.

Santo Domingo is owned 70% by Capstone and 30% by Korea Resources Corp. A February 2020 technical report outlined an 18-year operation with a life of mine average throughput of 60,500 t/d for annual output of 137 Mlb (62,142 t) of copper, 4.2 Mt of iron ore and 17,000 oz of gold at the project. Development capital for this study came in at $1.51 billion (excluding cobalt processing).

As part of the MoU, MSD will allow PASA to study, at its own cost, the project engineering and conduct a market study over the 90-day period.

PASA is looking to potentially acquire, construct, operate and maintain the deep-water port, including financing its development, Capstone said. Once in operation, Santo Domingo will receive preferred service as its volumes will represent a baseload of business for the port.

The MOU also gives PASA 90 days to evaluate the replacement of the 110 km magnetite concentrate pipeline with a railway as part of its rail business, Ferrocarril del Pacifico SA.

The project infrastructure under consideration in this MoU represents some $400 million of the capital expenditure identified in the most recent technical report, Capstone says, and includes:

Marine works including pier;
Iron concentrate pipeline from Santo Domingo mine to port;
Magnetite filter plant and stockpile building;
Copper storage building; and
Ship loading and support facilities.

“Over the past three months we have seen a surge in interest in our fully permitted Santo Domingo project,” Darren Pylot, President and CEO of Capstone, said. “I believe this relationship with Puerto Ventanas will serve as a major catalyst for our Santo Domingo project. Our path forward includes successful culmination of the strategic sales process, executing a gold stream agreement and arranging project debt financing.”

Dr Albert Garcia, VP, Projects at Capstone, said the partnership with PASA, coupled with the fixed cost, turnkey proposal from POSCO E&C, significantly “de-risks” the overall project.

Capstone prepares Cozamin for introduction of paste backfill, dry-stack tailings

Capstone Mining eyes Santo Domingo IOCG project capex cuts with PASA MoU