Tag Archives: Paterson & Cooke

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

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.”

Paterson & Cooke floats new port concept by Zanaga Iron Ore

Zanaga Iron Ore says a concept study on the viability of using a floating dewatering, storage and offloading (FDSO) port facility shows the potential for a $184 million reduction in capital costs for the 12 Mt/y Stage One development at the Zanaga iron ore project in the Republic of Congo.

Following an approach in 2019 from a leading engineering procurement and construction (EPC) company specialised in the development of floating mooring and operating facilities, in recent months the Zanaga project team has been actively investigating the potential to use an offshore floating port instead of the transhipping solution envisaged in the 2014 feasibility study, the company said. This transhipping solution involved Zanaga’s slurry pipeline terminating at the coast of the Republic of Congo, whereby the slurry material would be dewatered in a coastal based location north of Pointe Noire.

Zanaga is planned as a large scale iron ore mine, processing and infrastructure operation to produce 30 Mt/y of high-grade iron ore (pellet feed) concentrate over a 30-year life of mine, to be developed in two stages. Stage One consists of 12 Mt/y of pellet feed, with the Stage Two 18 Mt/y expansion to 30 Mt/y of pellet feed.

The feasibility study envisaged a slurry pipeline for transport of iron ore concentrate from the mine to the port facilities, with the port facilities and infrastructure for dewatering and handling of the iron ore products located within a proposed third-party constructed port facility.

According to the latest concept study, the floating port solution could provide a number of advantages both technically and economically over previous solutions.

“The solution involves extending Zanaga’s slurry pipeline straight out into the ocean, with significantly reduced land-based facilities,” the company said. “The pipeline would run along the ocean floor to a fixed mooring point where the pipeline would connect to the FDSO vessel.”

The slurry would be processed onboard by a dewatering plant and the pellet feed concentrate would be stored within the vessel. Offloading facilities would be built into the vessel to allow the FDSO to load cape size vessels directly. By utilising the FDSO, Zanaga’s materials handling steps would be reduced to only three phases, providing significant efficiencies and a more seamless operation, the company said.

The FDSO evaluation process has been led by Paterson & Cooke, leading experts in slurry pipeline design and engineering. P&C has completed a concept level report involving a comparison of the three port solutions available for the Zanaga project, namely transhipping, deep water port, or the new FDSO port, Zanaga said.

“The results of the investigation have been very positive from a technical and economic perspective,” the company said. “Potential has been indicated for a $184 million reduction to total capital costs of the 12 Mt/y Stage One project, resulting in a reduction of total capital cost from $2.219 billion to $2.035 billion.”

While the study was conceptual in nature, it compared favourably with the transhipping and deep water port options the company had previously weighed for the project, it said. The capital cost associated with the FDSO was $111 million, compared with $295 million for the transhipping option and $899 million for the deep water port.

On top of this, operating costs are expected to be maintained at around $6.50/t due to previously high transshipping costs being substituted by a lease cost to the EPC contractor providing the solution, it said.

Clifford Elphick, Non-Executive Chairman of Zanaga Iron Ore, said: “This evaluation exercise demonstrates the clear potential of a floating port facility to enhance significantly the economics of the Zanaga project through the reduction of upfront capital costs and enhanced internal rate of return.

“In addition, there is potential to achieve significant ancillary technical benefits such as reduced environmental impact, elimination of dredging, and significant flexibility on coastal route selection.”

On top of this development, Zanaga said the project team had made progress on evaluating the early production project (EPP) potential of the asset.

Having ditched plans to explore a logistics route through Gabon, it said the team was now evaluating a range of capacities from 1-5 Mt/y involving optimising process plant design and reviewing in-country logistics solutions for an upgraded truck and rail solution using upgraded road and rail infrastructure within the Republic of Congo.

“In terms of power supply, heavy fuel oil is available in RoC in sufficient quantities to support such a project and pricing has been obtained from the national oil company allowing the project team to evaluate the viability of such an option to support the EPP’s power consumption requirements,” the company said.

“In addition, potential hydropower sites have also been identified in the area of the future mine. One site located 70 km to the north on the Ogooué river site seems promising, with a potential capacity of 20 MW to 40 MW.”

A detailed study is underway to further evaluate the potential of the site, it added.

“The project team continue to evaluate the potential for the EPP to operate as a standalone project, or as an initial pathway to production during the construction period of the 30 Mt/y staged development project,” it concluded.