Cañariaco Copper Project — 2024 Technical Report

This technical report describes the proposed process flowsheet and design criteria for a 120,000 t/d copper concentrator, based on metallurgical testwork on Norte and Sur deposit samples.

Report context

This NI 43-101 Technical Report and Preliminary Economic Assessment for the Cañariaco Copper Project is dated May 31, 2024. The report presents a process plant design for treating porphyry copper sulfide mineralized material from the Norte and Sur deposits, with a 28-year life of mine. The proposed flowsheet was developed from extensive metallurgical testwork completed on samples of Norte mineralized material and preliminary metallurgical testwork results for the Sur deposit.

Processing route

Proposed Flowsheet Overview

The process flowsheet is designed for 120,000 t/d at 91.3% availability. The proposed flowsheet features conventional processes: one mill feed primary gyratory crusher near the Norte pit with a dedicated overland mill feed conveyor to the mill feed stockpile at the process plant; one waste rock mineral sizer near the Norte pit with a dedicated overland waste rock conveyor to the CPSF; and one gyratory crusher near the Sur pit for both mill feed and waste rock, deferred until Sur mining commences in year 17.

The comminution circuit comprises a single GMD SAG mill with pebble crushing and screen classification, followed by two lines of ball mills with cyclone classification. The flotation circuit consists of rougher flotation followed by secondary regrind with cyclone classification, then three stages of cleaner flotation with cleaner scavenger flotation cells for copper concentrate production. The plant includes copper concentrate thickening, filtration, and loadout facilities, as well as tailing thickening and filtration for dry stack tailings disposal.

Crushing and Conveying

Norte Pit mineralized material is hauled from the pit and directly tipped into the mill feed gyratory crusher dump pocket, fed at a feed size (F80) of 312 mm and crushed to product size (P80) of 85 mm. The waste rock from the Norte Pit is directly tipped into a waste rock dump pocket above an apron feeder which feeds the waste rock mineral sizer, sized to a P100 of 500 mm and conveyed to the CPSF.

The crushing circuit will have an availability of 75%. The total throughput of mineralized material will have an average capacity of 6,667 t/h and waste at 11,598 t/h. The mineralized material and waste rock conveyors were sized for maximum instantaneous throughput of 7,200 t/h and 16,700 t/h respectively.

Once mining starts in the Sur pit, run-of-mine mineralized material and waste rock is hauled and direct tipped into the Sur gyratory crusher dump pocket. The Sur crusher will alternate between crushing waste rock and mineralized material in batches to a P80 of 85 mm, conveyed in discrete lots to the Norte crushing facility to be diverted onto either the mill feed or waste rock overland conveyors.

Major equipment includes: Norte Pit mineralized material primary gyratory crusher (1,650 kW) with a two tip position dump pocket; Norte Pit waste rock apron feeder and mineral sizer (800 kW); mill feed overland conveyor (18 MW); waste rock overland conveyor (45 MW); Sur Pit mineralized material/waste rock primary gyratory crusher (1,650 kW), to be installed in Year 16; and dual purpose overland conveyor to Norte crusher station (0.4 MW), to be installed in Year 16.

Stockpile and Reclaim

Mineralized material from the Norte and Sur pits conveyed on the mill feed overland conveyor will be stored in a stockpile with live capacity of 14 hours. Two apron feeders reclaim material to load the SAG mill feed conveyor for grinding.

Grinding

The grinding circuit will consist of a GMD SAG mill operating in open circuit with discharge screen oversize reporting to a pebble crusher. The pebble crusher is closed circuit with screening. SAG screen and pebble crusher screen undersize reports to two parallel ball mills in closed circuit configuration with hydrocyclones. The circuit treats on average 5,475 t/h of mineralized material at an availability of 91.3%, sized based on a grinding circuit feed size of F80 of 85 mm and a circuit product size of P80 of 200 µm.

Major equipment includes: one GMD SAG mill (30 MW) with discharge screen; three pebble crushers (1 MW each) with discharge screens; and two ball mills (18.5 MW each) with cyclone clusters.

Rougher Flotation and Regrind

Ball mill cyclone overflow gravitates to the rougher flotation circuit via a trash screen. The undersize slurry is conditioned with lime to achieve pulp pH of 10 and a mixture of A3894 and potassium amyl xanthate (PAX) collector and MIBC frother. Conditioned slurry flows into a single line of flotation cells with a residence time of 27 minutes. Rougher concentrate is then pumped into the regrind feed hopper.

The rougher concentrate is mixed with the primary regrind mill product and cleaner scavenger concentrate in the primary regrind cyclone feed pumpbox and pumped to the primary regrind cyclones for classification. Primary regrind cyclone underflow reports to the primary regrind mill which overflows back into the primary regrind cyclone feed pumpbox. Primary regrind cyclone overflow reports to the secondary regrind cyclone feed pumpbox. Secondary regrind cyclone overflow reports to the first stage of cleaner flotation while the underflow reports to the secondary regrind mill.

Reground slurry is cleaned in three stages of cleaner flotation cells. First copper cleaner tailings are directed to the cleaner scavenger flotation cells to maximize copper recovery. Second cleaner concentrate advances to the third cleaner flotation, with tailings returning to the first cleaner flotation. Third cleaner concentrate, the final concentrate product, is pumped to the concentrate thickener; third cleaner tailings return to the second cleaner flotation.

Major equipment includes: eight rougher flotation cells 600 m³ (450 kW); primary regrind mill (11 MW ball mill); primary regrind cyclone pack; secondary regrind mill (9 MW high intensity mill); secondary regrind cyclone pack; five cleaner 1 cells 200 m³ (200 kW); four cleaner scavenger cells 200 m³ (200 kW); three cleaner 2 cells 200 m³ (200 kW); and two cleaner 3 cells 200 m³ (200 kW).

Copper Concentrate Thickening and Filtration

The copper concentrate thickening and filtration circuit will consist of a single high-rate thickener, filter feed tank and a pressure filter. Copper concentrate from the flotation Cleaner 3 circuit is pumped to the concentrate thickener. Flocculant is added to enhance settling. Concentrate thickener overflow reports to the process water tank; underflow solids are collected at a density of 60% w/w solids. Thickener underflow is pumped to an agitated filter feed tank prior to pressure filtration. Filter cake is discharged to the concentrate stockpile and loaded onto trucks via a front-end loader.

Major equipment includes: one high-rate thickener (25 m) and two horizontal plate pressure filters.

Tailings Thickening and Filtration

Copper rougher tailings and copper cleaner scavenger tailings are combined and pumped to the tailings thickener. Flocculant is added to enhance settling, resulting in an underflow density of 60% w/w solids. Overflow is directed to the process water tank. Underflow is pumped to tailings filter feed tank, then fed into plate and frame pressure filters to achieve a moisture level below 15% w/w. Filtered cake is conveyed to a transfer station to be mixed with waste rock from the waste rock stockpile, then conveyed by waste rock overland conveyor to the dry stack tailings facility.

Major equipment includes: one high-rate thickener (87 m); twelve vertical plate pressure filters and discharge belt feeders; and filtered cake conveyor.

Testwork Basis

The process flowsheet was developed based on extensive metallurgical testwork completed on samples of Norte mineralized material and on preliminary metallurgical testwork results for the Sur deposit. Reagent and consumables consumptions are based on testwork results and standard industry practices.

Key reported parameters

Technical qualifications

The proposed flowsheet and design criteria are based on extensive metallurgical testwork completed on samples of Norte mineralized material and on preliminary metallurgical testwork results for the Sur deposit. The report does not present actual operating data from the project site, as this is a proposed design for a project that has not yet been constructed. Reagent and consumables consumptions are based on testwork results and standard industry practices. The Sur deposit crushing and conveying infrastructure is deferred until year 17 of operation, and its design is correspondingly preliminary. The report constitutes a Preliminary Economic Assessment and does not represent feasibility-level engineering.

Source: Cañariaco Copper Project, NI 43-101 Technical Report & Preliminary Economic Assessment, May 31, 2024, Sections 17.1–17.4.4