This report describes the proposed recovery methods for the Marimaca 1-23 Claim Project, which will use the existing Ivan Plant facilities for copper oxide ore treatment via crushing, agglomeration, heap leaching, solvent extraction, and electrowinning.
Report context
This technical report presents a definitive feasibility study for the Marimaca 1-23 Claim Project, located in the Antofagasta region, II Region, Chile. The processing strategy is based on the acquisition of the Ivan Plant, located approximately 20 km south of Marimaca, with ore to be trucked to the plant for treatment. The plant last operated in 2012.
Processing route
Plant acquisition and design basis
The project will process ore from the Marimaca mine at the Ivan Plant facilities. The proposed flowsheet is a conventional copper oxide treatment circuit comprising crushing, acid agglomeration, heap leaching, solvent extraction, and electrowinning.
The plant design is based on annual working rates of 360 days for the crushing plant and 365 days for the leaching and SX-EW circuits. The crushing, agglomeration, and leaching circuits have a nominal throughput of 1.8 Mtpa, while the SX-EW plant will operate at a nominal capacity of 10.0 ktca.
The average head grade considered for plant design is 0.80% CuT. Available resources were estimated at 24.6 Mt, establishing a Life of Mine of 12 years and a Life of Plant of 15 years.
Crushing
The Ivan plant has two crushing lines, designated Line 1 and Line 3. A previously existing Line 2 was disabled and its equipment was redistributed to the other lines. The design incorporates an expansion of Line 1 with a third comminution stage to achieve a nominal capacity of 278 t/h, feeding an existing 1,600 live tons capacity stockpile.
The first crushing stage operates in open circuit with pre-screens and a jaw crusher. The second stage also operates in open circuit with pre-screens and a cone crusher. The third stage has a closed inverse circuit with a pre-screen and two parallel cone crushers. The two tertiary crushers are to be taken from Line 3.
The crushing plant will use nine re-utilized conveyors, with required maintenance. Specifically, conveyor 2204403-005 will require motor and reducer replacement to 30 HP to increase belt velocity. The dust suppression system will be rehabilitated, with new connections added for ore transfer in the tertiary stage.
Agglomeration
The existing agglomeration plant will be reconditioned for a nominal capacity of 278 t/h. The Line 1 agglomeration circuit will be utilized, including a vibrating feeder and conveyor feeding an existing 2.0 m diameter by 6.0 m long agglomeration drum.
A new sample cutter will be installed for ore control from the crushing stage. The acid and water supply manifolds to the agglomeration process will be replaced, with new manifolds featuring instrumentation and automation control. Due to high corrosion levels, conveyor 220-4403-007 at the drum discharge, the feeding chute, and the acid and water dosing flutes will be replaced.
Heap leaching
Agglomerated ore will be transported by trucks to the leaching pads, where a surface area of approximately 170,184 m² is available. Ore will be treated in 25 dynamic heaps, each 1.5 m high, with two modules per heap. The projected pad area is equivalent to 50 leaching days, for an estimated leaching cycle of 35 effective leaching days.
Five existing ponds are located in the leaching area. Three will be reutilized for normal operation and reconditioned according to the process circuit, while one old pond will be reconditioned as an emergency reserve for controlled conduction of operational pond overflows.
Pregnant leach solution is expected to have an approximate copper concentration of 4 g/L, collected in an 8,300 m³ capacity PLS pond. Spent ore pads will be irrigated with raffinate and an intermediate solution, conveyed to a 13,550 m³ capacity ILS pond. A reconditioned 2,700 m³ raffinate pond is also included.
Irrigation will be by aspersion using grids over the heaps, maintaining the original plant grid configuration. A main matrix will allow heaps to be irrigated with raffinate or ILS according to heap stage. Each heap will have a pipeline manifold with adjustable irrigation flow.
Two horizontal centrifuge pumps in parallel with 110 kW engines will propel ILS through a 315 mm HDPE PN16 main pipe. The raffinate system will also have two horizontal centrifuge pumps in parallel, each with a 150 kW engine and a 315 mm HDPE PN16 main pipe. PLS will be pumped to the SX plant by two parallel 55 kW pumps through a 315 mm HDPE PN10 main pipe.
Spent ore will be transported to the existing ripio waste disposal site, with the authorized area verified as having sufficient capacity for the total amount throughout the Life of Mine.
Solvent extraction
The SX circuit is based on a reversible chemical reaction of ionic exchange between a copper-bearing PLS solution and an immiscible organic solution. The extraction step transfers copper ions to the organic phase, releasing hydrogen ions and increasing acidity of the resulting raffinate. In the re-extraction step, the loaded organic is contacted with poor electrolyte from the EW plant, where high acidity reverses the reaction. Copper transfers to the aqueous phase and is returned to the electrolyte.
Because the PLS concentration is calculated at close to 4 g Cu/L, the existing mixer-settler equipment was verified as having insufficient capacity for expected project flows. New equipment will be used for a nominal capacity of 263 m³/h. The SX circuit will comprise four mixer-settlers: two extraction stages in series (E1 and E2), one washing stage (L1), and one re-extraction stage (S1).
The tank farm requires no modifications, apart from adding a second charged organic tank of 5 m diameter and 3 m high. All piping and electrical engines in the SX area and tank farm will be replaced to comply with explosion-resistant standards.
Electrowinning
The existing EW building will house the electrowinning plant, which is divided into two sectors with thirty electrolytic cells. Each cell is constructed of vinyl-ester polymer concrete with capacity for 36 permanent stainless steel cathodes and 37 lead/calcium/tin alloy anodes. An electric circuit fed by two transformers and two DC rectifiers generates the current for electrolytic copper deposition on the stainless steel cathodes. No modifications are planned for the electrowinning stage, only flooring and structure refurbishment.
Rehabilitation works
The rehabilitation plan characterizes damage to existing concrete and steel facilities into categories. Light damage involves surface rehabilitation through partial stripping of linings and installation of acid protection systems. Medium damage involves deep cleaning or partial demolition to remove residues that may cause long-term structural weakening. Severe damage involves demolition of concrete in poor condition and removal of polluted soil to reach ground suitable for new foundations. Steel structures damaged by acid exposure will be replaced.
New works include construction of new structures according to plant expansion requirements, including excavation, compacted filling, concrete, and structure erection.
The rehabilitation program by area identifies severe damage and new works needed at the crushing, agglomeration, and leaching areas. The EW, SX, and tank farm areas each require light, medium, and severe damage repairs plus new works. The acid supply area requires light and severe damage repairs plus new works, and the water supply area requires severe damage repairs and new works.
Leaching pond recovery and new pad construction
For solution reservoirs, the project considers removing existing HDPE geomembranes and support material from ponds detected as eroded or not fit for new lining. Two HDPE layers (primary and safety) will be installed with a permeable geonet medium between them for conducting and detecting filtrations through a leak detector system.
Fifty leaching pads are configured according to process requirements, projected in existing available space across three terraces of different dimensions. Works include removing sterile material from existing pads, surface profiling, and preparation for new pad structures. The pad system includes base impermeabilization and a draining system with drains for collecting and conducting solutions to a main collecting gutter, then to PLS or ILS reservoirs.
Key reported parameters
| Parameter | Value | Basis |
|---|---|---|
| Processing rate | 1.8 Mtpa | Design |
| Crushing plant annual operating days | 360 days/year | Design |
| Leaching/SX-EW annual operating days | 365 days/year | Design |
| Cathode production | 10.0 ktca | Design |
| Average head grade | 0.80% CuT | Design |
| Design criteria average grade | 0.75% | Design |
| Average recovery | 65% based on CuT | Design |
| Acid consumption | 35 kg/t | Design |
| Agglomeration/leach crushing capacity | 278 t/h | Design |
| Agglomeration drum | 2.0 m dia. x 6.0 m long | Existing equipment |
| PLS pond capacity | 8,300 m³ | Reconditioned |
| ILS pond capacity | 13,550 m³ | Reconditioned |
| Raffinate pond capacity | 2,700 m³ | Reconditioned |
| SX plant nominal capacity | 263 m³/h | New equipment |
| SX circuit stages | 2 extraction, 1 wash, 1 re-extraction | Design |
| Leaching pad area | Approx. 170,184 m² | Existing |
| Number of leaching heaps | 25 | Design |
| Heap height | 1.5 m | Design |
| Leaching cycle | 35 effective days | Design |
| Leaching days projected | 50 days | Design |
| Trucking distance | 24 km | Design |
| Water supply | 54 m³/h (15 L/s) | Design |
| Water consumption | 0.25 m³/t | Design |
| ILS pumps | 2 x 110 kW horizontal centrifuge, parallel | Design |
| Raffinate pumps | 2 x 150 kW horizontal centrifuge, parallel | Design |
| PLS pumps | 2 x 55 kW, parallel | Design |
| ILS/raffinate pipe | 315 mm HDPE PN16 | Design |
| PLS pipe | 315 mm HDPE PN10 | Design |
Project website: https://marimaca.com/coro-consolidates-100-ownership-of-marimaca-project-and-announces-c16-8-million-financing/
Technical qualifications
The report does not include metallurgical testwork results beyond referencing general flow diagrams based on metallurgical test work. No specific recovery, grade, or throughput performance data based on actual operating experience from the Ivan plant is presented. The design parameters for recovery, acid consumption, and PLS concentration are stated as design criteria, not demonstrated operational results.
The report does not provide detail on the metallurgical testwork methodology, sample representativity, or testwork laboratory. No information is given on locked-cycle or pilot-scale test programs.
The leach cycle of 35 effective days is described as estimated, and the projected area equivalent to 50 leaching days appears to be a design assumption. The SX circuit configuration was determined from calculated PLS concentration, with verification that existing equipment has insufficient capacity for expected flows.
Where equipment is described as re-utilized, the report identifies required maintenance or rehabilitation works but does not quantify the condition assessment methodology or remaining equipment life. The reported pond capacities and pad areas are from the existing site configuration, with reconditioning or partial new construction required.
The EW plant description confirms no modifications beyond flooring and structure refurbishment, but no production rate for historical EW operation is provided. The two-electrode configuration and cell counts are given as existing plant details, not performance data.
Source: Marimaca 1-23 Claim Project, 2023 Technical Report, Recovery Methods section.
