The PEA proposes a 2,400 tpd processing plant incorporating mineralized material sorting, grinding, gravity concentration, and CIL gold recovery based on historical metallurgical test work.
Report context
This NI 43-101 Technical Report and Preliminary Economic Assessment (PEA) for the Chimo Mine and East Cadillac Properties, including the West Nordeau gold deposits, is dated May 2023. The processing flowsheet selected for the study is based on historical metallurgical test work conducted at SGS (formerly Lakefield Research) and COREM (formerly CRM). No metallurgical test work was performed for this PEA. Mineralized material sorting tests were performed at COREM on representative samples to assess the effect of preconcentrating the mineralized material before it enters the processing plant on surface. Historical metallurgical test work and results are presented in Item 13 of the report.
Processing route
Mineralized material sorter circuit
Mineralized material produced at the mine site will be crushed underground using a jaw crusher. The crushed material will be transported to the surface and stored in a 2,400 t silo. From the silo, the mineralized material is conveyed to the mineralized material sorter building. A vibrating feeder feeds a secondary cone crusher via a conveyor to produce a feed suitable for mineralized material sorting. From the crusher, the mineralized material is conveyed to a triple deck screen (3 m wide x 7.3 m long) that sizes the material into three products: a fine product of minus 19 mm, a product of minus 32 mm plus 19 mm to the mineralized material sorters, and a coarse product of plus 32 mm that returns to the cone crusher. The mineralized material is conveyed to four mineralized material sorters to be preconcentrated. Two products come from the sorters: a preconcentrated mineralized material that is conveyed to the crusher building and rejects that are transported to an outside stockpile.
Crushing circuit
The preconcentrated mineralized material from the mineralized material sorter (minus 32 mm plus 19 mm) is fed to the tertiary crushing plant. A belt conveyor feeds a vibrating double deck screen (1.8 m wide x 4.8 m long) having a 19 mm top deck and 12 mm lower deck. The screen oversize feeds a tertiary cone crusher which operates in closed circuit with the screen, while the undersize (minus 12 mm) is transported to a fine mineralized material triodetic dome on a belt conveyor. The crushed mineralized material is stored in the dome containing a minimum of two days of mineralized material reserve for the concentrator. Belt feeders installed under the dome feed the ball mill via conveyor.
Grinding and gravity circuit
A conveyor feeds a 4.5 m diameter x 7.6 m long overflow ball mill with a 2,400 kW motor. The ball mill operating in a closed circuit with cyclones grinds the mineralized material to a P80 of 74 µm. A QS30 Knelson concentrator installed in the grinding circuit recovers free gold from the cyclone underflow stream. The gravity concentrates are leached in an intensive leach reactor Acacia. The Knelson concentrator tails return to the mill discharge pump box. The pregnant leach solution from the Acacia is pumped to a loaded carbon tank prior to feeding it into an electrowinning cell in the gold room. The Acacia tails are pumped to the CIL feed mixing tank.
CIL circuit
Cyclone overflow is sent by gravity to a 20 m thickener to raise density to 45-50 percent solids. Thickener underflow and Acacia circuit tailings are pumped to a cyanidation feed mix tank before leaching. The conditioned slurries are pumped to the CIL tanks. The CIL circuit consists of a series of six tanks, each 14 m in diameter, agitated mechanically by a 112 kW motor. Lime is added to the tanks to maintain a pH of around 11. Sodium cyanide and air are added to the tanks to leach gold. Gold-loaded carbon moves counter-current to the slurry flow to the first tank and is then pumped to the loaded carbon tank. The pregnant solution from the Acacia circuit is also pumped to the loaded carbon tank before feeding the electrowinning cell. The residue from the CIL circuit feeds a cyanide destruction tank. The detoxed slurry is pumped to a tailings pond or a backfill plant.
Energy, water and consumable requirements
The total electrical connected load for the process plant is estimated at 7.608 MW including running and standby loads. The operating demand load is estimated at 7.165 MW. The plant will be hooked up to the Hydro-Quebec grid. All power consumed will be hydroelectric. Consumption is estimated at 38.14 kWh/tonne.
The water requirement for the process plant is met by two sources: fresh water and process water (recycled water). Process plant water requirements are estimated at 375 cubic meters per hour. Fresh water requirements will be minimized by recycling the process water. Fresh water is required mainly for reagent preparation, Knelson concentrator and pump gland seals. Most of the equipment in the process plant uses process water recycled from thickeners overflow and tailings pond.
Consumables are used in three main areas. For grinding, forged steel balls are used as grinding media in the ball mill. For cyanidation, sodium cyanide (NaCN) and quicklime (CaO) are used in the cyanidation circuit; the Acacia circuit also consumes cyanide for leaching gold. For dewatering, flocculants are used in thickeners.
Plant control system
The process control system used in the plant will be a programmable logic controller (PLC) and SCADA based system. The general control philosophy will be a high level of automation and remote control to allow process functions with minimal operator intervention. Instrumentation will be provided within the plant to measure and control key process parameters.
Key reported parameters
| Description | Value | Unit | Basis |
|---|---|---|---|
| Process plant throughput | 2,400 | tpd | Design criteria |
| Crushing plant availability | 65 | % | Design criteria |
| Process plant availability | 90 | % | Design criteria |
| Average gold feed grade | 4.55 | g/t | Design criteria |
| Grind size P80 | 74 | µm | Design criteria |
| CIL retention time | 48 | hours | Design criteria |
| Gold recovery by gravity circuit | 38 | % | Design criteria |
| Gold recovery by CIL | 95 | % | Design criteria |
| Overall gold recovery | 93.1 | % | Design criteria |
| Cyanidation plant gold production | 119,318 | oz/y | Design criteria |
| Total electrical connected load | 7.608 | MW | Design estimate |
| Operating demand load | 7.165 | MW | Design estimate |
| Energy consumption | 38.14 | kWh/tonne | Design estimate |
| Process plant water requirement | 375 | m³/h | Design estimate |
Project website: https://ressourcescartier.com/news/as-part-of-its-new-development-strategy-cartier-introduces-the-chimo-tailings-project/
Source: Table 17-1 – Process Design Criteria Basis; Sections 17.8, 17.9. Values presented are from historical metallurgical test work, Bumigeme’s database and benchmark values.
Technical qualifications
No metallurgical test work was performed for this PEA. The process flowsheet selected for the study is based entirely on historical metallurgical test work. Mineralized material sorting tests were performed at COREM on some representative samples to assess the effect of preconcentrating the mineralized material.
Source: NI 43-101 Technical Report & PEA – For the Chimo Mine and East Cadillac Properties Including West Nordeau Gold Deposits – May 2023.
