This technical report presents the feasibility-update design for the NorthMet copper-nickel project, with mineral processing and hydrometallurgical testwork results and proposed plant flowsheets.
Report context
The NorthMet Copper-Nickel Project, located near Hoyt Lakes, Minnesota USA, is the subject of a Feasibility Update technical report dated December 30, 2022 (Revision 0, document M3-PN220283). The report describes proposed mineral processing facilities, supported by metallurgical testwork programs, and includes an optional Phase II hydrometallurgical plant design.
Processing route
Comminution circuit testwork and process development
Section 13.2 of the report describes comminution circuit test work and process development undertaken to support the proposed flowsheet.
Flotation circuit testwork and process development
Section 13.3 details flotation circuit test work and process development. The flotation circuit design is described in Section 13.4, and flotation circuit simulation is addressed in Section 13.4.1.
Metallurgical modelling for recovery and concentrate quality
Metallurgical modelling for recovery and concentrate quality is presented in Section 13.5. Cobalt recovery modelling is covered separately in Section 13.5.1.
Hydrometallurgical testwork
Section 13.6 describes hydrometallurgical test work, including the following specific programs:
- PLATSOL™ Leaching Pilot Plant Testing (Section 13.6.1)
- Precipitation of PGMs by Copper Sulfide (Section 13.6.2)
- Copper Concentrate Enrichment (Section 13.6.3)
- Residual Copper Precipitation (Section 13.6.4)
- Bulk Iron/Aluminum Removal (Section 13.6.5)
- Mixed Hydroxide Precipitation (MHP) (Section 13.6.6)
- Magnesium Removal (Section 13.6.7)
Proposed process plant flowsheet
Section 17.2 (Process Plant Flowsheet Development) describes the proposed processing stages:
- Primary and Secondary Crushing (Section 17.2.1)
- Milling (Section 17.2.2)
- Flotation (Section 17.2.3)
- Tailings Disposal (Section 17.2.4)
- Concentrate Thickening and Filtration (Section 17.2.5)
- Concentrate Storage (Section 17.2.6)
- Reagents (Section 17.2.7)
- Air Services (Section 17.2.8)
- Water Circuits (Section 17.2.9)
- Sampling and Metal Accounting (Section 17.2.10)
Phase II hydrometallurgical plant (optional)
Section 17.4 describes the Phase II Optional Hydrometallurgical Plant, including:
- Autoclave (Section 17.4.1)
- Gold and Platinum Group Metals Recovery (Section 17.4.2)
- Concentrate Enrichment (Section 17.4.3)
- Copper Sulfide Precipitation (Section 17.4.4)
- Iron, Aluminum and Acid Removal (Section 17.4.5)
- Mixed Hydroxide Precipitation Recovery (Section 17.4.6)
- Magnesium Removal (Section 17.4.7)
- Process Consumables (Section 17.4.8)
- Hydrometallurgical Plant Water (Section 17.4.9)
- Metal Recoveries (Section 17.4.10)
Hydrometallurgical residue management
Section 17.5 addresses hydrometallurgical residue management, and Section 17.5.2 covers hydrometallurgical residue cell design and operations.
Key reported parameters
| Parameter | Value | Basis |
|---|---|---|
| Flotation circuit simulation | Described in Section 13.4.1 | Design development |
| PLATSOL™ Leaching Pilot Plant Testing | Described in Section 13.6.1 | Testwork |
| Precipitation of PGMs by Copper Sulfide | Described in Section 13.6.2 | Testwork |
| Copper Concentrate Enrichment | Described in Section 13.6.3 | Testwork |
| Residual Copper Precipitation | Described in Section 13.6.4 | Testwork |
| Bulk Iron/Aluminum Removal | Described in Section 13.6.5 | Testwork |
| Mixed Hydroxide Precipitation (MHP) | Described in Section 13.6.6 | Testwork |
| Magnesium Removal | Described in Section 13.6.7 | Testwork |
| Phase II Hydrometallurgical Plant | Optional | Proposed design |
Project website: https://www.dnr.state.mn.us/polymet/permitting/index.html
Technical qualifications
This technical report is a Feasibility Update for the NorthMet Copper-Nickel Project. The report contains forward-looking statements as defined under applicable Canadian securities legislation, Section 27A of the United States Securities Act of 1933, and Section 21E of the United States Securities Exchange Act of 1934. Forward-looking statements are based on opinions, assumptions, estimates, and analyses subject to significant risks, uncertainties, contingencies, and other factors that may cause actual results and events to differ materially from those expressed or implied. The report identifies that forward-looking statements include, but are not limited to, objectives, strategies, intentions, expectations, production, costs, capital, and exploration expenditures, including estimated economics of future financial and operating performance and prospects, based on successful closing of the Transaction and ability to obtain all necessary environmental and government approvals to completion.
Source: NorthMet Copper-Nickel Project, Feasibility Update, Hoyt Lakes, Minnesota USA, Form 43-101F1 Technical Report, M3-PN220283, Revision 0, December 30, 2022, Sections 13 and 17.
