This feasibility study update describes the proposed centralized processing plant design for the Lynn Lake gold project in Manitoba, Canada, based on metallurgical testwork and historical operating data.
Report context
The Lynn Lake Project is located near Lynn Lake, Manitoba, Canada. This technical report, with an effective date of August 2, 2023, and issue date of August 22, 2023, presents a feasibility study update for the project. The report incorporates metallurgical testwork results, proposed process design criteria, and historical operating information from previous mining operations at the site.
Processing route
Proposed process flowsheet
The proposed processing plant employs a conventional gold recovery flowsheet consisting of crushing, grinding, gravity concentration, flotation, leaching, and carbon-in-pulp (CIP) recovery. The plant is designed for a nominal processing throughput, with material from both the MacLellan and Gordon deposits being treated at a centralized facility.
Comminution
The comminution circuit includes primary crushing followed by grinding. Metallurgical testwork for comminution was conducted on samples from both deposits to determine work indices and design parameters for the grinding circuit.
Gravity concentration
A gravity concentration circuit is incorporated into the flowsheet to recover free gold prior to flotation and leaching. Testwork results on gravity recovery are reported from laboratory-scale testing.
Flotation
The flotation circuit is designed to produce a sulphide concentrate that is then subjected to leaching. Flotation testwork was performed on representative samples from the MacLellan and Gordon ore types to determine reagent schemes, residence times, and expected recoveries.
Leaching and carbon-in-pulp
The leach circuit includes cyanidation of the flotation concentrate followed by carbon-in-pulp recovery of dissolved gold. Leaching testwork included cyanide dose optimization, leach kinetics, and oxygen consumption measurements. CIP modelling was conducted based on testwork results to estimate carbon loading and recovery efficiency.
Cyanide detoxification
A cyanide detoxification circuit is included in the proposed plant design. Testwork was conducted to evaluate detoxification methods and reagent consumption for treating process tailings prior to deposition in the tailings management facility.
Environmental testing
Metallurgical testwork included environmental characterization of process tailings, including acid rock drainage potential and geochemical stability testing.
Historical operating data
The report references historical mining and processing operations at the Lynn Lake site. Previous operators processed ore through facilities that are no longer in operation. The feasibility study update incorporates relevant historical metallurgical data where applicable to support the proposed plant design.
Testwork program
The metallurgical testwork program included samples from both the MacLellan and Gordon deposits. Sample selection was based on representative ore types, mineralization styles, and grade ranges expected during the proposed mine life. Testwork included mineralogical characterization, head assays, comminution testing, gravity recovery testing, flotation testing, leaching studies, and cyanide detoxification trials.
Mineralogy
Mineralogical studies were conducted on composite samples to identify gold occurrence, sulphide mineral assemblages, and gangue mineralogy. These studies informed the selection of process routes and reagent schemes.
Head assays
Head assays were performed on all metallurgical testwork samples to establish grade, sulphur content, and other relevant chemical parameters for process design.
Materials handling
Materials handling testwork included evaluation of ore sorting potential and handling characteristics of the proposed feed materials.
Key reported parameters
| Parameter | Unit | Design | Actual/Testwork | Basis |
|---|---|---|---|---|
| Plant throughput | t/d | Not specified | Not specified | Proposed design |
| Crushing work index | kWh/t | Not specified | Testwork result | Testwork |
| Grinding work index | kWh/t | Not specified | Testwork result | Testwork |
| Gravity recovery | % | Not specified | Testwork result | Testwork |
| Flotation recovery | % | Not specified | Testwork result | Testwork |
| Leach recovery | % | Not specified | Testwork result | Testwork |
| Overall gold recovery | % | Not specified | Testwork result | Testwork |
| Cyanide consumption | kg/t | Not specified | Testwork result | Testwork |
| Oxygen consumption | kg/t | Not specified | Testwork result | Testwork |
Project website: https://www.alamosgold.com/operations/development-projects/lynn-lake-canada/default.aspx
Technical qualifications
This feasibility study update contains forward-looking information as defined under applicable Canadian and U.S. securities laws. The report notes that actual results may differ from forward-looking statements due to uncertainties and contingencies inherent in mining and mineral processing. Specific limitations include:
- Testwork results are based on representative samples and may not fully show variability across the deposits
- Proposed plant design parameters are preliminary and subject to change with additional engineering
- Historical operating data may not be representative of future performance under proposed mining and processing plans
- The report does not provide final process design or detailed equipment specifications for all unit operations
*Source: Feasibility Study Update NI-43-101 Technical Report for the Lynn Lake Project, Lynn Lake, Manitoba, Canada. Effective Date: August 2, 2023. Sections 13 (Mineral Processing and Metallurgical Testing) and 17 (Recovery Methods).*
