This technical report describes the mineral processing and metallurgical testwork programs supporting the proposed heap leach operation at the El Castillo gold mine in Durango, Mexico.
Report context
This NI 43-101 technical report for the El Castillo Gold Mine has an effective date of October 1, 2021. The project is located in Durango, Mexico. The report presents historical operating data, proposed design parameters, and metallurgical testwork results for oxide, transition, and sulphide ore types from the El Castillo property, including the San Juan concession.
Processing route
Process flow sheet
The proposed recovery method is a conventional heap leach operation. The process flow sheet involves crushing, agglomeration, stacking, cyanide leaching, carbon adsorption, and gold recovery. The report states that the flow sheet is described in Section 17.1 of the original technical report, but no detailed flow sheet diagram or further process description is provided in the excerpted evidence.
Operational performance
The report includes a summary of operational performance under Section 17.2. Historical operational data are referenced but not detailed in the excerpted evidence.
Energy, water, and process materials requirements
Section 17.3 of the original report addresses energy, water, and process materials requirements, but specific values are not provided in the excerpted evidence.
Metallurgical testwork programs
Oxide ore testwork
Metallurgical testing on El Castillo oxide ore included bottle roll tests conducted by KCA in 2004, heap leach tests by Castle in 2005, and column leach tests by KCA in 2006. These programs evaluated gold extraction from oxide material.
Transition ore testwork
Transition ore was tested through metallurgical studies on RC drill cuttings by KCA in 2010 and on drill core by KCA in 2011. These programs investigated the leaching characteristics of transition material.
Sulphide ore testwork
Sulphide ore metallurgical studies were conducted on drill core by KCA in 2011, with additional studies on drill core from the Main Zone by KCA in 2011.
Argonaut column testing
Argonaut conducted column testing of different ore lithologies to evaluate gold recovery under various crush sizes and leaching conditions.
San Juan concession testwork
Metallurgical studies on the North and South areas of the San Juan concession were performed by KCA in 2018 under Program 009. Additional metallurgical studies on the North and South areas were completed by KCA in 2018 under Program 010. A crush size versus recovery study on the North area was conducted by KCA in 2018 under Program 011. Program 012, also by KCA in 2018, evaluated crush size versus gold recovery and tested RC cuttings from planned mining areas.
In-house metallurgical investigations
Argonaut conducted in-house metallurgical investigations to supplement the external testwork programs.
Metallurgical variability and deleterious elements
The report addresses metallurgical variability in Section 13.3 and deleterious elements in Section 13.4, but specific results are not provided in the excerpted evidence.
Recovery estimates
Recovery estimates are presented in Section 13.5 of the original report, with the basis for these estimates described in the metallurgical testwork sections.
Key reported parameters
| Parameter | Units | Value | Basis |
|---|---|---|---|
| Gold recovery | % | Not specified | Testwork (various programs) |
| Crush size | mm | Not specified | Testwork (Program 011, 012) |
| Leach duration | days | Not specified | Testwork |
| Cyanide consumption | kg/t | Not specified | Operational data/testwork |
| Lime consumption | kg/t | Not specified | Operational data/testwork |
Project website: https://www.alamosgold.com/news-and-events/news/news-details/2024/Alamos-Gold-Press-Release/default.aspx
Technical qualifications
The report relies on metallurgical testwork conducted by Kappes, Cassiday & Associates (KCA) and by Argonaut in-house. Historical operating data are from the existing El Castillo heap leach operation. The report does not provide specific gold recovery values, crush sizes, reagent consumptions, or leach durations in the excerpted evidence. No detailed process flow sheet is presented in the excerpted sections. Column leach and bottle roll test results are referenced but individual recovery percentages are not included in the excerpted evidence. The report does not contain operating cost or capital cost estimates in the processing sections excerpted. Economic analysis, risks and opportunities, interpretation and conclusions, and recommendations are referenced in Sections 1.21 through 1.24 but are not provided in the excerpted evidence.
Source: El Castillo Gold Mine, Durango, Mexico NI 43-101 Technical Report, effective date October 1, 2021. Sections 1.15, 13.0, 17.0.
