This feasibility study presents a phased processing plant design for sulphide and oxide ore at the Cordero silver project in Chihuahua State, Mexico, based on extensive metallurgical testwork.
Report context
This technical report, with an effective date of February 16, 2024, was prepared as a National Instrument 43-101 Technical Report and Feasibility Study for Discovery Silver Corp. The report covers the Cordero Silver Project located in Chihuahua State, Mexico, and was prepared by Ausenco Engineering Canada ULC, Ausenco Sustainability ULC, Ausenco Chile Limitada, AGP Mining Consultants Inc., RedDot3D Inc., and WSP USA Environment & Infrastructure Inc.
Processing route
Overview
The recovery methods section describes a process plant designed in three phases to treat sulphide and oxide mineralization. The proposed flowsheet is based on the metallurgical testwork program described in Section 13 of the report.
Phase 1 Design (Years 1 to 3)
Phase 1 processing is designed for the initial three years of operation. The proposed flowsheet includes a crushing circuit, grinding, and flotation to produce lead-silver and zinc concentrates. The design incorporates carbon preflotation to remove organic carbon materials that could interfere with concentrate quality. Primary grinding is followed by sequential flotation to produce separate lead and zinc concentrates.
Phase 2 (Years 4-6)
The Phase 2 design represents an expansion of the processing facilities for years four through six. Additional grinding capacity and flotation cells are included in the proposed design to handle increased throughput.
Phase 3 (Years 7+)
Phase 3 further expands the plant design for years seven and beyond to treat the remaining ore types and sustain production levels.
Comminution Testwork
Metallurgical testwork for comminution included measurements of Bond work index, abrasion index, and other hardness parameters. Testwork data were used to support the design of crushing and grinding circuits.
Flotation Testwork
Testwork included flowsheet development studies, locked cycle tests at the pre-feasibility study and feasibility study levels, and variability flotation testing. Carbon preflotation testwork was conducted to evaluate the removal of organic carbon. Primary grind size versus recovery relationships were investigated. FS locked cycle tests were completed to confirm the proposed flowsheet performance, and variability flotation testwork was conducted on geometallurgical samples to assess metallurgical response across the deposit.
Dewatering Testwork
Thickener and filtration testwork was completed at both the PFS and FS levels. PFS thickener testwork and FS thickener testwork evaluated settling characteristics. PFS filtration testwork and FS filtration testwork assessed dewatering performance for concentrate products.
Regrind Energy Consumption
Signature plot test results and small sample tests were completed to determine energy requirements for regrinding. Levin tests were also conducted as part of the regrind circuit design basis.
Recovery Models
Recovery models were developed from the testwork dataset for the sulphide ore component. A correction was applied for the FS flowsheet recovery, and a separate correction was applied for the oxide ore component. The models were back-tested against the available data. Metal recoveries over mine life were reported based on these models.
Key reported parameters
| Parameter | Basis | Value |
|---|---|---|
| Process plant design | Proposed (Feasibility Study) | Three-phase expansion |
| Phase 1 duration | Proposed | Years 1-3 |
| Phase 2 duration | Proposed | Years 4-6 |
| Phase 3 duration | Proposed | Years 7+ |
| Flotation approach | Proposed | Sequential lead-silver then zinc |
| Carbon preflotation | Proposed | Included in flowsheet |
| Comminution testwork | Testwork | Bond work index, abrasion index |
| Flotation locked cycle tests (PFS) | Testwork | Completed |
| Flotation locked cycle tests (FS) | Testwork | Completed |
| Variability flotation testwork | Testwork | Completed on geometallurgical samples |
| Thickener testwork (PFS) | Testwork | Completed |
| Thickener testwork (FS) | Testwork | Completed |
| Filtration testwork (PFS) | Testwork | Completed |
| Filtration testwork (FS) | Testwork | Completed |
| Regrind signature plot tests | Testwork | Completed |
| Levin tests | Testwork | Completed |
| Recovery model – sulphide | Testwork-based | Developed and corrected for FS flowsheet |
| Recovery model – oxide | Testwork-based | Separate correction applied |
| Acid-base accounting (ABA) testwork | Testwork | Completed |
| Net acid generation (NAG) testwork | Testwork | Completed |
| Dense media separation testwork | Testwork | Completed |
| Ore sorting testwork | Testwork | Completed |
| Mineralogical analysis | Testwork | Completed on geometallurgical variability samples |
Project website: https://discoverysilver.com/projects/cordero/overview/
Technical qualifications
This technical report is based on a feasibility study level of accuracy. The processing sections rely on metallurgical testwork conducted on representative samples. No operating data from a producing mine at the Cordero property were available; all processing information is based on proposed design and testwork results. The report specifically notes that one qualified person (Tommaso Roberto Raponi) had not visited the Cordero property. The recovery models represent estimates based on testwork and may differ from actual performance. The report was prepared under National Instrument 43-101 standards and contains forward-looking information based on assumptions stated in the document.
Source: Cordero Silver Project, NI 43-101 Technical Report & Feasibility Study, Chihuahua State, Mexico, effective date February 16, 2024, report date March 28, 2024. Section 13 Mineral processing and Metallurgical Testing; Section 17 Recovery Methods.
