Overview
Nestled in the mineral-rich state of Sinaloa, Mexico, the Panuco Silver-Gold Project represents a significant and strategic development in the global precious metals sector. Owned and operated by Vizsla Silver Corp., a Canadian mineral exploration and development company, the project is poised to become a major producer of silver and gold doré. The recently completed NI 43-101 Technical Report and Feasibility Study, prepared by the renowned engineering firm Ausenco, outlines a robust, economically viable operation with an 11-year mine life. The project’s significance lies not only in its substantial resource base but also in its innovative, two-phase processing strategy designed to maximize recovery and operational efficiency. This phased approach allows the operation to begin production with a simpler, lower-capital flowsheet before expanding to a more complex circuit optimized for the full range of ore types. The Panuco Project is a cornerstone asset for Vizsla Silver, demonstrating the company’s commitment to responsible development and its potential to deliver long-term value to shareholders while contributing to the local economy in Mexico. This article delves into the sophisticated mineral processing technology that will transform run-of-mine ore into high-purity doré bars, highlighting the engineering excellence and sustainable practices embedded in the plant’s design.
Key Process Stages
The Panuco Project employs a sophisticated, two-phase mineral processing circuit that evolves to handle different ore types over the mine’s life. The initial phase (Years 1-3) utilizes a conventional whole-ore leach (WOL) circuit for higher-grade Copala ore. In Year 4, the plant expands to incorporate bulk flotation and concentrate leaching to efficiently process the Napoleon deposit material, increasing overall throughput. The core recovery method throughout is cyanide leaching followed by Merrill-Crowe precipitation, a proven technology for gold and silver extraction.
- Stage 1: Three-Stage Crushing Run-of-mine (ROM) ore, with a top size of 265 mm (F80), is reduced to a fine product of 9 mm (P80) through a primary jaw crusher, secondary cone crusher, and tertiary cone crusher operating in closed circuit with a double-deck vibrating screen. A surge bin and crushed ore stockpile ensure continuous feed to the grinding circuit, with the crushing plant designed for 65% availability.
- Stage 2: Grinding & Classification Crushed ore is fed to a ball mill operating in closed circuit with a hydrocyclone cluster. The circuit is designed to achieve a primary grind size (P80) of 50 microns in Phase 1 and 70 microns in Phase 2. A high circulating load (500% in Phase 1, 400% in Phase 2) ensures efficient size reduction. The cyclone overflow, now a fine slurry, reports to downstream processing.
- Stage 3: Phase 1 – Whole Ore Leach & Phase 2 – Bulk Flotation In Phase 1, the fine slurry reports directly to a pre-leach thickener and then into a series of four agitated leach tanks for 96 hours. In Phase 2
- Stage 4: Leaching & Solid-Liquid Separation Leaching occurs with cyanide and oxygen in agitated tanks. In Phase 1, the entire ore stream is leached. In Phase 2, the reground flotation concentrate is leached separately for 48 hours, while the flotation tailings are leached for 79 hours. The leached slurry then enters a five-stage Counter-Current Decantation (CCD) circuit. Here, thickeners wash the precious metal-bearing solution from the leached solids, recovering over 99% of the dissolved gold and silver into a “pregnant” solution.
- Stage 5: Merrill-Crowe Recovery & Refining The clarified pregnant solution is deaerated and contacted with zinc powder and lead nitrate in the Merrill-Crowe circuit. The gold and silver precipitate onto the zinc, and this precipitate is filtered off. The filter cake is dried, mixed with fluxes, and smelted in an electric furnace to produce doré bars with a typical composition of 95-98% silver and 1-3% gold.
- Stage 6: Tailings & Detoxification The washed solids from the CCD circuit, now barren, are treated in a cyanide detoxification circuit using the SO2/air (INCO) process to destroy weak acid dissociable (WAD) cyanide to levels below 1 mg/L. The detoxified slurry is thickened, and the underflow is pumped to a tailings storage facility or to a paste backfill plant for environmentally responsible mine backfilling.
Critical Data
The following table summarizes the key design and operational parameters for the Panuco Project processing plant, as defined in the Feasibility Study.
| Parameter | Value | Unit | Notes |
|---|---|---|---|
| Plant Throughput (Phase 1) | 3,300 | tpd | 1.2 Mt/a, Years 1-3 |
| Plant Throughput (Phase 2) | 4,000 | tpd | 1.5 Mt/a, Year 4+ |
| Design Silver Head Grade (Phase 1) | 432 | g/t | Copala ore |
| Design Silver Head Grade (Phase 2) | 230 | g/t | Napoleon ore blend |
| Target Grind Size (P80) – Phase 1 | 50 | µm | Whole Ore Leach circuit |
| Target Grind Size (P80) – Phase 2 | 70 | µm | Bulk ore grind for flotation |
| Regrind Size (P80) – Phase 2 | 20 | µm | Flotation concentrate regrind |
| Installed Power (Phase 1) | 13.0 | MW | Total for process plant |
| Installed Power (Phase 2) | 14.2 | MW | Includes flotation & regrind |
| Bond Ball Mill Work Index | 18.3 | kWh/t | Design hardness parameter |
| Bulk Leach Residence Time (Phase 1) | 96 | hours | Whole Ore Leach |
| Flotation Tailings Leach Time (Phase 2) | 79 | hours | Post-flotation |
| Concentrate Leach Residence Time | 48 | hours | For reground flotation concentrate |
| Process Plant Availability | 92 | % | Excluding crushing (65%) |
Additional Interesting Data and Summary
Beyond the core process flowsheet, the Panuco Project design incorporates several noteworthy technical and sustainability features. The reagent consumption estimates reveal the scale of operation: annual usage includes approximately 4,700 tonnes of sodium cyanide and 7,800 tonnes of quicklime in Phase 2. The plant includes a state-of-the-art, on-site oxygen generation plant using Vacuum Swing Adsorption (VSA) technology to produce 93% pure oxygen at 6 bar for the leaching and detox circuits, improving efficiency and safety by eliminating reliance on delivered liquid oxygen.
Environmental stewardship is a key pillar of the design. The comprehensive cyanide management plan includes destruction of WAD cyanide to strict international standards (<1 mg/L) before tailings are disposed of. Furthermore, the integration of a paste backfill plant is a significant sustainable mining practice. This facility can process up to 4,000 tpd of tailings, mixing them with cement to create a paste that can be pumped back underground to fill mined-out voids. This practice improves geotechnical stability, reduces the surface footprint of the tailings storage facility, and minimizes long-term environmental liability.
The project’s economic viability is supported by this technically sound design. The phased expansion strategy mitigates initial capital risk while positioning the operation to efficiently process the full life-of-mine ore schedule. The use of proven, reliable equipment like jaw and cone crushers, ball mills, and conventional flotation cells ensures operational robustness. With an estimated life of 11 years and a clear path to production outlined in the 2025 Feasibility Study, the Panuco Project stands as a model of modern, responsible, and efficient mineral project development, poised to become a meaningful contributor to the global silver and gold supply.
Source: NI 43-101 Technical Report | Feasibility | Project: Panuco Project | Date: November 2025
Further Reading
- Panuco Project
- Panuco Project, Mexico
- VIZSLA SILVER DELIVERS POSITIVE FEASIBILITY STUDY FOR THE PANUCO PROJECT
- Overview
- Advancing the Panuco Silver-Gold Project with a strategic path to cashflow
Technical report and processing history
The following archived source profiles have been consolidated here to preserve the project’s processing history and study context.
Panuco Project — 2025 Technical Report
Panuco Project — 2025 Technical Report
| Company | Not Specified |
| Date | 2025-11-04 |
| Region | Not Specified |
| Commodities | Gold, Silver |
| Mine Type | Not Specified |
| Throughput | 3,300 t/d (Phase 1), 4,000 t/d (Phase 2) |
| Mine Life | 11 years |
| Status | Development |
Executive Summary
This NI 43-101 Technical Report outlines the process design for the Panuco Project, focusing on the recovery of gold and silver from the Panuco deposits. The plant design utilizes a staged expansion approach to accommodate different ore types from the Copala and Napoleon deposits. Phase 1 (Years 1-3) employs a simple Whole Ore Leach flowsheet treating Copala material at a throughput of 1.2 Mt/a (3,300 t/d). Phase 2 (Year 4+) introduces bulk flotation with concentrate regrind and leach to handle Napoleon material, increasing throughput to 1.5 Mt/a (4,000 t/d).
The recovery circuit is based on crushing, grinding, cyanide leaching, and precious metal recovery to doré via counter current decantation (CCD) and the Merrill Crowe process. Phase 1 utilizes a three-stage crushing circuit followed by ball milling and bulk leaching. Phase 2 adds a flotation circuit with forced air tank cells and a stirred regrind mill to improve recoveries from sulphide mineralization. The design assumes specific availabilities of 65% for the crushing plant and 92% for other processing circuits.
Final recovery involves zinc precipitation in the Merrill Crowe circuit, followed by smelting into silver-gold doré bars. The process includes comprehensive reagent handling for cyanide, lime, and flotation collectors, along with cyanide detoxification using the SO2/Air process. Tailings are managed through thickening and a paste backfill plant, ensuring environmental compliance and operational efficiency over the 11-year life of mine.
Reports
Entities
Concepts
Website: https://vizslasilvercorp.com/projects/panuco-project/overview/
Report Date: 2025-11-04
Region: Not Specified
Project Status: Development
Commodity: Gold, Silver
Throughput: 3,300 t/d (Phase 1), 4,000 t/d (Phase 2)
Mine Life: 11 years
Mine Type: Not Specified
Ore type:
Panuco Project — 2024 Technical Report
Panuco Project — 2024 Technical Report
| Company | Not Specified |
| Mine | Panuco Project |
| Date | July 24, 2024 |
| Region | Not Specified |
| Commodities | Gold, Silver, Lead, Zinc |
Executive Summary
The Panuco Project Technical Report outlines a staged process design for the recovery of precious and base metals from the Panuco deposits, specifically Copala and Napoleon materials. The plant is designed to operate with two 12-hour shifts per day, 365 days per year, with assumed availabilities of 65% for the crushing plant and 92% for other processing circuits. The design incorporates a phased expansion approach to optimize recovery based on the introduction of different ore types over the life of mine.
Phase 1 (Years 1 to 3) utilizes a whole ore leach flowsheet with a throughput of 1.2 Mt/a, involving three-stage crushing, ball milling, and cyanide leaching followed by Merrill Crowe recovery. Phase 2 (Years 4+) converts the plant to a bulk flotation configuration with concentrate regrind and concentrate leach, increasing throughput to 1.5 Mt/a to accommodate Napoleon material. The process includes counter-current decantation, cyanide detoxification using the SO2/air process, and a paste backfill plant for tailings management.
The design is based on previous test work programs, Ausenco’s database, and in-house process modelling. Key design criteria include specific grinding sizes, leaching residence times, and reagent consumptions tailored to the head grades of Silver, Gold, Lead, and Zinc. The project represents a development stage technical assessment with an 11-year life of mine.
Website: https://vizslasilvercorp.com/projects/panuco-project/overview/
Report Date: July 24, 2024
Region: Not Specified
Project Status:
Commodity: Gold, Silver, Lead, Zinc
Throughput:
Mine Life:
Mine Type:
Ore type:
Panuco Project: Silver-Gold Processing Circuit
Overview
The Panuco processing plant is designed to treat mineralized material through a phased approach, initially employing whole ore cyanide leaching (Years 1-3) before transitioning to bulk flotation with concentrate regrind and leaching (Year 4+). The plant operates with two 12-hour shifts daily at 92% availability for most circuits, processing 1.2 Mt/a in Phase 1 and expanding to 1.5 Mt/a in Phase 2.
Key Process Stages
- Phase 1 (Years 1-3): Three-stage crushing → Ball milling → Whole ore cyanide leaching → Merrill Crowe recovery
- Phase 2 (Year 4+): Bulk flotation added → Concentrate regrind → Separate concentrate and tailings leaching circuits
- Crushing: ROM feed (F80 265mm) reduced to P80 9mm via jaw crusher + two cone crushers
- Grinding: Ball mill in closed circuit with cyclones producing P80 70µm
- Leaching: 96-hour residence for whole ore (Phase 1), 48-hour for concentrate + 72-hour for tailings (Phase 2)
- Gold Recovery: Merrill Crowe zinc precipitation producing doré bars
- Tailings: Cyanide detoxification (SO2/air process) followed by thickening for TSF or paste backfill
Critical Data
| Parameter | Phase 1 | Phase 2 |
|---|---|---|
| Throughput | 1.2 Mt/a | 1.5 Mt/a |
| Crushing Availability | 65% | 65% |
| Grinding P80 | 70 µm | 70 µm |
| Bond Ball Mill Work Index | 18.3 kWh/t | 18.3 kWh/t |
| Leach Residence Time | 96 hours | 48h concentrate + 72h tailings |
| Installed Power | 5.4 MW | 6.1 MW |
| Annual Lime Consumption | 2,020 t | 2,152 t |
| Annual Cyanide Consumption | 1,200 t | 1,295 t |
Circuit Components
Crushing
- Vibrating grizzly + static screen
- Primary jaw crusher
- Secondary & tertiary cone crushers
- 9mm product sizing
Grinding
- Ball mill with cyclone classification
- 400% circulating load
- 35% solids in cyclone overflow
Leaching
- Oxygen sparging system
- Lime for pH control (target pH 10.5-11)
- 5-stage CCD washing circuit
Reagents
- Collector: Potassium amyl xanthate (PAX)
- Frother: Methyl isobutyl carbinol (MIBC)
- Cyanide destruction: SO2/air with Cu catalyst
Based on filing data from 2024-2025.
