GoGold's 2025 feasibility study for the Los Ricos South silver-gold project in Jalisco, Mexico, leaches for over 96 hours and recovers copper as a sulphide concentrate. Tailings are filtered for dry stacking.
The Feasibility Study and Updated Mineral Resource Estimate of the Los Ricos South Project, Jalisco, Mexico, NI 43-101 Technical Report, was prepared for GoGold Resources Inc., with an effective date of January 14, 2025. Ausenco designed the process flowsheet, which is based on metallurgical testwork and experience with similar plants and local operations, using well-proven unit operations. The plant treats 2,000 t/d (0.72 Mtpa) of underground and open pit ore to produce doré and a secondary copper sulphide concentrate. Nominal head grades are 1.39 g/t Au, 145 g/t Ag and 0.10% Cu. Nominal overall recoveries are 92.7% for gold, 85.6% for silver and 72.6% for copper.
Critical Data
| Parameter | Value | Unit | Notes |
|---|---|---|---|
| Report effective date | January 14, 2025 | Not applicable | Feasibility study for GoGold Resources Inc. |
| Throughput | 2,000 t/d (0.72 Mtpa) | Not applicable | Availability: crushing 70%, plant 92%, filtration 85% |
| Nominal / design head grade | Au 1.39 / 2.98 g/t, Ag 145 / 344 g/t, Cu 0.10 / 0.25% | Not applicable | Design criteria table |
| Nominal / design recovery | Au 92.7 / 93.1, Ag 85.6 / 87.3, Cu 72.6 / 75.4 | % | Overall |
| Ball mill work index | 19.0 | kWh/t | Design; SMC Axb 37.8 |
| Jaw crusher | Metso C106, 112 kW, CSS 70 mm | Not applicable | k80 250 to 72 mm at about 119 t/h |
| SAG mill | 7.3 m x 4.27 m, 3,600 kW VSD | Not applicable | Single stage, k80 74 µm, 450% circulating load |
| Pre-leach thickener | 16 m, 35 to 55% solids | Not applicable | High rate |
| Leach | Four 15.4 m x 16.8 m tanks, over 96 h | Not applicable | pH 10.5 to 11.0 |
| CCD | Five 16 m thickeners and 19 m clarifier | Not applicable | Wash efficiency 99.3 / 99.7% Au / Ag |
| Metal recovery | Merrill-Crowe with acid digestion of copper | Not applicable | MC 98.0% Au, 98.5% Ag |
| Cyanide destruction | SO2/air to below 5 ppm CNWAD | Not applicable | After SART |
| Tailings | Pressure filtered to 16% moisture | Not applicable | Dry stacking |
Overview
Run-of-mine ore is crushed in a jaw crusher and ground in a single-stage SAG mill closed with cyclones. It is thickened and leached with cyanide in four tanks. Pregnant solution is recovered by five-stage counter-current decantation (CCD) and a clarifier, then passed through clarifying filters, deaeration and zinc precipitation (Merrill-Crowe). Mercury is retorted from the precipitate, copper is removed by acid digestion, and the precipitate is refined to doré. A sulphidization, acidification, recycle and thickening (SART) plant recovers copper as a sulphide concentrate and regenerates cyanide. Washed tailings are detoxified, thickened and pressure filtered for dry stacking.
Key Process Stages
Crushing. Trucks tip onto a static grizzly hopper or the ROM pad, from which a front-end loader reclaims. An apron feeder feeds the jaw crusher, and a tramp magnet sits at the head of the product conveyor. A surge bin with 10 minutes of capacity feeds the SAG mill. Overflow goes to an emergency stockpile with 16 hours of storage and its own reclaim hopper and feeder.
Grinding. The grate-discharge SAG mill does not recycle pebbles, and trommel oversize reports to a scats bunker. Barren solution, high in cyanide, is added at the mill feed and cyclone feed pumpbox. A cluster of ten 250 mm cyclones, eight operating, produces k80 74 µm at about 91 t/h.
Thickening and leaching. Cyclone overflow passes a trash screen to the 16 m pre-leach thickener with flocculant. Four agitated leach tanks at 55% solids give over 96 hours of residence, with air supplied through the agitator shafts and milk of lime holding the pH. Any single tank can be bypassed. Estimated leach extraction is about 93% for gold and 86% for silver.
CCD washing. Leached slurry flows counter-current through five 16 m high-rate thickeners, with barren solution and process water added at CCD No. 5. Overflow from the first thickener goes to a 19 m clarifier and a pregnant solution tank.
Merrill-Crowe, refining and SART. Clarified solution is filtered, deaerated and precipitated with zinc dust at a nominal 5:1 Zn to Au+Ag ratio. The precipitate is retorted for mercury and acid digested to remove copper and zinc, then refined to doré. The SART plant treats barren solution to recover copper as a sulphide concentrate.
Cyanide destruction and tailings. Washed CCD underflow is detoxified by the SO2/air process to below 5 ppm weak-acid-dissociable cyanide. It is then thickened and pressure filtered to 16% moisture for dry stacking.
Additional Interesting Data and Summary
The design head grades are roughly double the nominal grades, so the Merrill-Crowe, acid digestion and SART circuits can handle higher-grade periods. Nominal copper recovery in Merrill-Crowe is 12.8%, up to a maximum of 20%. The CCD wash ratio and zinc addition rates are set in the design criteria.
In summary, the 2025 Los Ricos South feasibility study is a 2,000 t/d single-stage SAG, long-residence leach and CCD plant with Merrill-Crowe. SART recovers copper and cyanide, and filtered tailings are dry stacked.
Key Processes
- Jaw crushing with emergency stockpile
- Single-stage SAG milling to k80 74 µm
- Pre-leach thickening
- Agitated cyanide leaching (over 96 hours)
- Five-stage counter-current decantation
- Merrill-Crowe zinc precipitation, mercury retorting and acid digestion
- Refining to doré
- SART copper recovery and cyanide regeneration
- SO2/air cyanide destruction, tailings filtration and dry stacking
Source: Feasibility Study and Updated Mineral Resource Estimate of the Los Ricos South Project, Jalisco, Mexico, NI 43-101 Technical Report for GoGold Resources Inc., effective date January 14, 2025.
Consolidated report summaries
The following former standalone pages about this operation were consolidated here on October 25, 2026. They are retained for source traceability; dates and figures reflect each report’s own effective date and may be superseded by the current information above.
Los Ricos South Updated PEA — 2023 Technical Report
The processing route comprises conventional crushing, grinding, whole-ore cyanidation, Merrill Crowe and SART recovery, and dry-stack tailings disposal.
Report context
The technical report, dated 2023, presents an updated preliminary economic assessment for the Los Ricos South project. The process plant design is based on a nominal 1,750 tpd throughput for Years 1–3 and a nominal 4,000 tpd throughput for Years 4–12, treating mineralized material with average grades of 1.18 g/t Au, 125 g/t Ag, and 0.09% Cu. The report references testwork detailed in Section 13 that supports the flowsheet development and design criteria.
Processing route
Primary crushing
The proposed crushing circuit reduces run-of-mine mineralized feed from a nominal top size of 300 mm to a product of 80% passing 150 mm for the SAG mill feed. The front-end circuit includes a ROM feed hopper with a 100 t surge bin, a rock breaker, a vibrating grizzly apron feeder, a 762 mm x 1219 mm jaw crusher with 75 kW installed power processing a nominal 100 t/h, and associated conveyor transfer belts with a belt scale and belt magnet.
Crushed feed stockpile and reclaim
A stockpile with 1,750 t live capacity provides production surge capacity. Three variable-speed reclaim apron feeders discharge onto the SAG mill feed conveyor, controlling the feed rate to 80 t/h.
Grinding circuit
The grinding circuit is a two-stage process comprising a SAG mill, screen, pebble crusher, and a ball mill in closed circuit with classifying cyclones. The SAG mill is 5.65 m diameter x 2.5 m EGL with 1,400 Hp installed power and variable frequency drive. Oversize material from the classifying screen is sent to a 125 Hp pebble crusher and recirculated to the SAG mill feed belt. Screen undersize feeds the ball mill pump box. The ball mill is 4.1 m diameter x 6.4 m EGL with 2,200 Hp installed power. Cyclone classification uses three operating 6gMAX20 units. Recycled process water is added to the SAG mill feed to achieve 74% slurry density. The grinding circuit final product size has a design P80 of 74 µm.
Pre-leach thickening
Ball mill cyclone overflow at approximately 35% solids feeds an 18 m diameter high-rate pre-leach thickener with 7.5 kW drive. The cyclone overflow is thickened to a minimum pulp density of 50% solids. Thickener overflow water is recirculated to the grinding circuit. Thickener underflow feeds the cyanide leaching circuit.
Cyanide leaching circuit
The leaching circuit consists of one pre-leach aeration tank (8 m diameter x 10 m high with 25 kW agitator) and six mechanically agitated leach tanks (13 m diameter x 17 m high, each with 40 kW agitator). Flow is by gravity between tanks with bypass options. Leach residence time per tank is 16 hours for an approximate total of 96 hours. Lime addition maintains leach pH between 10.5 and 11.0. Cyanide addition at a feed concentration of 1,200 ppm is accomplished within the circuit. Air spargers with an air blower system are integral to the leach tanks.
Post-leach thickening and tailings dewatering
Slurry from the last leach tank feeds an 18 m diameter post-leach thickener for initial pregnant solution recovery. Thickener underflow at approximately 50% solids feeds three tailings dewatering filters for solution washing and dewatering. Filter discharge density is 84% solids, producing dry stackable tailings with approximately 16% moisture. The filters include a washing system to recover pregnant metal-bearing solution. Collected solution is pumped to the Merrill Crowe recovery area.
Merrill Crowe circuit and refinery
Pregnant solution containing silver, gold, and copper complexes is pumped to a conventional Merrill Crowe zinc precipitation circuit at a design flowrate of 125 m³/hr. The circuit includes two clarification filters (140 m² rotating disc units), a deaeration tower (1.56 m diameter x 6.25 m high), a high vacuum pump, a zinc addition skid with zinc cone and lead nitrate system, two precipitation feed pumps, and two precipitate filters (92 m² recessed plate units). The resultant sludge is dried, fluxed, and smelted in a 400 kW induction furnace to produce saleable doré. Barren solution is pumped to the SART copper recovery circuit.
SART circuit
SART feed solution is pumped at 125 m³/hr with a copper concentration of 800 mg/L. Sodium hydrosulphide is injected prior to the copper contactor. The solution enters a 3.5 m diameter x 4.0 m high copper contactor and is acidified with sulphuric acid to a controlled pH of 4.5. This precipitates copper sulphide (Cu₂S) and regenerates cyanide associated with soluble copper. The copper precipitate (65% Cu) overflows to a 7.5 m diameter copper clarifier, then is filtered and dewatered to 30% moisture for shipment as a saleable product. Clarifier overflow is pumped to neutralization tanks where lime solution raises pH to 10.5, producing gypsum that is removed in a downstream gypsum clarifier. Overflow solution is returned to the process.
Reagent handling
Main plant reagents include hydrated lime, sodium cyanide, flocculant, diatomaceous earth, zinc dust, lead nitrate, and fluxes. SART reagents include lime slurry, sodium hydrosulphide, sulphuric acid, anionic flocculant, caustic soda, and hydrogen peroxide.
Water supply
Make-up water is supplied from the Martin Dam, a single collection dam located approximately 3.5 km from the proposed processing site. A 200 mm diameter HDPE feed line with multiple high-head pumps is proposed. Dry-stack tailings recycle water back to the process, with tailings designed at 16% moisture.
Key reported parameters
| Parameter | Units | Value | Basis |
|---|---|---|---|
| Feed Characteristics | |||
| Specific Gravity | g/cm³ | 2.60 | Design |
| Bulk Density | t/m³ | 1.65 | Design |
| Moisture Content | % | 3.0 | Design |
| SMC Axb – design | kWh/t | 35.2 | Design |
| Bond Ball Mill Work Index – design (hard) | kWh/t | 20.8 | Design |
| Bond Abrasion Index (very abrasive) | g | 0.72 | Design |
| JKSimMet Simulation (SAG) – overall circuit | mw | 1.04 | Design |
| JKSimMet Simulation (Ball) – overall circuit | mw | 1.64 | Design |
| Milling Circuit Feed Size – F80 | mm | 150 | Design |
| Milling Circuit Product Size – P80 | um | 74 | Design |
| Leach Feed Slurry Density | % | 55 | Design |
| Pre-Aeration Residence Time (minimal) | h | 4 | Design |
| Bulk Leach Residence Time | h | 96 | Design |
| Total Cyanide Leach Consumption Rate | kg/t | 1.25 | Design |
| Total Lime Leach Consumption Rate | kg/t | 0.8 | Design |
| Au and Ag Metal Recovery System | Merrill Crowe | Design | |
| Cu₂S Recovery System and CN⁻ Regeneration | SART | Design | |
| Dewatered Tailings Moisture – Pressure Filtration | % | 16 | Design |
| Peak Wash Ratio | m³/t | 1.44 | Design |
| Plant Availability/Utilization | |||
| Overall Process Plant Feed – Nominal (Years 1-3) | tpa | 639,000 | Design |
| Process Plant Feed – Nominal (Years 1-3) | tpd | 1,750 | Design |
| Crushing Plant Feed (Years 1-3) | tpd | 1,750 | Design |
| Crusher Plant – Plant Utilization | % | 75.0 | Design |
| Grinding, Leach and Refinery Utilization | % | 92.0 | Design |
| Primary Crushing Circuit Throughput Rate | t/h | 98 | Design |
| Grinding and Leach Process Rate | t/h | 80 | Design |
| Process Plant Feed Characteristics | |||
| Gold Head Grade – Nominal | g/t | 1.18 | Design |
| Silver Head Grade – Nominal | g/t | 125 | Design |
| Copper Head Grade – Nominal | % | 0.09 | Design |
| Metal Recoveries (LOM – Abra and Eagle) | |||
| Overall Gold Recovery – design | % | 95.0 | Design (based on whole feed cyanidation) |
| Overall Silver Recovery – design | % | 86.0 | Design (based on whole feed cyanidation) |
| Overall Copper Recovery – design | % | 77.0 | Design (based on whole feed cyanidation) |
Project website: https://gogoldresources.com/properties/los-ricos/
Note: Process plant recoveries are estimated at 95% Au, 84% Ag Phase 1, 86% Ag Phase 2, and 77% Cu for leaching with 95% Cu for SART.
Technical qualifications
The report constitutes a preliminary economic assessment and includes inferred mineral resources that are considered too speculative geologically to have the economic considerations applied to them that would enable them to be categorized as mineral reserves. The recovery methods show optimized testwork detailed in Section 13 of the report. There are no metals streaming or hedging agreements in place. Metal prices and the exchange rate are based on approximate August 31, 2023 three-year monthly trailing averages and are subject to spot market conditions. The report states that currently there are no contracts in place that are material to the Los Ricos South Project.
Source: GoGold Resources Inc., Los Ricos South Updated PEA, Report No. 448, P&E Mining Consultants Inc., 2023, Sections 1.15, 1.16, 1.17, and 17.0–17.4.
Los Ricos South: Gold-Silver-Copper Processing Circuit
Overview
The Los Ricos South (LRS) process plant is designed to treat 2,000 tonnes per day of ore to produce doré as final product and a copper sulphide concentrate secondary product. Located at the mine site, the facility receives run-of-mine ore from underground operations, employing conventional unit operations including crushing, grinding, leaching, and Merrill Crowe precipitation.
Key Process Stages
- Primary Crushing: Metso C106 jaw crusher reduces ROM feed from 250mm to 72mm (k80)
- Grinding: Single-stage SAG mill (7.3m x 4.27m, 3,600 kW) in closed circuit with cyclones produces 74µm product
- Leaching: Four 15.4m x 16.8m agitated tanks with 96 hours residence time at 55% w/w solids
- CCD Circuit: Five-stage counter-current decantation with 99% wash efficiency
- Merrill Crowe: Zinc precipitation achieves 98% Au and 98.5% Ag recovery
- SART Plant: Recovers 90% of copper while regenerating cyanide
- Tailings: SO2/air detoxification followed by pressure filtration to 16% moisture
Critical Data
| Parameter | Value |
|---|---|
| Annual Throughput | 0.72 Mtpa |
| Daily Throughput | 2,000 tpd |
| Design Head Grade (Au) | 2.98 g/t |
| Design Head Grade (Ag) | 344 g/t |
| Overall Au Recovery | 93.1% |
| Overall Ag Recovery | 87.3% |
| SAG Mill Power | 3,600 kW |
| Leach Residence Time | 96 hours |
| Tailings Moisture | 16% w/w |
Reagent Consumption
| Reagent | Annual Usage (tpa) |
|---|---|
| Sodium Cyanide | 1,036 |
| Hydrated Lime | 4,767 |
| Sodium Hydrosulphide | 996 |
| Sulphuric Acid | 4,482 |
| Zinc Powder | 211 |
Based on filing data from 2024-2025.
Los Ricos South PEA — 2021 Technical Report
This article summarizes the process design and metallurgical testwork reported in the February 22, 2021 preliminary economic assessment for the Los Ricos South project in Jalisco, Mexico, distinguishing planned facilities from historical and laboratory data.
Report context
The February 22, 2021 technical report (effective January 20, 2021) presents a preliminary economic assessment for the Los Ricos South project located in Jalisco, Mexico, at latitude 21° 02’ 45” N and longitude 103° 56’ 08” W. The report was prepared for GoGold Resources Inc. and includes a proposed processing facility, associated infrastructure, and metallurgical testwork programs. This article focuses solely on the processing and recovery methods sections, with no coverage of economic analysis beyond stated report contents.
Processing route
Proposed plant design
The report describes a processing plant designed to treat open pit and underground feed, with the flowsheet presented in section 17.0 of the technical report. The design criteria and plant description are presented as the basis for the preliminary economic assessment, with no claim of construction or operational status.
Primary crushing
Ore is delivered to a primary crushing circuit, where run-of-mine material is reduced to a size suitable for conveying to a crushed feed stockpile. The design specifies a primary crusher followed by a crushed feed stockpile and reclaim system.
Grinding circuit
The grinding circuit comprises a semi-autogenous grinding mill, a ball mill, and associated classification equipment. The design criteria include a target grind size to achieve suitable liberation for downstream leaching, with the circuit configured to process the planned throughput.
Pre-leach thickening and filtration
Following grinding, the slurry reports to a pre-leach thickener and pre-leach filter to adjust pulp density and remove excess water prior to cyanidation. This step is designed to optimize leach performance by controlling cyanide and oxygen concentrations.
Leaching and recovery
The report specifies a carbon-in-leach or Merrill-Crowe recovery process, with the Merrill-Crowe circuit and refinery detailed for gold and silver recovery. A SART (Sulfidization, Acidification, Recycling and Thickening) circuit is included to recover cyanide and base metals, with the report noting the need to manage reactive sulfur and prevent cyanide losses.
Tailings dewatering
Tailings are processed through a dewatering circuit to recover water for recycle to the plant, reducing fresh water demand and minimizing environmental impact.
Ancillary facilities
The plant includes reagent handling and storage, an assay and metallurgical laboratory, water supply, and air supply systems. These are described as supporting infrastructure for continuous plant operation.
Historical processing data
The report references historical metallurgical treatment of Cinco Minas mineralization from 1910–1911, where the deposit was processed using conventional cyanidation and amalgamation methods of that era. No modern performance data is provided from these operations, and the historical records are noted as qualitative context rather than design basis.
Testwork program (2020)
A 2020 testwork program was completed by SGS and reported on November 27, 2020, covering grindability, leaching characteristics, and acid-base accounting. The testwork included:
- Head assays for multi-element analysis
- Grindability testing via SPI®, Bond rod mill, Bond ball mill, and Bond abrasion tests
- Unconfined compressive strength (UCS) tests
- Acid-base accounting (ABA/NAG) testing
The metallurgical testwork investigated cyanidation behavior and recovery, with results supporting the proposed process flow sheet. The report notes that additional testwork and optimization are recommended for the next phase of project evaluation.
Design vs. actual basis
The processing route is presented as a design basis for the PEA, with no actual operating data from a commercial plant at this project. The 2020 SGS testwork provides laboratory-scale evidence of grindability and leach response, while the historical 1910–1911 data is qualitative and not used for design purposes.
Key reported parameters
| Parameter | Value | Units | Basis |
|---|---|---|---|
| Primary crushing | Single-stage jaw crusher | – | Proposed design |
| Crushed feed stockpile | Covered, with reclaim | – | Proposed design |
| Grinding | SAG mill + ball mill, closed circuit | – | Proposed design |
| Target grind size | Not stated in extracted text | µm | Design |
| Pre-leach thickening | High-rate thickener | – | Proposed design |
| Pre-leach filtration | Pressure or vacuum filter | – | Proposed design |
| Leach | Carbon-in-leach or Merrill-Crowe | – | Proposed design |
| Recovery circuit | Merrill-Crowe + refinery | – | Proposed design |
| SART circuit | Included | – | Proposed design |
| Tailings dewatering | Thickening + filtration | – | Proposed design |
| Grindability – SPI® | Reported | kWh/t | 2020 SGS testwork |
| Bond rod mill work index | Reported | kWh/t | 2020 SGS testwork |
| Bond ball mill work index | Reported | kWh/t | 2020 SGS testwork |
| Bond abrasion index | Reported | – | 2020 SGS testwork |
| UCS | Reported | MPa | 2020 SGS testwork |
| Head grade (Au, Ag) | Reported | g/t | 2020 SGS testwork |
| Leach recovery | Reported | % | 2020 SGS testwork |
| Historical treatment (1910–1911) | Cyanidation + amalgamation | – | Historical records |
Project website: https://gogoldresources.com/properties/los-ricos/
Technical qualifications
The following limitations apply to the processing and metallurgical sections of the technical report:
- The process plant design is based on preliminary engineering at a PEA level of confidence; it is not a feasibility study and does not provide a basis for construction.
- The 2020 SGS testwork was performed on limited samples and may not be fully representative of the deposit’s variability.
- Grindability and leach test results are laboratory-scale; scale-up to commercial operation requires further testwork and engineering.
- The historical 1910–1911 metallurgical data is provided for context only and does not constitute a modern process design basis.
- The SART circuit design is based on conceptual considerations for cyanide management; no pilot-scale data is mentioned in the extracted text.
- ABA/NAG testing indicates acid-generating potential, but the report notes that additional geochemical testing is needed to confirm long-term water quality implications.
- The report recommends additional testwork and optimization for the Los Ricos South process, including variability testing, pilot plant runs, and trade-off studies for the SART circuit.
Source: GoGold Resources Inc., *Preliminary Economic Assessment of the Los Ricos South Project, Jalisco, Mexico*, NI 43-101 Technical Report, Report No. 390, effective date January 20, 2021, report date February 22, 2021, Sections 13.0, 17.0.
