This technical report describes the processing facilities at the Morelos Property, covering both the currently operating ELG Process Plant and the proposed Media Luna flowsheet, supported by historical operating data and testwork.
Report context
This technical report, dated 31 March 2022, documents the recovery methods for the Morelos Property. The report covers two distinct processing operations: the existing ELG Process Plant, which has been in commercial operation since March 2016, and the proposed Media Luna (ML) Process Plant, for which a mineral beneficiation process has been designed.
Processing route
ELG Process Plant
The ELG Process Plant process design description follows these steps: Primary Crushing and Grinding, Cyanide leach, CIP, Tails filtration, SART, ADR, Electrowinning, and Onsite smelting to doré bars. The recovery methods described are all currently in operation.
The basic process flow is crushing, grinding, agitation leaching, carbon adsorption, carbon acid wash, carbon desorption (stripping), carbon regeneration, gold electrowinning, gold smelting, tailing detoxification, tailing filtration and disposal. In late 2016, the SART plant was added to the process to deal with elevated copper identified in the ELG ore during ramp up.
Tailings generated from the process in the Filtration Plant are stored in the Filtered Tailings Storage Facility (FTSF). Process water is reclaimed and recycled, minimizing water consumed by process.
Crushing and Grinding: Two identical crushing systems are installed to process ROM ore from the El Limón and Guajes pits. A RopeCon conveyor system delivers ore from the El Limón crusher to the processing plant over approximately 1 km horizontal and 385 m vertical distance. At each crusher location, a 200-tonne capacity feed hopper is fed from rear dump haul trucks of 100 tonne capacity. The 1.067 m by 1.651 m primary gyratory crushers produce a 150-mm product. A coarse ore stockpile has a live capacity of 14,000 tonnes. Ore is ground to a final product size averaging 80% passing 85-95 µm in a SAG and ball mill grinding circuit. The SAG mill is 9.15 m diameter by 4.15 m EGL with a 7,000 kW motor. The ball mill is 7.3 m diameter by 12.65 m EGL with two 7,000 kW motors.
Leaching and CIP: A 32 m diameter high-rate thickener thickens grinding cyclone overflow to 50% solids. Precious metals are leached in five to eight of eleven installed 15.55 m diameter by 21.34 m high agitated tanks, each providing a working volume of 3,815 m³ at 20.1 m slurry level. Six to seven leach tanks typically provide retention time of approximately 18 to 26 hours. Oxygen is sparged into the first two leach tanks. Cyanide solution is added to tanks as required. The pH is maintained over 10.5. Leached gold and silver are adsorbed onto activated carbon in the CIP circuit, which consists of six 250 m³ AAC Pump Cell tanks in carousel configuration, nominally containing 48 g/L of 6 by 12 mesh granular activated carbon.
SART Plant: The SART plant removes ~90-95% of copper from the feed and produces a saleable high grade (~40-50% Cu) copper precipitate. Sulfuric acid reduces solution pH to 4.5, with sodium hydrosulphide added for precipitation of copper sulphide. The design production rate of copper filter cake is approximately 31.8 t/d (wet basis at 50% moisture content) with a copper content of about 42.6% Cu (dry basis). The copper thickener overflow is neutralized using slaked lime to above pH 10.5.
Tailing Detoxification, Dewatering and Disposal: WAD cyanide is oxidized by the SO₂/Air process using MT-2000 (ammonium bisulfite) with oxygen injection. The filter plant consists of seven Diemme high pressure filters (HPF) and two Delkor horizontal belt filters (HBF). The HPFs throughput is approximately 100 tonnes per hour each, producing filter cake at 17% moisture. The HBFs throughput is 160 tonnes per hour each, producing cake at 18% moisture. Each HBF has a filtering area of 162 m².
Carbon Stripping and Regeneration: Carbon stripping uses a pressure Zadra process circulating 140°C caustic cyanide solutions upward through a partially fluidized bed of carbon in 12-tonne batches. For reactivation, carbon is heated to 700-750°C in a horizontal rotary carbon reactivation kiln.
Refining: Gold is recovered from pregnant strip solution by electrowinning, with four 3.5 m³ electrowinning cells in parallel at a flow rate of 45 m³/h. Sludge is retorted at up to 600-700°C prior to smelting to doré bars.
Media Luna Process Plant (Proposed)
The proposed ML process will make extensive use of the existing ELG Process Plant and facilities. The envisioned process would produce three salable products: a copper/gold/silver concentrate, doré containing gold and silver, and a copper precipitate.
The ML process will use the existing ELG comminution plant followed by sequential flotation to produce a copper/gold/silver concentrate, followed by further flotation of the copper rougher tailing to produce Fe-S concentrate and tails streams. The flowsheet is based on the results of metallurgical testing conducted by Base Metallurgical Laboratories Ltd. in Kamloops, British Columbia.
The design basis for the ML ore processing facility is 10,600 dry t/d, nominally operating at a 92% availability. The footprint of the ML process plant fits within the current ELG Mine Complex area.
Process Description:
A new conveyor will transport material from the Guajes Tunnel directly to the ELG plant area. ML material will be stockpiled separately from ELG ores. After grinding, the ML ore will pass through copper sulphide rougher and Fe-S rougher flotation circuits.
The copper rougher flotation circuit consists of seven cells of 100 m³ each. The copper rougher concentrate will be reground (target P80 30 µm) and cleaned through three cleaning stages to generate a saleable copper-gold-silver concentrate. The copper cleaner circuit is envisioned to have six 20 m³ cells for first stage, four 20 m³ cleaner scavenger cells, six 16 m³ cells for second cleaner, and four 16 m³ cells for third cleaner.
The Fe-S rougher flotation circuit envisions five 100 m³ cells. The Fe-S rougher concentrate will be combined with copper cleaner tailing and, after regrind to 80% passing 30 µm, will be subject to leaching for gold and silver utilizing part of the existing ELG leach circuit.
The Fe-S flotation tailing will be subjected to Cyanide Leach/CIP through the existing ELG plant. Cyanide will be recovered from the CIP tails stream via the existing cyanide recovery thickener and a new water treatment plant. Reverse osmosis will be used to maximize recovery of cyanide and gold to the SART and CIC circuits.
Tailings Systems: Two tails streams will be generated and pumped to a new tailings handling facility at the Guajes portal area. Tailings will be placed as either backfill in the ML mine or thickened via a new 30 m diameter Guajes thickener and stored in the Guajes Pit Tails Storage Facility (GTSF). The priority will be to place the higher Fe-S content tails as backfill material.
Water Systems: Two distinct water circuits will be used. The water treatment plant has two main components: high cyanide content streams passed through reverse osmosis to concentrate cyanide species for the SART plant, and low cyanide content streams sent to a solution DETOX circuit to generate cyanide free solution for reuse in the grinding and flotation circuit.
Early Fe-S Process Plant: The installation of the Fe-S flotation circuit, regrind and separate leaching is planned to be accelerated by several months to enable recovery and reagent saving benefits when processing high cyanide consuming ELG ores. This early Fe-S circuit does not add any additional major equipment compared to the full ML design, though the future copper rougher flotation cells are to be installed to accommodate the higher mill production rate for the period prior to the reduction in throughput for ML ores.
Key reported parameters
| Parameter | Units | ELG (2021 Actual) | ML Design (min-avg-max) |
|---|---|---|---|
| Mill Feed | t/d | 12,362 | 10,600 |
| Plant Availability | % | 88.6 | 92.0 |
| Feed Grades | |||
| Gold | g/t Au | 3.65 | 1.45 – 2.57 – 4.07 |
| Silver | g/t Ag | 3.91 | 2.89 – 21.8 – 39.9 |
| Copper | % Cu | 0.15 | 0.20 – 0.73 – 1.18 |
| Overall Recovery | |||
| Gold | % | 88.3 | 90.0 |
| Silver | % | 30.6 | 86.0 |
| Copper | % | – | 93.0 |
| Copper Concentrate Recovery | |||
| Mass | t/d | – | 120 – 280 – 460 |
| Copper | % of feed | – | 82 – 90 – 92 |
| Gold | % of feed | – | 52 – 58 – 65 |
| Copper Concentrate Grade | |||
| Copper | % Cu | – | 22.0 – 24.5 – 29.0 |
| Gold | g/t Au | – | 26.0 – 60 – 160 |
| Silver | g/t Ag | – | 240 – 660 – 910 |
| ML Reagent Usage | |||
| Sodium Cyanide (leaching) | kg/t mill feed | – | 3.01 |
| Lime (leaching) | kg/t mill feed | – | 2.00 |
| Calcium Hydroxide (flotation) | kg/t mill feed | – | 3.00 |
Project website: https://www.properstar.ca/mexico/morelos/buy/house
Technical qualifications
The report states that the SART plant was added to address operational issues caused by the presence of soluble copper in the ore. The current bottleneck in the ELG Process Plant is the grinding circuit, which is currently being optimized to balance the workload between the SAG Mill, Ball Mill and Pebble Crusher.
The ML reagent usage estimates are supported by test work completed to date and may be revised as a result of new information. Separate leaching of the high metal sulphide concentrate results in a reduction in overall cyanide consumption of 20-30% as compared to bulk leaching. Metallurgical testing indicates that minor blending of ELG open pit ores with ML and ELG underground ores does not negatively affect the copper flotation process.
The longer than designed retention times required for reactivation does not allow thermal regeneration of carbon after every strip cycle. The deportment of gold in the mineralized ores is highly variable, and at times the Fe-S flotation tails may contain insufficient soluble gold to cover operational costs for processing that stream.
Source: Morelos Property , Form 43-101F1 Technical Report, M3-PN200103, 31 March 2022, Revision 0. Relevant sections: 17 Recovery Methods; 17.1 ELG Process Plant; 17.2 Media Luna Process Plant; 17.3 Media Luna Early Fe-S Process Plant.
Consolidated report summaries
The following former standalone pages about this operation were consolidated here in October 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.
ELG Mine Complex — 2018 Technical Report
This report details the process design, current operation, and recent modifications at the ELG Mine Complex processing plant.
Report context
This technical report, dated 4 September 2018 (Revision 0), describes the ELG Mine Complex (Morelos Property) processing facilities. The ELG Process Plant has been in commercial operation since March 2016. The design basis is 14,000 tonnes per day at 90% mill availability, with current operation at approximately 13,000 tpd (approximately 90% of design). The reported bottleneck in the grinding circuit is under optimization to balance workload between the SAG mill, ball mill, and pebble crusher.
Processing route
Crushing and grinding
Two identical crushing systems process run-of-mine ore from the El Limón and Guajes pits. Each crusher location has a 200-tonne capacity feed hopper fed directly by 100-tonne rear dump haul trucks. Primary gyratory crushers (1.067 m by 1.651 m) produce a 150-mm product for the SAG mill circuit. The El Limón pit uses a RopeCon conveyor system, installed in 2015 and operational since 2016, to transport crushed ore over approximately 1 km horizontal and 300 m vertical distance to the coarse ore stockpile. The Guajes pit uses a belt conveyor (1.219 m wide by 149 m long) to the same stockpile, which has a live capacity of 14,000 tonnes.
Crushed ore is reclaimed by two feeders onto a 1.22 m wide by 200 m long conveyor belt feeding the SAG mill. Primary grinding uses a 9.15 m diameter by 4.15 m effective grinding length SAG mill with a 7,000 kW motor, in closed circuit with a discharge screen and pebble crusher. Secondary grinding uses a 7.3 m diameter by 12.65 m effective grinding length ball mill with two 7,000 kW motors in closed circuit with hydrocyclones. Final product size averages 80% minus 83 microns. Cyanide addition to the grinding circuit has been discontinued as sufficient cyanide is present in recycled process water.
Leaching and carbon-in-pulp
A 32 m diameter high-rate thickener thickens cyclone overflow to 50% solids for the leach circuit. Leaching occurs in four to eight of eleven installed tanks (15.55 m diameter by 21.34 m high, each providing 3,815 m³ working volume at 20.1 m slurry level). Operating four or six leach tanks provides approximately 18 to 26 hours retention time at plug-flow for cyanide leaching at 50% solids. The pH is maintained above 10.5, and cyanide addition follows a recipe dictated by copper content, maintaining a cyanide-to-copper molar ratio above 3.5.
Gold and silver are adsorbed onto activated carbon in the CIP circuit, consisting of six 250 m³ AAC Pump Cell tanks in carousel configuration. Each CIP tank nominally contains 50 g/L of 6 by 12 mesh granular activated carbon, with 12 tonnes of carbon per cell. Carbon harvesting occurs once daily. Slurry from the last CIP tank passes over a carbon safety screen with 0.5 mm slotted panels before reporting to the cyanide recovery thickener.
SART plant
In late 2016, a SART (sulfidization-acidification-recycling-thickening) plant was added to address elevated copper in the ELG ore during ramp-up. The SART plant was expected to be in full operation by July 2018. It removes approximately 45% of copper per cycle from the cyanide recovery thickener overflow through sulphide addition at acidic pH of about 4.0, producing a saleable high-grade (>50%) Cu₂S precipitate. Design criteria include 15,600 tpd feed with 34% copper dissolution and approximately 1,800 ppm copper in process solution.
Tailing detoxification, dewatering, and disposal
CIP tailings are pumped to a 32 m diameter high-rate cyanide recovery thickener. Thickener underflow reports to cyanide detoxification, where WAD cyanide is oxidized by the SO₂/air process, typically using MT-2000 (ammonium metabisulphite) with oxygen injection. Two detoxification reactors (9.7 m diameter by 11.6 m high, each 803 m³ working volume) operate in parallel providing approximately 2 hours residence time.
Detoxified tailings are filtered using seven Diemme pressure filters and two Delkor horizontal belt filters. Each horizontal belt filter has a 162 m² bed surface, with throughput of 100 tonnes per hour producing cake at 18% moisture. Maximum filter plant throughput is estimated at up to 17,840 tpd. Filter cake at approximately 20% moisture is transported by conveyor to a filtered tailings storage facility.
Carbon stripping and regeneration
Loaded carbon undergoes cold washing with 50,000 ppm NaCN solution (stripping 50-80% of copper), followed by acid washing with dilute hydrochloric acid to remove inorganic contaminants. Carbon stripping uses a pressure Zadra process at 140°C, circulating approximately 12 bed volumes at 2 bed volumes per hour. Thermal reactivation occurs every second or third cycle in a horizontal rotary kiln at 700-750°C.
Refining
Pregnant solution is pumped at 13.71 m³/h through four 6 m³ electrowinning cells. Gold sludge is filtered, retorted at 600-700°C to remove mercury, then mixed with fluxes and melted in a diesel-fired furnace to produce doré bars.
Key reported parameters
| Parameter | Design | Actual/Current | Testwork Basis |
|---|---|---|---|
| Plant throughput | 14,000 tpd at 90% availability | ~13,000 tpd (~90% of design) | , |
| Grinding product size | , | 80% minus 83 microns | , |
| Leach retention time (4-6 tanks) | , | ~18 to 26 hours | , |
| Leach slurry density | , | 50% solids | , |
| Leach pH | , | >10.5 | , |
| Cyanide-to-copper molar ratio in leach | , | >3.5 | , |
| CIP carbon concentration | , | 50 g/L (6×12 mesh) | , |
| SART copper removal per cycle | , | ~45% | , |
| SART Cu₂S precipitate grade | >50% Cu | , | , |
| SART copper filter cake production (design) | 31.8 t/d wet (50% moisture) | , | , |
| SART copper filter cake grade (design) | 42.6% Cu (dry basis) | , | , |
| SART design copper production | 6.7 t/d (as Cu) | , | , |
| SART "80-percentile" copper production | ~3.5 t/d (as Cu) at 91% availability | , | , |
| SART feed design | 15,600 tpd, 34% Cu dissolution, ~1,800 ppm Cu | , | , |
| Detoxification residence time | , | ~2 hours (parallel tanks) | , |
| Horizontal belt filter throughput | , | 100 t/h per filter | , |
| Horizontal belt filter cake moisture | , | 18% | , |
| Maximum filter plant throughput | , | up to 17,840 tpd | , |
| Electrowinning flow rate | , | 13.71 m³/h | , |
| Carbon reactivation temperature | , | 700-750°C | , |
| Coarse ore stockpile live capacity | 14,000 tonnes | , | , |
| FTSF design storage capacity | Up to 49 million tonnes | , | Projection: 42 million tonnes |
Project website: https://torexgold.com/assets/morelos/
Technical qualifications
The SART plant and additional filter capacity were in the final stages of construction and commissioning at the time of this report; the SART plant was expected to be in full operation July 2018. The SART plant is bypassed during maintenance. The grinding circuit is identified as a current bottleneck, with optimization ongoing. Horizontal belt filter capacity figures are based on operational test results. The copper sulphate catalyst for detoxification was anticipated but found unnecessary due to sufficient copper in plant solution. Design criteria are summarized in Appendix B of the source report.
Source: M3-PN170117, Morelos Property, Form 43-101F1 Technical Report, 4 September 2018, Revision 0, Section 17: Recovery Methods.
