This technical report describes the proposed processing route for the Yerington Copper Project, comprising two sites that will produce LME Grade A copper cathode through heap leaching, solvent extraction, and electrowinning.
Report context
The Yerington Copper Project consists of two sites: the MacArthur Site and the Yerington Site. The MacArthur Site, located 5.1 miles northwest of the main Yerington Site, will have three pits providing ore to its heap leach pad and solvent extraction facility. The Yerington Site will have the Yerington Pit providing sulfide ore to its crushing and agglomeration circuit and the heap leach pad. The rich electrolyte from both sites will be combined to feed into the electrowinning circuit to produce LME Grade A copper cathode. This report is dated as a 2023 NI 43-101 technical report for the prefeasibility study.
Processing route
MacArthur Site – Heap Leaching
The MacArthur Site primarily processes oxide copper ore from three pits: MacArthur, North MacArthur, and Gallagher. Copper recovery is approximately 46 to 59% based on test work from each of the run-of-mine ores. The leach cycle is approximately 90 days with an irrigation rate of 0.0025 gpm/ft². The leach cycle distribution is 75% in the first year and 25% in the second year.
MacArthur Site – Solvent Extraction Facility
The solvent extraction facility will receive pregnant leach solution from the MacArthur PLS pond. The facility will consist of one train with a total of three solvent extraction mixer-settlers and one stripping mixer-settler. At nominal flow of 17,800 gpm, the extraction circuit will operate with two settlers in series and the third settler in parallel. All extraction mixer-settlers have been designed identically and will accommodate equal flowrates. Under high flow conditions, the second stage extraction mixer-settler will become the third parallel extraction mixer-settler. The organic handling equipment includes a crud treatment package.
After solvent extraction, the rich electrolyte is pumped through a 12-inch pipeline in a lined trench approximately five miles to the Yerington Site for electrowinning. After electrowinning, the lean electrolyte from the Yerington Site will be pumped back to the MacArthur Site for reuse in the solvent extraction stripping circuit. There will be a minor lean electrolyte bleed stream from the lean electrolyte to the raffinate stream.
Yerington Site – Crushing and Agglomeration
Sulfide ore from the Yerington Pit will be brought by haul truck to two dump hoppers. Feeders supply two dual shaft mineral sizers deployed as primary crushers, reducing feed size of F80 at 6 inches to P80 at 3.5 inches. The crushed coarse ore will be transported to the coarse ore stockpile by two conveyors.
Coarse sulfide ore will enter the secondary crushing circuit through reclaim feeders. The secondary crushing circuit comprises three parallel trains, each including a feed bin, screen feeder, vibrating sizing screen, and cone crusher. Each train is designed to process a nominal rate of 1,553 STPH or a design rate of 1,864 STPH. The secondary crusher feed bin has a residence time of 15 minutes with a total capacity of 750 ST.
The tertiary crushing circuit comprises five parallel trains, each including a feed bin, apron feeder, vibrating sizing screen, and cone crusher. Each cone crusher will have a nominal throughput capacity of 593 STPH. The tertiary crusher feed bin will have a residence time of 15 minutes with a total capacity of 740 ST. Final crushed product will be P80 of 0.5 inches and P50 of 0.28 inches.
The fine ore stockpile will be reclaimed through reclaim feeders, conveyors, and bins, followed by agglomeration feeders and feed conveyors. Three agglomerators operating in parallel will process the ore with moisture from between 3% and 5% and increase it to 7% with raffinate solution.
Yerington Site – Nuton Technology
Nuton Technology will be implemented to enhance copper extraction from the sulfide ore. Nuton Technology introduces proprietary bacteria and additives to the ore which, when coupled with heap leach operating parameters, facilitates the process of chalcopyrite oxidation and leaching. Pyrite and a process solution stream carrying bacteria inoculum from the Nuton Technology package and pyrite will be added to the agglomerators for sulfide ore. Catalytic additives have not been included in the current design. Their potential value will be reassessed once all Phase 2 test columns have been mass-balanced and for future sample testing and studies.
Pyrite is added to the ore to maintain elevated temperature inside the heap leach facility. Nuton has developed a portfolio of patents directed to biological oxidation of pyrite and heap leach technologies, and implementation of Nuton Technology will target pyrite addition to maintain active leaching areas between 50°C and 60°C to achieve the modeled 73% recovery.
Yerington Site – Sulfide and Oxide Heap Leaching
The copper recovery for Yerington Sulfide is 73%, Yerington Oxide is 68%, and Yerington VLT is 69%. The leach cycle for Yerington Oxide is approximately 90 days with an irrigation rate of 0.0025 gpm/ft². The leach cycle for Yerington sulfide is 180 days with an irrigation rate of 0.0025 gpm/ft². The oxide PLS will partially offset the raffinate solution to the Yerington West HLF when the Yerington East HLF is in operation.
Yerington Site – Solvent Extraction Facility
The solvent extraction facility will have the same layout as MacArthur’s facility, with equipment sized larger due to higher PLS flowrates. It will consist of two trains with a total of three solvent extraction mixer-settlers and one stripping mixer-settler for each train. At nominal flow of 24,100 gpm, the extraction mixer-settlers have been designed identically and will accommodate equal flowrates. Each train can operate with one or two stage extraction depending on the volume of flow. Under high flow conditions, the second stage extraction mixer-settler will become the third parallel extraction mixer-settler.
Electrowinning, Cathode Stripping and Handling
The copper rich electrolyte from MacArthur SX and Yerington SX will combine into one stream. It will pass through a set of parallel dual media filters and heat exchangers to remove any remaining organics and increase the electrolyte temperature. Guar and cobalt will be added to the copper rich electrolyte before the electrolyte enters the electrowinning circuit. The dosage rates are 0.4 lbs/ST Cu for guar and 3.5 lbs/ST Cu for cobalt sulfate heptahydrate.
The electrowinning circuit will consist of 128 cells with 85 lead anodes and 84 cathodes. One rectifier will be used for the electrowinning. The nominal design production rate is 75,000 tpy and maximum of 90,000 tpy.
Sulfuric Acid Plant and Cogeneration Plant
Two sulfuric acid plants with a capacity of 1,500 STPD will produce the sulfuric acid needed for both the Yerington and MacArthur Sites. Sulfur prill will be transported onto site via rail as raw material for sulfuric acid production. Two cogeneration plants will also be in operation in conjunction with the sulfuric acid plants, where a turbine will produce electricity from the excess steam generated by the plant. Some of the steam will be used for liquifying sulfur and heating Yerington’s PLS. Excess sulfuric acid generated by the acid plants will be sold and transported to the market by train.
Key reported parameters
| Parameter | Units | Design / Testwork Basis |
|---|---|---|
| Copper Recovery (MacArthur) | ||
| Oxide MacArthur | % | 59 (testwork, ROM) |
| Oxide North MacArthur | % | 46 (testwork, ROM) |
| Oxide Gallagher | % | 46 (testwork, ROM) |
| Copper Recovery (Yerington) | ||
| Yerington Sulfide (Nuton) | % | 73 |
| Yerington Oxide | % | 68 |
| Yerington VLT | % | 69 |
| Leach Cycles | ||
| MacArthur irrigation rate | gpm/ft² | 0.0025 |
| MacArthur leach cycle | days | 90 |
| Yerington oxide leach cycle | days | 90 |
| Yerington sulfide leach cycle | days | 180 |
| Leach Cycle Distribution | ||
| MacArthur Year 1 | % | 75 |
| MacArthur Year 2 | % | 25 |
| Yerington sulfide Year 1 | % | 65 |
| Yerington sulfide Year 2 | % | 30 |
| Yerington sulfide Year 3 | % | 5 |
| Crushing | ||
| Primary crusher F80 | inches | 6 |
| Primary crusher P80 | inches | 3.5 |
| Final product P80 | inches | 0.5 |
| Final product P50 | inches | 0.28 |
| Secondary train nominal rate | STPH | 1,553 |
| Secondary train design rate | STPH | 1,864 |
| Tertiary crusher nominal throughput | STPH | 593 |
| SX Facility – MacArthur | ||
| Nominal flow | gpm | 17,800 |
| Extraction mixer-settlers | number | 3 |
| Stripping mixer-settlers | number | 1 |
| SX Facility – Yerington | ||
| Nominal flow | gpm | 24,100 |
| Trains | number | 2 |
| Extraction mixer-settlers per train | number | 3 |
| Stripping mixer-settlers per train | number | 1 |
| Electrowinning | ||
| Cells | number | 128 |
| Anodes per cell | number | 85 |
| Cathodes per cell | number | 84 |
| Nominal production rate | tpy | 75,000 |
| Maximum production rate | tpy | 90,000 |
| Total Copper LOM Production | ||
| MacArthur | ton | 161,610 |
| Yerington | ton | 559,742 |
| Total | ton | 721,352 |
| Sulfuric Acid Plants | ||
| Capacity per plant | STPD | 1,500 |
| Reagent Consumption per Unit | ||
| MacArthur gross acid (MacArthur pit) | lb/ton feed | 24 |
| MacArthur gross acid (North Ridge pit) | lb/ton feed | 44 |
| MacArthur gross acid (Gallagher pit) | lb/ton feed | 46 |
| Yerington sulfide gross acid | lb/ton feed | 30 |
| Yerington oxide gross acid | lb/ton feed | 20 |
| Yerington VLT gross acid | lb/ton feed | 15 |
| Diluent (MacArthur SX) | gal/ton Cu | 7.5 |
| Extractant (MacArthur SX) | gal/ton Cu | 1.9 |
| SX acid (MacArthur) | ton acid/ton Cu | 0.5 |
| Diluent (Yerington SX) | gal/ton Cu | 6.23 |
| Extractant (Yerington SX) | gal/ton Cu | 1.56 |
| SX acid (Yerington) | ton acid/ton Cu | 0.52 |
| Guar addition | lbs/ST Cu | 0.4 |
| Cobalt sulfate heptahydrate | lbs/ST Cu | 3.5 |
Project website: https://lioncg.com/
Technical qualifications
This report is a prefeasibility study level (PFS) technical report under NI 43-101. The copper recoveries for MacArthur are based on test work from each of the run-of-mine ores. The Yerington sulfide recovery of 73% is modeled based on implementation of Nuton Technology, which introduces proprietary bacteria and additives. Catalytic additives have not been included in the current design, and their potential value will be reassessed once all Phase 2 test columns have been mass-balanced and for future sample testing and studies. The report does not provide final design details for the full processing circuit, and certain parameters remain subject to further testwork and engineering.
Source: Yerington Copper Project , 2023 Technical Report, Recovery Methods section.
