Artemis Gold's 2024 expansion study for the Blackwater gold mine in central British Columbia adds a 9 Mt/a SABC stream in Phase 2 and a 9.5 Mt/a stream in Phase 3, each with its own gravity, leach-CIL, elution and cyanide destruction circuits.
The Blackwater Gold Mine NI 43-101 Technical Report on 2024 Expansion Study, British Columbia, was prepared for Artemis Gold Inc. by Moose Mountain Technical Services, JAT MetConsult, Knight Piésold, ERM, Lorax Environmental Services and Lycopodium Minerals Canada, and is dated April 2024. The flowsheet is based on the testwork in the report's Section 13 and on unit operations that are well proven in industry. The existing Phase 1 plant treats 6 Mt a year. Phase 2 adds a 9 Mt/a stream for a total of 15 Mt/a. Phase 3 adds a 9.5 Mt/a stream, and an optimization of Phase 1 to 6.5 Mt/a brings the total to 25 Mt/a.
Critical Data
| Parameter | Value | Unit | Notes |
|---|---|---|---|
| Report date | April 2024 | Not applicable | 2024 Expansion Study for Artemis Gold Inc. |
| Phase 1 (existing) | 6.0, optimized to 6.5 | Mt/a | Optimization done with Phase 3 |
| Phase 2 | 9.0 added, 15 total | Mt/a | Dedicated SABC stream |
| Phase 3 | 9.5 added, 25 total | Mt/a | Dedicated primary crusher and SABC stream |
| Annual operating hours | 6,132 crushing in Phases 1 and 3 optimization, 6,570 in Phases 2 and 3 | h | Design basis table |
| Grind size | P80 150 | µm | Cyclone overflow, all phases |
| Gravity concentrators | Two (Phase 1) or three (Phases 2 and 3) | Not applicable | Semi-batch centrifugal units with ILR |
| Leach and CIL tanks | 1 pre-aeration, 2 or 3 leach, 6 or 7 CIL per phase | Not applicable | Oxygen through the agitator shafts |
| Elution | 12 t AARL (Phase 1), 18 t split AARL (Phases 2 and 3) | Not applicable | Strip at 130°C |
| Carbon reactivation | Electric rotary kiln at 650 to 750°C | Not applicable | One kiln per phase |
| Cyanide destruction | SO2/oxygen, about 90 min | Not applicable | CNWAD from 200 ppm design to below 25 ppm |
| Tailings | Unthickened, by gravity to the TSF | Not applicable | Decant return line for process water |
Overview
Each phase is a separate processing stream with crushing, milling, gravity recovery and intensive leaching, pre-oxidation, leach and carbon-in-leach (CIL), cyanide detoxification and an elution plant. Reagents, oxygen, air and water services from the existing plant are reused or expanded. A new gold room is built during Phase 2, with the Phase 1 gold room equipment moved into it, and is expanded in Phase 3. The drying ovens, furnace and other gold room facilities are shared by all phases.
Key Process Stages
Crushing. Run-of-mine ore is tipped or loaded into the feed bin of a primary gyratory crusher. Phases 1 and 2 share one primary crusher, and Phase 3 has its own. In Phase 1, a secondary cone crusher in open circuit and two tertiary cone crushers with screens produce a fine product for an 8-hour live stockpile. Phase 2 draws ore from the primary crusher through a distribution bin that returns a fraction to the Phase 1 line and sends the rest to a secondary screen and cone crusher. The product goes to a 12-hour stockpile. Phase 3 is set up the same way from its own crusher, and part of its ore goes to the Phase 1 circuit. Tramp metal magnets protect the secondary cone crushers.
Reclaim. Phase 1 uses two reclaim belt feeders and Phases 2 and 3 two apron feeders each, with one able to stand by and each sized for full plant capacity. In Phases 2 and 3, quicklime is added to the mill feed conveyor, controlled by leach pH and feed rate.
Grinding. Phase 1 grinds in a single-stage ball mill closed with hydrocyclones. Phases 2 and 3 use a SAG mill with a pebble crusher and a ball mill closed with cyclones (SABC). Cyclone overflow at P80 150 µm goes to a trash screen to remove grit and woodchips.
Gravity and intensive leaching. Part of the mill discharge is screened and treated in semi-batch centrifugal concentrators. The concentrate is leached in an intensive leach reactor (ILR) drum with about 1.2% w/v NaCN and 2.0% w/v NaOH and oxygen. The pregnant solution goes to a dedicated electrowinning cell in the gold room.
Leach and CIL. Each phase has a pre-aeration tank, two (Phase 1) or three (Phases 2 and 3) leach tanks and six (Phases 1 and 2) or seven (Phase 3) CIL tanks. Oxygen is added to all tanks through the agitator shafts. Cyanide is normally added to the first two tanks under the control of a cyanide analyzer. Carbon moves counter-current to the slurry by recessed impeller pumps, and loaded carbon is pumped from the first CIL tank to the loaded carbon screen. pH is kept above 10.5 with milk of lime.
Acid wash, elution and electrowinning. Loaded carbon soaks in 3% hydrochloric acid for 30 minutes. It is then stripped by the AARL process (Phase 1, 12 t) or split AARL (Phases 2 and 3, 18 t) with 3.0% NaOH and 2.0% NaCN at 130°C. Pregnant eluate passes through four of six electrowinning cells per phase with stainless steel mesh cathodes. The sludge is filtered, dried, mixed with fluxes and smelted in an electric induction furnace to doré.
Carbon reactivation. Barren carbon is reactivated at 650 to 750°C in superheated steam in an electric rotary kiln, quenched, sized and returned to the last two CIL tanks.
Cyanide destruction. CIL tails pass two tanks in parallel for about 90 minutes of SO2/oxygen treatment with milk of lime and copper sulphate. This reduces weak-acid-dissociable cyanide from 200 ppm (design; 100 ppm operating) to below 25 ppm. A carbon safety screen recovers fine carbon before the tailings go to the TSF.
Additional Interesting Data and Summary
Phase 1 sends tailings to the TSF by gravity. In the later phases the tailings slurry is pumped to the tailings disposal facility. Dry dust extraction systems serve the crusher discharge, transfer and feeder points.
In summary, the 2024 Blackwater expansion study keeps a conventional gravity, leach and CIL flowsheet and grows it by adding two parallel SABC streams. Each phase has its own gravity, leach, elution and detox circuits, taking the plant from 6 to 25 Mt a year.
Key Processes
- Primary gyratory crushing with secondary and tertiary cone crushing
- Single-stage ball milling (Phase 1) and SABC grinding (Phases 2 and 3) to P80 150 µm
- Centrifugal gravity concentration with intensive cyanide leaching
- Pre-aeration with oxygen, leach and carbon-in-leach
- Acid wash, AARL and split AARL elution, electrowinning and smelting to doré
- Rotary kiln carbon reactivation
- SO2/oxygen cyanide destruction
Source: Blackwater Gold Mine, British Columbia, NI 43-101 Technical Report on 2024 Expansion Study, prepared for Artemis Gold Inc., April 2024.
Earlier report summaries
Earlier versions of this profile, based on older technical reports, are retained below for source traceability. Dates and figures reflect each report’s own effective date and are superseded by the current information above.
Blackwater Gold Project — Pre-Feasibility Report
The proposed processing plant will treat 15,000 tonnes per day through a conventional crushing, grinding, leaching, and carbon-in-pulp flowsheet supported by testwork and prior feasibility study data.
Report context
The Blackwater Gold Project NI 43-101 Pre-Feasibility Report documents a process design based on testwork described in Section 13 of the report, together with information from a 2014 feasibility study. The proposed flowsheet is similar to many gold plants worldwide, with design details adapted from successful operation at Atlantic Gold's gold ore leach plant in Nova Scotia.
Processing route
Overall flowsheet
The proposed plant will consist of three-stage crushing; grinding in a single ball mill with gravity concentration incorporated into the grinding circuit; leaching with pre-oxidation; carbon-in-pulp adsorption of gold and silver; elution and electrowinning; smelting to gold silver doré; and cyanide destruction using an SO₂ air system.
Primary crushing
Ore will be loaded into a 360-tonne capacity feed bin of the primary crusher either directly from the ore truck or from a stockpile using a wheel loader. An apron feeder, with a fines conveyor installed beneath it, will feed the ore into a 250 kW jaw crusher (1.27 x 1.52 m) over an inclined vibrating grizzly to remove fines prior to the crusher. A hydraulic hammer will be installed to allow breaking of any oversize blocks.
Crushed ore will be fed to a 1.8 x 4.2 m vibrating screen, with minus 19 mm undersize material reporting to the product conveyor. Oversize will be conveyed to a secondary cone crusher (300 kW) with a closed side setting of 44 mm. Product from the crusher will be conveyed to a 2.4 x 6 m vibrating screen where minus 19 mm material will report to the product conveyor. Oversize will be conveyed to a pair of tertiary cone crushers (300 kW each, the same model as the secondary crusher except for the liner) with a closed side setting of 19 mm. The crushed product will be conveyed to the final 2.4 x 6 m screen, with undersize reporting to the product conveyor. Oversize will be conveyed back to the tertiary crushers. The product conveyor will transport the minus 19 mm ore to a covered stockpile where a tripper on the conveyor will deposit the material. A concrete tunnel under the stockpile will house the mill feed conveyor, and the crushed ore will be fed onto the mill feed conveyor at a controlled rate by three vibrating feeders.
All crushers and screens are to be installed in closed buildings to accommodate low temperatures and heavy snowfall at site. The circuit layout was designed to accommodate the three screens in one building and all cone crushers in another. These buildings will allow the use of dry fog for dust control. All conveyors will be fitted with walkways and the belts will be covered.
Milling
Crushed ore will be fed at a design feed rate of 680 tonnes per hour into a 7.3 x 12.5 m ball mill with a double pinion drive (two x 7 MW motors). The mill discharge will report to a pump box from which the slurry will be pumped to the cyclones and to the gravity recovery circuit. Both streams will have one duty pump and one standby. The ball mill will be fed with 75 mm balls and 0.5 kg/t of lime.
A cyclone cluster (four operating, two standby) will separate the P80 150 µm product, with cyclone underflow flowing directly to the ball mill. A gravity concentrator feed rate of 800 tonnes per hour is specified, with minus 2.0 mm feed to the concentrators. Concentrate to intensive leach is designed at 3.4 tonnes per day, with 30% gold recovery by gravity.
Leaching and carbon-in-pulp
Pre-leach thickening is not required. Solids feed to leach is 48%. Pre-aeration residence time is 2 hours, based on testwork. Leach residence time is 48 hours, based on testwork. Eight leach tanks are specified. Sodium cyanide consumption is 0.6 kg/t and lime consumption (quick lime) is 0.8 kg/t.
CIP residence time is 3 hours, with carbon concentration of 30 kg/m³ and carbon loading of 1,250 g/t gold.
Cyanide destruction
Feed solution CNWAD is 350 mg/L, with a discharge target of less than 1.0 mg/L. Residence time is 1 hour in two tanks. SO₂ consumption is 0.67 g/g CNWAD, lime consumption (quick lime) is 7.8 g/g CNWAD, and copper sulfate concentration is 15 mg/L.
Key reported parameters
| Parameter | Unit | Nominal Value | Basis |
|---|---|---|---|
| General | |||
| Daily Throughput | t/d | 15,000 | Design |
| Process Plant Availability | % | 92 | Design |
| Design Feed Rate | t/hr | 679 | Design |
| LOM Head Grade Au | g/t | 1.3 | Design |
| LOM Head Grade Ag | g/t | 5.1 | Design |
| Overall Recovery Au | % | 93 | Testwork |
| Overall Recovery Ag | % | 60 | Testwork |
| Crushing | |||
| Crushing work index | kWh/t | 0 | From 2013 FS |
| Maximum feed size | mm | 1,400 | Design |
| Product size (P80) | mm | 13 | Design |
| Crushed ore stockpile | t | 45,000 | Design consideration |
| Grinding | |||
| Bond Ball Mill Work Index | kWh/t | 21.1 | 75% percentile from 2019 testwork |
| Bond Abrasion Index | g | 0.25 | 75% percentile from 2019 testwork |
| Ball Mill Diameter | m | 7.3 | Design |
| Ball Mill Length | m | 12.5 | Design |
| Installed Ball Mill Power | MW | 14 | Design |
| Circulating Load | % | 250 | Design |
| Product size (P80) | µm | 150 | Design |
| Gravity Concentration | |||
| Gold Recovery by Gravity | % | 30 | Design |
| Concentrate to Intensive Leach | t/day | 3.4 | Design |
| Leaching | |||
| Pre-aeration Residence Time | h | 2 | Testwork |
| Leach Residence Time | h | 48 | Testwork |
| Number of Leach Tanks | # | 8 | Design |
| Sodium Cyanide Consumption | kg/t | 0.6 | Design |
| Lime consumption (quick lime) | kg/t | 0.8 | Design |
| CIP Residence Time | h | 3 | Design |
| Carbon Loading (gold) | g/t | 1,250 | Design |
| Cyanide Destruction | |||
| SO₂ Consumption | g/g CNWAD | 0.67 | Design |
| Lime consumption (quick lime) | g/g CNWAD | 7.8 | Design |
Project website: https://www.artemisgoldinc.com/news/media-releases/2020/artemis-to-acquire-blackwater-project-from-new-gold
Project website: https://www.artemisgoldinc.com/news/artemis-gold-announces-expanded-phase-2-development-at-blackwater-mine
Project website: https://www.artemisgoldinc.com/blackwater-project/blackwater-gold-project/overview/
Technical qualifications
The process design criteria were developed based on testwork described in Section 13 of the report, together with information from the 2014 FS. The crushing work index value of 0 kWh/t is sourced from the 2013 FS. Bond Ball Mill Work Index and Bond Abrasion Index values represent the 75th percentile from 2019 testwork. Certain values, including crusher ore stockpile live capacity, are identified as approximate calculations or design considerations. The overall flowsheet and each unit process are summarised in Figure 17-1 of the report.
Source: Blackwater Gold Project NI 43-101 Pre-Feasibility Report, Section 17 Recovery Methods (pages 195–200).
