Royal Nickel Corporation's 2019 report for the Dumont nickel project near Amos, Québec, recovers nickel from sulphides and from the nickel-iron alloy awaruite. The plant combines slimes flotation, sulphide flotation, low-intensity magnetic separation, regrinding and awaruite flotation.
The Technical Report on the Dumont Ni Project, Launay and Trécesson Townships, Quebec, Canada, was prepared for Royal Nickel Corporation with Ausenco as process plant designer, with an effective date of 30 May 2019 and a completion date of 11 July 2019. The plant is built in two phases. The initial plant treats 52.5 kt/d (19.2 Mt a year), and a duplicate plant later raises capacity to 105 kt/d (38.3 Mt a year). Each plant is designed for a head grade of 0.37% Ni at 92% availability (8,059 hours a year). Comminution was sized from SGS-Lakefield variability testwork at the 75th percentile of each hardness value.
Critical Data
| Parameter | Value | Unit | Notes |
|---|---|---|---|
| Report effective date | 30 May 2019 | Not applicable | For Royal Nickel Corporation |
| Throughput | 52.5 kt/d per plant, 105 kt/d combined | Not applicable | 19.2 and 38.3 Mt/a |
| Head grade | 0.37 | % Ni | Design for each plant |
| Availability | 92 (8,059 h/a) | % | After ramp-up |
| Primary crusher | 1600 x 2900 gyratory | Not applicable | P80 90 mm, partially buried |
| SAG mill | 11.6 m x 6.7 m EGL, 22 MW | Not applicable | Trommel classification |
| Ball mills | Two 7.9 m x 12.3 m EGL, 16 MW each | Not applicable | P80 180 µm |
| Desliming | Two-stage cyclones, 400 and 100 mm | Not applicable | About 20% mass to slimes |
| Sulphide roughers | Three trains of nine 300 m³ cells | Not applicable | 90 minutes |
| Magnetic separation | LIMS on sulphide rougher and cleaner tails | Not applicable | About 12% mass recovery |
| Magnetic concentrate regrind | 6.7 m x 9.6 m EGL, 8 MW ball mill | Not applicable | P80 41 µm |
| Awaruite flotation | Five 70 m³ roughers per train, four 1.5 m³ cleaners | Not applicable | 70 and 21 minutes |
| Tailings thickeners | Two 55 m high-rate | Not applicable | Coarse to 55% solids, slimes to 35% |
Overview
Ore is crushed in a gyratory crusher and ground in a SAG mill and two ball mills. Two stages of cyclones deslime the slurry, and the slimes are floated separately. The deslimed slurry goes through nickel sulphide rougher, scavenger and cleaner flotation. The sulphide rougher and cleaner tails pass low-intensity magnetic separation (LIMS), and the magnetic concentrate is reground. It then goes through sulphide scavenger flotation, two further LIMS stages and awaruite rougher and cleaner flotation. The slimes, sulphide and awaruite cleaner concentrates are combined, thickened and filtered for shipment by rail or truck to third-party processors. Coarse and slimes tailings are thickened separately and pumped to the tailings storage facility (TSF).
Key Process Stages
Crushing and stockpile. Trucks dump from both sides into a 323 m³ live hopper over the gyratory crusher, which is in an enclosed building and takes feed up to 1.2 m. A sacrificial conveyor feeds a covered conical stockpile with 12 hours of live capacity. Three apron feeders each handle 60% of mill throughput.
Grinding. The 22 MW SAG mill discharges through a trommel. Two 16 MW ball mills in closed circuit with hydrocyclones grind to P80 180 µm. Ausenco notes that the 92% availability is likely conservative given the ore's low abrasion index.
Desliming and slimes flotation. The first desliming stage splits at an overflow P80 of about 35 µm and the second at about 12 µm. Slimes go to eleven 300 m³ rougher cells (33 minutes), then to three cleaner stages of four 50 m³, three 5 m³ and three 1.5 m³ cells.
Sulphide flotation. Twenty-seven 300 m³ rougher cells in three trains give 90 minutes. Cleaning uses seven 200 m³, six 20 m³ and six 5 m³ cells, with 45, 13 and 10 minutes of retention.
Magnetic recovery, regrind and awaruite flotation. Two trains of seven 3.6 m LIMS units treat the sulphide rougher and cleaner tails. The magnetic concentrate is reground in an 8 MW ball mill to P80 41 µm. Six 200 m³ cells give 62 minutes of magnetic sulphide scavenger flotation. Two more stages of five LIMS units each follow, with a stage mass recovery of 5.4% of plant feed. Awaruite is then floated in 70 m³ rougher cells and 1.5 m³ cleaner cells.
Concentrate and tailings. The combined nickel concentrate is thickened in a 14 m high-rate thickener and dewatered in a horizontal recessed-plate diaphragm pressure filter. Magnetic separation and awaruite rougher tails go to a 55 m thickener at 55% solids. Slimes tails, dosed with a little thickened coarse tailings to aid settling, go to a second 55 m thickener at 35% solids. Each stream has its own pipeline to the TSF, which holds the first 19 years of tailings.
Reagents and water. Reagents are KAX20 collector, Calgon and CMC depressants, MIBC and Cytec 65 frothers, sulphuric acid and flocculants. Process water comes mainly from thickener overflows and the TSF, with pit dewatering as a supplementary source. Potable water is made by reverse osmosis.
Additional Interesting Data and Summary
The flowsheet was based conceptually on comparable large flotation plants and confirmed or changed through trade-off studies and testwork. The report notes that the phase 2 plant design will need to be revisited once phase 1 operates, to set its optimum design point.
In summary, the 2019 Dumont report designs a very large, low-grade nickel concentrator in two identical 52.5 kt/d phases. It combines desliming, sulphide flotation and magnetic separation with regrinding and flotation to recover both nickel sulphides and awaruite into one concentrate.
Key Processes
- Gyratory crushing and covered stockpile
- SAG and ball milling to P80 180 µm
- Two-stage hydrocyclone desliming and slimes flotation
- Nickel sulphide rougher, scavenger and three-stage cleaner flotation
- Low-intensity magnetic separation of flotation tails
- Magnetic concentrate regrind to P80 41 µm
- Magnetic sulphide scavenger and awaruite flotation
- Concentrate thickening and pressure filtration
- Separate coarse and slimes tailings thickening
Source: Technical Report on the Dumont Ni Project, Launay and Trécesson Townships, Quebec, Canada, prepared for Royal Nickel Corporation, effective date 30 May 2019.
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.
Dumont Nickel Project — 2012 Technical Report
The proposed two-phase process plant will treat run-of-mine ore at a nominal 50 kt/d base rate, expandable to 100 kt/d, to produce nickel concentrate via crushing, grinding, desliming, flotation and magnetic separation.
Report context
This 22 June 2012 technical report describes the recovery methods proposed for the Dumont Nickel Project. The process plant and associated service facilities are designed to process run-of-mine (ROM) ore delivered to primary crushers to produce nickel concentrate and tailings. The report presents design criteria, plant design basis, throughput and availability assumptions, processing strategy, head grade selection, flowsheet development and unit process selection.
Processing route
General process description
The proposed process encompasses crushing and grinding of the ROM ore, desliming via hydrocyclone circuit, slimes flotation, nickel sulphide rougher flotation, nickel sulphide cleaning flotation, magnetic recovery of sulphide rougher tailings, regrind of magnetic concentration and sulphide 1st cleaner tailings, and nickel alloy rougher and cleaner flotation.
Concentrate will be thickened, filtered and stored on site prior to being loaded onto railcars or trucks for transport to third-party smelters. The slimes flotation tailings, magnetic separation tailings, alloy rougher tailings and alloy 1st cleaner scavenger tailings will be combined and thickened before placement in the tailings storage facility (TSF).
Phased plant design
The process plant will be built in two phases. Initially, the plant will be designed to process 50 kt/d with allowances for a duplicate process expansion to increase plant capacity to 100 kt/d. Common facilities will include concentrate thickening and handling and reagent storage and preparation.
Plant design basis
The key criteria selected for the base plant (50 kt/d) and expansion plant (100 kt/d) designs are: a nominal base plant treatment rate of 50 kt/d and a nominal expansion plant treatment rate of 50 kt/d for a combined 100 kt/d treatment rate; design availability of 92% (after ramp-up), which equates to 8059 operating hours per year, with standby equipment in critical areas; and sufficient plant design flexibility for treatment of all ore types at design throughput.
Comminution circuit
For each 50 kt/d plant, Ausenco selected one 11.6 m (38 ft) diameter SAG mill and two 7.9 m (26 ft) diameter ball mills. The SAG mill is rated at 22 MW, 11.6 m diameter with 6.7 m EGL, utilizing a trommel screen for classification and oversize recirculation. The two ball mills are each rated at 12 MW, 7.9 m diameter with 11.0 m EGL, in closed circuit with hydrocyclones, grinding to a product size of nominally 80% passing (P80) 150 µm. The selection and sizing of the crushing and grinding circuits was determined through evaluation of variability comminution testwork performed at SGS-Lakefield. Testwork provided a crusher work index, Bond ball and rod mill indices, Bond abrasion index, SMC and JK Axb values for the selected samples. Ausenco elected to use the 75th percentile of each of these values in the design.
Primary crushing and stockpile
Ore from the open pit is crushed using a primary gyratory crusher (assisted with a rock breaker) to a crushed product size of nominally 80% passing (P80) 101 mm. Crushed ore is fed onto the covered stockpile feed conveyor. A covered conical stockpile of crushed ore with a live capacity of 18 hours is served by three apron feeders, each capable of feeding 60% of the full mill throughput.
Desliming circuit
A two-stage desliming circuit via hydrocyclones is proposed. The first stage splits mass with a cut size (D50c) of 40 µm. The second stage splits mass with a cut size (D50c) of 10 µm. Hydrocyclone sizes for each stage are 400 mm and 100 mm, respectively.
Flotation circuit design
Slimes flotation consists of two trains of six 300 m³ forced air tank flotation cells per train to provide 30 minutes of retention time.
Nickel sulphide rougher flotation consists of two trains of seven 300 m³ forced air tank flotation cells per train to provide 60 minutes of retention time.
Nickel sulphide cleaning flotation comprises 1st cleaner, 2nd cleaner and 3rd cleaner stages consisting of five 110 m³ cells each.
Flotation circuit residence times as designed are: slimes 30 minutes, sulphide roughers 60 minutes, sulphide 1st cleaners 15 minutes, sulphide 2nd cleaners 12 minutes, sulphide 3rd cleaners 12 minutes, magnetic sulphide 36 minutes, awaruite roughers 60 minutes, alloy 1st cleaners 18 minutes, alloy 1st cleaner scavenger 18 minutes, and alloy 2nd cleaners 15 minutes.
Magnetic separation
Magnetic recovery of sulphide rougher tailings is included in the flowsheet, followed by regrind of magnetic concentration and sulphide 1st cleaner tailings. Magnetic separation tailings are combined with other tailings streams for thickening and disposal.
Nickel concentrate handling
Concentrate is thickened at a design flux of 0.25 t/m²/h and filtered at a design filtration rate of 450 kg/m²/h. Tailings thickening flux is designed at 0.75 kg/m²/h with tailings thickener underflow density of 40% w/w.
Reagents
Reagent consumptions as designed include: PAX at 140 g/t, MIBC at 19 g/t, Cytec 65 (frothing agent) at 6 g/t, Calgon at 50 g/t, CMC at 25 g/t, sulphuric acid at 8 kg/t, copper sulphate at 30 g/t, and flocculant at 30 g/t.
Media consumption
SAG mill media consumption is designed at 1087 t/a for the 50 kt/d plant and 2175 t/a for the 100 kt/d plant. Ball mill media consumption is designed at 1831 t/a for the 50 kt/d plant and 3662 t/a for the 100 kt/d plant. Regrind mill media consumption is designed at 283 t/a for the 50 kt/d plant and 565 t/a for the 100 kt/d plant.
Throughput and availability
Ausenco nominated an overall plant availability of 92% or 8059 hours per annum. This is described as an industry standard for a large, multi-train flotation plant with moderately abrasive ore. Benchmarking indicates that operating plants have consistently achieved this level. Given the low abrasion index of the Dumont ore, this availability is likely conservative.
Head grade
Each plant is designed to treat ROM ore with a head grade of 0.35% Ni. The design head grade was selected prior to final completion of the mine plan; however, it represents roughly 95% of the peak quarterly head grade. Additionally, 0.35% Ni falls in the 95th percentile of all quarterly maximum head grades. The design head grade value was noted to be revisited in the next phase of study.
Flowsheet development basis
The process plant flowsheet design for the Dumont circuit was conceptually based on those of comparable large flotation plants and then confirmed or altered based on trade-off studies and metallurgical testwork. The process plant design is based on a flowsheet with unit process operations that are well proven in the minerals processing industry.
Key reported parameters
| Parameter | Units | Design 50 kt/d | Design 100 kt/d |
|---|---|---|---|
| Crusher feed | kt/d | 50 | 100 |
| Crusher feed | Mt/a | 18.25 | 36.50 |
| Crusher availability | % | 75 | 75 |
| Crusher throughput | t/h | 3019 | 6039 |
| Crusher selection size | inches | 60 x 89 | 60 x 89 |
| Crusher quantity | number | 1 | 2 |
| Mill throughput | Mt/a | 18.25 | 36.50 |
| Mill/flotation availability | % | 92 | 92 |
| Mill throughput | t/h | 2264 | 4529 |
| Bond work index (BWI) | kWh/t | 20.7 | 20.7 |
| Rod mill work index (RWI) | kWh/t | 15.7 | 15.7 |
| Crusher work index (CWI) | kWh/t | 15.3 | 15.3 |
| SMC value | kWh/m³ | 5.33 | 5.33 |
| JK Axb | – | 47.6 | 47.6 |
| Specific gravity | t/m³ | 2.57 | 2.57 |
| Grind size P80 | µm | 150 | 150 |
| Head grade nickel | % Ni | 0.35 | 0.35 |
| Head grade sulphur | % S | 0.10 | 0.10 |
| Head grade iron | % Fe | 5.71 | 5.71 |
| Sulphide nickel recovery | % | 56 | 56 |
| Alloy nickel recovery | % | 4 | 4 |
| Overall nickel recovery | % | 60 | 60 |
| Slimes flotation residence time | minutes | 30 | 30 |
| Sulphide rougher residence time | minutes | 60 | 60 |
| Sulphide 1st cleaner residence time | minutes | 15 | 15 |
| Sulphide 2nd cleaner residence time | minutes | 12 | 12 |
| Sulphide 3rd cleaner residence time | minutes | 12 | 12 |
| Magnetic sulphide residence time | minutes | 36 | 36 |
| Awaruite rougher residence time | minutes | 60 | 60 |
| Alloy 1st cleaner residence time | minutes | 18 | 18 |
| Alloy 1st cleaner scavenger residence time | minutes | 18 | 18 |
| Alloy 2nd cleaner residence time | minutes | 15 | 15 |
| Nickel concentrate filtration rate | kg/m²/h | 450 | 450 |
| Concentrate thickening flux | t/m²/h | 0.25 | 0.25 |
| Tailings thickening flux | kg/m²/h | 0.75 | 0.75 |
| Tailings thickener underflow density | % w/w | 40 | 40 |
| PAX consumption | g/t | 140 | 140 |
| MIBC consumption | g/t | 19 | 19 |
| Cytec 65 consumption | g/t | 6 | 6 |
| Calgon consumption | g/t | 50 | 50 |
| CMC consumption | g/t | 25 | 25 |
| Sulphuric acid consumption (H₂SO₄) | kg/t | 8 | 8 |
| Copper sulphate consumption (CuSO₄) | g/t | 30 | 30 |
| Flocculant consumption | g/t | 30 | 30 |
| SAG mill media consumption | t/a | 1087 | 2175 |
| Ball mill media consumption | t/a | 1831 | 3662 |
| Regrind mill media consumption | t/a | 283 | 565 |
Project website: https://insidexploration.com/dumont-project-summary/
Technical qualifications
The overall engineering approach described in the report was to design robust process plants that could handle a wide range of ore variability and operating conditions. The design criteria and plant design basis are stated as proposed design values. The comminution circuit selection and sizing were based on metallurgical testwork performed at SGS-Lakefield, using the 75th percentile of variability testwork values. The flowsheet was conceptually based on comparable large flotation plants and confirmed or altered based on trade-off studies and metallurgical testwork. The design head grade of 0.35% Ni was selected prior to final completion of the mine plan, and the report notes this value will be revisited in the next phase of study. The report contains no historical operating data from a Dumont plant, as this is a proposed design. Testwork data are limited to the comminution variability study, reagent consumption trials and metallurgical testwork used to develop and confirm the flowsheet.
Source: Dumont Nickel Project , 2012 Technical Report, 2139-RPT-003, Rev 0, 22 June 2012, Section 17 Recovery Methods.
2139-RPT-003 — Dumont Nickel Project Recovery Methods
This report details the proposed processing route for the Dumont Nickel Project, based on design criteria established in June 2012.
Report context
Report 2139-RPT-003, Revision 0, dated 22 June 2012, presents the recovery methods section for the Dumont Nickel Project. The document outlines the proposed process plant design for treating run-of-mine ore to produce nickel concentrate and tailings. The report addresses the general processing strategy, design criteria, unit process selection, and equipment sizing for a plant to be built in two phases, initially at 50 kt/d with provision for expansion to 100 kt/d.
Processing route
General processing strategy
The proposed process plant and associated service facilities will process ROM ore delivered to primary crushers to produce nickel concentrate and tailings. The proposed process encompasses crushing and grinding of the ROM ore, desliming via a hydrocyclone circuit, slimes flotation, nickel sulphide rougher flotation, nickel sulphide cleaning flotation, magnetic recovery of sulphide rougher tailings, regrind of magnetic concentration and sulphide 1st cleaner tailings, and nickel alloy rougher and cleaner flotation.
Concentrate will be thickened, filtered, and stored on site prior to being loaded onto railcars or trucks for transport to third-party smelters. The slimes flotation tailings, magnetic separation tailings, alloy rougher tailings, and alloy 1st cleaner scavenger tailings will be combined and thickened before placement in the tailings storage facility.
Plant design basis and phasing
The process plant will be built in two phases. Initially, the plant will be designed to process 50 kt/d with allowances for a duplicate process expansion to increase plant capacity to 100 kt/d. Common facilities will include concentrate thickening and handling, and reagent storage and preparation.
The key criteria selected for the base plant (50 kt/d) and expansion plant (100 kt/d) designs are: a nominal base plant treatment rate of 50 kt/d and a nominal expansion plant treatment rate of 50 kt/d for a combined 100 kt/d treatment rate; design availability of 92% (after ramp-up), which equates to 8,059 operating hours per year, with standby equipment in critical areas; and sufficient plant design flexibility for treatment of all ore types at design throughput.
Comminution circuit
The comminution circuit design was determined through evaluation of variability comminution testwork performed at SGS-Lakefield. Testwork provided a crusher work index, Bond ball and rod mill indices, Bond abrasion index, SMC, and JK Axb values for the selected samples. Ausenco elected to use the 75th percentile of each of these values in the design.
For each 50 kt/d plant, Ausenco selected one 11.6 m (38 ft) diameter SAG mill and two 7.9 m (26 ft) diameter ball mills. The circuit is designed to achieve the design throughput for design competency ore, with potential for increased throughputs for softer ores. An overall plant availability of 92% or 8,059 h/a is nominated, considered an industry standard for a large, multi-train flotation plant with moderately abrasive ore.
Crushing and stockpile
Ore from the open pit is crushed using a primary gyratory crusher (assisted with a rock breaker) to a crushed product size of nominally 80% passing (P80) 101 mm. Crushed ore is fed onto the covered stockpile feed conveyor. A covered conical stockpile of crushed ore with a live capacity of 18 h is provided, with three apron feeders, each capable of feeding 60% of the full mill throughput.
Grinding and classification
A 22 MW SAG mill, 11.6 m diameter (38 ft) with 6.7 m EGL (22 ft), utilizes a trommel screen for classification and oversize recirculation. Two 12 MW ball mills, 7.9 m diameter (26 ft) with 11.0 m EGL (36 ft), operate in closed circuit with hydrocyclones, grinding to a product size of nominally 80% passing (P80) 150 µm.
Desliming circuit
A two-stage desliming circuit via hydrocyclones is specified. The first stage splits mass with a cut size (D50c) of 40 µm. The second stage splits mass with a cut size (D50c) of 10 µm. Hydrocyclone sizes for each stage are 400 mm and 100 mm, respectively.
Flotation circuit design
The flotation circuit comprises multiple stages with specified residence times. Slimes flotation consists of two trains of six 300 m³ forced air tank flotation cells per train to provide 30 minutes of retention time. Nickel sulphide rougher flotation consists of two trains of seven 300 m³ forced air tank flotation cells per train to provide 60 minutes of retention time. Nickel sulphide 1st cleaner, 2nd cleaner, and 3rd cleaner flotation are specified, with residence times of 15, 12, and 12 minutes respectively. Magnetic sulphide flotation provides 36 minutes of retention time. Awaruite roughers provide 60 minutes, with alloy 1st cleaners at 18 minutes, alloy 1st cleaner scavenger at 18 minutes, and alloy 2nd cleaners at 15 minutes.
Magnetic separation
The flowsheet includes magnetic recovery of sulphide rougher tailings, with regrind of magnetic concentration and sulphide 1st cleaner tailings.
Concentrate handling and tailings disposal
Nickel concentrate thickening operates at a flux of 0.25 t/m²/h, with filtration at 450 kg/m²/h. Tailings thickening operates at 0.75 kg/m²/h, with underflow density at 40% w/w.
Key reported parameters
| Criteria | Unit | Design 50 kt/d | Design 100 kt/d |
|---|---|---|---|
| Crusher feed | kt/d | 50 | 100 |
| Mt/a | 18.25 | 36.50 | |
| Crusher availability | % | 75 | 75 |
| Crusher throughput | t/h | 3,019 | 6,039 |
| Mill/flotation availability | % | 92 | 92 |
| Mill throughput | t/h | 2,264 | 4,529 |
| Bond ball mill work index (BWI) | kWh/t | 20.7 | 20.7 |
| Bond rod mill work index (RWI) | kWh/t | 15.7 | 15.7 |
| Bond crusher work index (CWI) | kWh/t | 15.3 | 15.3 |
| Specific gravity | t/m³ | 2.57 | 2.57 |
| Grind size P80 | µm | 150 | 150 |
| Head grade (design) | % Ni | 0.35 | 0.35 |
| % S | 0.10 | 0.10 | |
| % Fe | 5.71 | 5.71 | |
| Sulphide nickel recovery (design) | % | 56 | 56 |
| Alloy nickel recovery (design) | % | 4 | 4 |
| Overall nickel recovery (design) | % | 60 | 60 |
| Flotation residence times | |||
| Slimes flotation | min | 30 | 30 |
| Sulphide roughers | min | 60 | 60 |
| Sulphide 1st cleaners | min | 15 | 15 |
| Sulphide 2nd cleaners | min | 12 | 12 |
| Sulphide 3rd cleaners | min | 12 | 12 |
| Magnetic sulphide | min | 36 | 36 |
| Awaruite roughers | min | 60 | 60 |
| Alloy 1st cleaners | min | 18 | 18 |
| Alloy 1st cleaner scavenger | min | 18 | 18 |
| Alloy 2nd cleaners | min | 15 | 15 |
| Reagent consumptions | |||
| PAX | g/t | 140 | 140 |
| MIBC | g/t | 19 | 19 |
| Cytec 65 (frothing agent) | g/t | 6 | 6 |
| Calgon | g/t | 50 | 50 |
| CMC | g/t | 25 | 25 |
| Sulphuric acid (H2SO4) | kg/t | 8 | 8 |
| Copper sulphate (CuSO4) | g/t | 30 | 30 |
| Flocculant | g/t | 30 | 30 |
| Media consumption | |||
| SAG mill media | t/a | 1,087 | 2,175 |
| Ball mill media | t/a | 1,831 | 3,662 |
| Regrind mill media | t/a | 283 | 565 |
Project website: http://docs.openinfo.gov.bc.ca/d70769413a_response_package_fin-2013-00353.xls
Technical qualifications
The design head grade of 0.35% Ni was selected prior to final completion of the mine plan; however, it represents roughly 95% of the peak quarterly head grade. Additionally, 0.35% Ni falls in the 95th percentile of all quarterly maximum head grades. The report states that the design head grade value will be revisited in the next phase of study.
The comminution circuit design was based on evaluation of variability comminution testwork, with Ausenco electing to use the 75th percentile of each value in the design.
The report notes that given the low abrasion index of the Dumont ore, the nominated availability of 92% is likely conservative.
The process plant flowsheet design was conceptually based on those of comparable large flotation plants and then confirmed or altered based on trade-off studies and metallurgical testwork.
Source: 2139-RPT-003, Recovery Methods section, 22 June 2012.
