The Rovina Valley project process plant design employs conventional froth flotation to recover copper and gold concentrate from Colnic and Rovina porphyry orebodies.
Report context
The Rovina Valley NI 43-101 Updated Technical Report, Rev0, documents the mineral processing recovery methods for a proposed plant designed to treat 7.2 Mt/a of Colnic ore for the first seven years and Rovina ore for the next nine years of the life of mine. The report presents the process plant overview, flowsheet development, and detailed process description based on test work programmes and trade-off studies.
Processing route
Crushing and stockpiling
The process plant design incorporates a single-stage gyratory primary crushing circuit. Run-of-mine ore is delivered into a receiving bin feeding directly to the primary crusher. The crusher product reports to a product bin and is transported via an apron feeder to a sacrificial conveyor equipped with a belt weightometer, tramp metal magnet, and metal detector. Crushed ore is conveyed via an overland conveyor to a stockpile that provides surge capacity for the milling circuit.
Milling
The grinding circuit employs a semi-autogenous grinding (SAG) mill in conjunction with a ball mill and pebble crushing (SABC) configuration. The SAG mill is equipped with a variable-speed drive. Six vibrating feeders with variable-speed drives regulate ore withdrawal from the stockpile onto the mill feed conveyor.
The SAG mill discharge passes through a trommel screen. Screen oversize reports to the pebble crushing circuit for further size reduction, with crushed pebbles returned to the mill feed conveyor. Overband magnets and metal detectors on the pebble crusher feed conveyors remove tramp steel. A bypass system diverts material around the pebble crusher during maintenance.
SAG mill trommel screen undersize combines with ball mill discharge in a common sump and is pumped to a hydrocyclone cluster. Cyclone underflow gravitates to the ball mill; cyclone overflow reports to a trash removal screen before advancing to flotation.
Flotation circuit
The flotation circuit consists of: a rougher scalper flotation Jameson cell; rougher and scavenger flotation tank cells; concentrate regrind; and three-stage cleaner flotation column cells. Flotation feed passes through a conditioning tank where collector, promoter, and hydrated lime are added.
Rougher scalper concentrate reports to final concentrate thickening. Rougher-scavenger concentrate is transferred to an open-circuit IsaMill™ regrind mill for further liberation. After regrinding, the material advances to the three-stage cleaner flotation circuit. Cleaner 3 concentrate reports to final concentrate thickening; tails from each cleaner stage are recycled to the preceding stage.
Concentrate dewatering and bagging
Final concentrate from the rougher scalper and Cleaner 3 flotation cells is thickened in a high-rate thickener. Thickener underflow is pumped to a filter feed tank and then to pressure filters. Filter cake is discharged and transported by front-end loader to a load-out system for bagging into bulk bags.
Tailings dewatering and disposal
Flotation tails from the rougher-scavenger circuit and Cleaner 1 circuit are separately thickened in high-rate thickeners and filtered using pressure filters. Tailings filter cake is conveyed and stacked at the waste management facility. Cleaner tails are stored separately from scavenger tails due to high pyrite content and acid-producing characteristics.
Reagents and services
Reagent facilities include mixing, storage, and distribution for: hydrated lime (slaked on site, pH control to 9.5–11), flocculant (SNF AN905 SH), collector (potassium amyl xanthate, PAX), promoter (Aerophine 3418A), and frother (Aerofroth 65). Low-pressure blowers supply air to rougher-scavenger flotation; low-pressure compressors supply air to cleaner flotation. High-pressure compressors provide instrument and plant air. Water services include process, raw, gland, potable, and fire water distribution systems.
Key reported parameters
| Parameter | Unit | Design Value (Colnic) | Design Value (Rovina) | Basis |
|---|---|---|---|---|
| Plant throughput | Mt/a | 7.2 | 7.2 | Client |
| Crushing utilisation/availability | % | 70 | 70 | SENET/Industry |
| Milling utilisation/availability | % | 91 | 91 | SENET/OMC |
| Cu head grade (LOM) | % | 0.10 | 0.24 | DRA Mining |
| Au head grade (LOM) | g/t | 0.62 | 0.26 | DRA Mining |
| Cu recovery (LOM) | % | 88.5 | 92.5 | SENET/Test Work |
| Au recovery (LOM) | % | 80.0 | 78.8 | SENET/Test Work |
| Cu product grade (LOM) | % | 20.3 | 22.1 | SENET/Test Work |
| Au product grade (LOM) | g/t | 65.87 | 22.92 | SENET/Test Work |
| Primary crushing product size (P80) | mm | 150 | 150 | OMC |
| Mill circuit product size (P80) | µm | 75 | 75 | Test Work |
| Concentrate regrind product size (P80) | µm | 13.5 | 13.5 | Test Work |
| Rougher flotation residence time (laboratory) | min | 5.8 | 5.8 | Test Work |
| Scavenger flotation residence time (laboratory) | min | 5.4 | 5.4 | Test Work |
| Concentrate thickener specific settling rate | t/(m²/h) | 0.649 | 0.649 | Test Work |
| Concentrate filter cake moisture | % | 8.5 | 8.5 | Test Work |
| Scavenger tails thickener specific settling rate | t/(m²/h) | 0.578 | 0.578 | Test Work |
| Scavenger tails filter cake moisture | % | 14.5 | 14.5 | Test Work |
| Cleaner tails thickener specific settling rate | t/(m²/h) | 0.649 | 0.649 | Test Work |
| Cleaner tails filter cake moisture | % | 14.5 | 14.5 | Test Work |
| Collector (PAX) consumption | g/t ore | 13 | 13 | Test Work |
| Promoter (Aerophine 3418A) consumption | g/t ore | 18.1 | 18.1 | Test Work |
| Frother (Aerofroth 65) consumption | g/t ore | 20.5 | 20.5 | Test Work |
| Lime consumption | g/t ore | 580 | 580 | Test Work |
| Flocculant consumption | g/t ore | 37 | 37 | Test Work |
Technical qualifications
The report presents a proposed process plant design based on test work programmes conducted by SGS Lakefield, Eriez, and Pocock laboratories on samples from the Colnic and Rovina porphyry orebodies. Flowsheet development incorporated trade-off studies and simulations by specialised consultants including Orway Mineral Consultants (OMC) for comminution and Adroit Process Equipment (APE) for filtration. The report does not present historical operating data from this plant, as the facility is in the design phase. All process design criteria are based on bench scale and pilot laboratory tests unless otherwise noted. The simplified process flowsheet and plant general arrangement are shown in figures referenced in the report but not reproduced here.
Source: SP0829 Rovina Valley NI 43-101 Updated Technical Report Rev0, Section 17 Recovery Methods.
