The Cotabambas Project processing design envisions an 80,000 t/d plant incorporating crushing, grinding, flotation, concentrate dewatering, and tailings disposal.
Report context
The Cotabambas Project is located in Apurimac, Perú. This NI 43‑101 Technical Report on an updated Preliminary Economic Assessment was dated November 2015. The process description below is drawn from Section 17.0 Recovery Methods of that report.
Processing route
Crushing
The primary crushing station is designed as a fixed 60 × 113 inch gyratory crusher. Mine haul trucks will dump run‑of‑mine material directly into the crusher dump pocket. Crushed mill feed will be discharged to two apron feeders, which will feed a sacrificial coarse ore conveyor and then a stockpile conveyor.
The coarse ore stockpile will be conical with a live capacity of 80,000 t, providing an equivalent of 24 hours of plant feed. This stockpile will serve as a buffer between mining/crushing operations and the process plant, allowing the plant to continue operating during intermittent stoppages of feed from the crusher or the mine. Mill feed will be reclaimed from the stockpile by four apron feeders installed in a concrete tunnel below the stockpile. The feeders will discharge material onto the SAG mill feed conveyor. Solid lime and grinding media will be added to the SAG mill feed as required to maintain the grinding charge and to condition the mill circuit slurry pH for subsequent flotation.
Grinding
The grinding circuit configuration consists of an open‑circuit SAG mill followed by two ball mills in closed circuit with cyclones. SAG mill discharge will be screened, and pebble oversize material (>15 mm) will be crushed by two cone crushers, then recycled back to the SAG mill feed conveyor. The SAG mill discharge screen undersize slurry will be transferred to a ball mill discharge cyclone feed pumpbox from a SAG mill discharge transfer pumpbox.
The SAG mill is sized at 40 ft diameter × 26 ft length, powered by a 28 MW gearless motor drive. The two ball mills are sized at 28 ft diameter × 40 ft length, each driven by a 22 MW gearless motor drive, fixed‑speed, operating in parallel. Ball mill discharge will be combined with the SAG mill product in the ball mill discharge cyclone feed pumpbox.
The ball mill pumpbox, with two cyclone feed pumps operating in parallel, will feed four clusters of 12 D26 cyclones (10 operating, 2 standby). Two clusters will operate in closed circuit with each ball mill. Cyclone overflow at about 30% solids will be transferred to flotation, and the underflow at about 70% solids will discharge to the ball mill feed hoppers. The average final product size from the grinding circuit will be P₈₀ 106 µm.
Flotation
The flotation circuit is designed to recover copper‑ and gold‑bearing minerals into a final concentrate. It consists of a rougher flotation stage, regrinding, a first cleaner stage followed by a cleaner‑scavenger stage, and two stages of re‑cleaner (second and third cleaner) using conventional flotation tank cells.
The ball mill circuit product will feed a bank of seven rougher cells, each 600 m³. Rougher tailings will be pumped to the flotation tailings thickener. Rougher concentrate and cleaner‑scavenger concentrate will feed two regrind hydrocyclone clusters, each of 12 D10 hydrocyclones (10 operating, 2 standby). Each cluster will be coupled to one regrind mill. The underflow from the hydrocyclones will be fed to the regrinding circuit, consisting of two regrind mill units. The regrind circuit product will have a P₈₀ of [value not stated in source].
Key reported parameters
| Parameter | Value | Units | Basis |
|---|---|---|---|
| Nominal processing capacity | 80,000 | t/d | Design |
| Coarse ore stockpile live capacity | 80,000 | t | Design (equivalent to 24 h of plant feed) |
| SAG mill dimensions | 40 ft × 26 ft | ft | Design |
| SAG mill drive power | 28 | MW | Design (gearless motor drive) |
| Ball mill dimensions (each) | 28 ft × 40 ft | ft | Design |
| Ball mill drive power (each) | 22 | MW | Design (gearless motor drive, fixed‑speed) |
| Grinding circuit final product size | P₈₀ 106 | µm | Design |
| Rougher cells | 7 | cells | Design (600 m³ each) |
| Regrind mills | 2 | units | Design |
| Cyclone overflow solids | ~30 | % | Design estimate |
| Cyclone underflow solids | ~70 | % | Design estimate |
Project website: https://panoro.com/en/cotabambas-project/cotabambas-project/
Technical qualifications
The description above represents a proposed plant design from the 2015 NI 43‑101 Technical Report on an updated Preliminary Economic Assessment. No historical operating data or testwork results for this flowsheet are provided in the source. The simplified process flow diagram (Figure 17‑1, prepared by Amec Foster Wheeler, 2015) is referenced but not reproduced here.
Source: Cotabambas Project, Apurimac, Perú – NI 43‑101 Technical Report on Updated Preliminary Economic Assessment, November 2015, Section 17.0 Recovery Methods.
