The 2012 Preliminary Economic Assessment for the Kipawa Project describes a two-site plant flowsheet comprising a mine-site crushing, grinding, and magnetic separation concentrator and a separate hydrometallurgical facility near Temiscaming, Quebec.
The Kipawa Project, as assessed in the 2012 Preliminary Economic Assessment prepared for Matamec Explorations Inc., is a rare earth oxides (TREO) development. The selected process configuration separates the ore beneficiation from the chemical treatment. The concentrator, located at the mine site, applies physical upgrading to produce a concentrate. This concentrate is then transported to a hydrometallurgical plant near the town of Temiscaming for further treatment. The design basis for the project is an annual feed of 1,500,000 tonnes of ore at a grade of 0.5% TREO, with a total TREO recovery of 81% targeted for the combined flowsheet.
Critical Data
| Parameter | Value | Unit | Notes |
|---|---|---|---|
| Annual feed | 1,500,000 | t ore/a | Mine site design criteria |
| Total rare earth oxide (TREO) grade | 0.5 | % | |
| Plant availability | 91 | % | |
| Daily ore tonnage | 4,516 | t/d | |
| Hourly tonnage | 188.2 | t/h | |
| TREO recovery to concentrate | 90 | % | |
| Concentrator tailings loss | 10 | % | |
| Hydromet residues loss | 9 | % | |
| Allowance for soluble loss | 1 | % | |
| Total losses | 20 | % | |
| Total TREO recovery | 81 | % | |
| Annual TREO production | 6,000 | t/a | |
| Concentrate | 35.0 | % of ore | |
| Concentrate | 65.9 | t/h | |
| Concentrate bulk density | 1.6 | t/m3 | |
| Concentrate TREO | 1.286 | % | |
| Thickener unit area | 0.4 | m2/tpd | Residue thickening |
| Filtration rate | 200.0 | kg/h.m2 | Residue filtration |
| Filter type | drum | Not stated | |
| Filtercake moisture | 25 | % | |
| Concentrator installed power | 4,675 | kW | |
| Concentrator operating power | 3,558 | kW | |
| Hydromet installed power | 5,067 | kW | |
| Hydromet operating power | 4,047 | kW | |
| Mine site genset capacity | 4.8 | MW | Diesel |
Overview
The project is an open-pit rare earth operation with a process design that is divided into two distinct locations. The mine-site plant performs crushing, grinding, and magnetic separation to create a concentrate. The design criteria state a feed rate of 188.2 tonnes per hour, which corresponds to 1,500,000 tonnes of ore per year. The concentrate produced is then transported by truck to a hydrometallurgical facility near Temiscaming. This separate plant receives the concentrate at a rate of 65.9 tonnes per hour and processes it to extract rare earth oxides.
Key Process Stages
The process commences with ore being hauled by trucks to a jaw crusher feed hopper. Crushed material is conveyed to a coarse ore bin with a live capacity of approximately 2,200 metric tonnes, sized for 12 hours of operation. From the bin, four vibrating feeders recover the stored material and feed the mill feed conveyor.
The crushed ore is sent to a semi-autogenous grinding (SAG) mill operating in open circuit, followed by a rod mill in closed circuit with a screen to produce a ground product. The ground material is then cycloned to remove fines below 200 mesh (75 microns). These fines are concentrated in rare earths and are thickened and taken as part of the final concentrate.
The magnetic separation stage uses low intensity wet magnetic separation (LIMS) to reject a magnetic concentrate. This is followed by wet high intensity magnetic separation (WHIMS) to recover rare earths as a concentrate, with the non-magnetic fraction rejected to tailings. The final concentrate is thickened, filtered, and stored in a silo before being shipped by truck to the hydromet plant.
At the hydrometallurgical site, the concentrate is re-ground in a ball mill prior to leaching with sulphuric acid in a train of atmospheric leach tanks. The resulting solution is processed through a solution circuit where the precipitate is filtered and calcined to yield a final product. The barren solution is recycled to the extent possible, with the balance reporting to the residue neutralization circuit.
Additional Interesting Data and Summary
The mine site electrical power requirement is estimated at 3.6 MW operating, with diesel gensets providing 4.8 MW of installed capacity. The hydrometallurgical facility has an operating power demand of 4.0 MW against an installed capacity of 5.1 MW. Design factors of 10% to 15% were applied to most equipment sizing to accommodate throughput variations. The tailings facility, with a total capacity of 11.7 Mm³, is assumed to be non-acid generating and therefore requires no watertight geomembrane. The tailings are designed with a 2.5H:1V slope, a crest width of 5 metres, and a maximum dyke height of 8 metres.
Key Processes
- Crushing (jaw crusher)
- Grinding (SAG mill, rod mill, ball mill)
- Magnetic separation (LIMS, WHIMS)
- Leaching (atmospheric sulphuric acid)
- Solution purification (precipitation and calcination)
- Tailings disposal (dry stacking)
Source: Kipawa Project , 2012 Preliminary Economic Assessment, 2012.
Project website: Kipawa Project, 2012 Preliminary Economic Assessment
