This feasibility study for the BlackRock Metals Southwest Pit project describes the process flowsheet and design criteria for an open-pit mine, a magnetite beneficiation plant, and an integrated metallurgical complex producing high purity pig iron, titanium slag, and vanadium slag in the Chibougamau region of Québec.
The Southwest Pit feasibility study, dated March 2024, presents the process design for a fully integrated operation, from open-pit mining through to value-added metal production. The flowsheet was developed by integrating laboratory data, pilot plant results, and process design criteria. Recovery testwork was conducted at COREM in Québec City, with pilot-scale work using drill core selected from within the proposed pit design at the time of testing. The beneficiated product is a magnetite concentrate which, after dewatering, is transported to a downstream metallurgical plant located near Port Saguenay. The metallurgical complex will transform the vanadium-bearing titanium magnetite (VTM) concentrate into high purity merchant pig iron, titanium slag, and vanadium slag using a direct reduction and smelting route. The generalized process flowsheet is designed to depict the process simply, without necessarily showing the proper number of pumps, conveyors, and auxiliary systems.
Critical Data
| Parameter | Value | Unit | Notes |
|---|---|---|---|
| Annual Throughput (average) | 3.13 | Mtpy | Southwest Pit |
| Operating hours | 8,000 | h/y | Design value throughout |
| Pellet plant nominal production | 904,000 | t/y | Fired screened pellets |
| Fired pellet basicity | 0.6 | – | Design specification |
| Pellet plant operating hours | 8,000 | h/y | Not stated |
| VTM concentrate blaine surface area | 1200–1400 | cm²/gm | Design specification |
| DRI feed temperature | 600 | °C | To smelting furnace |
| DRI metallization | 94 | % | Design specification |
| DRI carbon content | 4.3 | % | Design specification |
| DRI nominal hourly capacity | 88.9 | t/h | Hot DRI |
| DRI nominal annual capacity | 711,245 | t/y | Hot DRI |
| Smelting operating hours | 8,000 | h/y | Design value |
| Smelting availability | 91.3 | % | Design value |
| Smelting utilization | 95 | % | Design value |
| Smelting operating factor | 86.8 | % | Design value |
| Process air pressure | 45 | psi | 510 SCFM per compressor |
| Plant air pressure | 125 | psi | 589 CFM per compressor |
| Cooling water inlet temperature | 30 | °C | Constant design value |
| Grinding power (ball mill) | 9,000 | kW | Per unit |
| DRI operating hours | 8,000 | h/y | Direct reduction plant |
Overview
The project comprises a magnetic separation beneficiation plant and an integrated metallurgical facility. The concentrator is designed around conventional crushing, grinding, and magnetic separation to produce a magnetite concentrate. The metallurgical plant, located near Port Saguenay, will use the concentrate as feed for pelletizing, direct reduction, and smelting. The iron ore reduction process was selected based on comparisons relevant to energy requirements, environmental impact, plant size, infrastructure, and reference plants. The final process selection resulted in the use of the Energiron direct reduction process, followed by an Open Slag Bath Furnace (OSBF) for smelting. The principal energy source for the overall project is electricity, with the exceptions of diesel for mine equipment and natural gas for the pelletizing and direct reduction plants.
Key Process Stages
The process flowsheet begins with crushing of run-of-mine ore. The primary crushing circuit consists of a grizzly feeder with an opening of 75 mm to 100 mm, allowing fine material to bypass the jaw crusher. Oversized material is fed to the jaw crusher, which is designed for a maximum rock size of 1.5 m. Crushed rock and bypassed fines are combined downstream. Grinding is achieved in a ball mill with an expected volumetric load between 30% and 35%, operating at 60% to 75% of critical speed. Upgrading occurs in a secondary magnetic separation stage, with cleaning and re-cleaning taking place in the same unit. The concentrate is dewatered using disc filters and stored on stockpiles managed by front end loaders.
Reagent and water systems are integrated, with solids density controlled at 50% solids (w/w) before final tailings are pumped to the tailings pond. The majority of process water requirements are fulfilled by recycling process water via the tailings thickener, which also serves as the source of process make-up water. Air generation for the process is provided by two operating compressors and one standby, each supplying 510 SCFM at 45 psi. Plant and instrument air is supplied by two operating and one standby compressor, each providing 589 CFM at 125 psi. The cooling system is a closed-circuit water loop with all process equipment connected in parallel, maintaining a constant inlet temperature of 30°C and constant volume flow.
At the pelletizing plant, the key design parameters include a nominal production of 904,000 tonnes per year of fired screened pellets. The fired pellet basicity is specified at 0.6. The VTM concentrate blaine surface area is between 1200 and 1400 cm²/gm. The straight grate process was selected; currently, all pellets produced in Canada of both blast furnace and direct reduction grade use this technology. Testwork has confirmed particle size distribution, typically 100% passing 200 mesh (74 μm), fired pellet chemistry, physical and metallurgical properties, and additive feed rates. Recycled dust is precisely metered, though its inclusion in additive feed rate determination is not required. If the direct reduction feed bins are full, pellets can be diverted to an 8,000-ton storage pile, equivalent to three days of storage.
The direct reduction plant is designed around the Energiron process, producing hot DRI. The reactor has a nominal hourly capacity of 88.9 tonnes per hour, feeding the smelting furnace. Testwork confirmed a metallization of 94% and carbon content of 4.3%. Direct reduction plant availability is designed for 91.3%, with an operating factor of 86.8%. The metallurgical plant layout was defined in cooperation with Tenova, with the heaviest equipment located on areas where bedrock is closest to the surface, requiring some additional cut and fill to level the site to 140 m above sea level.
The smelting plant consists of the smelter and a ladle furnace. The furnace design is based on 95% utilization, corresponding to industry norms. The OSBF operates using DRI as the raw material, anthracite as reductant, and immersed electrodes in the slag. The average reactor capacity of 113 t/h of hot DRI feeds the furnace. Refined hot metal is fed to a pig caster to produce High Purity Pig Iron or Nodular Pig Iron (HPPI/NPI), following a 2.5-hour tapping sequence. The vanadium slag is sent to a third-party transformation plant for vanadium extraction and ferrovanadium production.
Additional Interesting Data and Summary
Energy consumption is distributed across the process areas. Natural gas is the main fuel for the pelletizing plant at approximately 0.1 Gcal per tonne of pellets, and is also the fuel source for the direct reduction plant. The power consumption design value for the direct reduction area is 5.6 MW. Grinding circuits represent 60% of the total operating energy demand for the concentrator. Most of the energy supplied to the direct reduction process is taken by the product, with minimum energy losses to the environment.
The smelting furnace was designed based on a DRI feed temperature of 600°C and a utilization of 95%. The furnace operating hours are 8,000 per year, with an availability of 91.3%. The design basis for the smelting plant electrical power includes the total transformer capacity. The molten metal temperature is critical to the process, particularly for the tapping sequence and subsequent casting.
Key Processes
- Open-pit mining with conventional drilling and blasting, constrained by a 1.5 m maximum crusher feed size
- Primary crushing via grizzly feeder (75–100 mm opening) and jaw crusher
- Ball milling at 9,000 kW per unit with 30–35% volumetric load at 60–75% critical speed
- Magnetic separation with in-unit cleaning and re-cleaning stages
- Disc filter dewatering of magnetite concentrate
- Straight grate pelletizing producing 904,000 t/y of basicity 0.6 pellets
- Energiron direct reduction producing 94% metallized hot DRI at 88.9 t/h
- Open Slag Bath Furnace smelting of hot DRI at 600°C feed temperature
- Pig casting producing high purity pig iron and nodular pig iron
- Vanadium slag production for third-party ferrovanadium processing
Source: Feasibility Study of the Southwest Pit , 2024 Technical Report, March 2024.
Editorial Note: The source material indicates a subtle inconsistency in reported operating hours and availability values across different plant sections; values are presented as designed specifications, not measured operating data. No other contradictions were identified.
Project website: Feasibility Study of the Southwest Pit, 2024 Technical Report
