The 2014 NI 43-101 Technical Report presents a Feasibility Study for the LabMag Taconite Project, detailing a conventional magnetite processing circuit designed to produce high-grade iron ore concentrate and pellets.
The LabMag Taconite Project, developed by New Millennium Iron Corp., is the subject of a 2014 Technical Report summarizing a Feasibility Study for a processing plant designed to treat approximately 88 Mt/y of taconite ore. The design is based on extensive metallurgical test work and aims to produce high-grade iron ore pellets and concentrate. The process flow sheet utilizes proven mineral processing technology in what is described as a conventional magnetite ore processing circuit to produce direct reduction (DR) and blast furnace (BF) pellet feed concentrates. The design incorporates dry comminution with two stages of conventional crushing and one stage of high pressure grinding rolls (HPGR) with screening.
The process design criteria were developed from test work on samples selected from the taconite deposits, including work on individual samples, composite samples, and vendor test work. The LabMag and KéMag ore characteristics are similar; therefore, the same flow sheet and plant design can be used for either ore body and still meet the concentrate quality requirements. The design philosophy is driven by a requirement for established and proven processes. The plant is based on four distinct parallel lines, each with three circuits.
Critical Data
| Parameter | Value | Unit | Notes |
|---|---|---|---|
| Iron Concentrate Production Target (Dry) | 22,000,000 | t/y | Design target |
| Run of Mine Production – Design (Dry) | 86,140,000 | t/y | Design value |
| Run of Mine Humidity | 2 | % | Design value |
| Weight Recovery (Including Flotation) | 25.54 | % | Based on design and flotation recovery |
| Feed Fe Grade | 32.5 | wt % | Design value |
| Magnetite, Fe3O4 | 27 | wt % | Design value |
| Hematite, Fe2O3 / Gangue Minerals | 13 | wt % | Design value |
| Quartz, SiO2 (Representing Gangue Materials) | 60 | wt % | Design value |
Overview
The technical report covers the Feasibility Study for the LabMag Taconite Project, with a processing plant designed to treat approximately 88 Mt/y of taconite ore at a dry tonnage weight recovery of 27% and a feed Fe grade of approximately 30%. This design permits the production of 22 Mt/y of iron concentrate. The process plant flow sheet and design criteria are based on results from metallurgical test work. The concentrator is designed to produce both DR and BF pellet feed concentrates using a conventional magnetite processing circuit. The process plant and flotation plant are designed to operate at an availability of 92% and 95%, respectively.
The project is supported by a substantial test work program conducted between 2005 and 2013. The metallurgical test work included bench scale tests, pilot plant campaigns, and vendor-specific tests for equipment sizing. Design criteria derived from the test work were used to establish the basis for the flow sheet and mass balances. The flotation circuit adds a key step to the magnetic separation process to ensure the final concentrate meets silica specifications. An important design consideration is the magnetite weight recovery, as any hematite present will not be recovered in the concentration process; therefore, the run of mine (ROM) needed to produce the required concentrate tonnage is calculated based on weight recovery and design factors.
Key Process Stages
The ore processing begins with a dry comminution flow sheet that includes two stages of conventional crushing and one stage of HPGR with screening. Following comminution, the ore is processed through a concentration circuit. The process flow sheet then utilizes flotation as the key step for silica reduction, operating in four distinct parallel lines.
All flotation steps are designed to use tank type flotation cells. The flotation plant comprises four lines, each with three circuits. The silica rougher flotation circuit is designed to remove 77% of the silica. The design allows for flexibility in the final concentrate silica content: when all four flotation lines are in operation, the lowest achievable silica content is produced; when some lines are bypassed, the final concentrate silica content results from blending the concentrates from the magnetic separation with material that has been floated.
The concentrate is processed in a filtration and pelletizing plant designed with two pellet lines, each with a capacity of 8.5 Mt/y. This section of the plant was engineered by Outotec, including the development of design criteria and the design for filtration, additives preparation, balling, and pelletizing. A market study for high quality BF and DR grade pellets determined the chemical and metallurgical design criteria. A dedicated test program, including twelve tests (nine for BF and three for DR grade), was undertaken to develop the design basis for the proposed equipment.
The pelletizing process includes several stages, such as mixing, balling, and induration. The additives required for pelletizing, including limestone, dolomite, and bentonite, are received as bulk materials. The process water and slurry handling systems are designed to recover and recycle materials. A key design philosophy is the "No Freezing, No Plugging" approach for the slurry transportation system, which will be buried. The plant is also designed with a process control system to monitor and control all significant variables.
Additional Interesting Data and Summary
The process plant boasts several unique design aspects. A comprehensive water management system is integral to the operation, with significant process water additions to the mixer, additive grinding, and dust slurry systems. The plant is designed to minimize iron unit losses, with the design philosophy that no iron units will be lost throughout the process, except for very limited quantities of dust in the clean gases of the stacks. The burners in the pelletizing plant are designed to use heavy fuel oil.
The filtration and pelletizing plant incorporates a circulating water system where hot water is cooled via heat exchangers. A high level of plant automation is implemented, with a distributed plant structure for automation and data acquisition. The control system is designed to monitor and control all significant variables and provides necessary sequencing, interlocking, and safety functions. Operation, engineering, and process control stations will be selected from the product range of one supplier only. The advanced control and safety system will have a distributed plant structure, with connections between operator, engineering, and process control stations via an Ethernet TCP/IP structure.
The overall process design is based on extensive test work. Data from the metallurgical testing program formed the basis for the design criteria, which include vendor information, assumptions based on industry experience, and information from similar recent projects. Twelve tests were undertaken to develop the design basis for the equipment, with the conditions of Tests #9 and #10, for DR and BF pellets respectively, selected as the basis for final equipment design and process guarantees. The report also describes a pelletizing test program where bentonite levels were maintained at 0.48% to 0.49% throughout the tests. To achieve optimum drying and firing during the pelletizing process, the specific surface of the concentrate was limited to 1,800 Blaine, and firing patterns were varied to obtain the desired physical and metallurgical qualities.
Key Processes
- Dry comminution with two-stage conventional crushing and one stage of HPGR with screening
- Conventional magnetite concentration circuit
- Tank-type flotation cells for silica removal in four parallel lines
- Filtration and pelletizing plant with two lines, each with 8.5 Mt/y capacity
- Mixing, balling, and induration for pellet production
- Heavy fuel oil burners for the pelletizing furnace
- Comprehensive plant automation and control system
Source: LabMag Taconite Project , 2014 Technical Report, 2014.
Project website: LabMag Taconite Project, 2014 Technical Report
