Magnetic Separation Equipment for Iron Ore: Current Status and Key Technologies

Magnetic separation is a core process in iron ore beneficiation, with diverse equipment types tailored to different magnetic minerals and particle sizes. Based on global technological advancements, this article systematically introduces key magnetic separators and their applications.

I. Magnetic Separators for Magnetite

1.    Magnetic Pulley
Featuring axial or radial magnetic pole arrangements, it is used for coarse magnetite pre-concentration, with a maximum capacity of 250 t/(h·m) and a feed size range of 10-100 mm.

2.    Cylindrical Magnetic Separators

o    Dry Permanent Magnet Drum Separators: Suitable for dry processing of fine magnetite in arid regions, with a feed size limit of 30 mm and a capacity of 20 t/(h·m).

o    Wet Permanent Magnet Drum Separators: Flexible trough designs (co-current, counter-current, semi-counter-current) enhance adaptability. Ceramic-coated drums improve wear resistance, achieving a capacity of 60 t/(h·m).

3.    Magnetic Column
Combines electromagnetic fields with upward water flow to remove gangue via magnetic aggregation-loosening cycles. Ideal for fine magnetite (-0.074 mm) cleaning, though limited by low throughput.

4.    Magnetic Screen
A magnetic-gravity hybrid device for concentrate upgrading, yet constrained by processing capacity.

5.    Tailings Recovery Machine
Direct-contact permanent magnet equipment for scavenging residual magnetite from tailings.

6.    Auxiliary Equipment

o    Magnetic Dewatering Tank: Removes slimes and fine gangue.

o    Pre-magnetizer and Demagnetizer: Pre-magnetizers optimize separation efficiency; demagnetizers eliminate remanence for downstream processes.

II. Magnetic Separators for Weakly Magnetic Ores

1.    Electromagnetic Roll Separators
Closed magnetic systems for coarse hematite, with a field strength of 1.87 T. High energy costs limit their use, replaced increasingly by rare-earth roll separators.

2.    Rare-Earth Roll Separators
Energy-efficient dry separators (13,000-20,000 Oe) for coarse weakly magnetic ores (-50+0.1 mm), handling up to 30 t/(h·m).

3.    Flat-Ring and Vertical-Ring Separators

o    Flat-Ring Separators (e.g., ShP-type): Based on Jones’ multi-layer induction poles, effective for hematite separation.

o    Vertical-Ring HGMS (e.g., Slon-type): Integrates pulsating mechanisms for fine-grained red ore, widely used in China.

4.    High-Gradient Magnetic Separators (HGMS)
Designed for -30 μm weakly magnetic particles. The Sala HGMS (Sweden) achieves 600 t/h capacity, while domestic R&D faces cost challenges.

III. Trends and Challenges

1.    Magnetite Equipment: Develop high-capacity magnetic columns (≥100 t/h) and novel weak-field devices for ultrafine and roasted ores.

2.    Weakly Magnetic Ore Equipment: Prioritize large-scale, intelligent, and energy-saving designs to enhance fine particle recovery.

3.    Multidisciplinary Integration: Optimize separation efficiency by combining magnetic physics, fluid dynamics, and smart controls.

Conclusion

Innovation in magnetic separation equipment is vital for efficient iron ore utilization. Future efforts should focus on independent R&D, standardization, and intelligent upgrades to support sustainable development in China’s iron ore industry.