Abstract

With the continuous development and utilization of iron ore resources, easily beneficiated coarse-grained magnetite resources are gradually decreasing, and fine-grained disseminated magnetite has become an important research target in the mineral processing industry. Traditional drum magnetic separators show excellent performance in coarse-grained magnetite separation, while magnetic columns and other advanced separation equipment can achieve good results in fine-grained magnetite upgrading. However, for ultra-fine magnetite particles smaller than 75 μm, conventional magnetic separation equipment often has limited separation efficiency due to fine particle size, strong magnetic aggregation, and serious entrainment problems.

To improve the separation performance of fine-grained magnetite, Guote Intelligent Equipment has developed an innovative Permanent Magnet Combined Box Magnetic Separator based on a mechanical oscillating magnetic system and a combined force field. The equipment creates periodic variations in magnetic field intensity within the separation zone, enabling efficient capture of fine magnetite particles while reducing gangue entrainment.

Industrial test results from the Jiajiabao Iron Mine of Benxi Iron & Steel Group showed that the equipment achieved excellent upgrading performance. Under optimized operating conditions, the concentrate reached a TFe grade of 67.81% with an iron recovery rate of 96.11%, demonstrating significant application potential for fine-grained magnetite beneficiation.

Keywords:
Fine-grained magnetite; Permanent magnet box magnetic separator; Magnetite beneficiation; Composite magnetic field; Iron ore processing equipment

1. Challenges in Fine-Grained Magnetite Separation

Magnetite is one of the most important iron-bearing minerals, and magnetic separation technology is widely used for its beneficiation due to the strong magnetic properties of magnetite.

Currently, different types of magnetic separators are selected according to mineral particle size characteristics.

For relatively coarse-grained magnetite, drum magnetic separators are commonly used due to their advantages of:

• Simple structure;
• Large processing capacity;
• Stable operation;
• Low maintenance requirements.

They are widely applied in iron ore pre-concentration and roughing operations.

For finer magnetite particles, magnetic columns and other upgrading equipment can effectively improve concentrate quality by combining magnetic force, gravity, and hydraulic separation effects.

However, as mineral processing plants increasingly process finely disseminated ores, a large amount of ultra-fine magnetite particles (-75 μm) enter the beneficiation circuit.

Fine magnetite separation faces several technical challenges:

• Difficult liberation of mineral particles;
• Weak magnetic response of ultra-fine particles;
• Strong magnetic aggregation;
• Increased gangue entrainment;
• Difficulty in improving concentrate grade.

As a result, conventional magnetic separation equipment often suffers from:

• Reduced recovery of valuable magnetic minerals;
• Increased impurity content in concentrates;
• Limited improvement in iron grade.

Therefore, developing efficient magnetic separation equipment for fine-grained magnetite upgrading has become an important direction in modern mineral processing technology.

2. Structure and Working Principle of the Permanent Magnet Combined Box Magnetic Separator

To overcome the challenges of fine-grained magnetite separation, Guote Intelligent Equipment developed the Permanent Magnet Combined Box Magnetic Separator.

The equipment mainly consists of:

• Frame system;
• Permanent magnetic system;
• Magnetic plates;
• Separation box;
• Feeding and water supply system;
• Transmission system.

Unlike traditional magnetic separators with fixed magnetic systems, this equipment adopts an innovative mechanically oscillating magnetic system.

During operation, the magnetic systems located on both sides of the separation box move back and forth, causing periodic changes in magnetic field intensity within the separation area.

The separation process includes two main stages:

Strong Magnetic Field Stage

When the magnetic system moves closer to the separation area, a high-intensity magnetic field is generated.

Fine magnetite particles are attracted by magnetic force, forming magnetic chains and rapidly moving toward the magnetic area for effective recovery.

This stage improves the capture efficiency of fine magnetic particles.

Weak Magnetic Field Stage

When the magnetic system moves away from the separation area, the magnetic field intensity decreases.

At this stage, flushing water can effectively:

• Break magnetic chains;
• Remove entrained gangue minerals;
• Improve concentrate quality.

Through alternating strong and weak magnetic fields, the equipment achieves a continuous process of:

Magnetic capture → Dispersion → Cleaning → Upgrading

This significantly improves the separation performance of fine-grained magnetite.

3. Technical Advantages of the Permanent Magnet Combined Box Magnetic Separator

3.1 Improved Recovery of Fine Magnetite Through Composite Magnetic Fields

The mechanical oscillating magnetic system creates a dynamic magnetic environment rather than a constant magnetic field.

The alternating magnetic field enables:

• Efficient capture under strong magnetic conditions;
• Improved cleaning under weak magnetic conditions;
• Reduced gangue entrainment;
• Higher concentrate quality.

This effectively solves the common problems of fine magnetite separation, including difficult recovery and poor upgrading performance.

3.2 Energy Saving with Permanent Magnetic Design

The equipment uses high-performance permanent magnetic materials as the magnetic source.

Compared with electromagnetic magnetic separators, it offers:

• No continuous excitation power consumption;
• Stable magnetic performance;
• Lower operating costs;
• Improved energy efficiency.

The permanent magnetic design makes the equipment more environmentally friendly and economical for long-term operation.

3.3 Lower Water Consumption with Box-Type Separation Structure

Traditional magnetic columns generally adopt cylindrical separation chambers, while the Permanent Magnet Combined Box Magnetic Separator uses a rectangular box-type structure.

Compared with cylindrical equipment, it provides:

• More efficient utilization of separation space;
• More uniform magnetic field distribution;
• Lower water consumption;
• Easier operation and maintenance.

These advantages make it especially suitable for fine-grained magnetite upgrading applications.

3.4 Modular Design for Different Processing Capacities

The equipment adopts a modular structural design.

By increasing or reducing the number of separation boxes and magnetic plates, the equipment capacity can be flexibly adjusted according to different production requirements.

It can meet the needs of:

• Small-scale beneficiation plants;
• Medium-sized processing facilities;
• Large industrial iron ore projects.

4. Industrial Test and Performance Evaluation

To verify the upgrading performance of the Permanent Magnet Combined Box Magnetic Separator, a three-stage magnetic separation concentrate from the Jiajiabao Iron Mine of Benxi Iron & Steel Group was selected as the test material.

The characteristics of the test sample were:

• Particle size below 75 μm: 96.50%;
• Original TFe grade: 62.83%.

After upgrading treatment under optimized operating conditions, the equipment achieved the following results:

The test results demonstrate that the Permanent Magnet Combined Box Magnetic Separator can significantly improve iron concentrate grade while maintaining a high recovery rate.

This confirms its effectiveness for fine-grained magnetite beneficiation and shows strong potential for industrial application.

5. Application Prospects

With global iron ore resources becoming increasingly characterized by:

• Low grade;
• Fine dissemination;
• Complex mineral composition;

improving the utilization efficiency of fine-grained iron resources has become a major challenge for the mining industry.

The Permanent Magnet Combined Box Magnetic Separator provides a new solution for fine magnetite upgrading through innovative oscillating magnetic technology and composite magnetic field separation.

Potential applications include:

• Magnetite concentrate upgrading;
• Iron ore tailings recovery;
• Fine particle iron recovery;
• Comprehensive utilization of low-grade iron resources.

Conclusion

The Permanent Magnet Combined Box Magnetic Separator creates a dynamic composite magnetic field through an innovative oscillating magnetic system, enabling efficient recovery and upgrading of fine-grained magnetite.

Industrial test results demonstrate that the equipment has significant advantages in:

• Improving iron concentrate grade;
• Maintaining high recovery rates;
• Reducing energy consumption;
• Enhancing resource utilization efficiency.

As a professional mineral processing equipment manufacturer, Guote Intelligent Equipment continues to develop advanced magnetic separation technologies and provide efficient, energy-saving, and intelligent mineral processing solutions for global mining customers.

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