NdFeB Powder Oxidation via Magnetization and Spontaneous Combustion
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Solution Overview
Problem
Current oxidizing roasting processes for recycling NdFeB magnets are hazardous due to the risk of metal fire and explosion, with slow oxidation rates and high energy consumption, and existing methods fail to ensure safe and efficient conversion of NdFeB powder to metal oxides.
Innovation Solution
A three-stage process involving magnetization, drying, and high-temperature oxidation of NdFeB powder material, where the powder is first magnetized and dried to prevent dust formation, then heated to spontaneous combustion, and finally oxidized at high temperatures to achieve complete oxidation while minimizing risks of fire and explosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rotary kiln is used for oxidizing roasting NdFeB powder material, then the material can be fully in contact with air during roasting, but the oxidation reaction rate is slow and energy consumption is high
Solution Approach 1:
The patent changes the physical state parameter of NdFeB powder by magnetizing it to form a radial arrangement, which fundamentally alters how the material interacts with air during roasting. This parameter change enables rapid oxidation without requiring prolonged heating times, thus improving both oxidation completeness and reaction rate simultaneously
Solution Approach 2:
The patent applies preliminary magnetization treatment to the NdFeB powder before roasting. This preliminary action creates a radial structure that facilitates better air contact and heat distribution during the subsequent roasting process, eliminating the need for slow, prolonged heating in traditional rotary kilns
2Productivity
If rotary kiln is used for oxidizing roasting NdFeB powder material, then the material can be processed continuously, but dust is raised in a confined space presenting fire and explosion risk
Solution Approach 1:
The patent converts the harmful property of NdFeB powder (prone to spontaneous combustion and dust explosion) into a beneficial feature by utilizing its magnetic properties. The magnetized radial arrangement controls dust behavior and prevents explosive dispersion while maintaining continuous processing capability
Solution Approach 2:
The patent introduces magnetic field as an intermediary to control the behavior of NdFeB powder during processing. This intermediary field organizes the powder into a radial structure that prevents dangerous dust cloud formation while allowing continuous operation
3Productivity
If NdFeB powder is heated to spontaneous combustion for oxidation, then oxidation efficiency is improved, but the risk of metal fire and explosion increases
Solution Approach 1:
The patent applies preliminary magnetization to NdFeB powder before heating, which creates a radial structure that controls the spontaneous combustion process. This preliminary action ensures that when spontaneous combustion occurs, it follows a controlled pattern that maintains high oxidation efficiency while preventing uncontrolled fire and explosion hazards
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method significantly reduces the risk of metal fire and explosion, enhances oxidation efficiency, and lowers energy consumption by controlling the spontaneous combustion process and ensuring complete oxidation of NdFeB powder to metal oxides, thereby facilitating safer and more efficient recycling of rare earth elements.
Implementation Method 1
heating the magnetized and dried NdFeB powder material to spontaneous combustion
Implementation Method 2
The NdFeB powder material has a spontaneous combustion temperature of about 150° C. and a lower explosive limit of 20-30 g/m3
Implementation Method 3
the magnetized NdFeB is in a radial form, which can realize rapid drying of the NdFeB powder material, and powder particles magnetically attract each other
Implementation Method 4
the high temperature generated during the spontaneous combustion process promotes edge cohesion between the powder particles
Data Source
AI summary
A method for safely oxidising roasting NdFeB powder material. The method may include: S1: magnetizing and drying the NdFeB powder material; S2: heating the magnetized and dried NdFeB powder material to spontaneous combustion, and then preparing the spontaneous combustion product into a powder; and S3: magnetizing and then oxidising roasting the powder to obtain NdFeB oxide.