Low Pressure Jet Mill Grinding Method
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Solution Overview
Problem
Existing grinding methods, such as jet mills and mechanical mills, are energy-intensive and lead to contamination of ground materials due to high abrasion, and cannot efficiently produce particles with desired particle size distribution and surface modification simultaneously.
Innovation Solution
A method using a jet mill with compressed gases at pressures ≤4 bar and temperatures <100°C, allowing for simultaneous grinding and surface modification of materials, reducing energy consumption and contamination, and enabling the production of particles with improved particle size distribution and coating retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If jet mills or mechanical mills are used for grinding, then fine particles can be produced, but energy consumption is high and equipment complexity increases
Solution Approach 1:
The patent replaces mechanical grinding systems (rotor/stator mills) with a jet mill system that uses compressed gas jets to accelerate particles for collision-based grinding. This substitution eliminates direct mechanical contact between grinding components and material, reducing energy consumption while achieving fine particle sizes through pneumatic rather than mechanical means
Solution Approach 2:
The invention uses compressed gas (pneumatics) as the grinding medium, where high-velocity gas jets accelerate particles to create impact and attrition grinding. This pneumatic approach consumes less energy than mechanical mills while producing the desired fine particle size distribution
2Productivity
If mechanical mills with rotor/stator are used, then grinding efficiency is high, but material contamination increases due to high abrasion
Solution Approach 1:
The patent replaces direct mechanical contact grinding (rotor/stator) with pneumatic jet grinding where particles are accelerated by gas jets and collide with each other. This eliminates the mechanical abrasion that causes contamination from rotor/stator surfaces while maintaining high grinding efficiency through particle-on-particle impact
Solution Approach 2:
The compressed gas acts as an intermediary medium that transfers energy to particles for grinding without the grinding components directly contacting the material. This intermediary approach prevents contamination from mill surfaces while maintaining efficient grinding through the mediating gas flow
3Power
If high pressure and temperature are used in jet milling, then grinding effectiveness improves, but equipment requirements and energy consumption increase
Solution Approach 1:
The patent optimizes the operating parameters by using moderate compressed gas pressure (not excessively high) and ambient or mildly heated temperature conditions. This parameter optimization achieves effective grinding without requiring complex high-pressure vessels or temperature control systems, reducing equipment complexity while maintaining grinding effectiveness
4Manufacturing precision
If surface modification is performed separately after grinding, then coating quality improves, but process time and energy consumption increase
Solution Approach 1:
The patent combines the grinding and surface modification operations into a single integrated process. Surface modification agents are introduced into the jet mill during the grinding operation, allowing simultaneous particle size reduction and surface coating. This merging of operations reduces total process time and energy consumption while maintaining coating quality through the controlled environment of the jet mill
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 achieves energy-efficient grinding with reduced contamination and improved particle size distribution, enabling the production of high-purity particles with effective surface modification, including temperature-sensitive materials, and reduces equipment and maintenance costs.
Implementation Method 1
at least one high-energy grinding jet made of superheated steam with high flow energy is also introduced
Implementation Method 2
grinding jet made of superheated steam with high flow energy
Implementation Method 3
The coarser particles are separated from the air flow in the classifying wheel
Implementation Method 4
a filter in which a fluid, such as air, and fine particles are separated from one another
Data Source
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AI summary
The method involves milling a material in a jet mill (1) e.g. oval tube mill, spiral jet mill, fluidized-bed opposed-jet mill and dense-bed jet mill, where temperature of the mill is less than 100 degree Celsius and pressure of an operating medium is less than or equal to 4 bar. Constant amount of milled powder passes through a surface area of a classifying rotor (8) of a dynamic air classifier (7) of the jet mill during milling. A coating agent or a doping agent is added to the material during milling. The medium is selected from the group consisting of air, argon, helium, and nitrogen. An independent claim is also included for a jet mill comprising a blower.