Heterogeneous Matrix Grinding Using Impact Stops and Material Accumulation
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Solution Overview
Problem
Existing grinding technologies are inefficient and costly for heterogeneous mixtures of fragile and plastic materials, failing to achieve fine particle sizes below 1 mm with high productivity, low energy consumption, and minimal tool wear.
Innovation Solution
A grinding process utilizing a cylindrical drum with actuator means and stop means, where kinetic energy is applied through flexible elements to impact materials against fixed stops, avoiding shear and excessive stress, allowing for efficient grinding of heterogeneous mixtures with low energy consumption and reduced tool wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If impact mills are used for fragile materials, then breaking efficiency is improved, but plastic materials are not ground effectively and cause blockage
Solution Approach 1:
The grinding process is segmented into multiple stages with different mechanisms: initial impact breaking for fragile materials, followed by shear grinding between closely spaced rotors for plastic materials. This segmentation allows each stage to optimize for its specific material type without causing blockage or inefficiency.
Solution Approach 2:
A screen or classifier acts as an intermediary between the impact breaking stage and the shear grinding stage, separating materials by size and directing them to appropriate processing zones. This ensures that plastic materials are properly prepared for shear grinding and prevents blockage.
2Productivity
If blade mills are used for plastic materials, then grinding efficiency is improved, but fragile materials cause rapid tool wear
Solution Approach 1:
The mill is segmented into distinct zones: an impact breaking zone for fragile materials using robust hammers or impactors, and a shear grinding zone for plastic materials using closely spaced rotors with blades. This segmentation protects the blade mill components from excessive wear by fragile materials while maintaining high grinding efficiency for plastics.
Solution Approach 2:
Fragile materials undergo preliminary impact breaking before entering the shear grinding zone. This preliminary action reduces them to smaller, less abrasive particles that will not rapidly wear the blades during the subsequent shear grinding process.
3Manufacturing precision
If high shear stress is applied to plastic materials, then particle size reduction is improved, but fragile materials deteriorate rapidly
Solution Approach 1:
The processing sequence is segmented to apply impact stress first for size reduction, then shear stress for final particle size control. This segmentation allows fragile materials to be broken without excessive shear that would cause deterioration, while plastic materials receive the necessary shear for precise particle size control.
Solution Approach 2:
The mill operates with dynamically adjusted parameters: high impact energy for initial breaking, then controlled shear stress in the second stage. The rotor speed and clearance are optimized to provide sufficient shear for plastic materials while the preliminary impact stage has already reduced fragile materials to less susceptible sizes.
4Speed
If impact energy is increased for fragile materials, then breaking speed is improved, but plastic materials undergo excessive heating
Solution Approach 1:
The energy application is segmented: high impact energy is applied only in the first stage for fragile material breaking, where rapid breaking is needed. The second stage uses lower energy shear grinding for plastic materials, where excessive heating would be harmful. This segmentation controls temperature rise while maintaining breaking speed.
Solution Approach 2:
The mill operates continuously with material flowing through both stages without interruption. The preliminary impact stage quickly breaks fragile materials, and the continuous flow through the shear grinding stage completes the size reduction without allowing excessive heat buildup, as the process is efficient and uninterrupted.
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
Achieves high productivity (2.0-3.5 tons/hour per cubic meter) and low energy consumption (40-80 kWh/ton) for grinding materials to an average particle size of 1 mm, with reduced maintenance costs and improved material handling efficiency.
Implementation Method 1
applying by means of suitable moving actuator means kinetic energy to said heterogeneous matrix by projecting the materials of the matrix at high speed against suitable fixed stop means
Implementation Method 2
grinding under the effect of impacts occurring between the material projected by the actuator means and the material accumulated on said stop means
Data Source
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AI summary
Process for grinding heterogeneous matrices comprising fragile materials and plastic materials, comprising the steps of: (i) introducing in a mill or similar device a heterogeneous matrix comprising plastic materials and fragile materials of variable dimension; (ii) applying, by suitable moving actuator means, kinetic energy to said heterogeneous matrix, by projecting the materials of the matrix at high speed against suitable fixed stop means provided on said mill; (ill) proceeding to grinding under the effect of impacts occurring between the material projected by the actuator means and the material accumulated on said stop means; (iv) discharging the portion of processed material reduced under a prefixed maximum diameter, characterized in that said stop means are configured so that they can hold removably the material projected against the same in an outer region with respect to the volume interested by the movement of said actuator means.