Agitator Ball Mill Ceramic Lining Heat Dissipation

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Solution Overview

Problem

Agitator mills face challenges in achieving high power input during grinding without overheating the material and ensuring uniform grinding results, particularly in larger volumes or high power inputs, where cooling is insufficient and grinding aids may not mix adequately with the product.

Innovation Solution

The agitator mill features a one-piece ceramic container tube with specific cam geometry and material selection, such as silicon carbide, to enhance heat dissipation and stability, reducing the risk of cam breakage and improving mixing efficiency by optimizing cam dimensions and arrangement within the grinding container.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the grinding container is made with ceramic material for abrasion resistance and chemical inertness, then the durability and chemical stability are improved, but the heat dissipation capability deteriorates due to ceramic's lower thermal conductivity compared to metal

Engineering Contradiction:
Improvedurability and chemical stabilityVSAvoidheat dissipation capability
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The grinding container is segmented into a metal outer shell and a ceramic inner lining, allowing each material to perform its optimal function: metal for heat dissipation and ceramic for abrasion resistance and chemical inertness

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The grinding container uses a composite structure combining metal and ceramic materials, leveraging the thermal conductivity of metal and the wear resistance and chemical stability of ceramic to achieve both heat dissipation and durability

Inventive Principle:
Principle #40Composite materials

2Productivity

If high power input is applied during grinding to increase productivity, then the comminution efficiency is improved, but the material temperature increases excessively causing overheating

Engineering Contradiction:
Improvecomminution efficiencyVSAvoidmaterial temperature
Core Design Contradiction:
ProductivityVSTemperature

Solution Approach 1:

A cooling intermediary system is introduced between the grinding zone and the environment, using cooling channels and cooling media to actively remove heat generated during high-power grinding operations

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The cooling system utilizes phase transitions of cooling media (such as liquid to vapor) to absorb and remove excessive heat from the grinding zone, maintaining material temperature within acceptable limits during high-power operation

Inventive Principle:
Principle #36Phase transitions

3Productivity

If the grinding gap is largely filled with grinding aids to increase comminution effect, then the grinding efficiency is improved, but the mixing between grinding aids and product becomes insufficient leading to inadequate grinding results

Engineering Contradiction:
Improvegrinding efficiencyVSAvoidgrinding result uniformity
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The grinding container and rotor are designed with dynamic geometric features such as variable gap widths and optimized cam profiles that promote continuous movement and redistribution of grinding aids, ensuring uniform mixing and contact with the product throughout the grinding process

Inventive Principle:
Principle #15Dynamics

4Strength

If ceramic material is used for the grinding container to ensure abrasion resistance, then the wear resistance is improved, but the sensitivity to thermal shock and temperature-related stresses increases

Engineering Contradiction:
Improvewear resistanceVSAvoidresistance to thermal shock
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The grinding container is segmented into a metal outer shell with high thermal conductivity for heat dissipation and a ceramic inner lining for wear resistance, isolating the ceramic from direct thermal shock while maintaining its mechanical benefits

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The composite structure combines metal and ceramic materials, where the metal shell acts as a thermal buffer protecting the ceramic lining from thermal shock and temperature-related stresses while the ceramic provides abrasion resistance

Inventive Principle:
Principle #40Composite materials

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

This configuration allows for effective cooling and reproducibly good grinding results by minimizing temperature-related stresses and improving the interaction between grinding aids and material, leading to enhanced comminution performance.

Implementation Method 1

the large base dissipates heat more effectively into the grinding container

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

high thermal conductivity, good resistance to acids and alkalis and are also light and retain their positive properties up to temperatures well above 1000°C

Methodology Applied
Scientific EffectThermal conductivity: Conduction (thermal)

Implementation Method 3

low sensitivity to thermal shock

Methodology Applied
Scientific EffectThermal shock resistance: Thermal Shock

Data Source

PatentEP3357580B2Agitator ball mill with ceramic lining
Publication Date: 2022.11.02 NETZSCH FEINMAHL TECHNIK GMBH
  • EP3357580B2 patent drawingFigure 1
  • EP3357580B2 patent drawingFigure 2
  • EP3357580B2 patent drawingFigure 3

AI summary

The invention relates to a stirred ball mill (10) comprising: - a grinding container (12) whose inner surface (28) is made of a ceramic material, wherein the grinding container (12) extends along an axis (X) and has an inner diameter (d); - a rotor (20) arranged inside the grinding container (12) and rotatable about the axis (X), with a surface (30) facing the inner surface of the grinding container (12), wherein a grinding gap (32) with a grinding gap width (MS) is formed between the surface (30) of the rotor (20) and the inner surface of the grinding container (12); - several cams (34) which are attached to the inner surface (28) of the grinding container (12) and extend radially inwards from the inner surface of the grinding container with a height (h) normal to the inner surface of the grinding container.According to the invention, - the inside of the grinding container (12) is formed by a one-piece container tube (14) made of ceramic material, - the ratio of the height (h) of each cam (34) and the inner diameter (d) of the grinding container (12) is ≤ 0.05, and - the ratio of the height (h) of each cam (34) and the grinding gap width (MS) is ≤ 0.35.