Dynamic Element for Ball Mill Separation

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Solution Overview

Problem

Existing agitator ball mills face challenges in preventing the discharge of auxiliary grinding bodies, which affects the efficiency and consistency of the grinding process.

Innovation Solution

A separating unit comprising a dynamic element with radially extending channels or vanes, arranged between the separating device and the end part of the grinding container, generates a material flow that prevents auxiliary grinding bodies from being discharged, utilizing a conical active surface with adjustable distance and angle to optimize the separation process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a separating device is used to prevent discharge of auxiliary grinding bodies, then the reliability of the grinding process is improved, but the device complexity increases due to the additional separating unit

Engineering Contradiction:
Improveprevention of auxiliary grinding body dischargeVSAvoidseparating unit structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies the dynamics principle by introducing a dynamic element that rotates together with the agitator shaft. This dynamic element generates a material flow that actively transports ground material and auxiliary grinding bodies away from the separating device outlet, preventing discharge while integrating with the existing agitator system. The rotating dynamic element creates centrifugal forces and material circulation that dynamically control the separation process without requiring complex stationary structures.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent merges the separating function with the existing agitator system by coupling the dynamic element to the agitator shaft. The separating device is positioned within the grinding container and works in conjunction with the agitator's rotational motion. This integration allows the separating function to be achieved without adding an entirely independent system, reducing overall device complexity while maintaining reliability.

Inventive Principle:
Principle #5Merging (Combining)

2Volume of moving object

If the separating device is positioned close to the grinding container end part, then the volume of the separating unit is reduced, but the manufacturing precision required increases to ensure proper gap clearance

Engineering Contradiction:
Improveseparating unit volumeVSAvoidgap clearance between dynamic element and end part
Core Design Contradiction:
Volume of moving objectVSManufacturing precision

Solution Approach 1:

The dynamic element rotates with the agitator shaft, creating dynamic material flow that compensates for small variations in gap clearance. The rotational motion generates centrifugal forces and material circulation patterns that ensure consistent separation performance even with minor manufacturing tolerances in the gap dimension.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent specifies a controlled gap distance range (0.5 mm to 30 mm) between the dynamic element and the grinding container end part, allowing flexibility in manufacturing while maintaining functional effectiveness. This parameter range accommodates normal manufacturing tolerances without requiring ultra-precise fabrication, balancing volume reduction with manufacturability.

Inventive Principle:
Principle #35Parameter changes

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 dynamic element's material flow circulation ensures that auxiliary grinding bodies are retained within the grinding container, enhancing the grinding process efficiency by maintaining a consistent distribution of grinding media and preventing their discharge, adaptable to different sizes and types of grinding aids.

Implementation Method 1

During operation of the separating device, the wing elements generate a counter-pressure on the mixture of good and grinding media, so that due to the centrifugal force and the different specific density, the grinding media are separated from the product and transported back into the interior

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 2

The stirring elements are designed and dimensioned in such a way that during operation of the agitator ball mill, part of the mixture continuously flows back radially inwards to the central opening over the edge of the disk having the central opening. From there, the mixture flows back into the space between the discs. This maintains an even axial distribution of the grinding media inside the grinding chamber

Methodology Applied
Scientific EffectMaterial flow circulation: Convection

Data Source

PatentEP2646160B1Dynamic element for the separating device of a stirring ball mill
Publication Date: 2016.02.03 NETZSCH FEINMAHL TECHNIK GMBH
  • EP2646160B1 patent drawingFigure 1
  • EP2646160B1 patent drawingFigure 2
  • EP2646160B1 patent drawingFigure 3a

AI summary

The invention relates to a stirring ball mill (20) having a cylindrical milling container (22). The milling container (22) has at least one inlet for material to be ground (24) and at least one outlet for material to be ground (26). A stirring shaft (22) connected to a drive is arranged in the milling container (28). The stirring shaft (28) transmits part of the drive energy of the drive to the milling aid elements. The milling aid elements are loosely distributed in the milling container (22). Furthermore, the stirring ball mill (20) has a separating device (30) associated with the outlet for material to be ground, wherein the separating device (30) is arranged about a rotational axis and/or rotates about said rotational axis. The separating device (30)comprises at least two components, of which one component is at least one separating device (31) and a second component is a dynamic element (32) for creating a material flow.