Mill Load Toe Angle Measurement via Power Oscillation Frequency Analysis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for controlling autogenous and semi-autogenous grinding processes are challenging due to sensitivity to changing parameters, and existing methods for measuring the degree of fullness in a mill are unreliable, especially when rotation velocity is not constant, leading to inaccurate power draw measurements.
Innovation Solution
A method using frequency domain analysis of oscillations in the mill power draw or torque, independent of rotation velocity, which compensates for speed fluctuations by collecting power and rotation angle samples at a constant interval, allowing for precise calculation of the toe angle and degree of fullness through Fourier transformation and interpolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional power draw measurement is used to control grinding, then control is simple, but measurement precision deteriorates due to sensitivity to changing parameters and non-constant rotation velocity
Solution Approach 1:
The patent replaces direct mechanical power draw measurement with frequency domain analysis of oscillations. By analyzing the frequency characteristics of power oscillations rather than relying on raw power draw values, the system achieves more stable and accurate measurements that are independent of rotation velocity variations, thus resolving the contradiction between operational simplicity and measurement precision.
Solution Approach 2:
The patent transforms the measurement approach by changing from time-domain power draw values to frequency-domain characteristics. This parameter transformation allows the system to extract stable degree of fullness information from oscillation frequencies that remain consistent even when rotation velocity varies, thereby improving measurement precision while maintaining control simplicity.
2Ease of manufacture
If mass measurement is used to determine degree of fullness, then installation is simple, but reliability deteriorates due to measurement drift and sensitivity to load density variations
Solution Approach 1:
The patent replaces mass measurement systems with frequency domain analysis of power oscillations. This substitution eliminates the issues of measurement drift and load density sensitivity by using oscillation frequency characteristics that directly reflect the degree of fullness in a reliable and stable manner, while maintaining installation simplicity.
Solution Approach 2:
The patent introduces frequency domain analysis as an intermediary between the physical state of the mill and the measurement system. By analyzing the frequency characteristics of power oscillations, the system obtains a stable and reliable indicator of degree of fullness that is not directly affected by mass measurement limitations or load density variations.
3Measurement precision
If frequency domain analysis is applied to power oscillation, then measurement precision improves for degree of fullness, but device complexity increases due to signal processing requirements
Solution Approach 1:
The patent applies frequency domain analysis selectively to the power oscillation signal rather than requiring complex comprehensive signal processing. By focusing the analysis on the specific frequency characteristics related to lifter bar impacts, the system achieves high measurement precision for degree of fullness while keeping the overall device complexity manageable through targeted signal processing.
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 approach provides a stable and descriptive measurement of the mill's state, enabling more accurate control of the grinding process and optimization of the mill's operation by determining the toe angle and degree of fullness, thus improving grinding efficiency and avoiding overload situations.
Implementation Method 1
the oscillation occurring in the mill power draw or torque... created as the mill lifter bars hit the load contained in the mill
Implementation Method 2
frequency domain analysis of the oscillation... By means of a frequency domain analysis of the oscillation, the oscillation phase can be calculated
Data Source
AI summary
The invention relates to a method for defining the degree of fullness in a mill and the load toe angle (φk), where there are used oscillations directed to the mill electric motor, in order to define the toe of the mill load composed of the mass to be ground. According to the invention, from the obtained measurements (P(n)) related to the mill draw or torque, there is defined the phase (θ) of the mill oscillation by using a frequency domain analysis, and that by means of the mill oscillation phase (θ), there is defined the load toe angle (φk).