Mill Drum Filling Level Detection via Drive Torque Analysis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for determining the filling level in a rotating drum of a mill, such as ball or SAG mills, are inaccurate and require additional sensors, making it difficult to optimize mill operation efficiently.
Innovation Solution
A method involving a drive torque test sequence that sets the drum into rotational movement, analyzes the temporal speed characteristic, and determines the filling level using inertia torque measurements, allowing for accurate and automated filling level determination without additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods (weight sensors, acoustic sensors, rotating vane, pendulum, vibration measuring) are used to determine filling level, then measurement capability is provided, but device complexity increases and/or measurement precision remains insufficient for rotating mill drums
Solution Approach 1:
The existing drive system serves dual purposes: it both drives the mill drum and acts as the measurement system for determining filling level. The drive torque and speed measurements already available for process control are reused to calculate inertia torque and determine filling level, eliminating the need for separate measurement sensors and reducing system complexity.
Solution Approach 2:
The drive system is made multi-functional by using it both for its primary function (driving the mill drum) and for measurement (determining filling level through inertia torque calculation). This universal use of the drive system resolves the contradiction by providing measurement capability without adding dedicated measurement devices.
2Device complexity
If empirical estimation by operating staff is used, then no additional sensors are required, but measurement precision and reliability are very inaccurate
Solution Approach 1:
The method uses feedback from the drive system's own measurements (torque and speed) to continuously determine filling level. By monitoring the relationship between drive torque, drum speed, and acceleration, the system provides continuous quantitative feedback on filling level without requiring external sensors or subjective estimation.
Solution Approach 2:
The patent replaces subjective human estimation with an automated calculation based on mechanical measurements. The filling level is determined through mathematical calculation of inertia torque from measured drive parameters, substituting empirical judgment with objective mechanical measurement and computation.
3Measurement precision
If additional sensors are installed for measurement, then measurement capability is improved, but ease of operation and device simplicity deteriorate
Solution Approach 1:
The drive system performs self-measurement by using its own operational parameters (torque and speed) to determine filling level. This self-service approach eliminates the need for external measurement sensors and maintains operational simplicity while providing accurate measurement through automated calculation.
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 method provides a more accurate and automated way to determine the filling level, improving mill operation efficiency by enabling precise control of the drum speed and preventing overfilling or underfilling, thus reducing energy consumption and extending equipment lifespan.
Implementation Method 1
applying to the drum a drive torque by a drive that sets the drum into a rotational movement
Implementation Method 2
a speed frequency signal that is tested in particular with regard to the frequency components involved can be generated from the acquired temporal speed characteristic by means of a Fourier transformation during the analysis of the speed characteristic
Implementation Method 3
an inertia torque of the loaded and driven drum is determined during analysis of the speed characteristic
Data Source
AI summary
The method is used to determine the filling level of a loaded mill container (2). The container (2) has a drive torque (M) applied to it by means of a drive (6), and causes it to rotate. The drive torque (M) on the drive (6) is set by means of a predeterminable drive test sequence. A time/rotation speed profile of a rotation speed of the container (2) which results from the drive test sequence is recorded, and is analyzed. The filling level is determined on the basis of the results of the analysis. The method produces up to date, accurate information, determined during the milling operation, about the filling level of the container (2).