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There is a need within the production industry for digitalization and the development of meaningful functionality for production operation. One such industry is aggregate production, characterized by continuous production operation, where the digital transformation can bring operational adaptability to customer demand. Dynamic process simulations have the ability to capture the change in production performance of aggregate production over time. However, there is a need to develop cost-efficient methodologies to integrate calibrations and validation of models. This paper presents a method of integrating an experimental and data-driven approach for calibration and validation for crushing plant equipment and a process model. The method uses an error minimization optimization formulation to calibrate the equipment models, followed by the validation of the process model. The paper discusses various details such as experimental calibration procedure, applied error functions, optimization problem formulation, and the future development needed to completely realize the procedure for industrial use. The validated simulation model can be used for performing process planning and process optimization activities for the crushing plant’s operation.
Kanishk Bhadani; Gauti Asbjörnsson; Barbara Schnitzer; Johannes Quist; Christian Hansson; Erik Hulthén; Magnus Evertsson. Applied Calibration and Validation Method of Dynamic Process Simulation for Crushing Plants. Minerals 2021, 11, 921 .
AMA StyleKanishk Bhadani, Gauti Asbjörnsson, Barbara Schnitzer, Johannes Quist, Christian Hansson, Erik Hulthén, Magnus Evertsson. Applied Calibration and Validation Method of Dynamic Process Simulation for Crushing Plants. Minerals. 2021; 11 (9):921.
Chicago/Turabian StyleKanishk Bhadani; Gauti Asbjörnsson; Barbara Schnitzer; Johannes Quist; Christian Hansson; Erik Hulthén; Magnus Evertsson. 2021. "Applied Calibration and Validation Method of Dynamic Process Simulation for Crushing Plants." Minerals 11, no. 9: 921.
This paper has two aims: to describe the current status and challenges of aggregates producers regarding the analysis and communication of environmental information of their products and to present a layout of a pre-verified tool with simulation capabilities that could assist aggregates producers with their environmental goals. Semi-structured interviews were conducted with three Swedish aggregates producers, an aggregates customer, and an expert agency. Additionally, published Environmental Product Declarations (EPDs) for aggregates and the EN 15804:2012 + A2:2019 were studied to reveal current practices and upcoming changes due to the updated standard. The synergies with process simulations were explored as a step towards using the EPD framework for continuous improvement of aggregates production. The interviews indicated that the main challenge for aggregates producers is the lack of easily available plant data for environmental calculations and clearly defined environmental goals at each plant. The proposed tool uses a common process flowsheet for both EPDs and simulations and has a pre-defined LCA module. The use of such a tool is expected to raise the environmental interest at aggregates plants and improve collaboration with LCA experts. Since the analysis is based on the Swedish aggregates market, the interview results are not directly generalizable to the European context.
Panagiota Papadopoulou; Diego Peñaloza; Gauti Asbjörnsson; Erik Hulthén; Magnus Evertsson. Development of a Pre-Verified EPD Tool with Process Simulation Capabilities for the Aggregates Industry. Sustainability 2021, 13, 9492 .
AMA StylePanagiota Papadopoulou, Diego Peñaloza, Gauti Asbjörnsson, Erik Hulthén, Magnus Evertsson. Development of a Pre-Verified EPD Tool with Process Simulation Capabilities for the Aggregates Industry. Sustainability. 2021; 13 (17):9492.
Chicago/Turabian StylePanagiota Papadopoulou; Diego Peñaloza; Gauti Asbjörnsson; Erik Hulthén; Magnus Evertsson. 2021. "Development of a Pre-Verified EPD Tool with Process Simulation Capabilities for the Aggregates Industry." Sustainability 13, no. 17: 9492.
In an aggregate crushing plant, the crusher performances will be affected by the variation from the incoming feed size distribution. Collecting accurate measurements of the size distribution on the conveyors can help both operators and control systems to make the right decisions in order to reduce overall power consumption and avoid undesirable operating conditions. In this work, a particle size distribution estimation method based on a DexiNed edge detection network, followed by the application of contour optimization, is proposed. The proposed framework was carried out in the four main steps. The first step, after image preprocessing, was to utilize a modified DexiNed convolutional neural network to predict the edge map of the rock image. Next, morphological transformation and watershed transformation from the OpenCV library were applied. Then, in the last step, the mass distribution was estimated from the pixel contour area. The accuracy and efficiency of the DexiNed method were demonstrated by comparing it with the ground-truth segmentation. The PSD estimation was validated with the laboratory screened rock samples.
Haijie Li; Gauti Asbjörnsson; Mats Lindqvist. Image Process of Rock Size Distribution Using DexiNed-Based Neural Network. Minerals 2021, 11, 736 .
AMA StyleHaijie Li, Gauti Asbjörnsson, Mats Lindqvist. Image Process of Rock Size Distribution Using DexiNed-Based Neural Network. Minerals. 2021; 11 (7):736.
Chicago/Turabian StyleHaijie Li; Gauti Asbjörnsson; Mats Lindqvist. 2021. "Image Process of Rock Size Distribution Using DexiNed-Based Neural Network." Minerals 11, no. 7: 736.
Process optimization and improvement strategies applied in a crushing plant are coupled with the measurement of such improvements, and one of the indicators for improvements is the mass flow at different parts of the circuit. The estimation of the mass flow using conveyor belt power consumption allows for a cost-effective solution. The principle behind the estimation is that the power draw from a conveyor belt is dependent on the load on the conveyor, conveyor speed, geometrical design, and overall efficiency of the conveyor. Calibration of the power-based belt scale is carried out periodically to ensure the accuracy of the measurement. In practical implementation, certain conveyors are not directly accessible for calibration to the physical measurement as these conveyors have limited access or it is too costly to interrupt the ongoing production process. For addressing this limitation, a better strategy is needed to calibrate the efficiency of the power-based belt scale and maintain the reliability of such a system. This paper presents the application of an optimization method for a data collection system to calibrate and maintain accurate mass flow estimation. This includes calibration of variables such as the efficiency of the power-based belt scale. The optimization method uses an error minimization optimization formulation together with the mass balancing of the crushing plant to determine the efficiency of accessible and non-accessible conveyors. Furthermore, a correlation matrix is developed to monitor and detect deviations in the estimation for the mass flow. The methods are applied and discussed for operational data from a full-scale crushing plant.
Kanishk Bhadani; Gauti Asbjörnsson; Erik Hulthén; Kristoffer Hofling; Magnus Evertsson. Application of Optimization Method for Calibration and Maintenance of Power-Based Belt Scale. Minerals 2021, 11, 412 .
AMA StyleKanishk Bhadani, Gauti Asbjörnsson, Erik Hulthén, Kristoffer Hofling, Magnus Evertsson. Application of Optimization Method for Calibration and Maintenance of Power-Based Belt Scale. Minerals. 2021; 11 (4):412.
Chicago/Turabian StyleKanishk Bhadani; Gauti Asbjörnsson; Erik Hulthén; Kristoffer Hofling; Magnus Evertsson. 2021. "Application of Optimization Method for Calibration and Maintenance of Power-Based Belt Scale." Minerals 11, no. 4: 412.
The worldwide shortage of natural sand has created a need for improved methods to create a replacement product. The use of vertical shaft impact (VSI) crushers is one possible solution, since VSI crushers can create particles with a good aspect ratio and smooth surfaces for use in different applications such as in construction. To evaluate the impact a VSI crusher has on the process performance, a more fit-for-purpose model is needed for process simulations. This paper aims to present a modelling framework to improve particle breakage prediction in VSI crushers. The model is based on the theory of energy-based breakage behavior. Particle collision energy data are extracted from discrete element method (DEM) simulations with particle velocities, i.e., rotor speed, as the input. A selection–breakage approach is then used to create the particle size distribution (PSD). For each site, the model is trained with two datasets for the PSDs at different VSI rotor tip speeds. This allows the model to predict the product output for different rotor tip speeds beyond the experimental configurations. A dataset from 24 different sites in Sweden is used for training and validating the model to showcase the robustness of the model. The model presented in this paper has a low barrier for implementation suitable for trying different speeds at existing sites and can be used as a replacement to a manual testing approach.
Simon Grunditz; Gauti Asbjörnsson; Erik Hulthén; Magnus Evertsson. Fit-for-Purpose VSI Modelling Framework for Process Simulation. Minerals 2020, 11, 40 .
AMA StyleSimon Grunditz, Gauti Asbjörnsson, Erik Hulthén, Magnus Evertsson. Fit-for-Purpose VSI Modelling Framework for Process Simulation. Minerals. 2020; 11 (1):40.
Chicago/Turabian StyleSimon Grunditz; Gauti Asbjörnsson; Erik Hulthén; Magnus Evertsson. 2020. "Fit-for-Purpose VSI Modelling Framework for Process Simulation." Minerals 11, no. 1: 40.
With strengthening focus on digitalization and flexibility, active and flexible fixtures can provide the right tools for manufacturing systems. However, fixturing solutions are often too individualized for processes and need a universal approach. Firstly, a system formulation of multiple workpieces interacting with each other is presented. Secondly, strategies for direct and indirect force control along with their characteristics have been developed. The stability of assembly of force-controlled components has been analyzed, and certain key characteristics have been presented. The position control under different signal types, including oscillatory, have been discussed. Finally, a set of experiments have been conducted for performance evaluation.
Ilker Erdem; Gauti Asbjörnsson; Henrik Kihlman. Workpiece force and position control for active and flexible fixtures in assembly. The International Journal of Advanced Manufacturing Technology 2020, 112, 333 -346.
AMA StyleIlker Erdem, Gauti Asbjörnsson, Henrik Kihlman. Workpiece force and position control for active and flexible fixtures in assembly. The International Journal of Advanced Manufacturing Technology. 2020; 112 (1-2):333-346.
Chicago/Turabian StyleIlker Erdem; Gauti Asbjörnsson; Henrik Kihlman. 2020. "Workpiece force and position control for active and flexible fixtures in assembly." The International Journal of Advanced Manufacturing Technology 112, no. 1-2: 333-346.
Screening is a key operation in a crushing plant that ensures adequate product quality of aggregates in mineral processing. The screening process can be divided into the two sub-processes of stratification and passage. The stratification process is affected by the relative difference between various properties, such as particle shape, size distribution, and material density. The discrete element method (DEM) is a suitable method for analyzing the interactions between individual particles and between particles and a screen deck in a controlled environment. The main benefit of using the DEM for simulating the screening process is that this method enables the tracking of individual particles in the material flow, and all of the collisions between particles and between particles and boundaries. This paper presents how different particle densities and flowrates affect material stratification and, in turn, the screening performance. The results of this study show that higher density particles have a higher probability of passage because of their higher stratification rate, which increases the probability that a particle will contact the screen deck during the process.
Ali Davoodi; Gauti Asbjörnsson; Erik Hulthén; Magnus Evertsson. Application of the Discrete Element Method to Study the Effects of Stream Characteristics on Screening Performance. Minerals 2019, 9, 788 .
AMA StyleAli Davoodi, Gauti Asbjörnsson, Erik Hulthén, Magnus Evertsson. Application of the Discrete Element Method to Study the Effects of Stream Characteristics on Screening Performance. Minerals. 2019; 9 (12):788.
Chicago/Turabian StyleAli Davoodi; Gauti Asbjörnsson; Erik Hulthén; Magnus Evertsson. 2019. "Application of the Discrete Element Method to Study the Effects of Stream Characteristics on Screening Performance." Minerals 9, no. 12: 788.
The performance of a crusher is an essential element in achieving efficient production of aggregates or metals. The process performance depends on the design and configuration of each process equipment, the configuration of the plant, the design of the control and physical properties of the incoming feed. Crushers, however, do not operate in an ideal condition, and as a result, the crusher’ structure, electrical drive and hydraulic system will experience an uneven load during operation. This paper aims to adapt a Hilbert transform to characterise the pressure variations in actual crushers during operation and to set up potential strategies for quantifying the variation. Two applications are also proposed for how this could be used in operation to compensate for the disturbances from unwanted loading conditions that affect the crusher performance.
G. Asbjörnsson; I. Erdem; M. Evertsson. Application of the Hilbert transform for diagnostic and control in crushing. Minerals Engineering 2019, 147, 106086 .
AMA StyleG. Asbjörnsson, I. Erdem, M. Evertsson. Application of the Hilbert transform for diagnostic and control in crushing. Minerals Engineering. 2019; 147 ():106086.
Chicago/Turabian StyleG. Asbjörnsson; I. Erdem; M. Evertsson. 2019. "Application of the Hilbert transform for diagnostic and control in crushing." Minerals Engineering 147, no. : 106086.
This paper presents feedforward control for oscillatory signal tracking using Hilbert transform. The proposed controller utilizes Hilbert transform and analysis techniques to determine the signal's amplitude, frequency, and phase. By using the frequency response of the linear time-invariant process model, an amplified and phase-shifted feedforward signal is reconstructed. The proposed controller also analyzes the system response to determine the differences from the model to modify the feedforward signal. Simulation experiments with multicomponent stationary, amplitude-, and frequency-modulated signals are also conducted. The results show that using an amplified and phase-shifted signal determined by Hilbert analysis can enable an effective tracking performance.
Ilker Erdem; Gauti Asbjörnsson; Henrik Kihlman. Feedforward control for oscillatory signal tracking using Hilbert transform. European Journal of Control 2019, 50, 41 -50.
AMA StyleIlker Erdem, Gauti Asbjörnsson, Henrik Kihlman. Feedforward control for oscillatory signal tracking using Hilbert transform. European Journal of Control. 2019; 50 ():41-50.
Chicago/Turabian StyleIlker Erdem; Gauti Asbjörnsson; Henrik Kihlman. 2019. "Feedforward control for oscillatory signal tracking using Hilbert transform." European Journal of Control 50, no. : 41-50.
Crushing is a harsh process and production units are subjected to wear and failure over time which will reduce the overall performance of the plant. To achieve optimum process performance, both time dependant process dynamics and operating conditions should be taken into account. In this paper the aim is to simulate the process from a more operational perspective to evaluate process performance and process optimum for different operations. The objective is to model and simulate the discrete phenomena that can cause the process to alter performance and implement it with dynamic process simulations. An approach for combining discrete event simulations with time-dependent simulations for process evaluation and optimization is presented. The proposed approach demonstrates a systematic way to evaluate the process performance and locating optimum process configuration, for a given condition. The developed models can be used to optimize different aspects of the operation depending on the defined objective function and the system boundaries. Optimization of process throughput by manipulating configuration of both the grizzly and the crushers, as well as the time between calibrations has been illustrated in this paper. Adjusting the process continuously and calibrating it at the appropriate time can have major benefits when it comes to the process availability and utilization, increasing performance by 4.1–9.3% in these cases. Evaluation of process robustness and availability with regards to process specific factors and variation gave an indication of the process and unit performance under a long operating period. By combining discrete and dynamic simulation, a higher simulation fidelity can be achieved to provide a more operational perspective to the optimization and process analysis.
Gauti Asbjörnsson; Magnus Bengtsson; Erik Hulthén; Magnus Evertsson. Modelling of discrete downtime in continuous crushing operation. Minerals Engineering 2016, 98, 22 -29.
AMA StyleGauti Asbjörnsson, Magnus Bengtsson, Erik Hulthén, Magnus Evertsson. Modelling of discrete downtime in continuous crushing operation. Minerals Engineering. 2016; 98 ():22-29.
Chicago/Turabian StyleGauti Asbjörnsson; Magnus Bengtsson; Erik Hulthén; Magnus Evertsson. 2016. "Modelling of discrete downtime in continuous crushing operation." Minerals Engineering 98, no. : 22-29.