S-L. Jämsä-Jounela

State of the art and challenges in mineral processing control

Abstract The objective of process control in the mineral industry is to optimise the recovery of the valuable minerals, while maintaining the quality of the concentrates delivered to the metal extraction plants. The paper presents a survey of the control approaches for ore size reduction and mineral separation processes. The present limitations of the measurement instrumentation are discussed, as well as the methods to upgrade the information delivered by the sensors. In practice, the overall economic optimisation goal must be hierarchically decomposed into simpler control problems. Model-based and AI methods are reviewed, mainly for grinding and flotation processes, and classified as mature, active or emerging.

Industrial applications of the intelligent fault diagnosis system

Process monitoring and fault diagnosis have been widely studied in recent years, and a large number of industrial applications are reviewed. For further improvement of the reliability and safety of the process and the process equipment, the automatic early detection and localisation of faults is of high interest. This paper presents an intelligent process fault diagnosis system. The system is capable of detecting faults of the process and equipment. The process monitoring is performed using Kohonen self-organizing maps and the analysis of the equipment failures are integrated to the system. The structure of the integrated system is described and its performance is illustrated by case studies.

Using principal component analysis and self-organizing map to estimate the physical quality of cathode copper

Abstract The growing interest in utilising multivariable statistical dimension reduction techniques, PCA and PLS, and neural networks in process monitoring and analysis has resulted in a number of successful industrial applications. This paper describes a process study on the effects of the chemical quality of the anodes on the physical quality of produced cathodes at a copper electrorefining plant through PCA, SOM and a combination of these two techniques. The clustering of anode analysis data over time was compared with the physical quality data of the cathodes.

USE OF UPPER BOUND DELAY ESTIMATE IN STABILITY ANALYSIS AND ROBUST CONTROL COMPENSATION IN NETWORKED CONTROL SYSTEMS

Abstract Recent interest in networked control systems (NCS) has instigated research in various areas of both communication networks and control. The analysis of NCS has often been performed either from the network, or the control point of view and not many papers exist were the analysis of both is done in the same context. Here an overall analysis is presented. In the paper the procedure of obtaining the upper bound delay value in the switched Ethernet network is proposed and the obtained delay estimate is used in stability analysis of the feedback loop and in the control compensation. The upper bound delay algorithm is based on the network calculus theory, the stability analysis uses the small gain theorem, and control compensating strategy is based on Smith predictor, where however the upper bound delay is utilised in obtaining the delay estimate.

Operation Cycle Optimisation of the Larox Pressure Filter

Abstract Artificial intelligence methods such as expert systems, fuzzy systems, neural networks and combinations of these, have become invaluable tools in helping operators to monitor and control processes. These methods can also be used to run processes in a more economically effective way and, in the case of equipment malfunction, they can propose appropriate corrective measures. In this paper a system for operation cycle optimisation of the Larox pressure filter is presented and some test results are discussed.

A TOOLBOX FOR ON-LINE PROCESS MONITORING WITH SOME INDUSTRIAL APPLICATIONS

Abstract On-line process monitoring with fault detection can provide stability and efficiency for a wide range of processes. A toolbox for on-line monitoring using Kohonen self-organizing maps (SOM), in conjunction with heuristic rules is described in this paper. Four different industrial applications using the toolbox are presented and discussed at the end of the paper.

Level control strategies for flotation cells

Abstract Flotation is a difficult process to run efficiently. One way to make flotation performance better is to improve cell level control. However, controlling pulp levels in flotation cells is a complex control task because of strong interactions between the levels in flotation cells. Therefore advanced controllers are needed to give good level control. This paper deals with a model of six flotation cells in series. Simulations are performed to compare different control strategies. Four control strategies are considered: one SISO controller and three different MIMO controllers. It is shown that level control performances of the MIMO controllers are significantly better than that of the classical SISO controller.

Control of Pulp Levels in Flotation Cells

Abstract The control of pulp levels in flotation cells is a complex control task because many different aspects such as cell structure and valve sizing, and their effects on control, have to be taken into account. Control becomes more and more difficult as the complexity of the cell configurations and the number of cells used in a configuration increase. In this paper the mathematical model of a flotation cell is first developed and several configurations of cells are constructed. Simulations are then performed in order to determine suitable control parameters for PI and feed-forward controllers of the cell levels. Finally, the effects of valve sizing and cell structure are presented and discussed.

Evaluation of Future Automation Trends in Control and Fault Diagnostics of a Flotation Plant

Abstract Industrial automation has recently been rapidly adopting new technologies. After being under development for over 20 years, fieldbusses for process automation are finally ready to be applied in practice. The impact of information technologies can also be seen in industrial fields. These new technologies are highly promising, and their utilisation in practice is worth investigating. Modern field devices offer a wide range of information in addition to single process values. The utilisation of this information for device-fault diagnostics in a flotation plant is discussed in this paper.

Transient Studies of Adsorption Kinetics

1.Abstract This paper deals with the adsorption of hydrogen on nickel. The kinetic parameters of a Langmuir-type adsorption model were estimated based on hydrogen pulse experiments conducted under isothermal conditions at several temperatures.