Browsing by Author "Remes, Antti"

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  • Advanced process monitoring and control methods in mineral processing applications
    (2012) Remes, Antti
     School of Electrical Engineering | Doctoral dissertation (article-based)
    In minerals processing the high material volumes yield the fact that benefits of even small improvements in the process efficiency are remarkable. On a daily basis, the efficiency of a concentrating plant relies on the performance of the process control system, and secondly, on the adequate information of the process state provided for the plant operators. This thesis addresses the problems in the monitoring and control of the selected, widely applied mineral concentration unit processes and the processing circuits. The case studies cover operations in the ore grinding stages, including size separation units, followed subsequently by the concentration and the thickening stages in the downstream process. The developed methods and applications are all verified with industrial data, industrially identified models or by the practical implementations and tests on the industrial case plants. Advanced control systems - including a rule-based, a fuzzy and a model predictive control, with different combinations and setups - are studied with simulated grinding and flotation processes. A new model-based expert system for controlling of the ground ore particle size and the circulating load of the grinding process is proposed. The system was tested with a simulation model representing an industrial milling of apatite ore. In a plant-wide process monitoring, a data-based modeling approach is applied to predict the concentrate quality and the impact of the grinding stage parameters on that. The plant model, used for the monitoring, is updated adaptively; this enables timely information on the process. The monitoring system was set up based on the data of a chromite ore processing plant. Two unit operations, a hindered settling separator and a thickener, were modeled from a viewpoint of equipment monitoring and control purposes. The hindered settling separator incorporates both a mechanistic particle-settling model and a separation efficiency characterization curve in a novel manner. Separation characteristics in a pyrite concentrate case and in a ground apatite ore case were studied with the model. Operation of a thickener was modeled based on on-line mass-balance estimation. The monitoring application was implemented in an industrial apatite concentrate thickener. This thesis demonstrates the benefits of the above described monitoring and control methods. The metallurgical performance improvements are pointed out for each case. Also this thesis outlines the practical implementation and robustness issues for the methods. Thus the thesis promotes the advantages of more extensive use of plant models in process operation purposes.
  • Development issues on the life cycle management of mineral grinding processes and equipment
    (2005) Remes, Antti; Suontaka, Ville; Saloheimo, Kari; Jämsä-Jounela, Sirkka-Liisa
     A4 Artikkeli konferenssijulkaisussa
    The requirements set on the performance of industrial equipment during their life-time are increasing due to the growing demand to minimize expenses and maximize production as a result of tightening global competition. The demand to optimize the equipment performance is making the ability to utilize different services during the equipment more important. Equipment performance optimization includes integration of the process and maintenance information. In this paper the life-cycle management concepts are reviewed and a general framework and a case study in the mineral processing field is presented and discussed.
  • Effect of speed and accuracy of on-line elemental analysis on flotation control performance
    (2007) Remes, Antti; Saloheimo, K.; Jämsä-Jounela, Sirkka-Liisa
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    In this paper the control performance of the flotation process is evaluated as a function of the measurement accuracy and sampling frequency of an on-stream analyzer. First, the performance of rule-based control and model predictive control (MPC) strategies is studied using discrete flotation models and the respective performance indices. Next, the net smelter return (NSR) is calculated for varying sampling rate and accuracy combinations using the PI controllers-based control strategy, mechanistic flotation models and the industrial process data as input. The control and economical performance of the process declines strongly when the sampling cycle is increased. The results also indicate that the speed of on-line analysis has a significant effect on the production economics, calculated as the average net smelter return.
  • XRF-analysaattorin tarkkuuden ja näytteenottotaajuuden vaikutus säädön hyvyyteen vaahdotusprosessissa
    (2001) Remes, Antti
     Helsinki University of Technology | Master's thesis
  • INTEGRATED APPROACH TO MONITORING AND CONTROL OF MINERAL GRINDING PROCESSES
    (2006) Remes, Antti; Karesvuori, Jarkko; Pekkarinen, Heikki; Jämsä-Jounela, Sirkka-Liisa
     A4 Artikkeli konferenssijulkaisussa
    To enhance the operation of mineral grinding processes, a greater number of monitoring services and control schemes are nowadays being offered by the equipment manufacturers. In this paper an integrated approach to grinding process monitoring and control is formulated and the components of the integrated automation for typical grinding processes are proposed. Furthermore, the benefits of the process monitoring services are studied on the basis of a specific case study - the Outokumpu Chrome Kemi concentrator. Finally, the results are discussed and a new control scheme is outlined.