Title page for ETD etd-07192012-160558


Document Type Master's Dissertation
Author Olivier, Laurentz Eugene
URN etd-07192012-160558
Document Title Peripheral control tools for a run-of-mine ore milling circuit
Degree MEng
Department Electrical, Electronic and Computer Engineering
Supervisor
Advisor Name Title
Prof I K Craig Supervisor
Keywords
  • dubbel-afskatting
  • maling
  • model-aanleg-verskil
  • onbehandelde
  • disturbance observer
  • fractional order
  • dual estimation
  • milling
  • partikel-filter
  • steuringsafskatter
  • erts
  • model-plant mismatch
  • particle filter
  • breuk-orde
  • run-of-mine ore
Date 2012-04-23
Availability unrestricted
Abstract
Run-of-mine ore milling circuits are generally difficult to control owing to the presence of strong external disturbances, poor process models and the unavailability of important process variable measurements. These shortcomings are common for processes in the mineral-processing industry. For processes that fall into this class, the peripheral control tools in the control loop are considered to be as important as the controller itself. This work addresses the implementation of peripheral control tools on a run-of-mine ore milling circuit to help overcome the deteriorated control performance resulting from the aforementioned shortcomings.

The effects of strong external disturbances are suppressed through the application of a disturbance observer. A fractional order disturbance observer is also implemented and a novel Bode ideal cutoff disturbance observer is introduced. The issue of poor process models is addressed through the detection of significant mismatch between the actual plant and the available model from process data. A closed-form expression is given for the case where the controller has a transfer function. If the controller does not have a transfer function, a partial correlation analysis is used to detect the transfer function elements in the model transfer function matrix that contain significant mismatch.

The mill states and important mill parameters are estimated with the use of particle filters. Simultaneous state and parameter estimation is compared with a novel dual particle filtering scheme. A sensitivity analysis shows the class of systems for which dual estimation would provide superiorestimation accuracy over simultaneous estimation. The implemented peripheral control tools show promise for current milling circuits where proportional-integral-derivative (PID) control is prevalent, and also for advanced control strategies, such as model predictive control, which are expected to become more common in the future.

AFRIKAANS : Maalkringe wat onbehandelde erts maal is oor die algemeen moeilik om te beheer as gevolg van die teenwoordigheid van sterk eksterne steurings, onakkurate aanlegmodelle en metings van belangrike prosesveranderlikes wat ontbreek. Hierdie probleme is algemeen vir aanlegte in die mineraalprosesseringsbedryf. Vir aanlegte in hierdie klas word die randbeheerinstrumente as net so belangrik as die beheerder beskou. Hierdie verhandeling beskryf die implementering van randbeheerinstrumente vir ín maalkring wat onbehandelde erts maal, om die verswakte beheerverrigting teen te werk wat veroorsaak word deur bogenoemde probleme.

Die impak van sterk eksterne steurings word teengewerk deur die implementering van ín steuringsafskatter. ín Breuk-orde-steuringsafskatter is ook geÔmplementeer en ín nuwe Bode ideale afsnysteuringsafskatter word voorgestel. Die kwessie van onakkurate aanlegmodelle word hanteer deur van die aanlegdata af vas te stel of daar ín verskil is tussen die aanleg en die beskikbare model van die aanleg. ín Uitdrukking word gegee vir hierdie verskil vir die geval waar die beheerder met ín oordragsfunksie voorgestel kan word. Indien die beheerder nie ín oordragsfunksie het nie, word van Ďn parsiŽle korrelasie-analise gebruik gemaak om die element, of elemente, in die aanleg se oordragsfunksiematriks te identifiseer wat van die werklike aanleg verskil.

Die toestande en belangrike parameters in die meul word beraam deur van partikel-filters gebruikte maak. Gelyktydige toestand- en parameter-beraming word vergelyk met ín nuwe dubbel-partikelfilter skema. ín Sensitiwiteitsanalise wys die klas van stelsels waarvoor dubbel-afskatting meer akkurate waardes sal gee as gelyktydige afskatting. Die voorgestelde randbeheerinstrumente is toepaslik vir huidige maalkringe waar PID-beheer algemeen is, asook vir gevorderde beheerstrategieŽ, soos model-voorspellende beheer, wat na verwagting in die toekoms meer algemeen sal word.

Copyright © 2011, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. p>Please cite as follows:

Olivier, LE 2011, Peripheral control tools for a run-of-mine ore milling circuit, MEng dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-07192012-160558/ >

E12/4/423/gm

Files
  Filename       Size       Approximate Download Time (Hours:Minutes:Seconds) 
 
 28.8 Modem   56K Modem   ISDN (64 Kb)   ISDN (128 Kb)   Higher-speed Access 
  dissertation.pdf 3.70 Mb 00:17:06 00:08:48 00:07:42 00:03:51 00:00:19

Browse All Available ETDs by ( Author | Department )

If you have more questions or technical problems, please Contact UPeTD.