Evaluation of the Economic Benefits of Milling Circuit Control

Hulbert, D.G.

doi:10.3182/20020721-6-es-1901.01164

Cited by 4 publications

(7 citation statements)

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“…The economic performance of milling circuit control systems is often not satisfactorily quantified (Hulbert, 1989(Hulbert, , 2002Lo et al, 1996;Radhakrishnan, 1999;Bourassa et al, 1995) although the primary objective, when installing a control system, is to gain as much monetary benefit as possible. It was therefore decided to ask survey respondents about the EPA process as it relates to their installations.…”

Section: Survey Results: Economic Performance Assessment Of Grinding mentioning

confidence: 99%

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Development of performance functions for economic performance assessment of process control systems

Wei

Craig

2009

Africon 2009

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Degree: PhD (Electronic Engineering) SummaryEconomic performance assessment (EPA) of control systems is receiving increasing attention in both academia and industry. It addresses the estimation of the potential benefits resulting from control upgrade projects and monitoring and improvement of economic performance of the control system. Economic performance of control systems can often be related to crucial controlled variables dynamically and when controlled variables move away from an optimal operating point either more profit will be made or more cost will be incurred. This relation can be modelled by performance functions (PFs). When the multivariate nature of a process's economic model is not considered, PFs of different controlled variables are referred to as individual performance functions. Otherwise, PFs of dependent controlled variables are referred to as joint performance functions.PFs play an important role in the latest techniques of EPA. There appears, however, to be no systematic method for developing PFs. The lack of such a method restrains further research into EPA, as without well-established PFs an EPA cannot be conducted smoothly and therefore cannot effectively support decision-making for management. The development of PFs is a bottleneck in the further research into EPA. Furthermore, the multivariate nature of processes has not been taken into account sufficiently as far as the relevant literature is concerned, which hampers the accuracy of PFs and accordingly the accuracy of economic assessment results.The contributions of this thesis lie in the following aspects:• A methodology for developing PFs is proposed, based on the PF development for an electric arc furnace, a grinding mill circuit and a stage of a bleach plant.• A comprehensive case study of an EPA of three controllers of a grinding mill circuit is conducted using a newly published framework to show the significance of PFs and how to perform an EPA systematically.• The current practice and guidelines on the control and functional/economic performance i assessment of grinding mill circuits are captured using a survey study.The multivariate nature of an electric arc furnace's economic model is investigated and joint performance functions are built based on individual performance functions. A multivariate economic assessment is conducted that shows how joint performance functions can help to provide a more accurate estimate of the economic performance of a controlled process.A web-based survey study on grinding mill circuits in mineral processing industries is conducted. One of its objectives is to obtain general PFs of grinding circuits. The survey results provide instructive insight into the PFs of grinding circuits. Furthermore, an in-depth literature review is conducted and the relationship between the product's particle size distribution of grinding mill circuits and mineral recovery in downstream flotation circuits is revealed. The PFs of a grinding mill circuit being considered are formed, based on the survey results and litera...

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Section: Survey Results: Economic Performance Assessment Of Grinding mentioning

confidence: 99%

“…The efficiency of the downstream process, e.g. leaching or flotation, is of primary importance (89%), which is confirmed by Hulbert (2002), Wills and Napier-Munn (2006) and Hodouin et al (2001). Circuit throughput is also an important factor (53%).…”

Section: Electrical Electronic and Computer Engineering University Omentioning

confidence: 86%

Development of performance functions for economic performance assessment of process control systems

Wei

Craig

2009

Africon 2009

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“…However, Hulbert (1989) states that good control of grinding mill circuits realizes relatively small benefits compared to those from subsequent process optimization. The economic performance of milling control systems is often not satisfactorily estimated (Hulbert, 1989(Hulbert, , 2002Lo et al, 1996;Radhakrishnan, 1999;Bourassa et al, 1995) despite the primary objective, when installing a control system, being to gain as much monetary benefit as possible. This fact is confirmed by the survey results reported in Wei and Craig (2009).…”

Section: The Economic Concerns Of Milling Circuit Control Systemsmentioning

confidence: 99%

“…However, the performance is often not estimated satisfactorily (Hulbert, 2002;Lo et al, 1996;Radhakrishnan, 1999;Bourassa et al, 1995). The contribution of this paper is the EPA of three single-loop proportional-integral-derivative (PID) controllers and a nonlinear model predictive controller (NMPC) for a ROM milling circuit using the aforementioned framework.…”

Section: Introductionmentioning

confidence: 99%

Economic performance assessment of two ROM ore milling circuit controllers

Wei¹,

Craig²

2009

Minerals Engineering

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a b s t r a c tEconomic performance assessment of control systems is receiving increasing attention in both academia and industry. A relevant framework is proposed in Bauer and Craig (Bauer, M., Craig, I.K., 2008. Economic assessment of advanced process control -a survey and framework. Journal of Process Control 18 (1), 2-18) based on a comprehensive survey of the methods for economic analysis of advanced process control systems. The framework provides a formal procedure for the economic assessment of control systems. A practically motivated simulation study is used to cast the economic performance assessment of a nonlinear model predictive controller and three single-loop PID controllers for a run-of-mine milling circuit into this framework. Performance functions of the milling circuit, which dynamically relate the circuit process variables to monetary values, are developed based on a survey study on milling circuits and an in-depth literature study.

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“…As the benefit of milling circuits is usually expressed in terms of liberation or particle size distribution of the product (Hulbert, 2002;SosaBlanco et al, 2000;Hodouin et al, 2001), the optimal operating region is defined as the limits conducive to the best grind. These limits were obtained by conducting two optimisation trials.…”

Section: Optimisation Frameworkmentioning

confidence: 99%

Benefits of optimisation and model predictive control on a fully autogenous mill with variable speed

Steyn

Sandrock

2013

Minerals Engineering

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Autogenous (AG) milling is utilised around the world for particle size reduction. The system exhibits highly non-linear behaviour in addition to being subject to unmeasured variability associated with most ore bodies. Anglo American Platinum aimed at improving online optimisation of the circuit by implementing industrial model predictive control (MPC) to reduce system variability and continuously drive towards the optimal operating point within system constraints.The industrial dynamic matrix controller commissioned on the AG mill with a variable speed drive resulted in a 66 % reduction in power and a 40 % reduction in load standard deviation. These are the main controlled variables of the mill. The controller also improved the objective function, effective power utilisation, by 11 %. This reduction in operated variable variability enabled a test campaign where the mill was controlled at various operating regions in order to establish the conditions conducive to the finest product size at a given mill feed rate.Moving the mill operating region from the benchmarked plant to the optimal grind environment and stabilising the mill at this point with the model predictive controller provided an estimated potential recovery increase of 0.32 % (absolute) due to better liberation.

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Evaluation of the Economic Benefits of Milling Circuit Control

Cited by 4 publications

References 4 publications

Development of performance functions for economic performance assessment of process control systems

Development of performance functions for economic performance assessment of process control systems

Economic performance assessment of two ROM ore milling circuit controllers

Benefits of optimisation and model predictive control on a fully autogenous mill with variable speed

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