Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Modeling and Control of Lime Addition in a Flotation Process
Linköping University, Department of Electrical Engineering, Automatic Control.
2017 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

Flotation is an important and versatile mineral processing technique that is used to separate hydrophobic materials from hydrophilic. This technique makes it possible to mine complex ores that otherwise would have been regarded as uneconomic and non-beneficial. In this case flotation is used to separate copper from the unwanted gangue.

The addition of lime is used to control the pH level in the flotation’s pulp, which governs the selectivity of the process, i.e. which minerals are recovered. Currently, fluctuating concentration grades of the produced metals have been observed in Boliden Aitik. Therefore, Boliden proposes a new control strategy which aims to maintain a constant ratio between the added lime and the incoming ore flow, but at the same time ensuring that the pH level is maintained within allowed limits.

The aim of this thesis is to develop a model that captures the most essential dynamics of a process stage where lime is added, and then evaluate the suggested control strategy by studying suitable control structures.

A linear model describing the system dynamics in a specific operating region is obtained by conducting step response experiments on the process. The model is then used to obtain a model describing the disturbances of the process, thereby yielding a complete model that describes the most important dynamics.

The most promising control structure utilizes the concept of selective control, where a ratio controller is allowed to maintain a constant ratio as long as the pH level is within allowed boundaries. The pH level is maintained within the boundaries with upper and lower bound pH controllers that utilize the concept of an equivalent control objective (known as the strong acid equivalent) in order to achieve satisfying pH control. The results show that the control structure is able to maintain a constant ratio, and also ensure that the pH level is kept within the allowed limits.

A cascade inspired pH ratio controller is also studied and evaluated. The results show that this pH ratio controller is only able to maintain a constant ratio as long as the incoming ore flow is constant. However, the outcomes also suggest that the concentration grades are either sensitive to variations in the ratio between added reagent and incoming ore flow, or that there is something else that causes them to vary.

Place, publisher, year, edition, pages
2017. , 50 p.
Keyword [en]
Automatic Control, Mineral Processing, Flotation Process, pH Control, System Identification, Modeling, Signal Processing
National Category
Control Engineering
Identifiers
URN: urn:nbn:se:liu:diva-139331ISRN: LiTH-ISY-EX--17/5071--SEOAI: oai:DiVA.org:liu-139331DiVA: diva2:1121140
External cooperation
Boliden Mineral AB
Subject / course
Automatic Control
Presentation
2017-06-14, Transformen, Linköpings universitet, Linköping, 10:15 (English)
Supervisors
Examiners
Available from: 2017-07-10 Created: 2017-07-10 Last updated: 2017-07-10Bibliographically approved

Open Access in DiVA

fulltext(1395 kB)50 downloads
File information
File name FULLTEXT01.pdfFile size 1395 kBChecksum SHA-512
677db867b6ec8a72be0192305a51da0ec8ab188faf8224ed2d4331b9495d0b4145124e4dfa33c4ca0ebe47d2619d9ec50ed098e5165444c13af7be23e366e214
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Tammia, Rasmus
By organisation
Automatic Control
Control Engineering

Search outside of DiVA

GoogleGoogle Scholar
Total: 50 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

urn-nbn

Altmetric score

urn-nbn
Total: 254 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf