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Larsson, S., Pålsson, B., Parian, M. & Jonsén, P. (2020). A novel approach for modelling of physical interactions between slurry, grinding media and mill structure in wet stirred media mills. Minerals Engineering, 148, Article ID 106180.
Open this publication in new window or tab >>A novel approach for modelling of physical interactions between slurry, grinding media and mill structure in wet stirred media mills
2020 (English)In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 148, article id 106180Article in journal (Refereed) Published
Abstract [en]

Wet comminution is an important process in the mineral processing industry. Modelling of wet comminution in stirred media mills requires the simultaneous modelling of grinding media, a moving internal stirrer, and slurry. In the present study, a novel approach for modelling the physical interactions between slurry, grinding media and mill structure in a stirred media mill is presented. The slurry is modelled with the particle finite element method (PFEM). The grinding media is modelled using the discrete element method (DEM) and the mill structure is modelled using the finite element method (FEM). The interactions between slurry, grinding media and mill structure are modelled by two-way couplings between the PFEM, the DEM and the FEM models. The coupled model of the present study is used to predict the motion of slurry and grinding media, and to calculate the power draw during wet comminution in a pilot scale horizontal stirred media mill. Furthermore, the model is used to compare a Newtonian and a non-Newtonian model of the slurry, where the non-Newtonian model is used to capture experimentally observed shear-thinning. The coupled PFEM-DEM-FEM model preserves the robustness and efficiency of each of the methods and it gives the possibility to use large time increments for the fluid, greatly reducing the computational expense. The coupled model of the present work provide information on the complex dynamics of slurry and grinding media. The numerical model is shown to be a useful tool for increasing the knowledge and understanding of wet comminution in stirred media mills.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Particle finite element method, Discrete element method, Coupled models, Stirred media mills
National Category
Applied Mechanics Metallurgy and Metallic Materials
Research subject
Mineral Processing; Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-73198 (URN)10.1016/j.mineng.2019.106180 (DOI)
Note

Validerad;2020;Nivå 2;2020-02-04 (johcin)

Available from: 2019-03-14 Created: 2019-03-14 Last updated: 2020-02-04Bibliographically approved
Lishchuk, V., Lund, C., Koch, P.-H., Mattias, G. & Pålsson, B. (2019). Geometallurgical characterisation of Leveäniemi iron ore: Unlocking the patterns. Minerals Engineering, 131, 325-335
Open this publication in new window or tab >>Geometallurgical characterisation of Leveäniemi iron ore: Unlocking the patterns
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2019 (English)In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 131, p. 325-335Article in journal (Refereed) Published
Abstract [en]

As part of a geometallurgical program for the Leveänimei iron ore mine, the Davis tube was used as proxy to classify ore types, predict iron recoveries in wet low-intensity magnetic separation (WLIMS), and to estimate liberation of mixed particles. The study was conducted by testing 13 iron ore samples with a Davis tube and a laboratory WLIMS. Ore feed was studied for modal mineralogy and liberation distribution with Automated Scanning Electron Microscopy. Data analyses to detect the patterns and data dependencies were done with multivariate statistics: principal component analysis, and projection to latent structures regression. Results show that a simple index (XLTU) based on mass pull (yield) in the Davis tube is capable of easy classification of magnetite ores. Using Davis tube mass pull and iron recovery, together with iron and Satmagan head grades may predict iron recovery in WLIMS. Also, the variability in Fe-oxides liberation pattern for magnetite semi-massive ores can be explained with the chemical composition of the Davis tube concentrate. It is concluded that the Davis tube test is better used only for marginal ores, since iron oxide minerals tend to be fully liberated in high-grade magnetite massive ores after grinding. The developed models may be used in populating a production block model.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Davis tube, Magnetic separation, Liberation, Apatite iron ore, Leveäniemi
National Category
Metallurgy and Metallic Materials
Research subject
Mineral Processing
Identifiers
urn:nbn:se:ltu:diva-71578 (URN)10.1016/j.mineng.2018.11.034 (DOI)000460495600036 ()2-s2.0-85057250019 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-12-05 (inah)

Available from: 2018-11-14 Created: 2018-11-14 Last updated: 2019-09-13Bibliographically approved
Pålsson, B. & Bucht, J. (2019). NARROW SIZE FRACTIONS OBTAINED FROM ELECTRICALLY HEATED SCREEN DECKS. In: Tommy Karlkvist (Ed.), Conference in Minerals Engineering 2019: . Paper presented at Conference in Minerals Engineering 2019.
Open this publication in new window or tab >>NARROW SIZE FRACTIONS OBTAINED FROM ELECTRICALLY HEATED SCREEN DECKS
2019 (English)In: Conference in Minerals Engineering 2019 / [ed] Tommy Karlkvist, 2019Conference paper, Published paper (Refereed)
Abstract [en]

A probalistic screen with electrically heated decks has been used to produce narrow size fractions of magnetite and olivine below 1 mm. The results indicate that the major limiting production factor is the amount of too fine materials in the desired size fraction. This can be corrected by re-screening the narrow size fraction in various ways, but the best result is had with an air classifier.

The best way to evaluate the screening results is to plot the proportion of finished product, and the loss of the correct fraction as a function of feed rate and moisture content. These being quantity results, they need to be supplemented with quality parameters, and the best seem to be the weight percentage of too coarse (plus material) and too fine (minus material) particles in the finished product. There appears to be some threshold level for the heating effect, but to what extent this is related to the screen deck type, the heat capacity, and density of the material, or the particle size, is still unclear.

Keywords
magnetite, olivine, classification, screening, mass balancing, particle size
National Category
Chemical Process Engineering
Research subject
Mineral Processing
Identifiers
urn:nbn:se:ltu:diva-77263 (URN)
Conference
Conference in Minerals Engineering 2019
Available from: 2019-12-29 Created: 2019-12-29 Last updated: 2019-12-29
Jonsén, P., Hammarberg, S., Pålsson, B. & Lindkvist, G. (2019). Preliminary validation of a new way to model physical interactions between pulp, charge and mill structure in tumbling mills. Minerals Engineering, 130, 76-84
Open this publication in new window or tab >>Preliminary validation of a new way to model physical interactions between pulp, charge and mill structure in tumbling mills
2019 (English)In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 130, p. 76-84Article in journal (Refereed) Published
Abstract [en]

Modelling of wet grinding in tumbling mills is an interesting challenge. A key factor is that the pulp fluid and its simultaneous interactions with both the charge and the mill structure have to be handled in a computationally efficient way. In this work, the pulp fluid is modelled with a Lagrange based method based on the particle finite element method (PFEM) that gives the opportunity to model free surface flow. This method gives robustness and stability to the fluid model and is efficient as it gives possibility to use larger time steps. The PFEM solver can be coupled to other solvers as in this case both the finite element method (FEM) solver for the mill structure and the DEM solver for the ball charge. The combined PFEM-DEM-FEM model presented here can predict charge motion and responses from the mill structure, as well as the pulp liquid flow and pressure. All cases presented here are numerically modelled and validated against experimentally measured driving torque signatures from an instrumented small-scale batch ball mill equipped with a torque meter and charge movements captured from high-speed video. Numerical results are in good agreement with experimental torque measurements and the PFEM solver also improves on efficiency and robustness for solving charge movements in wet tumbling mill systems.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Grinding, Modelling, Simulation, Validation
National Category
Applied Mechanics Metallurgy and Metallic Materials
Research subject
Solid Mechanics; Mineral Processing
Identifiers
urn:nbn:se:ltu:diva-71226 (URN)10.1016/j.mineng.2018.10.013 (DOI)000452937000010 ()2-s2.0-85054850385 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-10-16 (svasva)

Available from: 2018-10-16 Created: 2018-10-16 Last updated: 2019-02-01Bibliographically approved
Larsson, S., Pålsson, B., Parian, M. & Jonsén, P. (2019). Preliminary validation of a stirred media mill model. In: : . Paper presented at Conference in Minerals Engineering 2019.
Open this publication in new window or tab >>Preliminary validation of a stirred media mill model
2019 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Wet fine grinding is an important process in the minerals industry. Modelling of wet grinding in stirred media mills is challenging since it requires the simultaneous modelling of grinding media consisting of a huge number of small grinding bodies, moving internal stirrer, and the pulp fluid. All of them in interaction with each other. In the present study, wet grinding in a stirred media mill is studied using coupled incompressible computational fluid dynamics (ICFD) and discrete element method (DEM) and finite element method (FEM) simulations. The DEM is used to model the grinding media, and the pulp fluid flow is modelled using the ICFD. Moreover, the FEM is used to model the structure of the mill body and is in combination with DEM used to estimate the wear rate in the system. The present implementation of the coupled ICFD-DEM-FEM preserves the robustness and efficiency of both methods, and it gives the possibility to use large time steps for the fluid with very low computation times.

National Category
Applied Mechanics Metallurgy and Metallic Materials
Research subject
Solid Mechanics; Mineral Processing
Identifiers
urn:nbn:se:ltu:diva-72951 (URN)
Conference
Conference in Minerals Engineering 2019
Available from: 2019-02-19 Created: 2019-02-19 Last updated: 2019-02-22
Pålsson, B. & Bucht, J. (2019). USING ELECTRICALLY HEATED SCREEN DECKS FOR PRODUCING NARROW SUB-MILLIMETRE FRACTIONS. In: Barry A. Wills (Ed.), Physical Separation '19: . Paper presented at Physical Separation '19. Falmouth, UK
Open this publication in new window or tab >>USING ELECTRICALLY HEATED SCREEN DECKS FOR PRODUCING NARROW SUB-MILLIMETRE FRACTIONS
2019 (English)In: Physical Separation '19 / [ed] Barry A. Wills, Falmouth, UK, 2019Conference paper, Published paper (Refereed)
Abstract [en]

A probalistic screen with electrically heated decks has been used to produce narrow size fractions of magnetite and olivine below 1 mm. The results indicate that the major limiting production factor is the amount of too fine materials in the desired size fraction. This can be corrected by re-screening the narrow size fraction in various ways, but the best result is had with an air classifier.

The probalistic screen may be evaluated in the same way as a classifier with a cut point and sharpness of separation for each screen deck, and as a total for combinations of screen decks. However, the best way to evaluate the screening results is to plot the proportion of finished product, and the loss of the correct fraction as a function of feed rate and moisture content. These being quantity results, they need to be supplemented with quality parameters, and the best seem to be the percentage of too coarse and too fine particles in the finished product.

Place, publisher, year, edition, pages
Falmouth, UK: , 2019
Series
MEi Conferences
Keywords
magnetite, olivine, classification, screening, mass balancing, particle size
National Category
Chemical Process Engineering
Research subject
Mineral Processing
Identifiers
urn:nbn:se:ltu:diva-77264 (URN)
Conference
Physical Separation '19
Available from: 2019-12-29 Created: 2019-12-29 Last updated: 2019-12-29
Wanhainen, C., Pålsson, B., Martinsson, O. & Lahaye, Y. (2017). Rare earth mineralogy in tailings from Kiirunavaara iron ore, northern Sweden: Implications for mineral processing. Minerals & metallurgical processing, 34(4), 189-200
Open this publication in new window or tab >>Rare earth mineralogy in tailings from Kiirunavaara iron ore, northern Sweden: Implications for mineral processing
2017 (English)In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 34, no 4, p. 189-200Article in journal (Refereed) Published
Abstract [en]

Four main and three minor rare-earth-element (REE)-bearing minerals were identified and quantified in the Kiirunavaara apatite iron ore tailings using optical microscopy, an electron probe microanalyzer (EPMA) and a mineral liberation analyzer, and their chemical compositions were analyzed by the EPMA and laser ablation inductively coupled plasmamass spectrometry. REEs are shown to be contained in the minerals apatite, monazite, allanite, titanite, zircon, thorite and synchysite. In zircon, thorite and synchysite, they occurred in only trace amounts and contributed limited amounts to the total REE budget, and these are consequently of minor importance. Monazite occurred as inclusions in apatite and as free particles, 90 percent liberated. Allanite occurred to some degree in mixed grains with magnetite but also as free particles. Monazite mainly reported to the apatite concentrate, while allanite and titanite largely went to the tailings, the latter preferably to those fractions smaller than 38 μm. The amount of titanite in the finest tailings fraction was 2.3 weight percent, containing close to 1 percent REEs, with heavy rare earth elements (HREEs) making up 28 percent of the total REEs. However, a texturally distinct group of titanite grains showed an HREE/REE ratio of up to 67 percent. Furthermore, titanum dioxide analyses indicate that titanite is preferentially released into the tailings from the secondary magnetic separation step in the concentrator. Our data therefore suggest that titanite, occasionally enriched in HREEs, can be extracted from the processing stream and might thus be considered a new source for REEs at Kiirunavaara and similar deposits.

Place, publisher, year, edition, pages
Society for Mining, Metallurgy and Exploration, 2017
National Category
Geology Metallurgy and Metallic Materials
Research subject
Ore Geology; Mineral Processing
Identifiers
urn:nbn:se:ltu:diva-66621 (URN)10.19150/mmp.7859 (DOI)000419794200005 ()2-s2.0-85032955143 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-11-17 (andbra)

Available from: 2017-11-17 Created: 2017-11-17 Last updated: 2018-03-26Bibliographically approved
Tranvik, E., Becker, M., Pålsson, B., Franzidis, J.-P. & Bradshaw, D. J. (2017). Towards cleaner production: Using flotation to recover monazite from a heavy mineral sands zircon waste stream. Minerals Engineering, 101, 30-39
Open this publication in new window or tab >>Towards cleaner production: Using flotation to recover monazite from a heavy mineral sands zircon waste stream
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2017 (English)In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 101, p. 30-39Article in journal (Refereed) Published
Abstract [en]

In line with the principles of cleaner production, the removal of monazite via reverse flotation was investigated with a view to reducing the radioactivity of a heavy mineral sands waste stream. Another benefit was to create a potential REE by-product from the Namakwa Sands operation in South Africa. Understanding the mineralogy of the zircon waste stream was essential owing to the cemented nature of the deposit and the potential impact of surface coatings on the flotation performance. SEM, QEMSCAN and optical microscopy showed that amorphous SiO2 was the most abundant surface coating associated with both monazite and zircon, which is likely to constitute a major challenge in achieving flotation selectivity. A D-optimal statistical screening design was applied to find the most relevant flotation parameters and a full factorial design to find the optimal flotation conditions. The most promising results showed that monazite could be successfully removed from the zircon waste with an oleate collector at pH 10. The selectivity was found to be highly dependent on pH, with no selectivity at pH 9 and no mineral flotation at pH 11. Further work is recommended to confirm and optimise these conditions and test them on a larger scale.

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Metallurgy and Metallic Materials
Research subject
Mineral Processing
Identifiers
urn:nbn:se:ltu:diva-60639 (URN)10.1016/j.mineng.2016.10.011 (DOI)000392044600004 ()2-s2.0-85006733679 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2017-01-09 (andbra)

Available from: 2016-11-23 Created: 2016-11-23 Last updated: 2018-12-14Bibliographically approved
Sand, A., Stener, J., Toivakka, M., Carlson, J. & Pålsson, B. (2016). A Stokesian Dynamics Approach for Simulation of Magnetic Particle Suspensions (ed.). Paper presented at Computational Modelling '15 : 08/06/2015 - 10/06/2015. Minerals Engineering, 90(SI ), 70-76
Open this publication in new window or tab >>A Stokesian Dynamics Approach for Simulation of Magnetic Particle Suspensions
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2016 (English)In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 90, no SI , p. 70-76Article in journal (Refereed) Published
Abstract [en]

The dynamic behaviour of μm-scale ferromagnetic particles in suspension is of interest for various mineral beneficiation processes. It is, however, difficult to experimentally study such processes at the particle-level. In these instances it can be advantageous to resort to suitable particle simulation methods.Stokesian dynamics is a mesh-free numerical technique developed for suspensions of nm to mm size particles. The method inherently considers hydrodynamic interactions, but additional interaction models can be included depending on the system under investigation. We here present a Stokesian dynamics (SD) implementation, which allows for simulation of the motion of suspended magnetic particles in presence of an external magnetic field. The magnetic interaction model includes particle-field interactions as well as pairwise interactions between magnetised particles.Simulations are compared with experiments using a laboratory-scale flow cell. The method is shown to be realistic for studying ferromagnetic suspensions in mineral processing applications, and can be useful in understanding and predicting the efficiency of mineral separation processes.

National Category
Metallurgy and Metallic Materials Signal Processing
Research subject
Mineral Processing; Signal Processing
Identifiers
urn:nbn:se:ltu:diva-27464 (URN)10.1016/j.mineng.2015.10.015 (DOI)000375169200007 ()2-s2.0-84960865330 (Scopus ID)0eda3225-823b-4369-91a2-78b07835122b (Local ID)0eda3225-823b-4369-91a2-78b07835122b (Archive number)0eda3225-823b-4369-91a2-78b07835122b (OAI)
Conference
Computational Modelling '15 : 08/06/2015 - 10/06/2015
Note
Validerad; 2016; Nivå 1; 20151102 (andbra); Konferensartikel i tidskriftAvailable from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-07-10Bibliographically approved
Stener, J., Carlson, J. E., Pålsson, B. & Sand, A. (2016). Direct measurement of internal material flow in a bench scale wet Low-Intensity Magnetic Separator (ed.). Paper presented at Physical Separation '15 : 11/06/2015 - 12/06/2015. Minerals Engineering, 91, 55-65
Open this publication in new window or tab >>Direct measurement of internal material flow in a bench scale wet Low-Intensity Magnetic Separator
2016 (English)In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 91, p. 55-65Article in journal (Refereed) Published
Abstract [en]

In this work an ultrasound-based measurement method is used formonitoring suspension velocity and build-up of magnetic material inside awet Low-Intensity Magnetic Separator, a process used e.g. inbeneficiation of magnetite ores. Today the only available option is tomonitor material transport between unit operations; i.e. flow rate,solids concentration, and particle size distribution of suspension flowin pipes are measured online using standard equipment.An Acoustic Backscatter System is fitted to the tank of a separator, andused to monitor the internal flow. A method called Ultrasonic VelocityProfiling is used to capture internal velocity profiles. Simultaneously,the backscatter signal intensity is used to get indications about localsolids concentration of the flow, and build-up of magnetic material. Themethods are evaluated in realistic conditions, where the effect ofvarying factors relevant to machine performance is investigated. Theincluded factors are; the slurry feed rate, the slurry solidsconcentration, the magnet assembly angle, and the drum rotational speed.The presented method gives useful information about the internal materialflow inside the separator. The velocity measurements capture the,sometimes complex, internal flow patterns, for example the presence andvelocity of a recirculating flow in the dewatering zone. Additionally,keeping a balanced material loading in the concentrate dewatering zone isimportant to separator performance. Using the signal backscatterintensity it is possible to qualitatively monitor this material loading.Generally these direct measurements can aid in improvements to machinedesign, process optimization, and process control.

National Category
Metallurgy and Metallic Materials Signal Processing
Research subject
Mineral Processing; Signal Processing
Identifiers
urn:nbn:se:ltu:diva-29949 (URN)10.1016/j.mineng.2015.10.021 (DOI)000375513500006 ()2-s2.0-84977914569 (Scopus ID)395c8b74-5c0d-42d1-9239-9141cede269c (Local ID)395c8b74-5c0d-42d1-9239-9141cede269c (Archive number)395c8b74-5c0d-42d1-9239-9141cede269c (OAI)
Conference
Physical Separation '15 : 11/06/2015 - 12/06/2015
Projects
Wet LlMS - Measurements and models
Note
Validerad; 2016; Nivå 1; 20151007 (janste); Konferensartikel i tidskriftAvailable from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-07-10Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-8032-9388

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