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  • 1.
    Alatalo, Johanna
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Tano, Kent
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Comparing experimental measurements of mill lifter deflections with 2D and 3D DEM predictions2010In: Discrete element methods: simulations of discontinua : theory and applications / [ed] Antonio Munjiza, London: School of Advanced Study, University of London, 2010Conference paper (Refereed)
  • 2.
    Alatalo, Johanna
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Tano, Kent
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Evaluation of data from a pilot scale pebble mill2011In: Conference in minerals engineering: Luleå, 8-9 February 2011 / [ed] Johanna Alatalo, Luleå: Luleå tekniska universitet, 2011Conference paper (Other academic)
  • 3.
    Jonsén, Pär
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Alatalo, Johanna
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Tano, Kent
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Prediction of contact forces between a grinding charge and mill lifters2009In: 12th European Symposium on Comminution and Classification ESCC 2009, 2009Conference paper (Refereed)
  • 4.
    Jonsén, Pär
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Häggblad, Hans-Åke
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Tano, Kent
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Berggren, Andreas
    Technology and Development, Boliden Minerals, SE-93681 Boliden, Sweden.
    Modelling of the interaction between charge and lining in tumbling mills: Combination of numerical methods2011Conference paper (Other academic)
  • 5.
    Jonsén, Pär
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Häggblad, Hans-Åke
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Tano, Kent
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Berggren, Andreas
    Boliden Mineral AB.
    Novel simulation methods for mill charges2011In: Conference in minerals engineering: Luleå, 8-9 February 2011 / [ed] Johanna Alatalo, Luleå: Luleå tekniska universitet, 2011Conference paper (Other academic)
  • 6.
    Jonsén, Pär
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Häggblad, Hans-Åke
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Tano, Kent
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Berggren, Andreas
    Technology and Development, Boliden Minerals, SE-93681 Boliden, Sweden.
    Simulation of charge and structure behaviour in a tumbling mill2011In: 8th European LD-DYNA Users Conference May 23-24, 2011, Strasbourg, 2011Conference paper (Refereed)
    Abstract [en]

    For a long time discrete element methods (DEM) has been used as simulation tools to gain insight into particulate flow processes. The mechanical behaviour in tumbling mills is complex. To include all phenomena that occur in a single numerical model is today not possible. A common approach is to model milling charges using the DEM assuming a rigid mill structure. To close the gap between reality and numerical models in milling, more physically realistic methods have to be used. In this work, the finite element method (FEM) and the smoothed particle hydrodynamic (SPH) method are used together to model a ball mill charge in a tumbling mill. The mesh free formulation and the adaptive nature of the SPH method result in a method that handles extremely large deformations and thereby suits for modelling of grinding charges. The flexible rubber lifter and the lining are modelled with the finite element method. The mill structure consists of rubber lifter and liners and a mantel made of solid steel. For the elastic behaviour of the rubber, a Blatz-Ko hyper-elastic model is used. The supplier of the lining provided experimental data for the rubber. The deflection profile of the lifters obtained from SPH-FEM simulation shows a reasonably good correspondence to pilot mill measurements as measured by an embedded strain gauge sensor. This computational model makes it possible to predict charge pressure and shear stresses within the charge. It is also possible to predict contact forces for varying mill dimensions and liner combinations.

  • 7.
    Jonsén, Pär
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Stener, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Häggblad, Hans-Åke
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Tano, Kent
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Berggren, Andreas
    Boliden Mineral AB, New Boliden AB.
    Development of physically based tumbling mill models2014In: Proceedings of XXIII International Mineral Processing Congress: XXVII, Santiago, Chile 20-24 October 2014, Santiago: IMPC , 2014Conference paper (Refereed)
    Abstract [en]

    Numerical modelling of grinding in tumbling mills is traditionally done with the discrete element method (DEM). The grinding balls are then represented by DEM particles and the mill structure is considered rigid. To include more physical phenomena several numerical methods can be combined. One important improvement is to include the mill structure response, using the finite element method (FEM). The interaction between charge and lining can then be studied in detail. The pulp can also be included using a particle-based continuum method e.g. smoothed particle method (SPH). The strength of SPH lies in modelling of free surface flows and very large deformations and it is suited to model simultaneous fluid and granular flow. Still, the coarse particles (grinding balls) in the charge are suitable to be model using DEM. Each of these methods has their strength and weaknesses, but combined they can successfully mimic the main features of the charge movement. With these numerical tools the complex interaction between the different components of the grinding process; pulp, charge, lining and the mechanical behaviour of the mill, can be studied together. This work will present novel numerical approaches to model, simulate and validate charge behaviour in tumbling mills. These numerical models give possibilities to better understand the physical and mechanical behaviour of particulate material systems during grinding in a tumbling mill. This is important in order to develop and optimise future high-capacity grinding circuits and save energy.

  • 8.
    Jonsén, Pär
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Tano, Kent
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Berggren, Andreas
    Technology and Development, Boliden Minerals, SE-93681 Boliden, Sweden.
    Charge and structure behaviour in a tumbling mill2010In: The Fifth International Conference on Discrete Element Methods: Proceedings / [ed] Antonio Munjiza, London: Research Publishing Services, 2010, p. 490-495Conference paper (Refereed)
    Abstract [en]

    The grinding process in tumbling mills is complex and to include all phenomena that occur in a single numerical model is today not possi-ble. This paper presents the results of a study in which the deflection of a lifter bar in a pilot ball mill is measured by an embedded strain gauge sensor and compared to deflections predicted from finite ele-ment (FE) simulations. The flexible rubber lifter and the lining in a tumbling mill are modelled with the finite element method (FEM) and the grinding medium modelled with the distinct element method (DEM). The deflection profile obtained from DEM-FE simulation shows a reasonably good correspondence to pilot mill measurements. The approach presented here is a contribution to the validation of DEM-FE simulations and an introduction to the description of a bend-able rubber lifter implemented in a DEM-FEM mill model. It opens up the possibility to predict contact forces for varying mill dimensions and liner combinations. FEM is especially valuable in this case, since there are readily available libraries with material models. This is a fol-low-up work to previous preliminary result from a mono-size ball charge interaction study

  • 9.
    Jonsén, Pär
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Tano, Kent
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Berggren, Andreas
    Technology and Development, Boliden Minerals, SE-93681 Boliden, Sweden.
    Modelling of the interaction between charge and lining in tumbling mills2010In: Bergforsk 2010: Mineral Supply - a Grand Challange and Opportunity / [ed] Göran Bäckblom, 2010, p. 18-20Conference paper (Other academic)
  • 10.
    Jonsén, Pär
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Tano, Kent
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Berggren, Andreas
    Technology and Development, Boliden Minerals, SE-93681 Boliden, Sweden.
    Prediction of mill structure behaviour in a tumbling mill2010In: Conference in Minerals Engineering: Luleå, 2 -3 februari 2010 / [ed] Johanna Alatalo, Luleå: Luleå tekniska universitet, 2010, p. 85-98Conference paper (Other academic)
    Abstract [en]

    Computational demands and the lack of detailed experimental verification have limited the value of Distinct Element Method (DEM) modelling approaches in mill simulation studies. This paper presents the results of a study in which the deflection of a lifter bar in a pilot ball mill is measured by an embedded strain gauge sensor and compared to deflections predicted from finite element (FE) simulations. The flexible rubber lifter and the lining in a tumbling mill are modelled with the finite element method (FEM) and the grinding medium modelled with DEM. The deflection profile obtained from DEM-FE simulation shows a reasonably good correspondence to pilot mill measurements. To study the charge impact on the mill structure two different charges are used in the simulations. The approach presented here is a contribution to the validation of DEM-FE simulations and an introduction to the description of a bendable rubber lifter implemented in a DEM-FEM mill model. It opens up the possibility to predict contact forces for varying mill dimensions and liner combinations. FEM is especially valuable in this case, since there are readily available libraries with material models. This is a follow-up work to previous preliminary result from a mono-size ball charge interaction study.

  • 11.
    Jonsén, Pär
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Tano, Kent
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Berggren, Andreas
    Boliden Mineral AB.
    Prediction of mill structure behaviour in a tumbling mill2011In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 24, no 3-4, p. 236-244Article in journal (Refereed)
    Abstract [en]

    Computational demands and the lack of detailed experimental verification have limited the value of distinct element method (DEM) modelling approaches in mill simulation studies. This paper presents the results of a study in which the deflection of a lifter bar in a pilot ball mill is measured by an embedded strain gauge sensor and compared to deflections predicted from finite element (FE) simulations. The flexible rubber lifter and the lining in a tumbling mill are modelled with the finite element method (FEM) and the grinding medium is modelled with DEM. The deflection profile obtained from DEM-FE simulation shows a reasonably good correspondence to pilot mill measurements. To study the charge impact on the mill structure two different charges are used in the simulations. The approach is a contribution to the validation of DEM-FE simulations and an introduction to the description of a bendable rubber lifter implemented in a DEM-FEM mill model. It opens up the possibility to predict contact forces for varying mill dimensions and liner combinations. FEM is especially valuable in this case, since there are readily available libraries with material models.

  • 12.
    Larsson, Cecilia
    et al.
    LKAB.
    Adolfsson, Göran
    LKAB.
    Siikavaara, Johan
    LKAB.
    Tano, Kent
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Fraktionerad autogenmalning vid LKAB Kiruna: bättre malning?2004In: Konferens i mineralteknik / [ed] Marianne Thomaeus; Eric Forssberg, Föreningen Mineralteknisk Forskning / Swedish Mineral Processing Research Association , 2004Conference paper (Other academic)
  • 13.
    Ljung, Anna-Lena
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Lundström, Staffan
    Sjöström, Ulf
    Swerea MEFOS AB.
    Marjavaara, Daniel
    LKAB.
    Lindblom, Bo
    LKAB.
    Tano, Kent
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Drying of an iron ore pellet: investigation of the influence of surface irregularities and overall geometry2010In: Proceedings of the 3rd International Conference on Porous Media and its Applications in Science and Engineering, ICPM3, 2010Conference paper (Refereed)
    Abstract [en]

    In this paper, simulations of the first drying period of a single iron ore pellet are compared for: i) a scanned pellet from experiments ii) an oval pellet resembling the experimental one with equivalent volume iii) a spherical pellet with equivalent volume. The comparison provides information on how simplifications of an actual geometry might affect the result. The simulations are carried out with the commercial software ANSYS CFX 12.0 and the model is validated against experimental results with good agreement. The results show that the local moisture content at the surface is influenced by both surface irregularities and overall geometry. A smooth surface will decrease the local variation of moisture while a spherical geometry will, compared to an oval, increase the difference.

  • 14.
    Ljung, Anna-Lena
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Lundström, Staffan
    Tano, Kent
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Enkulemodell för torkning av järnmalmspellets2009In: Svenska mekanikdagarna: Södertälje 2009, Stockholm: Svenska nationalkommittén för mekanik , 2009, p. 104-Conference paper (Other academic)
  • 15.
    Ljung, Anna-Lena
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Lundström, Staffan
    Tano, Kent
    Fluid flow and heat transfer within and around a porous iron ore pellet placed in infinite space2008In: Proceedings of the 19th International Symposium on Transport Phenomena (ISTP-19): Reykjavik, Iceland, August 17-21, 2008 / [ed] Sigurdur Brynjolfsson; Olafur Petur Palsson; Jong H. Kim, University of Iceland, Faculty of Industrial Engineering, Mechanical Engineering and Computer Science , 2008Conference paper (Refereed)
    Abstract [en]

    The forced convective heating of a porous cylinder with properties similar to an iron ore pellet is here numerically investigated. The numerical setup is based on a two dimensional microporous model with surrounding flow field taken into account. The simulations are carried out with special attention directed towards minimizing numerical errors. With interface conditions provided by CFD, simulations show an increased heat transfer rate for the porous cylinder when compared to a solid.

  • 16.
    Ljung, Anna-Lena
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Lundström, Staffan
    Tano, Kent
    Heat, mass and momentum transfer within an iron ore pellet during drying2008In: Proceedings of CHT-08 ICHMT International Symposium on Advances in Computational Heat Transfer, International Centre for Heat and Mass Transfer , 2008Conference paper (Refereed)
    Abstract [en]

    Iron ore pellets is one of the most refined products for mining industry. Being such, there is a natural driving force to enhance the pelletization in order to optimize production and improve quality especially since the process is time and energy consuming. In order to be successful it is of highest importance that the pelletization process is known in detail. Following this demand, heat and mass transport within a single pellet during drying is modeled with aid of Computational Fluid Dynamics. A two dimensional rectangular domain is chosen to represent the porous media within the pellet and the governing equations are set up for one directional flow through it. Convective transport of water and air through the capillaries of the porous media is computed from Darcy's law being adapted to a two-fluid system. Vaporization by boiling is taken into account and two energy equations are used to calculate the temperature distribution, one for the liquid and solid, and one for the gas. To start with, iteration errors and discretization errors are found to be negligible. Following this a sensitivity analysis shows that it is important to use a realistic value of the convective heat transfer coefficient when the vaporization of water is the dominating drying mechanism while the temperature of the solid and capillary movement of water is not influenced to the same extent. The derived model can be applied to a number of numerical set-ups such as a single pellet in an infinite space.

  • 17.
    Ljung, Anna-Lena
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Lundström, Staffan
    Tano, Kent
    Simulation of convective drying of a cylindrical iron ore pellet2011In: International journal of numerical methods for heat & fluid flow, ISSN 0961-5539, E-ISSN 1758-6585, Vol. 21, no 6, p. 703-716Article in journal (Refereed)
    Abstract [en]

    Purpose – The purpose of this paper is to numerically model convective drying of a two-dimensional iron ore pellet subjected to turbulent flow.Design/methodology/approach – Simulations of the iron ore pellet drying process are carried out with commercial computational fluid dynamics software. The moisture distribution inside the pellet is calculated from a diffusion equation and drying due to evaporation at the surface is taken into account.Findings – The results show an initial warm up phase with a succeeding constant rate drying period. Constant drying rate will only be achieved if the surface temperature is constant. The falling rate period will subsequently start at the forward stagnation point when the minimum moisture content is reached, while other parts of the surface still provide enough moisture to allow surface evaporation. The phases will thus coexist for a period of time.Research limitations/implications – Owing to the complex physical processes involved in iron ore pellet drying, some parameters in the model are based on estimations. The effective diffusivity should, for example, in the future be investigated more thoroughly. It is also important to extend the model so that the falling rate drying period is also included. The model is at present undergoing further validation.Practical implications – The simulations can provide detailed information on some key fluid dynamics and physical processes that an iron ore pellet undergoes during drying.Originality/value – The simulations enhance the understanding of iron ore pellet drying and the model provides a complement to experimental investigations when optimizing the drying process.

  • 18.
    Ljung, Anna-Lena
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Lundström, Staffan
    Tano, Kent
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Simulation of heat transfer and fluid flow in a porous bed of iron ore pellets during up-draught drying2006In: Proceedings of the Fifth International Conference on CFD in the Process Industries: Hilton on the Park, Melbourne, Australia, 13-15 December 2006 / [ed] P.J. Witt, Melbourn: CSIRO Publishing, 2006Conference paper (Refereed)
    Abstract [en]

    Iron ore pellets is one of the most refined products for companies such as LKAB and it is therefore a global need for research in the area in order to optimize the production and improve quality. This work aim at modelling and optimizing the drying zone of a travelling grate pelletizing plant and to start with, a model of velocity and temperature distribution in the up-draught drying zone is developed with aid of computational fluid dynamics. The velocity distribution in the porous bed is described by laws of fluid dynamics in porous media. The dominating heat transfer mechanism is convection and two energy equations are required since the porous media region contains both fluid and solid. Result from simulations show a rapid cooling of air due to the high specific surface area in the porous material. Conclusions are that it is possible to simulate convective heat transfer within a porous media in ANSYS CFX 10.0. There are however some limitations when using the diffusive transport equation as the solid phase energy equation that need further investigation. Moisture content and condensation in the bed are not included in the present model and is therefore subject to future work

  • 19.
    Ljung, Anna-Lena
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Lundström, T. Staffan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Marjavaara, Daniel
    LKAB.
    Tano, Kent
    Influence of air humidity on drying of individual iron ore pellets2011In: Drying Technology, ISSN 0737-3937, E-ISSN 1532-2300, Vol. 29, no 9, p. 1101-1111Article in journal (Refereed)
    Abstract [en]

    The influence of air humidity on drying is investigated at four inlet air dew points; T dp = 273, 292, 313, and 333 K. A numerical model taking into account capillary transport of liquid and internal evaporation is applied to a spherical geometry representative for an individual iron ore pellet. Drying simulations are carried out with commercial computational fluid dynamic (CFD) software and the boundary conditions are calculated from the surrounding fluid flow. The results indicate that the effect of air humidity arises from the start of the first drying period, that is, the surface evaporation period, whereas the difference is reduced at the end of the period due to a prolonged stage of constant rate drying attained at high saturations. At low saturations, there is no constant drying stage because the surface becomes locally dry before the pellet temperature has stabilized at the wet bulb temperature. The magnitudes of the drying rates and moisture contents are rather similar at the time when internal drying becomes dominating (i.e., when the total surface evaporation rate is zero) for the respective dew points, yet the drying time is increased at high saturations. It was also found that the moisture gradients at the surface and inside the pellet increased with drying rate.

  • 20. Nordgren, Samuel
    et al.
    Dahl, Jan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Larsson, Mikael
    Lindblom, Bo
    LKAB.
    Savonen, Stefan
    LKAB.
    Tano, Kent
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Development of a process integration tool for an iron ore upgrading process system2007In: Mine planning and equipment selection and environmental issues and waste management in energy and mineral production: proceedings of the Sixteenth International Symposium on Mine Planning and Equipment Selection (MPES 2007) and the Tenth International Symposium on Environmental Issues and Waste Management in Energy and Mineral Production (SWEMP 2007) ; MPES 2007 and SWEMP 2007 ; held jointly in Bangkok, Thailand, December 11 - 13, 2007 / [ed] Rai K. Rai K., Irvine, Calif.: The Reading Matrix Inc. , 2007Conference paper (Refereed)
    Abstract [en]

    An industrial energy system is subject to different regulations and restrictions. Good integration between units within the production chain as well as integration with the community can lead to both environmental and energy savings. Process integration is a system oriented methodology to analyze whole production systems to find optimal system changes. A mathematical programming technique is being developed for the Swedish iron ore producing facility of LKAB in Malmberget. The mathematical model will be based on a mass and energy balance for the facility specified for the different unit operations. The development of a good mathematical model requires a systematic mapping of the energy and material flows within an iron ore producing facility. In this paper a conceptual model for the process integration tool is described.

  • 21. Oghazi, Pejman
    et al.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Tano, Kent
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    An attempt to apply traceability to grinding circuits2007In: Conference in Mineral Processing, Luleå, Sweden, February 6-7, 2007, 2007, p. 169-183Conference paper (Other academic)
  • 22. Oghazi, Pejman
    et al.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Tano, Kent
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Applying traceability to grinding circuits by using Particle Texture Analysis (PTA)2008In: Proceedings of Communion 08: Falmouth, UK, June 17-20 2008, Minerals Engineering International , 2008Conference paper (Refereed)
    Abstract [en]

    LKAB has started a new pelletizing plant at Malmberget, where the raw material will be a mix of ores from Kiruna and Malmberget. The new plant necessitated an investment in a new grinding section in the concentrator. As usual, the new section has larger mills. It also lacks the wet cobbing stage present in the old sections.Comparing the results from the new section with the old sections show that they give similar results. There are slight variations; the older mills produce a steeper final particle size distribution. Also, it appears that the new mills are more efficient, since they have higher calculated grindability indices.To better understand the differences between the sections, and the process implications of the new grinding section, a combination of Particle Texture Analysis (PTA) and the statistical method Multivariate Analysis (MVA) is used. It shows that it is possible to identify and follow systematic changes in the particle morphology of the mill products. Also, that there are differences between the old and new grinding sections.

  • 23. Oghazi, Pejman
    et al.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Tano, Kent
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Applying traceability to grinding circuits by using Particle Texture Analysis (PTA)2009In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 22, no 7-8, p. 710-718Article in journal (Refereed)
    Abstract [en]

    LKAB has started a new pelletizing plant at Malmberget, where the raw material will be a mix of ores from Kiruna and Malmberget. The new plant necessitated an investment in a new grinding section in the concentrator. As usual, the new section has larger mills. It also lacks the wet cobbing stage present in the old sections.Comparing the analysis data from the new grinding section with the old grinding sections it shows that they give similar results. There are slight variations; the older mills produce a steeper final particle size distribution. Also, it appears that the new mills are more efficient, since they have higher calculated grindability indices.To better understand the differences between the sections, and the process implications of the new grinding section, a combination of Particle Texture Analysis (PTA) and the statistical method multivariate data analysis (MVDA) is used. It shows that it is possible to identify and follow systematic changes in the particle morphology of the mill products. Also, that there are differences in process mineralogical aspect between the old and new grinding sections.

  • 24.
    Oghazi, Pejman
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Tano, Kent
    Classifying best access points for return of external flows into flowsheets2011In: Open Mineral Processing Journal, ISSN 1874-8414, E-ISSN 1874-8414, Vol. 4, p. 1-6Article in journal (Refereed)
    Abstract [en]

    External flows are process streams that come from auxiliary processes or events. They are re-routed into the ordinary flowsheet since they are thought to be too valuable to be sent to any tailings pond. External flows come from multiple sources, e.g. drainage sumps, spillage thickeners, depleted products etc. Therefore, external flows may fit or notfit into an existing flowsheet depending on several factors like, flow rate frequency, dilution ratio variation, chemical and mineralogical composition, particle size or particle morphology. By using Particle Texture Analysis to investigate external flows and compare them with existing ordinary flows it is possible to pinpoint from a process mineralogy via point to what extent the external flow fits into the ordinary processing flowsheet. Results from this information category helps to reach a higher quality of process knowledge and control for every step in the concentrator. Results show that some recycled flows reconnected to the main flow are not connected to the best point. A side effect of the analysis is that some flows may be sent to later grinding stages. Thus, decreasing the load on the primary mill, and increasing the retention time.

  • 25. Oghazi, Pejman
    et al.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Tano, Kent
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Kvarnström, Björn
    Traceability by multivariate analysis on morphology data from grinding circuit2008In: Conference in Minerals Engineering, Luleå, 2008, p. 81-95Conference paper (Other academic)
    Abstract [en]

    LKAB has started a new pelletization plant at Malmberget, the raw material is a mix from Kiruna and Malmberget. To achieve good products it is important to have a good control over the input material in the concentrators that is why the traceability of the process is a crucial factor. However, creating traceability in continuous processes imply vast challenges: process flows can be parallel, serial and reflux; sub processes can be continuous as well as batch-wise; large buffers; no interruptions in product handling. These challenges imply that loads of data from the material is needed for creating traceability. In this case the grinding sections have been in focus and the data are collected from the old and the new grinding sections. The main task is to find a way to make the traceability easy and practical. One way to reach good traceability would be to find a process mineralogical signature or identification. For having a good traceability we need information from the system. It is important to analyze and look into the variables that have a crucial importance to the process. By using Particle Texture analysis a good overview of how magnetite is liberated or associated to others minerals is shown. More important is that morphological data is produced for each mineral in the process. The number o variables made it difficult to compare the result, and by using multivariate analysis such as Principal Component Analysis (PCA) it is possible to have a better insight from the collected data.

  • 26.
    Sellgren, Anders
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Berggren, Andreas
    Boliden Mineral AB.
    Tano, Kent
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Some aspects of slurry flows in a mill2004In: Konferens i mineralteknik / [ed] Marianne Thomaeus; Eric Forssberg, Föreningen Mineralteknisk Forskning / Swedish Mineral Processing Research Association , 2004Conference paper (Other academic)
  • 27.
    Tano, Kent
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Continuous monitoring of mineral processes with special focus on tumbling mills: a multivariate approach2005Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Increasing emphasis on productivity and quality control has provided an impetus to research on better methodologies for diagnosis, modelling, monitoring, control and optimisation of mineral process systems. One of the biggest challenges facing the research community is the processing of raw sensor data into meaningful information. Information that to some extent express quality parameters such as chemical assays, size distribution and other metallurgical variables in the different process streams. This thesis shows how multivariate statistical methods can be used with great advantage to model process data as well as robust sensor data. The modelling approach has been applied on a large process section, a cobbing plant, as well as a single unit operation, a tumbling mill. The knowledge of conditions inside a tumbling mill are of limited extent, due to a very harsh and wearing environment. A strain gauge sensor that measure the deflection of a lifter bar when it hits the charge inside a tumbling mill is studied for different operating conditions in a pilot scale ball mill. The deflection of the lifter bar during every mill revolution gives rise to a characteristic signal profile that is shown to contain information on both the charge position and grinding performance. The results presented for prediction of grinding performance suggest that the strain gauge signal in combination with wavelet transformation and multivariate data analysis provide promising means for monitoring and control of process fluctuations. The low prediction error achieved for grinding performance clearly highlights the importance of well-planned experimental strategy including experimental design, signal pre-processing, multivariate modelling and validation. Results also demonstrate that different operating conditions is well distinguishable from each other and by that the finding of proper operating regimes are highly feasible. Grinding parameters that are normally measured in the laboratory are now readily modelled from the on-line signal. As a consequence this opens new possibilities for real time monitoring and control of the grinding process. A further objective of this work is to link computational results to the experimental data obtained from the instrumented pilot ball mill. The approach taken is to simulate the behaviour of a rubber lifter when it is exposed to forces from the grinding load in a two-dimensional Distinct Element Method (DEM) mill model. Typically walls in a DEM model are made up of rigid bodies where the equations of motion are not satisfied for each individual wall - i.e., forces acting on a wall do not influence its motion. Here the instrumented rubber lifter is represented as an assembly of bonded particles rather than walls in order to simulate deflection. The deflection profile obtained from the DEM simulation shows a reasonably good correspondence to the pilot mill measurements. The difference is attributed to the fact that time-dependent behaviour of the rubber lifter is ignored, resulting in rapid relaxation of the lifter when the exerted force is released. Mill charge features such as toe and shoulder position of the charge are well marked. However, DEM prediction shows lower values compared to measurements which is most likely an effect of the two dimensional model used and the inability to model the effect of slurry present in the mill. The news value of the thesis work is in the method for analysing the signal profile as well as the experimental verification in both pilot and full scale operation. The result is a contribution to improved mill lifter design and continuous monitoring of the grinding process.

  • 28.
    Tano, Kent
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Multivariate modelling and monitoring of mineral processes using partial least square regression1996Licentiate thesis, comprehensive summary (Other academic)
  • 29.
    Tano, Kent
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Berggren, A.
    Boliden Mineral AB.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    On-line measurement of charge position and filling level in industrial-scale mills2005In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 22, no 3, p. 121-129Article in journal (Refereed)
    Abstract [en]

    Pilot-scale experiments presented in this paper show good results in detecting charge movement when using the Metso Continuous Charge Measurement system (CCM). In this technique, a strain-gauge sensor is mounted on a steel plate that, in turn, is placed under one of the rubber lifters used to lift the charge. A deflection profile is registered and the signal pattern is correlated to charge position and filling level. Charge measurements in industrial-scale mills - a ball mill at the LKAB iron ore beneficiation plant in Malmberget and an AG-mill at the Boliden Aitik copper mine plant - as well as a comparison with a pilot scale ball mill are presented. The results indicate that the system is very capable of following the normal variations that occur in the mills. Determination of various charge parameters, such as volume and toe position, is shown to be both robust and accurate. A prediction error of less than ± 1% in the mill filling level was achieved, which should be adequate for process-control purposes. By studying the nature of the signal it is possible to get a better understanding of the dynamics of grinding circuits. The influence of the ore feed size on the dynamic charge behavior in an AG-mill was studied, and there were interesting indications of a change in slurry rheology. Another feature of the sensor is its ability to respond quickly to various operating conditions. This allows an operator to continuously follow the grinding process and to incorporate the signal into a control strategy for real-time actions, thereby running at optimal operating conditions.

  • 30.
    Tano, Kent
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Johansson, Ursula
    Luleå tekniska universitet.
    Forsling, Willis
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Studies of adsorption on mineral surfaces by FT spectroscopy1997In: Microchimica Acta, ISSN 0026-3672, E-ISSN 1436-5073, Vol. Suppl. 14, p. 647-648Article in journal (Refereed)
    Abstract [en]

    Specific surface reactions have been studied by adsorbing different type of substances on the surfaces of kaolinite and gamma-alumina. Analyses were performed by means of FT-Raman and diffuse reflectance mid-IR. The DRIFT spectra indicate isotopic exchange of hydroxyl groups on kaolinite and that it is possible to adsorb silanes at the surface. DRIFT and FT-Raman spectra indicate that the solvent map react with the gamma-alumina surface and that phosphate adsorption occurs at the surface.

  • 31.
    Tano, Kent
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Assessment of mill lifter bar deflection measurements using wavelets and discrete element methods2006In: WPMPS Workshop "Discrete Element Modeling" at the 5th International Conference for Conveying and Handling of Particulate Solids: CHoPS-05, 2006Conference paper (Refereed)
  • 32.
    Tano, Kent
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Assessment of mill lifter bar deflection measurements using wavelets and discrete element methods2008In: Granular Matter, ISSN 1434-5021, E-ISSN 1434-7636, Vol. 10, no 4, p. 279-283Article in journal (Refereed)
    Abstract [en]

    This paper shows how Partial Least Square Regression (PLS) methods can be used to model sensor data of spectral character. The modelling approach has been applied on a tumbling mill where a strain gauge sensor measures the deflection of a lifter bar when it hits the charge. The deflection of the lifter bar during every mill revolution gives rise to a characteristic signal profile that is shown to contain information on both the charge position and grinding performance. As a signal pre-processing method the discrete wavelet transform is used. It distinctly shows a capability of signal feature extraction where both time and frequency are of interest. Its well-known ability to achieve good data compression without loss of information is also demonstrated, a data reduction ratio of 20:1 is obtained here. Modelling results demonstrate that different operating conditions are well distinguishable from each other and by that the finding of proper operating regimes are highly feasible. Grinding parameters that are normally measured in the laboratory are now readily modelled from the on-line signal. A further objective of this paper is to link the experimentally obtained strain gauge sensor data with computational data from a discrete element mill model (DEM). This enables to visualise the charge motion and helps to interpret the complex phenomena that take place inside a grinding mill measured by the strain gauge sensor. The approach taken is to simulate the behaviour of a rubber lifter when it is exposed to forces from the grinding charge in a two-dimensional DEM mill model using a particle flow code. The deflection profile obtained from the DEM simulation shows a reasonably good correspondence to pilot mill measurements.

  • 33.
    Tano, Kent
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Alatalo, Johanna
    Validation of a computer simulated circuit design at the LKAB Malmberget concentrator2006In: 11th European Symposium on Comminution: Proceedings, 2006Conference paper (Refereed)
  • 34.
    Tano, Kent
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Alatalo, Johanna
    Lindqvist, L.
    The use of process simulation methodology in process design where time and performance is critical2006In: Advances in comminution: [third international symposium, 2006] / [ed] S. Komar Kawatra, Littleton, Colo: Society for Mining, Metalurgy and Exploration, 2006, p. 481-493Conference paper (Refereed)
    Abstract [en]

    In 2004, LKAB decided to start a basic engineering study in expanding its existing production lines at the Malmberget mine site. Current limitations in the underground mine capacity entail the need to use ore from other mine sites which result in varying ore properties regarding grindability and chemical composition. It was necessary to determine if the required particle size from an agglomeration point of view could be obtained with extreme ore types by design in a robust process and a proper control strategy. In addition, project time constraints forced a decision of final design of the ore beneficiation process to be based on a combination of pilot scale campaigns and process simulations.

  • 35.
    Tano, Kent
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Sellgren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    On-line lifter deflection measurements showing flow resistance effects in grinding mills2005In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 18, no 11, p. 1077-1085Article in journal (Refereed)
    Abstract [en]

    The deflection that a lifter bar is subjected to when passing through a grinding charge was measured using an embedded strain gauge sensor. The obtained signal profile is analysed and interpreted in relation to charge properties such as toe and charge angle for the grinding charge. The current work has focused on the charge and slurry flow behaviour when solids content is changed and how well the sensor reflects this. Bench scale measurements with a vane type viscometer, roughly evaluated in terms of apparent viscosity is used as a character for the resistance to motion of the slurry. The slurry flow resistance is strongly influenced by solids content and obviously by the addition of a dispersant. The strain gauge sensor reflected this change well, showing that toe and shoulder region of the charge varied in a systematic way. Results obtained also shows that change of slurry flow resistance exert an influence on grinding performance. A multivariate statistical method, partial least squares regression, is applied to the sensor data producing a model that can predict the change in slurry flow resistance. The output from the model also shows good properties to be used as a process-monitoring tool. The predictive capability of the model is believed to be of such quality that it can be used for process control.

  • 36.
    Tano, Kent
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Öberg, Eva
    LKAB.
    Samskog, Per-Olof
    Monredon, T
    Svedala-Cisa, Orléans.
    Broussaud, A.
    Svedala-Cisa, Orléans.
    Comparison of control strategies for a hematite processing plant1999In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 105, no 1-3, p. 443-450Article in journal (Refereed)
    Abstract [en]

    A model-assisted method is used for designing the control strategy for the new LKAB hematite plant in Malmberget (Sweden). Steady-state and dynamic process simulations successively help to select strategic controlled and manipulated variables, and specify the corresponding instrumentation. The control system implemented in the plant reflects the conclusions of the study. It includes an optimizing control system based on specified software, with a fuzzy logic expert system, a dynamic model of the process and an optimizer.

1 - 36 of 36
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