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  • 51. 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.

  • 52. Pourghahramani, Parviz
    et al.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Forssberg, Eric
    Multivariate projection and analysis of microstructural characteristics of mechanically activated hematite in different grinding mills2008In: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 87, no 3-4, p. 73-82Article in journal (Refereed)
    Abstract [en]

    A statistical analysis was done to investigate the relationship between grinding variables and structural changes during mechanical activation of hematite concentrate. Experiments were carried out according to a statistical design by varying the grinding time, media surface and mill type. Several multivariate techniques are applied to interpret the grinding processes.The variance analysis revealed that the media surface and grinding time significantly influence the five main response variables at 95% confidence level. The use of multivariate analysis allows the projection of high-dimensional data to a low subdimensional subspace. An overview of principal component analysis (PCA) on 27 variables yielded a three component model explaining 89% and predicting 76% of the total variance. It was found that the observations belonging to low and high levels of media surfaces fall into two groups. Most of the microstructural characteristics such as microstrain, dislocation and amorphization and granulometric surface area, BET specific surface area, specific energy input, stored energy, portion of smaller particles and stress energy coincide with high level of media surface group. The variables crystallite size, peak intensity and mean particle size appear with lower media surface. The PLS-DA (partial least squares discrimination analysis) made it possible to discriminate the three types of mills. From the projection of dummy variables, it was concluded that the vibratory mill caused comparatively less structural changes in hematite than the other mills in spite of releasing higher stress energy. The planetary mill introduced relatively higher dislocation defects and generated higher lattice strain. The hematite ground in the tumbling and planetary mills had comparatively higher X-ray amorphization degree and subsequently higher excess energy than the hematite ground in the vibratory mill. The tumbling mill produced relatively lower specific surface than the others. It was concluded that the products of the tumbling mill represented higher defect concentration (amorphization) per unit surface area despite releasing lower stress energy level. From the PLS modeling of the five main response variables, it was found that the X-variables specific energy input and stress energy are the most influencing factors.

  • 53.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Activity: Minerals engineering education at LTU2011Conference paper (Other (popular science, discussion, etc.))
  • 54.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Aktivitet: Konferens i mineralteknik 20092009Conference paper (Other (popular science, discussion, etc.))
  • 55.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Analys av restreagens med hjälp av jonkromatografi1987In: Konferens i mineralteknik: Luleå 10-12 februari 1987 / [ed] Börje Sköld; Eric Forssberg, MinFo , 1987, p. 197-213Conference paper (Other academic)
  • 56.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Computer-assisted calculations of chemical equilibria with relevance to the chromate depression of galena1991In: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 33, no 1-4, p. 207-221Article in journal (Refereed)
    Abstract [en]

    The computation of theoretical chemical equilibria, to simulate the conditions in the copper-lead separation bank of a flotation plant, is performed. The calculations, and results reported in the literature, indicate that chromate to a large extent acts as a redox controlling reagent in the pulp. If the action of dichromate/chromate essentially is that of an oxidant, then there ought to be cheaper and environmentally safer alternatives.

  • 57.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Förändrad och internationaliserad utbildning mineralteknik och processmetallurgi vid Ltu2005In: Konferens i mineralteknik / [ed] Marianne Thomaeus; Eric Forssberg, Föreningen Mineralteknisk Forskning / Swedish Mineral Processing Research Association , 2005Conference paper (Other academic)
    Abstract [sv]

    Under senare år har utbildningsprogrammet Kemiteknik vid LTU fått stora problem med rekryteringen av studenter. "Vanlig" rekrytering med mässor, broschyrer och via officiella Web-sidor fungerar dåligt. För gruv- och mineralbranschen är det allvarligt eftersom specialiseringen i mineralteknik och processmetallurgi hämtar sina studenter från Kemiteknik. Nu förändras grundutbildningen för att passa in i en Bologna-modell med 3 års grundutbildning följt av 2 år i ett master-program. Resultatet är en civilingenjörsutbildning i Kemiteknisk design, där de sista åren också finns inom internationella master-utbildningar. En av dessa heter Minerals and Metallurgical Engineering.

  • 58.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Höghållfast betong: självuttorkning och hållfasthet1990In: Bygg & Teknik, ISSN 0281-658X, no 7, p. 21-22, 25Article in journal (Other (popular science, discussion, etc.))
  • 59.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Implementing the Bologna process at LTU: a tool for flexibility2006In: Konferens i mineralteknik: Luleå, Sweden February 7-8, 2006 / [ed] Marianne Thomaeus; Eric Forssberg, 2006Conference paper (Other academic)
    Abstract [en]

    Due to shrinking enrolment in Chemical/Mining Engineering at LTU, several measures have been implemented to add flexibility in time and location of education. In addition, the Bologna model for higher education is already put into action with three Master programmes, which admitted students this educational year. A new School of Natural Resources is suggested to further add flexibility in running of courses, and serve as marketing point for studies at LTU.

  • 60.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Mineralteknik: aktuellt om utbildning och forskning2008In: Conference in Minerals Engineering, Luleå: Luleå tekniska universitet, 2008, p. 97-106Conference paper (Other academic)
    Abstract [sv]

    Utbildningsprogrammet i Kemiteknik har genom anpassning till Bologna-modellen fått en struktur, som gör det möjligt att samverka med andra utbildningsprogram och Master-program inom specialiseringen för mineralteknik och processmetallurgi. Eftersom gruvbranschen upptäckt att det behövs utbildade medarbetare har även efterfrågan på kortare utbildningar ökat. Forskningen börjar kunna utnyttja att branschen har framgångsrikt verkat för forskningsprogram med relevans för mineralteknik och metallurgi. Mineralteknik börjar rekrytera nya forskarstuderande och kan med industrins hjälp åter bli ett aktivt kunskapscentrum för gruvbranschen.

  • 61.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Mineralteknikutbildning i framtiden - en virtuell upplevelse?2004In: Konferens i mineralteknik / [ed] Marianne Thomaeus; Eric Forssberg, Föreningen Mineralteknisk Forskning / Swedish Mineral Processing Research Association , 2004Conference paper (Other academic)
  • 62.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Modelling the pulp chemistry of sulphide froth flotation1986Licentiate thesis, comprehensive summary (Other academic)
  • 63.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Pulp chemistry of sulphide froth flotation1988Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The pulp chemistry of chalcopyrite, galena and sphalerite is analyzed theoretically, with computer-aided modelling, and practically with ion chromatography. Ion chromatography is used for analyzing the inorganic and organic anion chemistry of sulphide flotation. The adaptation of modern, rapid analytical techniques to sampling in pulp environments has given valuable information on the metastable state of the processes. Data from the field measurements are then used to construct pulp chemistry models that satisfactorily explain observed phenomena in the flotation of sulphide minerals. The chemical models, presented mainly as predominance diagrams, incorporate the modelling concepts: 'surface molarity' which is the concentration of components emanating from a thin ]aver of the mineral surface. 'thiosulphate metastability' which is modelled through adjusted formation constants of sulphite and sulphate species, 'hydroxoxanthates' as models of metal-xanthate surface compounds/complexes, 'operational line' which describes the pe-pH path of a process point in a pulp chemistry system. Based on current knowledge, one can postulate that the formation of a 1:1-compound on the mineral surface is a pre-requisite for acceptable flotation results, and that the actual flotation area coincides with the formation of the stoichiometric bulk metal-collector compound. The direct ion chromatography measurement of xanthate, perxanthate and monothiocarbonate, implies that on-line optimization of reagent addition and reagent distribution is now possible.

  • 64.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Tolkning av flotationsförlopp med hjälp av pulpkemiska modeller1986In: Workshop i mineralteknik: Luleå 11-12 februari 1986 / [ed] Börje Sköld; Eric Forssberg, MinFo , 1986, p. 105-122Conference paper (Other academic)
  • 65.
    Pålsson, Bertil
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Bucht, Johan
    R&D Mineral Processing, LKAB.
    Fine screening with electrically heated screen decks2011Conference paper (Other academic)
    Abstract [en]

    The purpose was to test some specific applications with electrically heated screen decks, and to prepare a standard test procedure for evaluating probalistic screens. One application was the production of magnetite -1 mm from sinter fines, where very strong consolidation effects were discovered and had to be taken into consideration. Specifically, consolidated sinter fines with moisture content more than 1 % gave high losses.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 and too fine 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.

  • 66.
    Pålsson, Bertil
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Bucht, Johan
    LKAB/Minelco.
    Fine screening with electrically heated screen decks: report over initial tests and their evaluation2010In: Conference in Minerals Engineering: Luleå, 2 -3 februari 2010 / [ed] Johanna Alatalo, Luleå: Luleå tekniska universitet, 2010, p. 155-168Conference paper (Other academic)
    Abstract [en]

    Minelco by LKAB, Technology and Business Development, has commissioned Mineral Processing at LTU to conduct a series of investigations with a new screening device hitherto not used by LKAB. The screen, Mogensen Sizer G054 with electrically heated decks, was during the trials located in the pilot plant at Mineral Processing, where a test station was built for it. The purpose of the investigations was to test some specific applications, and to prepare a standard test procedure for evaluating screening tests with a Mogensen Sizer. One application was the production of magnetite -1 mm from sinter fines, where very strong consolidation effects were discovered and had to be taken into consideration. Specifically, consolidated sinter fines with moisture content more than 1 % gave high losses.The tests show that 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 and too fine particles in the finished product. The direct effect of the level of heat is not yet clear. There appears to be some threshold level for the heating, 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 not known.

  • 67.
    Pålsson, Bertil
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Forssberg, Eric
    Computer-assisted calculations of thermodynamic equilibria in sphalerite-xanthate systems1989In: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 26, no 3-4, p. 223-258Article in journal (Refereed)
    Abstract [en]

    Sphalerite flotation is analyzed on the basis that it occurs in a pulp chemistry environment, where the dominant variables are the electron activity (pe), and the hydrogen ion activity (pH). The literature indicates that sphalerite can be floated with long-chained xanthates in neutral pulps, and that hydroxoxanthates of Zn and Fe(III) are possible intermediate steps in the flotation process.Theoretical computations indicate the following properties: (1) the pulp carbonate content is the factor having the strongest influence on the nature of the surface of sphalerite/zinc minerals in flotation systems; (2) ethyl xanthate and zinc will not form any solid compounds; (3) the theoretically calculated precipitation area of zinc isopropyl xanthate coincides with pH-areas known for enhanced zinc flotation; (4) Zn(OH)iPX(s) and Zn(OH)AX(s) can be formed under conditions similar to those encountered in flotation; (5) Zn-ethyl xanthate complexes will not contribute significantly to the mobilization of Zn into solution, but might likewise cause a high, environmentally disquieting, content of metal-organic compounds in concentrator effluents; (6) Fe(III)-hydroxoxanthates, but not Fe(II)xanthates, can be formed under the conditions studied.Computational results obtained so far indicate that the contents, i.e. the metallic content of the solution, are controlled by the formation of solid bulk compounds such as hydrozincite, while the formation of simpler surface compounds (surface complexes) is controlled by conditions on the mineral surface. One way to take this into account would be to include an extra fluid phase, which will model the mineral/solution boundary layer.

  • 68. Pålsson, Bertil
    et al.
    Forssberg, Eric
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Computer-assisted calculations of thermodynamic equilibria in the galena-ethyl xanthate system1988In: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 23, no 1-2, p. 93-121Article in journal (Refereed)
    Abstract [en]

    Calculations show that thermodynamic data can be used to construct pulp chemistry models that describe events in mineral pulps. The introduction of kinetic restrictions derived from pulp chemistry analysis of full-scale flotation processes will additionally enhance the models. For the galena-ethyl xanthate system the pulp carbonate content is the factor which has the greatest influence on the nature of the surface of the galena/lead mineral in flotation system. The theoretically calculated upper precipitation limit of Pb(EtX)//2(s) is in good agreement with published data. Pb(OH)EtX//2(s) can be formed in carbonate-deficient environments in a bigger area than Pb(EtX)//2(s) where flotation has been observed while overdosing xanthate. The surface compound-Pb-EtX may be a ternary surface complex.

  • 69.
    Pålsson, Bertil
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Fredriksson, Andreas
    LKAB.
    Apatite for extraction: II. Flotation of apatite and rare earth elements from old tailings dumps2012In: XXVI International Mineral Processing Congress: IMPC 2012, New Delhi, India, September 24-28, 2012 : conference proceedings., New Delhi: The Indian Institute of Metals , 2012, p. 4064-4074Conference paper (Refereed)
    Abstract [en]

    The most common REE containing mineral that is worked today is bastnäsite. It means that mineral processes are adapted to it and that the metallurgical separation techniques for winning of individual REE are adapted to bastnäsite concentrates. For all other deposit types, suitable mineral processing methods and separation technologies need to be adapted and/or developed.Preliminary mineralogical analyses indicate that slightly less than half of the REE in the tailings dumps at LKAB/Kiruna are associated to apatite. The rest is in the minerals monazite (maybe associated to apatite) and allanite. At least allanite is probably not floatable with reagents commonly used for apatite. Mass and element distributions for the tailings sand reveal that very little apatite is present above 300 μm, and that approx. 30 % is below 20 μm. REE does not follow P2O5 completely and are also present in coarser fractions.Flotation results show that the best condition for both apatite and REE winning is pH 9, high collector addition and low dosage of water glass. Under these conditions, the lab-scale flotation gives an apatite concentrate with at least 30 % P2O5 at 70 % recovery. REE follows apatite in the cleaner steps but only partly. Its recovery is approx. half compared with apatite. The reason for the low REE recovery is likely to be that REE to a large extent is trapped in non-winnable minerals, especially allanite. The REE grades in the concentrate are expected to be in the range 3000 – 4500 g/ton.

  • 70.
    Pålsson, Bertil
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Fredriksson, Andreas
    R&D Mineral Processing, LKAB.
    Benefication of ree containing minerals2012In: Conference in Minerals Engineering Luleå 7-8 February 2012 / [ed] Jan Rosenkranz; Tommy Karlkvist, Luleå: Luleå tekniska universitet, 2012Conference paper (Refereed)
  • 71.
    Pålsson, Bertil
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Karlkvist, Tommy
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Mathew, Aji P.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Nano-entities for surface modification of minerals: Implications for flotation2017Conference paper (Other academic)
    Abstract [en]

    Adsorption of nano-entities (nano-cellulose and nano-chitin) on quartz and magnetite was investigated as a function of pH with measurement of Zeta potential as a tool. The results show strong adsorption of the nano-entities on both minerals, leading to charge reversal. However, the adsorption appears to be largely non-preferential over the concentration and pH ranges investigated.

    Micro-flotation results show that both nano-entities float quartz to the same extent, and that the same is true for magnetite. However, the amount floated is higher for quartz. There is also an indication that Chitin at pH 8 has some preference for quartz over magnetite.

    Mini-flotation results for mineral mixtures at pH 8 with Chitin and flotation reagents show that Chitin can selectively float quartz for the given conditions, but the recovery is low. If oleate is added, the selectivity is lost. This means that the nano-entity is probably not a cationic activator, rather it induces some little hydrophobicity to the quartz surface on its own.

  • 72.
    Pålsson, Bertil
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Martinsson, Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Wanhainen, Christina
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Fredriksson, Andreas
    Mining Technology R and D, LKAB Kiruna Mine.
    Unlocking Rare Earth Elements from European apatite‐iron ores2014In: ERES 2014 - 1st International Conference on European Rare Earth Resources: Book of Proceedings / [ed] Efthymios Balomenos; Dimitrios Panias; Ioannis Paspaliaris, Santorini: Heliotopos Conferences Ltd. , 2014, p. 211-220Conference paper (Refereed)
    Abstract [en]

    Rare Earth Elements are known to occur within apatite‐magnetite ores of the Kiruna type. Previously it was assumed that the REE was associated to the apatite part of the ore. It is now shown that the REE follows the apatite to a much less degree, and that the REE are contained in the minerals monazite, allanite and some unknown REE‐phase still to be identified. Monazite occurs as inclusions in the apatite as well as free particles. Allanite is to some degree in mixed grains with magnetite but also in free particles. Monazite mainly reports to the apatite concentrate while allanite largely goes to the tailings. Laboratory flotation also shows some preferential concentration of heavy REE over light REE to the apatite concentrate. A new EU project, REEcover, will characterise the REE phases in this type of iron ore and among the different process streams within the mineral beneficiation chain.

  • 73.
    Pålsson, Bertil
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Persson, H.
    Luleå tekniska universitet.
    Redox control in a pilot flotation column1996In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 9, no 1, p. 73-83Article in journal (Refereed)
    Abstract [en]

    Results from pilot-column flotation tests on a lead-zinc ore show that it is possible to control the redox potential of the column pulp by varying the oxygen activity of the flotation gas fed to the spargers. As a result, the process changes so that the fine zinc minerals are more actively floating in an oxidising environment, at the same time xanthate and frother consumptions increase.The placement of electrodes in the column does change the redox potential readings but only as a result of a change in the oxygen concentration of the pulp. However, the values from a Glassy-Carbon (GC) electrode are consistently lower than those from a Pt foil electrode at the same location. Actual positions of operating points as measured by GCelectrodes fall within the theoretical area for precipitation of lead xanthate.

  • 74.
    Pålsson, Bertil
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Persson, Håkan
    Luleå tekniska universitet.
    Pilotförsök med kolonnflotation1992In: Konferens i mineralteknik: Luleå, 4-5 februari, 1992 / [ed] Börje Sköld; Eric Forssberg, MinFo , 1992, p. 209-220Conference paper (Other academic)
  • 75.
    Pålsson, Bertil
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Wanhainen, Christina
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Recovery of Rare Earth Elements from Electronic Waste by Cryo-grinding2015Conference paper (Refereed)
  • 76.
    Pålsson, Bertil
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Yuan, Xuemin
    Luleå tekniska universitet.
    Influence of grinding and pre-treatment with different gases on complex sulphide mineral flotation1994In: Konferens i mineralteknik: Luleå, 8-9 februari, 1994 / [ed] Marianne Thomaeus; Eric Forssberg, MinFo , 1994, p. 241-251Conference paper (Other academic)
  • 77.
    Pålsson, Bertil
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Öberg, Eva
    Luleå tekniska universitet.
    Interpretation of electrode responses with the help of a multivariate technique1992In: Proceedings of the Third International Symposium on Electrochemistry in Mineral and Metal Processing III: [ held during the 181st Meeting of the Electrochemical Society, Inc., in St. Louis, Missouri, May 17 - 22, 1992] / [ed] Ro Woods; Paul E. Richardson, Pennington, NJ: Electrochemical Society, Incorporated , 1992, p. 146-158Conference paper (Refereed)
    Abstract [en]

    Laboratory measurements with different electrodes in parallel under conditions of varying chemistry of the flotation pulp are reported for the case of Cu--Pb separation. It is found that the redox potential as measured with a glassy-carbon electrode correlates better with the response of an oxygen probe, than the traditional platinum-foil redox electrode. The glassy-C electrode also behaves in a way which averages the responses of mineral electrodes of pyrite, galena and, to some extent, chalcopyrite

  • 78.
    Pålsson, Bertil
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Öberg, Eva
    Luleå tekniska universitet.
    Interpretation of electrode responses with the help of a multivariate technique1993In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 140, no 9, p. 2519-2525Article in journal (Refereed)
    Abstract [en]

    Laboratory measurements in flotation pulps with different electrodes in parallel under conditions of varying pulp chemistry are reported for copper-lead separation. The redox potential as measured with a glassy-carbon electrode correlates better with the response of an oxygen probe, than the traditional Pt-foil redox electrode. The glassy-carbon electrode also behaves in a way that averages the responses of mineral electrodes of pyrite, galena, and to some extent chalcopyrite.

  • 79. Rao, K. Hanumantha
    et al.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Forssberg, Eric
    Column flotation studies of Petiknäs complex sulfide ore: influence of collector and frother dosages on the selectivity between copper and lead1997In: Proceedings of the XX International Mineral Processing Congress: 21-26 September 1997, Aachen, Germany / [ed] Heinz Hoberg; Harro von Blottnitz, Clausthal-Zellerfeld: GDMB Gesellschaft fur Bergbau , 1997, Vol. 3: Flotation and other physical chemical processes, p. 503-514Conference paper (Refereed)
  • 80.
    Sand, Anders
    et al.
    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.
    Toivakka, Martti
    Åbo Akademi University.
    Carlson, Johan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    A Stokesian Dynamics Approach for Simulation of Magnetic Particle Suspensions2015In: Proceedings of Computational Modelling 2015: Minerals Engineering International, 2015Conference paper (Refereed)
  • 81.
    Sand, Anders
    et al.
    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.
    Toivakka, Martti
    Åbo Akademi University.
    Carlson, Johan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    A Stokesian Dynamics Approach for Simulation of Magnetic Particle Suspensions2016In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 90, no SI , p. 70-76Article in journal (Refereed)
    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.

  • 82.
    Sand, Anders
    et al.
    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.
    Toivakka, Martti
    Åbo Akademi University.
    Carlson, Johan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Simulation of Magnetic Particle Suspensions Using the Stokesian Dynamics Technique2015In: Proceedings of Conference in Minerals Engineering 2015, Luleå: Luleå tekniska universitet, 2015Conference paper (Other academic)
  • 83.
    Stener, Jan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Carlson, Johan E.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Sand, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Direct measurement of internal material flow in a bench scale wet Low-Intensity Magnetic Separator2016In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 91, p. 55-65Article in journal (Refereed)
    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.

  • 84.
    Stener, Jan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Carlson, Johan E.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Sand, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Direct measurement of internal material flow in bench scale wet Low-Intensity Magnetic Separator2015In: Proceedings of Physical Separation '15, Minerals Engineering International , 2015Conference paper (Other academic)
  • 85.
    Stener, Jan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Carlson, Johan E.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Sand, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Evaluation of the applicability of ultrasonic velocity profiling in conditions related to wet low intensity magnetic separation2013In: Proceedings of Physical Separation '13, Minerals Engineering International , 2013Conference paper (Other academic)
  • 86.
    Stener, Jan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Carlson, Johan E.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Sand, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Evaluation of the applicability of ultrasonic velocity profiling in conditions related to wet low intensity magnetic separation2014In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 62, p. 2-8Article in journal (Refereed)
    Abstract [en]

    The internal material transport and selection processes of the wet low-intensity magnetic separators (LIMS) are poorly understood; this calls for improved measurement techniques. In this work an ultrasonic velocity profiling (UVP) technique for measuring how material flow velocity varies with penetration depth is presented. A measurement depth of just a couple of centimetres would greatly improve the understanding of the separation process in a LIMS.When applied to flows of mineral suspensions with high volumetric solids concentration, similar to those in the separators, UVP is unique in combining:•Non-intrusive measurements.•Operates using just one sensor element (transducer).•Relatively good spatial resolution.•Penetrates opaque suspensions.•Fast sampling rate.Here, flows are studied in a rectangular duct (50 × 75 mm). Using magnetite suspensions, measurement through the whole depth of 50 mm is made with good accuracy. Velocity profiles are presented for solids concentrations of 5% and 9% solids by volume (20% and 36% by weight). Even at 9 vol% solids it is possible to reach a penetration depth of more than 25 mm.

  • 87.
    Stener, Jan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Carlson, Johan E.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Sand, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Robust estimation of particle velocity profiles in high concentration magnetite suspensions2013In: Proceedings of the 2013 International Congress on Ultrasonics / [ed] Gan Woon Siong; Lim Siak Piang; Khoo Boo Cheong, Singapore: Research Publishing Services, 2013Conference paper (Refereed)
    Abstract [en]

    In the mining industry magnetite particles are transported in aqueous suspension through different stages of the process. In some stages it is of interest to monitor both the concentration and particle velocity profiles over a cross-section of the flow. In this paper an ultrasonic flow meter method based on cross-correlation of backscattered sound is presented. High solid particle content (e.g. 20-40 wt%) makes this challenging and therefore the emphasis lies on developing robust signal processing techniques for particle velocity estimation. The developed method is evaluated in laboratory experiments on flows in a rectangular duct. Transducers with centre frequency 1, 2, 4 and 5 MHz are evaluated in flows with a solid content of 20% by weight (4.7 vol% solids). Using the 2 MHz transducer a penetration depth of 50 mm is reached.

  • 88.
    Stener, Jan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Carlson, Johan E.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Sand, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Ultrasonic velocity profiling of flows related to wet low intensity magnetic separation2013In: Conference in Minerals Engineering: Luleå 5-6 February 2013 / [ed] Jan Rosenkranz; Tommy Karlkvist, Luleå, 2013, p. 157-168Conference paper (Other academic)
    Abstract [en]

    The internal workings of wet Low Intensity Magnetic Separators (LIMS) are poorly understood. In this work an Ultrasonic Velocity Profiling (UVP) technique for measuring material flow speed at varying depth. A measurement depth of just a couple of centimetres will greatly improve our understanding of the separation process.When applied to flows of high density mineral suspensions, similar to those in wet LIMS, UVP is unique in combining:• Non-intrusive measurements.• A single transceiver element is sufficient.• Relatively good spatial resolution.• Penetrates opaque suspensions.• Fast sampling rate.Here, flows are studied in a simple rectangular geometry (50x75 mm), using dilute magnetite suspensions; measurement through the whole depth of 50 mm is made with good accuracy. Velocity profiles are presented for different sensors at solids concentrations of 5 vol% solids.

  • 89.
    Stener, Jan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Carlson, Johan E.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Sand, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Towards the measurement of local particle mass fractions in magnetite suspensions2014In: 2014 IEEE International Ultrasonics Symposium, IUS 2014: Chicago, Ill, 3-6 September 2014, Piscataway, NJ: IEEE Communications Society, 2014, p. 939-942Conference paper (Refereed)
    Abstract [en]

    In the mining industry, magnetite particles are transported in suspensions with water through different stages of the process. In some of these stages, it is of interest to monitor both the concentration and particle velocity over a cross-section of the flow. High particle concentration makes development of flow measurement techniques challenging. An additional challenge is that the flow is often accessible from one side only, which further limits the selection of applicable techniques. Previous work by the authors focused on using pulse-echo ultrasound for flow velocity profile estimation. In this paper the same setup is used to simultaneously study local variations in solids concentration. Ultrasound pulses are transmitted into the suspension, and the resulting backscatter is recorded. The statistics of the backscatter depend on solids concentration, particle size distribution, particle density, etc. We demonstrate how a short-time (windowed) Power Spectral Density (PSD) estimate can be used to obtain qualitative information about local solids concentration variations. For demonstration, a magnetite suspension carrying up to 7.5 vol% particles (29 wt%, mean particle size 34 μm) is pumped through a closed rectangular channel. When the pump is stopped, pulse-echo ultrasound (with a center frequency of 2.25 or 3.5 MHz) is used to monitor the sedimentation process. Nine snapshots of the process are included. These show a time lapse of the sedimentation, with 5 s between each image. It is clear that the short-time PSD is a good indicator of local mass fraction variations.

  • 90.
    Stener, Jan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Carlson, Johan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Sand, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Internal flow measurements in pilot scale wet low-intensity magnetic separation2016In: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 155, p. 55-63Article in journal (Refereed)
    Abstract [en]

    In the mining industry, ferromagnetic particles (e.g. magnetite) are concentrated using wet low-intensity magnetic separation (LIMS). The performance is to a large extent controlled by the internal flow conditions in the separator. In previous work, it was shown how an ultrasound pulse-echo setup can be used to simultaneously measure particle velocity profiles and local solids concentration variations in laboratory conditions. In this paper, a real-world case is demonstrated where the system is installed on one of the wet LIMS at the LKAB R&D facilities in Malmberget, Sweden. For the pilot scale experiments a setup with two ultrasound transducers, mounted at the bottom of the separator tank, is used. The design of experiments method is used to study the effects of the feed solids concentration, drum rotational speed, position of the concentrate weir, and the magnet assembly angle on the measured flow patterns. The results show that it is possible to detect changes in the flow velocity patterns and the local solids concentration, as the operational conditions of the separator are varied. Of the factors studied, the drum rotational speed has the strongest influence on the overall flow velocity in the dewatering zone. Also, the presence of a recirculating flow transporting gangue particles away from the concentrate is confirmed. The factor with the strongest influence on this recirculating flow is also the drum rotational speed, together with the magnet assembly angle. Using this method it is possible to make high quality measurements of internal flow velocity profiles. It is also possible to monitor material build-up on the separator drum, and e.g. detect overload of magnetic material. The insights gained, and the methods developed, have generated new possibilities to control, optimise, and develop the wet LIMS process.

  • 91.
    Stener, Jan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Carlson, Johan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Sand, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Monitoring Mineral Slurry Flow using Pulse-Echo Ultrasound2016In: Flow Measurement and Instrumentation, ISSN 0955-5986, E-ISSN 1873-6998, Vol. 50, p. 135-146Article in journal (Refereed)
    Abstract [en]

    Ultrasound based flow measurement methods have a large potential for the mining industry and its processing plants. Ultrasound travel through dense suspensions and is not affected by the magnetic fields sometimes present in this type of equipment.A cross-correlation based method is used for localized particle velocity measurements in one and two dimensions. Simultaneously, using the same data, information about local particle concentration is extracted from the power spectral density of the backscattered signal. Experiments are carried out both in simplified geometry and in full scale equipment in an iron ore pilot benefication plant.In the simple geometry it is possible to assess the precision of the methods by comparing the measurements to theory and numerical simulations. The results from the pilot plant experiments show that these methods can be applied to real world processes

  • 92.
    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.

  • 93.
    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)
  • 94.
    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.

  • 95.
    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)
  • 96.
    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.

  • 97.
    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.

  • 98.
    Tano, Kent T.
    et al.
    LKAB, Research and Development, SE-983 81 Malmberget.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Rannar, Stefan
    LKAB, Research and Development, SE-983 81 Malmberget.
    Alatalo, Johanna
    LKAB, Research and Development, SE-983 81 Malmberget.
    Feature Extraction of a Strain-Gauge Signal Using Wavelets for Monitoring of a Tumbling Mill2004In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 37, no 15, p. 35-39Article in journal (Refereed)
    Abstract [en]

    Techniques that measure the force acting on a lifter bar, when it hits the charge inside a tumbling mill, have got an increased interest because of its direct physical relation to the behavior of the grinding charge. The possibility to combine it with discrete element modeling (DEM), which gives an opportunity to visualize the charge motion, opens new possibilities to understand the complex phenomena that takes place inside a grinding mill. In this work, a method for the measurement of the apparent filling level in a pilot ball mill, the Metso Continuous Charge Measurement system (CCM) has been used. The technique uses a strain gauge sensor, mounted on a flat steel spring, which is fitted into a recess underneath a lifter bar. Deflection of the lifter bar during every mill revolution will then give rise to a characteristic signal pattern depending on different operating conditions.

    In this work, which should be treated as an introduction, we show how the discrete wavelet transform can be used in multivariate calibration. It will be shown that by using the fast wavelet transform on individual signals as a pre-processing method in regression modeling on CCM measurements, good compression is achieved with almost no loss of information. The predictive ability and diagnostics of the data compressed regression model is almost the same as for the uncompressed.

  • 99.
    Tranvik, Elin
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Minerals to Metals Initiative, Department of Chemical Engineering, University of Cape Town, Rondebosch, South Africa.
    Becker, Megan
    Chemical Engineering, University of Cape Town, South Africa.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Franzidis, Jean-Paul
    Chemical Engineering, University of Cape Town, South Africa.
    Bradshaw, Dee J.
    Chemical Engineering, University of Cape Town, South Africa.
    Towards cleaner production: Using flotation to recover monazite from a heavy mineral sands zircon waste stream2017In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 101, p. 30-39Article in journal (Refereed)
    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.

  • 100.
    Wanhainen, Christina
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Martinsson, Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Lahaye, Yann
    Finland Isotope Geosciences Laboratory, Geological Survey of Finland, Espoo.
    Rare earth mineralogy in tailings from Kiirunavaara iron ore, northern Sweden: Implications for mineral processing2017In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 34, no 4, p. 189-200Article in journal (Refereed)
    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.

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