Change search
Refine search result
1 - 29 of 29
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the 'Create feeds' function.
  • 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
    LKAB.
    Influence of pebble mill operating conditions on measurements with an in-mill sensor2011In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 28, no 4, p. 193-197Article in journal (Refereed)
    Abstract [en]

    Autogenous grinding is a process of reducing the particle size distribution of an extracted ore by using the ore itself as the grinding media. It is a process that is difficult to control and there is a lack of knowledge of the events occurring inside the mill. To find out more about how the mill behaves under different processing conditions, a full factorial test was performed with iron ore in a pilot-scale pebble mill at the LKAB R&D facility in Malmberget. To complement this work, a strain gauge detector was embedded in one of the mill’s rubber lifters, the Metso Minerals continuous charge measurement (CCM) system, and was used to get more information about the charge dynamics. The data from the experiments has been analyzed. For production purposes, an increase in the number of particles smaller than 45 μm can be regarded as a probable increase in the production rate. The analysis shows that there will be an increase in fines at 65% of critical speed, especially when the mill is 45% full. This setting will also increase the power consumption, but improves the grindability of the ore even more. The deflection of the lifters is smaller for lower critical speeds. A higher degree of filling also gives a smaller toe angle and a higher shoulder angle as expected.

  • 2.
    Forssberg, Eric
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Nordqvist, Tommy
    Luleå University of Technology.
    Pilot plant trials of new gravity concentration equipment1987In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 4, no 2, p. 87-89Article in journal (Refereed)
    Abstract [en]

    In this technical note, pilot-scale tests with two types of gravity concentrators, the Knelson separator and the Mark VIIA Reichert spiral concentrator are described. The experimental work was concentrated on the relatively untried Knelson separator. The materials tested have different concentration characteristics: one was an artificial ore with excellent liberation characteristics and a wide difference in density between valuable and gangue minerals; the others include a spiral concentrate containing gold from the gravity circuit of Boliden, Sweden, an old scheelite tailing from Yxsjoberg, Sweden, and an auriferous ore containing gold that had not been crushed to full liberation. The latter three materials contained other heavy minerals, e. g. pyrite, that can interfere with concentration.

  • 3.
    Forssberg, Eric
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Wang, Yanmin
    Recovery of hematite and chromite fines and ultrafines by wet magnetic methods1994In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 11, no 2, p. 87-96Article in journal (Refereed)
    Abstract [en]

    Wet magnetic separation methods for the recovery of hematite and chromite fines and ultrafines were investigated. These methods included wet high-intensity and high-gradient magnetic separation, carrier or 'piggy-back' magnetic separation, magnetic field-induced aggregation and magnetic seeding. This investigation indicated that wet magnetic separation is more efficient for fines and ultrafines. This investigation also indicated that other methods can be used to enhance the particle aggregation and/or the magnetic response. The magnetic behavior of these minerals with respect to the magnetizing field, temperature and particle size is also presented.

  • 4.
    Franca, S.C.A.
    et al.
    Center for Mineral Technology-CETEM, Cidade Universitaria, Rio de Janeiro.
    Millqvist, M.T.
    Luleå tekniska universitet.
    Luz, A.B.
    Center for Mineral Technology-CETEM, Cidade Universitaria, Rio de Janeiro.
    Beneficiation of Brazilian diatomite for the filtration application industry2003In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 20, no 1, p. 42-46Article in journal (Refereed)
    Abstract [en]

    Laboratory experiments were performed on a Brazilian diatomite from Bahia State to produce an industrial product for use as a filter aid. Bench and pilot-plant tests were conducted. The tests consisted of diatomite desegregation, organic matter and clay removal, filtration, drying and calcination. Calcination temperature and sodium carbonate addition influenced diatomite particle size distribution. Optimum filtration rates for calcined products were obtained at 900°C and 47 minute residence time with 3% (w/w) of sodium carbonate addition. The resultant products met the specifications for filter aids.

  • 5. He, Mingzhao
    et al.
    Forssberg, Eric
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Rheological behaviors in wet ultrafine grinding of limestone2007In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 24, no 1, p. 19-29Article in journal (Refereed)
    Abstract [en]

    This paper investigates the effects of solids concentration and the addition of Dispersant S40 on the flowability of original and ground limestone slurries. A rotational viscometer with a concentric cylinder geometry and a controlled-stress rheometer with a cone-and-plate geometry were used to characterize the rheological behaviors of limestone slurries. The rheological behavior of original limestone slurries ( < 100 gm) is transformed through different types of flows with increasing solids concentration. The use of Dispersant S40 can improve the slurry flowability by decreasing viscosity and eliminating Casson yield stress. It is therefore used as a grinding aid for the wet ultrafine grinding of limestone. The rheological behaviors of ground limestone slurries vary with grinding from a starting dilatant flow-ability to a resulting pseudoplastic one with an evident Casson yield stress in combination with a thixotropic character. The appearance of pseudoplastic flowability combining thixotropy is related to the fineness of a ground product and its specific surface area, which are both correlated to solids concentration and the additive amount of Dispersant S40. In addition, the accurate rheological characterization of time-dependent fluids is dependent on the instruments used and operation conditions.

  • 6. Hosseini, S. H.
    et al.
    Forssberg, Eric
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Adsorption studies of smithsonite flotation using dodecylamine and oleic acid2006In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 23, no 2, p. 87-96Article in journal (Refereed)
    Abstract [en]

    The interaction of various concentrations of sodium sulfide, dodecylamine (DDA) and oleicacid (OA) on smithsonite were investigated at different pH levels using zeta potential, contact angle, microflotation and diffilse-reflectance FT-IR studies. Flotation results show that the recovery and contact angle are enhanced to 94% and 115 degrees, respectively, with a dodecylamine concentration of 1.6 x 10(-3) M and a pH of 11.5. The optimum sodium sulfide consumption was found to be 2.6 x 10(-2) M. Zeta potential measurements showed less negative charge after DDA treatment on the surface of pure crystalline smithsonite. The recovery and contact angle for oleic acid flotation rises to 93% and 105 degrees respectively, with an oleic acid concentration of 1.1 x 10(-3) M and a pH of 10. The zeta potential in the case of using oleic acid showed a more negative charge after oleic acid treatment on the smithsonite surface. The FT-IR spectra studies of smithsonite conditioned with DDA confirmed the adsorption of DDA on the smithsonite surface. The spectra show that the mineral surface is changed partially to a ZnS layer after sodium sulfide treatment. The spectra confirmed the formation of zinc oleate on the smithsonite surface after oleic acid treatment. A comparison of the results using cationic and anionic collectors showed that the different adsorption densities of the reagents in two cases conferred different degrees of hydrophobicity on the smithsonite surface.

  • 7. Ikumapayi, Fatai
    et al.
    Mäkitalo, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Johansson, Björn
    Boliden Mineral AB.
    Kota, Hanumantha Rao
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Recycling process water in sulfide flotation: Part A: Effect of calcium and sulfate on sphalerite recovery2012In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 29, no 4, p. 183-191Article in journal (Refereed)
  • 8. Ikumapayi, Fatai
    et al.
    Sis, Hikmet
    Inonu University.
    Johansson, Björn
    Kota, Hanumantha Rao
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Recycling process water in sulfide flotation: Part B: Effect of H2O2 and process water components on sphalerite flotation from complex sulfide2012In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 29, no 4, p. 192-198Article in journal (Refereed)
    Abstract [en]

    Hydrogen peroxide production was measured during the grinding of a complex sulfide ore, and its oxidizing effect on solid surfaces was investigated using Fourier transform infrared spectroscopy (FTIR) with diffuse reflectance attachment measurement. In turn, an attempt was made to correlate the formation of hydrogen peroxide, surface oxidation and sphalerite flotation. Additionally, in order to predict and minimize detrimental production problems due to the recycling of process water in sulfide ore processing, the effects of major components of calcium and sulfate species present in recycled process water and the effect of temperature on sphalerite flotation were investigated through bench-scale flotation tests using complex sulfide ores. The significance of process water species in flotation was studied using tap water, process water and simulated water containing calcium and sulfate ions. Formation of hydrogen peroxide was revealed during the grinding of the complex sulfide ore, and its formation was counteracted by diethylenetriamine (DETA). The FTIR spectrum of the pulp solid fraction showed varying degrees of oxidized surface species, which are related to the concentration of H2O2 analyzed in pulp liquid. Bench-scale flotation using two different complex sulfide ores showed that sphalerite recovery is better in process water than in tap water. Flotation results also indicated a varied recovery of sphalerite at different temperatures in either tap water or process water

  • 9.
    Javadi, Alireza
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Kota, Hanumantha Rao
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Formation of hydrogen peroxide by chalcopyrite and its influence on flotation2013In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 30, no 4, p. 212-219Article in journal (Refereed)
    Abstract [en]

    Formation of hydrogen peroxide (H2O2), an oxidizing agent stronger than oxygen, by chalcopyrite (CuFeS2), which is a copper iron sulfide mineral, during grinding, was investigated. It was observed that chalcopyrite generated H2O2 in pulp liquid during wet grinding and also the solids when placed in water immediately after dry grinding. The generation of H2O2 in either wet or dry grinding was thought to be due to a reaction between chalcopyrite and water where the mineral surface is catalytically active in producing •OH free radicals by breaking down the water molecule. Effect of pH in grinding medium or water pH in which solids are added immediately after dry grinding showed lower the pH value more was the H2O2 generation. When chalcopyrite and pyrite are mixed in different proportions, the formation of H2O2 was seen to increase with increasing pyrite fraction in the mixed composition. The results of H2O2 formation in pulp liquid of chalcopyrite and together with pyrite at different experimental conditions have been explained by Eh-pH diagrams of these minerals. This study highlights the necessity of revisiting the electrochemical and/or galvanic interaction mechanisms between the chalcopyrite and pyrite in terms of their flotation behaviour.

  • 10.
    Jonsén, Pär
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Stener, Jan
    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.
    Häggblad, Hans-Åke
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Validation of tumbling mill charge induced torque as predicted by simulations2013In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 30, no 4, p. 220-225Article in journal (Refereed)
    Abstract [en]

    Understanding mill charge motion is important. In the charge, the center of gravity is shifted from the rotational center of the mill system, and its motion is induced by rotation of the mill, while at the same time the charge creates a torque into the mill system. Breakage of ore particles and wear of liners/ball media are closely linked to this motion. To study these phenomena in a physically correct manner, numerical models for different parts of the mill system are needed. Validations of such models are scarce, because of the difficulty to measure inside a tumbling mill.Experimental measurements in a lab mill were done for a number of load cases: varying feed material, mill filling, mill speed and pulp liquid. The mill is set up to measure the charge-induced torque. The accuracy is good with relative uncertainty smaller than ±2% for relevant load cases.A full three dimensional numerical model of the whole mill is used to predict induced torque. Agreement between predicted and measured torque at steady-state is good. In addition, the model can accurately predict the mill start-up behavior for torque and mill power. This proves that the model is physically correct, and can be used for modeling large-scale mills.

  • 11.
    Larsson, Sofia
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Marjavaara, Daniel
    LKAB.
    Lundström, Staffan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Simulation of the flow field in an iron ore pelletizing kiln2016In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 33, no 3, p. 144-148Article in journal (Refereed)
    Abstract [en]

    The flow field in a rotary kiln, used in an iron ore pelletizing process, was investigated using a three-dimensional computational fluid dynamics model. The model is isothermal, downscaled and simplified. The objective was to examine the possibility of capturing the unsteady motion of the flame seen in the real kiln. The results from the simulations were compared with recorded images of the real process. The results demonstrate the possibility of quickly getting an overview of the flow field in the kiln. The main, unsteady behavior of the flame was captured. The model may be used as a tool in the ongoing work of improving and optimizing the pelletizing process.

  • 12. Manouchehri, Hamid-Reza
    et al.
    Rao, K. Hanumantha
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Forssberg, Eric
    Changing potential for the electrical beneficiation of minerals by chemical pretreatment1999In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 16, no 3, p. 14-22Article in journal (Refereed)
    Abstract [en]

    The responses of calcite, feldspar and quartz minerals in a laboratory free-fall electrostatic separator after tribocharging with stainless steel, PVC and copper plates were investigated. The effects of H3BO3 and BaCl2 chemical pretreatment on the electrical properties of the above minerals were examined. The changes in the electrical properties are discussed along with the determined charge, dielectric constant and electrical conductivity of the mineral samples. The electrical properties of the minerals and their responses to the electrical field during separation after tribocharging and chemical pretreatment are explored relative to the electrical behavior of the minerals

  • 13. Manouchehri, Hamid-Reza
    et al.
    Rao, K. Hanumantha
    Forssberg, Eric
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Review of electrical separation methods: Part 1: Fundamental aspects2000In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 17, no 1, p. 23-36Article in journal (Refereed)
    Abstract [en]

    The fundamentals of electrical separation, the electrical properties of minerals, the principal methods used for charging minerals and their mechanisms, the effective factors controlling the acquisition of charges by minerals, the general configuration of commercial electric separators and the forces operating during electrical separation of minerals are reviewed and presented.

  • 14. Manouchehri, Hamid-Reza
    et al.
    Rao, K. Hanumantha
    Forssberg, Eric
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Review of electrical separation methods: Part 2: Practical considerations2000In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 17, no 3, p. 139-166Article in journal (Refereed)
    Abstract [en]

    This paper summarizes the practical considerations of the various electrical separation methods used in mineral processing. The effective factors related to mineral characteristics and equipment attributes are described and analyzed with reference to conventional industrial applications of the electrical methods. Some new aspects of electrical methods application and their potential for mineral beneficiation, apart from the mineral systems that have been successfully beneficiated, are also presented. In addition, wet dielectric separation, which now appears to be promising, is briefly cited.

  • 15. Manouchehri, Hamid-Reza
    et al.
    Rao, K. Hanumantha
    Forssberg, Eric
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Review on electrical separation in mineral separation technologuies: 1. Fundamental aspects2000In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 17, no 1, p. 23-36Article in journal (Refereed)
    Abstract [en]

    The fundamentals of electrical separation, the electrical properties of minerals, the principal methods used for charging minerals and their mechanisms, the effective factors controlling the acquisition of charges by minerals, the general configuration of commercial electric separators and the forces operating during electrical separation of minerals are reviewed and presented.

  • 16. Pugh, R.J.
    et al.
    Wang, Yanmin
    Forssberg, Eric
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Influence of magnetic and surface forces on the coagulation of hematite and chromite1994In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 11, no 3, p. 133-140Article in journal (Refereed)
    Abstract [en]

    The coagulation of dispersed ultrafine weakly magnetic oxide mineral particles (e.g., natural hematite and chromite) in an external magnetic field can be described by interparticle forces. Essentially, coagulation occurs when the short-range London-van der Waals interactions and the long-range magnetic forces outweigh the stabilizing electrical double-layer repulsion. Using the classical colloid chemistry theory, the various components of the potential energy for different-sized particles at a series of ionic strengths and magnetic field intensities were calculated.

  • 17.
    Rao, K. Hanumantha
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Forssberg, Eric
    Antti, Britt-Marie
    Luleå University of Technology.
    Flotation of mica minerals and selectivity between muscovite and biotite while using mixed anionic/cationic collectors1990In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 7, no 3, p. 127-132Article in journal (Refereed)
    Abstract [en]

    Selective flotation of muscovite from a material containing muscovite (15.4%), biotite (13%), and siliceous gangue (quartz and feldspar), using a mixed collector system of sodium oleate and dodecylamine acetate has been described. Muscovite is found to float in preference to biotite, when the pulp is initially conditioned with oleate followed by amine at basic pH values. The results indicate that a product containing 63% muscovite with a recovery of 93% can be obtained, while using 75-150 g/t of oleate and 96 g/t of amine. The biotite grade and recovery are found to be around 30% and 20%, respectively. A good selectivity between muscovite and siliceous gangue is obtained. A final product containing 95% muscovite with an overall recovery of 75% is obtained when the flotation concentrate is subjected to magnetic separation. These studies indicate the possibility of separating muscovite from biotite by using a mixture of collectors.

  • 18. Semberg, Pär
    et al.
    Andersson, Charlotte
    LKAB, Research & Development, 983 81 Malmberget.
    Björkman, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Interaction between iron oxides and olivine in magnetite pellets during reduction at 500°-1,300°C2014In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 31, no 2, p. 126-135Article in journal (Refereed)
    Abstract [en]

    In this study, the interaction between magnetite and the additive olivine was studied after oxidation as well as after isothermal reduction at temperatures in the 500º-1,300º C range. In the olivine sample, the forsteritic olivine particles react partly during the oxidation pretreatment to form magnesioferrite and vitreous silica along the particle corona. This breakdown of the olivine particles during oxidation liberates magnesium from the particles, which do not react until temperatures of above 1,150° C in reducing atmosphere. When the hematite in the sample is reduced, and when the temperature is high enough to allow solid-state diffusion at ~800º C, the magnesium of the magnesioferrite redistributes, so that the magnesium concentration approaches the same level throughout the iron oxide structure. For magnetite, this did not occur until 800° C. At 1,000° C, this magnesium reacts further with the silica in the glassy slag phase, which crystallizes into fayalitic olivine. At this temperature, the magnesium has diffused over distances of more than 600 µm from large olivine particles after 2 hrs reduction. From this point, the primary slag phase in the pellet, until melting, is solid fayalite. Upon reduction to metal, the metallization front concentrates the MgO in the remaining wustite, which can lead to MgO levels of up to 10 mole% locally. The melting point of the fayalite is raised from 1,145º C to a melting range of 1,238-1,264º C due to the MgO increase, as estimated based on phase diagrams, which were adapted to the pellets tested. Much of the olivine that remained unaltered in the oxidation process will be encapsulated by iron before the particles begin to dissolve in reducing conditions and, therefore, plays no role in the reduction before final melting of the particles occurs.

  • 19.
    Sharma, P K
    et al.
    Luleå tekniska universitet.
    Rao, Hanumantha
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Surface characterization of bacterial cells relevant to the mineral industry2005In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 22, no 1, p. 31-37Article in journal (Refereed)
    Abstract [en]

    Bacteria belonging to the Acidithiobacilli group are widely used in the mineral processing industry in bioleaching and biobeneficiation operations. Paenibacillus polymyxa has also found application in biobeneficiation studies. Microbial adhesion to mineral surface is an essential step for both biobeneficiation and bioleaching. Microbial adhesion depends on the physico-chemical characteristics of both the mineral and microbe. In the present study, physico-chemical characterization of the surface of iron-oxidizing bacteria grown with Fe ions and elemental S, Acidithiobacillus thiooxidans and Paenibacillus polymyxa were carried out. Surface hydrophobicity was evaluated using microbial adhesion-to-solvents test, contact angle measurement and surface energy evaluation. The surface composition of the bacterial cell surfaces was determined using X-ray photoelectron spectroscopy (XPS) and diffused reflectance infrared Fourier transform (DRIFT) spectroscopy.

  • 20.
    Sharma, P.K.
    et al.
    Luleå tekniska universitet.
    Rao, K. Hanumantha
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Role of a heterotrophic Paenibacillus polymyxa bacteria in the bioflotation of some sulfide minerals1999In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 16, no 4, p. 35-41Article in journal (Refereed)
    Abstract [en]

    A pure strain of Paenibacillus polymyxa and mineral-adapted strains are used to bring about surface chemical changes on pyrite and chalcopyrite and, thus, their flotation. Paenibacillus polymyxa was adapted by repeated subculturing in the presence of pyrite and chalcopyrite. The surface chemical changes of bacteria due to adaptation and of minerals after their interaction with bacterial cultures are evaluated by electrokinetic and infrared spectroscopy and are discussed with reference to their flotation responses. Interaction of bacterial cells, bacterial metabolites and whole bacterial cultures affected the Hallimond flotation behavior of the sulfide minerals. The Xanthate flotation results show that pyrite, but not chalcopyrite, is depressed when the tests are carried out after interaction with chalcopyrite-adapted Paenibacillus polymyxa. This investigation demonstrated that the surface chemical properties of bacteria can be manipulated successfully to achieve the desired effects in the flotation process.

  • 21.
    Singh, Maneesh
    et al.
    Luleå tekniska universitet.
    Björkman, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Strength of cement bonded briquettes2006In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 23, no 4, p. 203-213Article in journal (Refereed)
    Abstract [en]

    The cold-bond agglomeration process is increasingly being used as a means of recycling iron-rich steel plant byproducts back to the blast furnace. Even though an increasing number of plants are adopting this process, the use of cold-bonded agglomerates as burden material for the blast furnace is restricted to about 5% of the total burden material. This is because the cold-bonded agglomerates may lose their strength inside the furnace due to the dissociation of binder at high temperatures. This failure may result in the generation of fines, resulting in low bed permeability and higher dust content in stack gases. This paper describes the effects of temperature, degree of reduction, particle size of the raw material (d50), cement content, pellet-type and reduction under load on the compression strength and microstructure of cement-bonded briquettes comprising iron and steel plant byproducts.

  • 22.
    Sivamohan, R.
    et al.
    Luleå tekniska universitet.
    Huang, F.
    Processing of the finely and complexly interlayered calcite rich wollastonite ore from northern Sweden1989In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 6, no 2, p. 69-72Article in journal (Refereed)
    Abstract [en]

    A mineral processing strategy developed for the finely and complexly interlayered calcite rich wollastonite, microcline, and iron-garnet ore of Jokkmokk, northern Sweden, gives an overall calcite recovery of 89.4% at a grade of 90.7% CaCO3. The wollastonite product assays 53.0% CaSiO3 at a recovery of 92.2%. The significant elements of the developed strategy are stepwise grinding, wet high intensity magnetic separation (WHIMS), reverse flotation and starvation flotation. Stepwise grinding avoids the overgrinding of soft calcite. WHIMS removes the colored iron-garnet impurity and thereby increases the whiteness of the product. Reverse flotation enables a simple flotation circuit and starvation flotation helps to optimize the physicochemical conditions in cleaner flotation by giving rougher products of narrow particle size distributions. Moreover, with the reagent scheme developed in this work only one cleaner stage is necessary for the various rougher flotation products to be upgraded to give the foregoing results. In this paper, the strategy is presented in detail along with appropriate results

  • 23.
    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.

  • 24.
    Vidyadhar, A.
    et al.
    Luleå University of Technology.
    Rao, K. Hanumantha
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Forssberg, Eric
    Separation of feldspar from quartz: Mechanism of mixed cationic/anionic collector adsorption on minerals and flotation selectivity2002In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 19, no 3, p. 128-136Article in journal (Refereed)
    Abstract [en]

    Using pure albite and quartz minerals, the separation of albite from quartz using mixed cationic/anionic reagent schemes is assessed through Hallimond flotation, zeta potential and diffuse reflectance FTIR studies. The reagent schemes are tested in bench-scale flotation for the separation of albite from Greek Stefania feldspar ore. The single mineral flotation tests showed the feasibility of selective albite flotation from quartz at around pH 2 using a mixture of cationic diamine and anionic sulfonate collectors or a combined cationic-anionic collector of diamine-dioleate. In contrast to the selective flotation response of albite at pH 2, where albite is slightly negatively charged and quartz possess zero charge, the zeta potential and FTIR studies elucidate similar adsorption behavior of mixed collectors on both of the minerals. The infrared spectra not only showed the co-adsorption of anionic sulfonate or oleate with diamine on the surface but also showed that the diamine adsorption increases with the presence of anionic collector. The intrusion of anionic collector in between adjacent surface alkyl ammonium ions decreases electrostatic head-head repulsion, thereby increasing the diamine adsorption by increasing the hydrophobic tail-tail bonds. The discrepancy in the flotation and adsorption results at pH 2 is attributed to the coarse and fine size particles employed in these studies, respectively. The comparable adsorption on fine particles of albite and quartz at pH 2 is explained by the interaction of ammonium ions on silanol groups by hydrogen bonding besides electrostatic interactions. The bench-scale flotation results indeed showed that selective albite flotation takes place only after desliming the feed material. An albite concentrate exceeding 10% (by weight) Na2O is produced from a material containing about 6.5% (by weight) Na2O, where an albite product of more than 9% (by weight) Na2O is considered to be valuable.

  • 25.
    Vilinska, Annamaria
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Kota, Hanumantha Rao
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Surface thermodynamics and extended DLVO theory of Leptospirillum ferrooxidans cells' adhesion on sulfide minerals2011In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 28, no 3, p. 151-158Article in journal (Refereed)
    Abstract [en]

    The adhesion of Leptospirillum ferrooxidans bacterial cells onto the sulfide minerals pyrite and chalcopyrite was evaluated using two different physical-chemical approaches; thermodynamic and extended DLVO theory. For the parameters incorporated into calculations, the zeta potentials and contact angles of powdered solids and bacterial cells were acquired experimentally. The Hamaker constants essential for Lifshitz-van der Waals interaction. calculations were calculated following two different methods: macroscopic and microscopic. Adsorption tests were carried out at physiologic conditions to estimate the amount of cells adsorbed onto a mineral surface and the extent of alteration of that mineral surface in biobeneficiation. The free energy of adhesion was found to be negative for both minerals, indicating that the adhesion is energetically favored and preferred. The interaction energy diagrams of the total interacting force was also negative for the cases where the particles were charged oppositely; in the remaining cases, the total force was attractive after overcoming an energetic barrier caused by the repulsive electrostatic forces. Under the conditions of the adsorption test, the experimental results are in agreement with the theoretical; this suggests that the physical-chemical forces are crucial for bacterial adhesion.

  • 26.
    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.

  • 27.
    Westerstrand, Magnus
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Holmgren, Allan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    The impact of process water on the surface properties of magnetite as measured by the zeta potential and through leaching experiments2012In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 29, no 4, p. 199-206Article in journal (Refereed)
  • 28.
    Westerstrand, Magnus
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Öhlander, Björn
    Transport of Ca, Mg, Na, sulfate and other components of pellet production at the Kiirunavaara iron mine by process water and magnetite surfaces: a quantification2010In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 27, no 4, p. 224-231Article in journal (Refereed)
    Abstract [en]

    It is known that the water chemistry of the process water during ore refinement can affect product quality, such as iron pellet strength. The main objective of this study was to quantify the amounts of major elements, such as Ca, Mg, Na, S and Cl carried by process water and by magnetite grain surfaces to the end product, iron ore pellets made from magnetite ore from the Kiirunavaara Mine in northern Sweden. In addition, the amount of colloids (0.22μm – 1kD) in the process water was examined by ultrafiltration. The amounts of various elements sorbed to the magnetite surfaces were estimated by leaching with Milli-Q water, MgCl2, NH4-acetate and Na-acetate. Total dissolved solids were between 1,446 and 1,775 mg/l, dominated by Ca, S, Na and Cl (89%). The colloidal fraction was less than 3% for major ions. For Ca and Mg, sorption to magnetite surfaces was a much more important transport mechanism for the pelletizing process than evaporated process water, but for Na, Cl and S process water was an important carrier.

  • 29.
    Zeng, Yigen
    et al.
    Luleå University of Technology.
    Forssberg, Eric
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Energy consumption in fine crushing and dry rod grinding1992In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 9, no 2, p. 69-72Article in journal (Refereed)
    Abstract [en]

    Fine crushing and rod grinding have been investigated using a laboratory-scale jaw crusher and a rod mill. The net energy consumption in both crushing and grinding was evaluated from torque measurements. An empirical relationship was established between energy consumption, particle size and operating parameters. When the mill feed size is reduced, through fine crushing, to about 80% passing 3 mm, the energy consumption will be minimized in a comminution chain of fine crushing and coarse rod grinding. The results in fine crushing were compared with a large-scale test.

1 - 29 of 29
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf