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  • 1.
    Berglund, Gun
    Luleå tekniska universitet.
    Pulp Chemistry in Sulphide Mineral Flotation1991Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 33, nr 1-4, s. 21-31Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Variations in the oxidizing conditions of the pulp and their subsequent effects on flotation were examined for three types of natural sulphide ore, a complex pyrite ore, a sphalerite-galena ore and a chalcopyrite ore. Different gas mixtures ranging from pure nitrogen to pure oxygen were used to control the oxidizing conditions. The use of an oxygen rich flotation gas was found to be a suitable method for changing the oxidizing conditions and improving flotation under controlled conditions. The flotation results were correlated to the oxygen content and the redox potential, parameters which describe the pulp chemistry conditions.

  • 2.
    Bhaskar, Raju G.
    et al.
    Luleå tekniska universitet.
    Subrahmanyam, T.V
    Luleå tekniska universitet.
    Sun, Z.
    Luleå tekniska universitet.
    Forsling, Willis
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Shear-flocculation of quartz1991Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 32, nr 3-4, s. 283-294Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The present work deals with the shear-flocculation of quartz in aqueous solutions of dodecylamine chloride. The variables studied include pH, concentration of the amine, size of the coarse particles, stirring speed and time. The zeta potentials were correlated with flocculation behaviour. It was observed that particle hydrophobicity and pH were most important since the dodecylamine chloride-solution reactions are pH-and concentration-dependent.

  • 3.
    Chanturiya, Valentine
    et al.
    Institute of Problems of Complex Development of Mineral Resources.
    Makarov, Victor
    Kola Science Centre, Russian Academy of Sciences, Apatity.
    Forsling, Willis
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Makarov, Dimitriy
    Kola Science Centre, Russian Academy of Sciences, Apatity.
    Vasil'eva, Tatyana
    Kola Science Centre, Russian Academy of Sciences, Apatity.
    Trofimenko, Tatyana
    Kola Science Centre, Russian Academy of Sciences, Apatity.
    Kuznetsov, Victor
    Kola Science Centre, Russian Academy of Sciences, Apatity.
    The effect of crystallochemical peculiarities of nickel sulphide minerals on flotation of copper-nickel ore2004Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 74, nr 1-4, s. 289-301Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Flotation kinetics of pentlandite and violarite contained in copper-nickel ores and the effect of crystallochemical peculiarities of the minerals on their flotation features are studied. Studies of the effect of pentlandite crystallochemical features on its flotation properties have shown that the easiest to float is nickel-enriched pentladite, cobalt-enriched one being somewhat worse the worst being iron-enriched one. Pentlandite was found to be much better recovery to flotation concentrates than violarite. So, the process of violaritization of the surface of pentlandite grains, which may occur during the flotation, will negatively affect its characteristics.

  • 4. Dwari, Ranjan
    et al.
    Rao, K. Hanumantha
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Tribo-electrostatic behaviour of high ash non-coking Indian thermal coal2006Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 81, nr 2, s. 93-104Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The tribo-electrostatic method was applied to beneficiate non-coking Indian thermal coal from Ramagundam coal mines containing nearly 45% ash content. The microscopic studies revealed that quartz and kaolinite are the dominant minerals whereas illite, goethite, siderite and pyrite are the minor inclusions in the coal. Contact electrification of ash-forming minerals and coal matter was carried out using different tribo-charger materials of Al, Cu, brass, perspex and teflon. The Cu tribo-charger was found to be optimum to acquire differential charge between ash-forming inorganics and coal matter. The temperature effect on the magnitude of contact charge acquisition was found to be significant. Tests on a laboratory in-house built tribo-electrostatic free-fall separator with minus 300 μm coal showed that the ash content was reduced from 45% to about 18%, and a clean coal product as judged by the washability studies can be obtained. The results illustrate that the non-coking coals can be beneficiated using the scientific knowledge on the response and behaviour of coal and non-coal matters to electric charges.

  • 5. Dwari, Ranjan
    et al.
    Rao, K. Hanumantha
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Somasundaran, P.
    Henry Krumb School of Mines, Columbia University, New York.
    Characterisation of particle tribo-charging and electron transfer with reference to electrostatic dry coal cleaning2009Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 91, nr 3-4, s. 100-110Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The electrostatic beneficiation of coal is based on different tribo-charging characteristics of ash forming minerals and coal particles. In this work the tribo-charging of quartz and coal particles contacted with various metals and polymer materials have been measured and the charge acquisition was examined through surface energy calculations from liquid contact angle data. The contacts angles, before and after tribo-charging of solids, were measured with Krüss tensiometer using Washburn's equation where the sample holders in tensiometer are specially constructed with tribo-charger materials. The polarity and amount of charge acquired by quartz and carbon powders with metal tribo-chargers were found to be in good agreement with the reported work functions of the contacting surfaces. The results for the charge with polymer materials differed from the work function values, presumably due to surface contamination. The surface energy of quartz particles calculated from the measured contact angle data showed that the tribo-charging increases the surface energy. Both polar and non-polar components computed using Fowkes and Owens-Wendt approaches showed that these components increase after tribo-electrification. However, the polar component divided into acid and base parts, as in van Oss approach, manifest decreasing acid part and increasing base part. Since quartz charged negatively during tribo-charging with metal surfaces and therefore suggests acceptance of electrons, the determined acid-base surface energy components are consistent with the charge transfer process. The results also elucidate an explicit correlation between the charge generated by powders and the surface acceptor (acid) and donor (base) electronic state and thereby the work functions. Thus a method for characterising the changes in surface energetic structure of solids during tribo-electrification in terms of acid-base parameters of electron transfer between the contacting surfaces has been described for the first time.

  • 6.
    Forsling, Willis
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Sun, Zhong-Xi
    Luleå tekniska universitet.
    Use of surface complexation models in sulphide mineral flotation1997Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 51, nr 1-4, s. 81-95Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Surface complexation modelling is introduced to investigate the surface reactions in a mixed galena and sphalerite flotation system. Computer-assisted calculations based on surface complexation modelling (SCM) are performed to obtain the mineral surface distribution of ethyl xanthate as well as carbonate and excess sulphide ions as a function of pH. The significance of pe is demonstrated by computing the mineral surface speciation in a flotation system with xanthate and excess of sulphide ions. The results are used to evaluate the influences of pH, pe, the concentration of xanthate, sulphide or carbonate ions to the mineral flotability. The flotation mechanisms in galena-sphalerite system are discussed based on SCM.

  • 7.
    Forsmo, Seija
    et al.
    Luleå University of Technology, Agricola Research Centre.
    Hägglund, A.
    LKAB.
    Influence of the olivine additive fineness on the oxidation of magnetite pellets2003Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 70, nr 1-4, s. 109-122Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Olivine is used as an additive in Luossavaara-Kiirunavaara AB (LKAB) blast furnace pellets. The LKAB iron ore is magnetite which oxidizes to hematite during the sintering process. Olivine retards the oxidation of magnetite pellets if the threshold temperature of magnesioferrite formation is exceeded. In this study, we have developed a thermogravimetric measuring method to study the relationship between the olivine reactivity in green pellets and the olivine fineness. A less reactive olivine makes the pelletizing process more tolerant of excessively high temperatures in the green pellets during oxidation. The reactivity of olivine decreases when the amount of fine tail in olivine is decreased. The top size is limited by balling. Grinding tests in pilot scale show that if the olivine additive is ground in closed circuit with a ball mill keeping good control over the top size, the olivine fineness can be appreciably decreased without disturbing balling. The olivine reactivity can be decreased by 40% compared to the reference olivine in the production plant. Also, savings can be made on both the grinding energy and grinding media consumption. The results in both pilot scale and full production scale show that better oxidation in the grate due to a coarser olivine additive improves the low temperature reduction strength (LTD, ISO 13930) in pellets. The measuring method developed for the olivine reactivity enabled evaluation of different particle-sizing methods for olivine characterisation. The screening size fraction % - 45 mum showed a good correlation to olivine reactivity in green pellets within a very large measuring range. The correlation of laser diffraction analysis to the olivine reactivity showed, however, that the laser diffraction measuring method is affected too much by variations in the large particles.

  • 8.
    Forssberg, Eric
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Subrahmanyam, T.V.
    Departamento de Geologia, CCE/UFRN, Campus Universitario, 59.072, Natal.
    Nilsson, Leif K.
    Luleå University of Technology.
    Influence of grinding method on complex sulphide ore flotation: a pilot plant study1993Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 38, nr 3, s. 157-175Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The present work deals with plant investigations on the influence of conventional and autogenous grinding methods in the floatation of a complex sulphide ore. The study includes the investigation of the particle size and shape analysis and the pulp chemical measurements-Eh, pH, O2 concentration of cations and anions, at several stages of the grinding and flotation circuits. The rougher floatation concentrates of the Cu-Pb and Zn circuits were analysed to evaluate the floatation behaviour of chalcopyrite, galena and sphalerite. The results indicate better liberation of minerals in coarse size fractions for the pulp ground by autogenous mill while conventional grinding shows higher degree of liberation in the fine size range. Metallurgical analyses of the final floatation concentrates shows higher recoveries of Cu, Pb and Zn for the pulp ground by autogenous milling. The grades of Cu and Pb were better with conventional grinding but the recoveries were less than those obtained by autogenous grinding. Several interesting observations concerning pulp chemistry (e. g. the concentrations of Fe ions is lower in pulps ground by conventional method than by autogenous means!) are discussed.

  • 9.
    Forssberg, Eric
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Sundberg, Stellan
    Boliden Mineral AB.
    Zhai, Hongxin
    Research Institute of Beneficiation Machinery, Shenyang, Liaoning.
    Influence of different grinding methods on floatability1988Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 22, nr 1, s. 183-192Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Investigations have been in progress since the middle of 1981 to prove and explain differences in the influence of conventional and autogenous grinding on the floatability of sulphide minerals. Techniques for liberation and particle shape studies under the microscope, and measurement of pulp chemistry as to redox potential and contents of free oxygen and various sulphur-carrying ions were tested on samples from batch tests, pilot plant runs and commercial practice. The phenomena observed can partly be explained in terms of liberation and chemical characteristics of the pulp.

  • 10.
    Gao, Ming-Wei
    et al.
    Luleå tekniska universitet.
    Forssberg, Eric
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Study on the effect of parameters in stirred ball milling1993Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 37, nr 1, s. 45-59Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ultra-fine grinding involves a large number of parameters in its operation. In this paper, four important parameters of the Drais stirred ball mill, i.e., the bead density, slurry density, mill speed, and the effect of dispersant were selected for investigation. The experimental work was based on a factorial design and 27 milling tests were conducted. It is found that the bead density has an optimum value of 3.7 g/cc in this investigation. A lower slurry density and a smaller amount of dispersant appear to be better conditions. The mill speed should be as high as possible within the speed limit tested in this work for the best process efficiency.

  • 11.
    Gao, Ming-Wei
    et al.
    CSIRO Division of Minerals and the Centre for Mining, Technology and Equipment, Kenmore, Qld.
    Forssberg, Eric
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Weller, K.R.
    CSIRO Division of Minerals and the Centre for Mining, Technology and Equipment, Kenmore, Qld.
    Power predictions for a pilot scale stirred ball mill1996Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 44-45, s. 641-652Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The capacity of a stirred ball mill to grind to a certain product size efficiently depends strongly on the power intensity in the milling chamber. The dependence of power intensity on stirrer speed, slurry density, bead density and the amount of dispersant added to the feed was investigated using a 6-litre 11-kW horizontal stirred ball mill fitted with perforated disks as stirrers. Dolomite was ground at a fixed volumetric flow rate, but with slurry densities ranging from 65 to 75 percent by weight, stirrer speeds from 805 to 2253 rpm, bead densities from 2.5 to 5.4 g/ml and the dispersant level from 0.5 to 1.5 percent of dry solids. Three levels of the four variables were used in 27 continuous milling tests, set up as one-third of a 34 factorial design. All factors affected the power draft in a highly significant way. Speed, and to a lesser extent slurry density, were the dominant factors with significant non-linear effects. A six-term model, incorporating all significant effects, predicted the experimental results with an accuracy of about 12%. Increasing the power accelerated size reduction dramatically with only a small change to the energy efficiency of the process.

  • 12. He, Mingzhao
    et al.
    Forssberg, Eric
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Influence of slurry rheology on stirred media milling of quartzite2007Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 84, nr 1-4, s. 240-251Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The role of slurry rheology in stirred media milling of quartzite has been investigated by varying important grinding parameters such as media bead density and size, addition of chemicals, solids concentration, stirrer rotational speed as well as the combined effect of these factors. Media bead density has an evident but complex effect on stirred milling performance, depending on stirrer rotational speed and solids concentration. The effect of media bead size on the ultra-fine grinding of quartzite is relevant to the feed size. Optimal ratio of media bead size to the median size of a feed is between 150 and 200. The combined effect of grinding bead size and stirrer speed or solids concentration is insignificant. The addition of Dispersant S40 or a lower solids concentration results in better grinding performance (i.e., a higher energy efficiency and a smaller median size) due to the maintenance of lower viscosities at shear rates investigated during grinding. Stirrer rotational speed interacts with solids concentration. For a given solids concentration, an optimal stirrer speed exists. The observed phenomena can be explained by the interaction of slurry rheology and the stress intensity of individual grinding bead. In addition, an empirical particle size-energy model provides a good fit (R2 > 0.904) to the grinding results under the experimental conditions investigated. Furthermore, the wear of grinding media beads is involved. ZrO2 beads have a lowest wear rate whereas the wear of SiO2 beads is most serious. The wear rate of Al2O3 beads is related to bead size.

  • 13. He, Mingzhao
    et al.
    Wang, Yanmin
    Forssberg, Eric
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Parameter studies on the rheology of limestone slurries2006Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 78, nr 2, s. 63-77Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The influences of solids concentration, molecular weight of dispersant, particle size and distribution, and temperature on the rheological behaviour of limestone slurries have been investigated. The results reveal that when the solids concentration of a limestone slurry (< 100 μm) is increased from 60 wt.% (35.71 vol.%) to 78.5 wt.% (57.49 vol.%), the rheological behaviour of the slurry is transformed from a weakly dilatant characteristic to a pseudoplastic one with a yield stress, which is in combination with a thixotropic property at a higher solids concentration (i.e., ≥ 75 wt.% or 52.63 vol.%). At a certain shear rate, the apparent viscosity and the relative viscosity of the slurry increase exponentially with solids concentration. The extrapolated Bingham yield stress increases rather sharply in a power-law form with increasing solids concentration when the solids concentration of the slurry is larger than 70 wt.% (i.e., 46.36 vol.%)...

  • 14.
    Hoseinian, Fatemeh Sadat
    et al.
    Department of Mining and Metallurgical Engineering, Amirkabir University of Technology, Tehran.
    Irannajad, Mehdi
    Department of Mining and Metallurgical Engineering, Amirkabir University of Technology, Tehran.
    Javadi, Alireza
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Ion flotation for removal of Ni(II) and Zn(II) ions from wastewaters2015Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 143, s. 131-137Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ion flotation was applied to Ni(II) and Zn(II) cation removal from low concentration synthetic wastewaters. Ethylhexadecyldimethylammonium bromide (EHDABr) and sodium dodecyl sulfate (SDS) were used as collectors and Dowfroth250 and methyl isobutyl carbonyl (MIBC) as frothers. The effective parameters were investigated by the experimental design performed by DX7 software. In this regard, a two-level factorial method was used, and sixteen experiments including 6-level variables were designed. In the first step, the tests were conducted in a Hallimond tube. It was concluded from test results that the optimum conditions for the removal of Ni(II) and Zn(II) ions by initial concentrations of 10. ppm were: pH = 3, SDS = 300. ppm, Dowfroth250 = 90. ppm and air flow rate = 1.8. ml/min. In the second step, optimal results from the first step were evaluated in a mechanical flotation cell. In optimal conditions, the recovery of Ni(II) and Zn(II) ions were 88% and 92%, respectively at 60. min. This study showed that the use of ion flotation is a very effective method for Ni(II) and Zn(II) ion removal from industrial wastewaters. The flotation time in achieving an optimum recovery of Zn(II) ions is shorter than that for Ni(II) ions

  • 15.
    Javadi, Alireza
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Kota, Hanumantha Rao
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Formation of hydrogen peroxide by sphalerite2013Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 125, s. 78-85Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Formation of hydrogen peroxide (H2O2), an oxidizing agent stronger than oxygen, by sphalerite ((Zn, Fe) S) was examined during its grinding process. It was observed that sphalerite generated H2O2 in pulp liquid during wet grinding and also when the freshly ground solids 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 sphalerite and water where the mineral surface is catalytically active to produce OH• free radicals by breaking down the water molecule. Effect of pH on the formation of H2O2 by sphalerite was shown that the acidic pH generated more H2O2. Mixtures of pyrite, chalcopyrite and galena with sphalerite on the formation of H2O2 were also probed. It was shown that the concentration of H2O2 increases with increasing pyrite or chalcopyrite fraction in pyrite–sphalerite, chalcopyrite–sphalerite mixtures but with an increase in galena proportion, the concentration of H2O2 decreased in galena–sphalerite mixture. The oxidation or dissolution of one mineral than the other in a mixture can be explained better with the extent of H2O2 formation in the pulp liquid than galvanic interactions. It is clear of the greater role of H2O2 in the oxidation of sulphides or aiding the extensively reported galvanic interactions since the amount of H2O2 generated with a specific mineral followed the rest potential series. This study highlights the necessity of further investigations into the role of H2O2 in electrochemical and/or galvanic interaction mechanisms between pyrite, chalcopyrite and galena with sphalerite.

  • 16.
    Kalinkina, Elena V.
    et al.
    Kola Science Centre, Russian Academy of Sciences, Apatity.
    Kalinkin, Alexander M.
    Kola Science Centre, Russian Academy of Sciences, Apatity.
    Forsling, Willis
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Makarov, Victor N.
    Kola Science Centre, Russian Academy of Sciences, Apatity.
    Sorption of atmospheric carbon dioxide and structural changes of Ca and Mg silicate minerals during grinding: I. Diopside2001Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 61, nr 4, s. 273-288Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Processes which occur during dry grinding of the magnesium and calcium silicate minerals enstatite MgSiO3, åkermanite Ca2MgSi2O7 and wollastonite CaSiO3, have been studied with the use of diffuse reflectance Fourier transform infrared spectroscopy (DRIFT), powder X-ray diffraction, 29Si MAS-NMR spectroscopy, CO2-content analysis, and BET surface area measurements. It has been found that the extensive sorption of atmospheric CO2 (carbonization) by the ground mineral that was reported earlier for diopside CaMgSi2O6 also occurs for the minerals included in this study. The shape and position of the double peak of the CO32--group in the 1430-1515 cm-1 region in the FT-IR spectra of ground minerals are similar to that of ground diopside. CO2-content analysis and BET surface area measurements show that carbonate groups are present not only at the surface but also in the bulk of the ground minerals. The degree of carbonization of silicate depends on its calcium content. The higher the fraction of Ca in octahedral positions in the silicate structures, the higher the degree of carbonization. For synthetic wollastonite CaSiO3, which is a pure calcium silicate, the degree of carbonization is 102.6 mg CaCO3 per gram of sample after 36 h of grinding. The structure of silicate appears to be less important for the degree of carbonization during grinding.

  • 17. Kalinkina, Elena V
    et al.
    Kalinkin, Alexander M
    Forsling, Willis
    Makarov, Viktor N
    Sorption of atmospheric carbon dioxide and structural changes of Ca and Mg silicate minerals during grinding: II, Enstatite, akermanite and wollastonite2001Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 61, nr 4, s. 289-299Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Processes which occur during dry grinding of the magnesium and calcium silicate minerals enstatite MgSiO3, åkermanite Ca2MgSi2O7 and wollastonite CaSiO3, have been studied with the use of diffuse reflectance Fourier transform infrared spectroscopy (DRIFT), powder X-ray diffraction, 29Si MAS-NMR spectroscopy, CO2-content analysis, and BET surface area measurements. It has been found that the extensive sorption of atmospheric CO2 (carbonization) by the ground mineral that was reported earlier for diopside CaMgSi2O6 also occurs for the minerals included in this study. The shape and position of the double peak of the CO32--group in the 1430-1515 cm-1 region in the FT-IR spectra of ground minerals are similar to that of ground diopside. CO2-content analysis and BET surface area measurements show that carbonate groups are present not only at the surface but also in the bulk of the ground minerals. The degree of carbonization of silicate depends on its calcium content. The higher the fraction of Ca in octahedral positions in the silicate structures, the higher the degree of carbonization. For synthetic wollastonite CaSiO3, which is a pure calcium silicate, the degree of carbonization is 102.6 mg CaCO3 per gram of sample after 36 h of grinding. The structure of silicate appears to be less important for the degree of carbonization during grinding.

  • 18.
    Kundu, T.K.
    et al.
    Luleå University of Technology.
    Rao, K. Hanumantha
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Parker, S.C.
    School of Chemistry, University of Bath.
    Atomistic simulation of the surface structure of wollastonite and adsorption phenomena relevant to flotation2003Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 72, nr 1, s. 111-127Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Atomistic simulation techniques have been used to calculate the surface structure and stability of wollastonite crystal and its adsorption behaviour in the presence of molecular and dissociated water, and two widely used collector head group molecules of methanoic acid and methylamine. Seven predominant surfaces have been modelled and their calculated surface energies correspond well with their preferred morphological domination. Surfaces are identified having fourfold and threefold coordination of surface silicon. Threefold surface silicon are stabilized by addition of hydroxyl ion on them and proton on surface oxygen. Stable surfaces thus obtained are subjected to surface Ca2+ replacement by 2H+ by transforming 2O2− to 2OH−. Surface energy and reaction energy values indicate wollastonite surface stabilized to a great extent by adsorbing water in dissociated form. The Ca2+ replacement from the first few layers of the surface is energetically more favourable in acidic condition. Three Miller indexed surfaces terminating with fully coordinated silicon were reconstructed to make the surface free of lone oxygen, and these surface cuts were chosen to carry out simulation work for adsorption of molecules. A comparison of surface energies revealed that all the surfaces become stabilized in the presence of added molecules but the presence of methylamine decreases surface energy to lowest values. Adsorption of dissociated water is preferred by {100} and {102} surfaces, while {001} surface adsorbs methylamine strongly as the results show highly negative adsorption energies. In terms of pure molecule adsorption, the preferred adsorption sequence for all the surfaces is methylamine>methanoic acid>water. For {100} and {102} predominant surfaces, the difference in adsorption energy values is not much and we conclude that the collectors having long-chain hydrophobic alkyl chain, the two head group molecules considered, cannot render enough hydrophobicity due to inadequate adsorption on wollastonite. Thus the presence of activators/modifiers in actual wollastonite flotation practice is substantiated.

  • 19.
    Matin, S. S.
    et al.
    Islamic Azad University, Tehran, Iran.
    Hower, J. C.
    University of Kentucky, Lexington, USA.
    Farahzadi, L.
    Dr. Shariaty Technical College, Tehran, Iran.
    Chelgani, Saeed Chehreh
    University of Michigan, Ann Arbor, Michigan, USA.
    Explaining relationships among various coal analyses with coal grindability index by Random Forest2016Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 155, s. 140-146Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Application of Random Forest (RF) via variable importance measurements (VIMs) and prediction is a new data mining model, not yet wide spread in the applied science and engineering fields. In this study, the VIMs (proximate and ultimate analysis, petrography) processed by RF models were used for the prediction of Hardgrove Grindability Index (HGI) based on a wide range of Kentucky coal samples. VIMs, coupled with Pearson correlation, through various analyses indicated that total sulfur, liptinite, and vitrinite maximum reflectance (Rmax) are the most importance variables for the prediction of HGI. These effective predictors have been used as inputs for the prediction of HGI by a RF model. Results indicated that the RF model can model HGI quite satisfactorily when the R2 = 0.90 and 99% of predicted HGIs had less than 4 HGI unit error in the testing stage. According to the result, by providing nonlinear VIMs as well as an accurate prediction model, RF can be further employed as a reliable and accurate technique for the evaluation of complex relationships in coal processing investigations.

  • 20.
    Parian, Mehdi
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Lamberg, Pertti
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Rosenkranz, Jan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Developing a particle-based process model for unit operations of mineral processing: WLIMS2016Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 154, s. 53-65Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Process models in mineral processing can be classified based on the level of information required from the ore, i.e. the feed stream to the processing plant. Mineral processing models usually require information on total solid flow rate, mineralogical composition and particle size information. The most comprehensive level of mineral processing models is the particle-based one (liberation level), which gives particle-by-particle information on their mineralogical composition, size, density, shape i.e. all necessary information on the processed material for simulating unit operations. In flowsheet simulation, the major benefit of a particle-based model over other models is that it can be directly linked to any other particle-based unit models in the process simulation. This study aims to develop a unit operation model for a wet low intensity magnetic separator on particle property level. The experimental data was gathered in a plant survey of the KA3 iron ore concentrator of Luossavaara-Kiirunavaara AB in Kiruna. Corresponding feed, concentrate and tailings streams of the primary magnetic separator were sampled, assayed and mass balanced on mineral liberation level. The mass-balanced data showed that the behavior of individual particles in the magnetic separation is depending on their size and composition. The developed model involves a size and composition dependent entrapment parameter and a separation function that depends on the magnetic volume of the particle and the nature of gangue mineral. The model is capable of forecasting the behavior of particles in magnetic separation with the necessary accuracy. This study highlights the benefits that particle-based models in simulation offer whereas lower level process models fail to provide.

  • 21.
    Paul, Mehtap
    et al.
    Turkish Atomic Energy Authority, Ankara Nuclear Research and Training Center.
    Seferinoğlu, Meryem
    MTA, Mineral Research and Exploration Directorate, 06520 Balgat, Ankara.
    Ayçık, Gul Asiye
    Turkish Atomic Energy Authority, Ankara Nuclear Research and Training Center.
    Sandström, Åke
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Smith, Michael L.
    Anabolic Laboratories, Inc., Tempe, AZ.
    Paul, Jan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Acid leaching of ash and coal: time dependence and trace element occurrences2006Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 79, nr 1, s. 27-41Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The leaching of coal and coal/asphaltite/wood-ashes in sulfuric acid (pH 1.0, 25 °C, S/L, 1:10) was studied as a function of time; acid consumption and extracted metal concentrations are presented. Whole coals consumed acid rapidly during the first few minutes, followed by slow acid consumption. Wood-, lignite-, and asphaltite-ashes consumed acid in two stages, the rapid phase extending < 30 min and the slow phase extended up to 10 days. The rapid phase was dominated by the dissolution of Ca, K and Mg ions for wood-ash, by Ca, Al and Mg ions for lignite-ash and Ca and Mg ions for asphaltite-ash. The sulfur concentration in solution and the concentrations of Ca, Fe, K, Mg, Na, P, Al and Mn in the aqueous phase verified the neutralizing capacity of the untreated ashes as well as the formation of insoluble sulfates in the residues. The slow phase kinetics differed for different fuels and exhibited leaching of several abundant elements-Fe, Al, K, Na and Mn. Trace elements (Ba, Cd, Co, Cr, Cu, Mo, Ni, Pb, Th, U, V, Zn) sometimes required up to 32 h for maximal extraction from ashes. Suggestions are presented regarding the chemical nature of trace elements in the untreated coals and ashes and suitable residence times for economical industrial processes. We think it possible to combine bacteriological oxidation of sulfidic concentrates of acid leaching from ash of various qualities or even whole coals.

  • 22. Pourghahramani, Parviz
    et al.
    Forssberg, Eric
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Comparative study of microstructural characteristics and stored energy of mechanically activated hematite in different grinding environments2006Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 79, nr 2, s. 120-139Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hematite concentrate was mechanically treated using different milling machines and experimental conditions in air atmosphere. The changes in phase constitution, particles size, specific surface area, lattice parameters and X-ray amorphous phase fraction of activated hematite were determined. It was found that the agglomeration of the particles take place during extended milling with accessible pores for Nitrogen gas. The higher media surface brought about the largest specific surface area whatever milling devices used. After 9 h of grinding with higher media surface, the maximum and minimum specific surface area resulted from the grinding in the tumbling and vibratory mills, accounting for 6.83 m(2)/g and 18.42 m(2)/g, respectively. For the same grinding condition, tumbling mill produced the lowest X-ray amorphous phase. The maximum X-ray amorphous material estimated around 85% from the grinding in the planetary mill with higher media surface for 9 h of milling. Structural changes were followed by XRD line broadening analysis (LPA) using the integral breadth method and Warren-Averbach approach. From the Williamson-Hall plots, it was understood that strain and size contributions exist simultaneously in the milled samples. Besides, the physical broadening increases as milling time and media surface increase regardless of milling types. Besides, it was found that hematite crystal is 'soft' between (024) and other crystallographic directions.From the Warren-Averbach approach, it was observed that the higher grinding media surface and prolonged milling favor the generation of small crystallite, higher microstrain, limited crystallite length and subsequently uniform activation of hematite. After 9 h of milling with higher media surface in tumbling, vibratory and planetary mills, the surface weighted crystallite size reached 17.3, 12.2 and 5.6 nnn respectively. The maximum lattice strain, (1/2), in the grinding with tumbling, vibratory and planetary mills was found about 4.44 x 10(-3), 3.95 x 10(-3) and 5.23 x 10(-3), respectively. The maximum dislocation density accounted for 46.3 x 10(14) m/m(3) in the planetary milling with higher media surface after 9 h of milling. The evaluation of energy contributions of structural defects suggested that the energy contribution of the amorphization was dominant and amounted to 92-98% of the overall stored energy in hematite, depending on milling conditions. Finally, for a given stress energy, the products of tumbling mill represent higher reactivity potential

  • 23. Pourghahramani, Parviz
    et al.
    Forssberg, Eric
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Effects of mechanical activation on the reduction behavior of hematite concentrate2007Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 82, nr 2, s. 96-105Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effect of mechanical activation on the reduction behavior of a hematite concentrate has been examined using a combination of simultaneous thermal analysis (STA), X-ray diffraction (XRD), scanning electron microscope (SEM) analysis, and laser diffraction. The samples were activated in vibratory and planetary mills. Differential thermal analysis (DTA) and thermogravimetric (TG) analysis revealed that reduction of mechanically activated and initial hematite proceeds stepwise (Fe2O3 → Fe3O4 → Fe). The hydrogen reduction of mechanically activated samples initiates at low temperatures compared with the initial sample. The beginning temperature (onset) of the reduction decreases from 421 °C in the initial sample to 330 °C in the mechanically activated sample, depending on the grinding intensity. Further, the reduction of hematite to magnetite in the activated samples is more pronounced due to mechanical activation. At low temperatures, the activated samples give a higher degree of conversion than the initial samples regardless of which milling device is used. Hematite reduces completely to iron metal. A comparison of mill-type effect based on stress energy (specific grinding work) suggests that the mill-type effect is confined by a stress energy of 4300 kJ/kg. After releasing 4300 kJ/kg energy, mechanical activation by the planetary mill brings about a larger decrease in onset temperature and a slightly higher degree of conversion at lower temperatures than does activation by the vibratory mill for a given stress energy. A direct relationship between the reaction characters at lower temperatures and structure sensitivity character (S/X) and stored energy can be identified after releasing 4300 kJ/kg energy. However, partial sintering of material at higher temperatures during the reduction of the mechanically activated hematite became active, and the effects of disordering of the hematite structure vanished and subsequently the reduction reaction was retarded.

  • 24. Pourghahramani, Parviz
    et al.
    Forssberg, Eric
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Microstructure characterization of mechanically activated hematite using XRD line broadening2006Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 79, nr 2, s. 106-119Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effect of dry milling in a vibratory mill on the structural changes and microstructural characteristics of hematite using different methods was investigated. We have described the line profile analysis (LPA) to extract the size of coherently diffracting domains and the lattice strain of activated hematite in a vibratory mill. The Warren-Averbach and Williamson-Hall methods were used as the main tools for characterization. The changes in the particle size, surface area and new phase formation of hematite concentrate were also investigated. It was concluded that the breakage and agglomeration of particles take place mainly at lower and higher levels of specific energy input, respectively. The pores in agglomerates remain accessible for the nitrogen gas. Milling of hematite increased specific surface area up to 18.4 m(2)/g. The hematite milled under various levels of specific energy input did not undergo a significant reaction or phase transformation during milling. The Williamson-Hall method confirms its merit for a rapid overview of the line broadening effects and possible understanding of the main causes. The anisotropic character of line broadening for deformed hematite as a function of specific energy input was revealed. Higher level of specific energy input favors the generation of small crystallite size, higher microstrain, BET surface area, amorphization and line breadth. The Warren-Averbach method suggested that the nanocrystalline hematite with grain sizes of 73.5-12.2 nm was formed by mechanical treatment using different milling intensities in the vibratory mill. The root mean square strain (RMSS) at L = 10 nm varies between 1.7 x 10(-3) and 4.0 x 10(-3) depending on the level of energy input. Limits in the applicability of Williamson-Hall method and reliability of the results are discussed in detail.

  • 25. Pourghahramani, Parviz
    et al.
    Forssberg, Eric
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    The characterization of structural changes in hematite ground in a confined particle bed using Rietveld analysis2007Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 83, nr 1-2, s. 47-59Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The interparticle breakage of fine feed fraction of hematite concentrate was investigated by stressing two particle beds with a pressure between 255 and 1000 MPa. The experiments were conducted in such a way that the wall friction effects during compression were eliminated. The effects of interparticle breakage in a confined bed on the structural changes of hematite concentrate were studied using a combination analysis of XRD line broadening, BET and particle size measurements. The specific energy comminution was estimated using loading and de-loading hysteresis curves. It was found that energy absorption by the particle bed varies between 6 and 31 J/g depending on the applied pressures and bed heights. The experiments indicated that energy absorption was a major factor for the interparticle breakage of hematite. In addition, it was revealed that an increasing bed height brought about a higher stiffness and hence reduced energy absorption and subsequently declined the surface area, solid content as well as structural changes. The linear energy-force relationship stands well even if the particle-bed heights are changed. The maximum BET surface area was measured about 1.4 m2/g after energy absorption of 31 J/g by the particle bed. Structural changes were followed by XRD line broadening analysis using Rietveld refinement and Warren-Averbach approach. It was found that the intensity and the broadening of XRD diffraction patterns decreased and increased, respectively, by increasing energy absorption with a first approximation. With increasing absorbed energy by the bed up to 15 J/g the degree of amorphization increased sharply and afterwards continued to change slightly. The maximum X-ray amorphization was calculated at maximum energy absorption, accounting for 31%. The volume and surface weighted crystallite sizes reduced to about 108 and 53 nm, respectively, after releasing 31 J/g specific grinding energy. For the same energy, the root mean square strain (RMSS), <εL2 = 10 nm>1/2, and maximum lattice strain, e, increased to 9.4 × 10- 4 and 4.1 × 10- 3 respectively. The comparison of bed grinding with tumbling milling revealed that the grinding in tumbling mill needs much more energy to induce the same structural changes as in bed grinding. The results obtained from the two methods are discussed and compared in details.

  • 26. Pourghahramani, Parviz
    et al.
    Pålsson, Bertil
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Forssberg, Eric
    Multivariate projection and analysis of microstructural characteristics of mechanically activated hematite in different grinding mills2008Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 87, nr 3-4, s. 73-82Artikel i tidskrift (Refereegranskat)
    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.

  • 27.
    Pålsson, Bertil
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Computer-assisted calculations of chemical equilibria with relevance to the chromate depression of galena1991Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 33, nr 1-4, s. 207-221Artikel i tidskrift (Refereegranskat)
    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.

  • 28.
    Pålsson, Bertil
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Forssberg, Eric
    Computer-assisted calculations of thermodynamic equilibria in sphalerite-xanthate systems1989Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 26, nr 3-4, s. 223-258Artikel i tidskrift (Refereegranskat)
    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.

  • 29. Pålsson, Bertil
    et al.
    Forssberg, Eric
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Computer-assisted calculations of thermodynamic equilibria in the galena-ethyl xanthate system1988Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 23, nr 1-2, s. 93-121Artikel i tidskrift (Refereegranskat)
    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.

  • 30. Rao, K. Hanumantha
    et al.
    Antti, Britt-Marie
    Luleå University of Technology.
    Forssberg, Eric
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Flotation of phosphatic material containing carbonatic gangue using sodium oleate as collector and sodium silicate as modifier1989Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 26, nr 1, s. 123-140Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effect of sodium silicate as a depressant for calcite is examined in the flotation of phosphatic material containing calcite and siliceous gangue using sodium oleate as collector. Maximum flotation of apatite occurs at pH 8, whereas the pH at which calcite floats best varies with particle size. At pH 8 and 9, sodium silicate depresses calcite to some extent beyond 1500 g/t (2·10−3 M), and the depression is more pronounced at higher pH but the recovery of apatite is correspondingly low at these pH values. Selective action of silicate on calcite surfaces can be seen from the analysis of pulp liquid. However, for the pH range 7–11 and at any sodium silicate concentration, no significant selectivity between apatite and calcite is achieved.The influence of oleate concentration, pH and the concentration of sodium silicate on the flotation behaviour are discussed in detail.

  • 31.
    Rao, K. Hanumantha
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Antti, Britt-Marie
    Luleå University of Technology.
    Forssberg, Eric
    Mechanism of oleate interaction on salt-type minerals. Part II.: Adsorption and electrokinetic studies of apatite in the presence of sodium oleate and sodium metasilicate1990Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 28, nr 1, s. 59-79Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The mechanism of oleate interaction on apatite is investigated through adsorption and electrokinetic studies. The adsorption density at monolayer coverage corresponds to a condensed state of surfactant molecule with a molecular area of 33 Å2. The isotherm at pH 8 showed the monolayer coverage followed by the precipitation step of calcium oleate, whereas at pH values 9, 10 and 11, the isotherms showed bilayered structure of oleate on the surface before the precipitation step of calcium oleate. The vertical step characterizing calcium oleate precipitation after bilayer formation is found to be dependent on the solid/liquid ratio. The zeta-potentials correlate to the adsorption of oleate up to bilayer formation. The presence of sodium silicate has no influence on the adsorption of oleate.

  • 32.
    Rao, K. Hanumantha
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Forssberg, Eric
    Mixed collector systems in flotation1997Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 51, nr 1, s. 67-79Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The interactions between differently structured surfactant molecules at the solid/liquid and air/liquiid interfaces and their effectiveness for efficient flotation were recognised during the 1950's, while no sincere effort has been made to understand the mixed collector systems on flotation performance. In recent years, interest has increased for the use of mixtures of anionic/ nonionic and anionic/cationic collectors for enhancing the selectivity and recovery. This paper reviews the flotation studies reported on the use of various collector combinations and discusses the behaviour of mixed collectors at the mineral/water interface.

  • 33. Rao, K. Hanumantha
    et al.
    Forssberg, Eric
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Preface, Minerals Bioprocessing IV conference2001Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 62, nr 1-4, s. 1-2Artikel i tidskrift (Övrigt vetenskapligt)
  • 34. Rao, K. Hanumantha
    et al.
    K.S:, Narasimhan
    Regional Research Laboratory, CSIR, Bhubaneshwar 751 013, India.
    Selective flocculation applied to Barsuan iron ore tailings1985Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 14, s. 67-75Artikel i tidskrift (Refereegranskat)
  • 35. Rodríguez, Nathalie Pérez
    et al.
    Khoshkhoo, Mohammad
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Sandström, Åke
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Rodushkin, Ilya
    Alakangas, Lena
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Öhlander, Björn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Isotopic signature of Cu and Fe during bioleaching and electrochemical leaching of a chalcopyrite concentrate2015Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 134, s. 58-65Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Bioleaching is an important process in metallurgy and in environmental sciences, either for the acquisition of metals or for the formation of acid rock drainage. In this study the implications of the processes during bioleaching of a pyritic chalcopyrite concentrate were analysed regarding its Cu and Fe isotope fractionation. The development of the redox potential during the bioleaching experiment was then simulated in an electrochemical cell in absence of microorganisms to investigate the effect of microbial activity on the Cu and Fe isotope fractionations. The leaching experiments were performed for 28 days at 45 °C with a solid content of 2.5% (w/v) at pH 1.5. It was found that Cu dissolution efficiency was similar in both experiments and the leaching curves were linear with no sign of passivation due to presence of pyrite. The heavy Cu isotope (δ65Cu) was leached more easily and as a result the leachate was enriched with the heavy Cu isotope at the beginning of both experiments and as the leaching progressed δ65Cu values in the leachate became similar to the ones of the chalcopyrite concentrate, confirming an equilibrium fractionation happening in a closed system. There was no distinct difference in the Cu and Fe isotope fractionations in absence and presence of microorganisms. Finally based on Cu and Fe isotope signatures, a simplified method is suggested for the estimation of the leaching extent during the oxidisation of sulphide materials in natural systems.

  • 36.
    Sandström, Åke
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Mattsson, E.
    Stora Enso.
    Bacterial ferrous iron oxidation of acid mine drainage as pre-treatment for subsequent metal recovery2001Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 62, nr 1-4, s. 309-320Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mining activities at Falu copper mine in Sweden started around the year 1080 AD and continued until 1993. During all these centuries, the acid mine drainage has caused low pH values and high metal levels in the nearby Falu river and it's surroundings. This work is part of a plan to achieve a long-term solution to this environmental problem, where the aim is to treat the mine water overflow in such a way that a neutral pH and an essentially metal free aqueous effluent is obtained. The idea is to first oxidise the ferrous iron with bacteria, in order to be able to make a selective ferric iron precipitation at a pH of around 3. In this paper, only the initial stage of bacterial ferrous iron oxidation is discussed. A pilot plant was erected at the mine site with three 500 l reactors in series with a treatment capacity of up to approximately 500 l h exp -1 . The reactors were filled with plastic bodies in order to support the formation of a permanent biofilm to avoid bacterial washout. The pilot plant has been operating continuously for several months and the influence of flow rate, ferrous concentration, pH and temperature was investigated. The feasibility for a biological ferrous iron oxidation step was successfully demonstrated. With a ferrous concentration of 3.5 g l exp -1 , 35 deg C, pH 1.8 and a flow rate of 330 l h exp -1 a ferrous iron oxidation rate of 750 mg l exp -1 h exp -1 was achieved. The results obtained will be used to calculate the capital and operating cost for a full scale plant, capable of treating 25 m exp 3 of acid mine drainage per hour.Before the final decision, regarding the ferrous iron oxidation step is made, alternative processes such as hydrogen peroxide and ozone oxidation will be evaluated.

  • 37.
    Santhiya, D.
    et al.
    Indian Institute of Science.
    Subramanian, S.
    Indian Institute of Science.
    Natarajan, K.A.
    Indian Institute of Science.
    Rao, K. Hanumantha
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Forssberg, Eric
    Bio-modulation of galena and sphalerite surfaces using Thiobacillus thiooxidans2001Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 62, nr 1-4, s. 121-141Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The interaction of Thiobacillus thiooxidans (T. thiooxidans) with sphalerite and galena has been investigated through adsorption, electrokinetic, and flotation studies. The amount of T. thiooxidans cells adsorbed onto galena and sphalerite is found to be almost independent of pH. However, a greater amount of cells is adsorbed onto galena compared to sphalerite. The adsorption isotherms of T. thiooxidans onto both galena and sphalerite exhibit Langmuirian behaviour. Electrokinetic measurements reveal that the isoelectric points (iep) of galena and sphalerite are located around pH 2, while that of T. thiooxidans is around pH 3. The isoelectric points of the minerals are shifted to higher pH values after interaction, consequent to bacterial cell attachment, indicating specific adsorption. Additionally, the electrophoretic mobilities are found to become less negative as a function of time after bacterial interaction. Such a trend is also followed in the case of the cells after interaction with the minerals for different time intervals. On a comparative basis, the cells after interaction with sphalerite are less negative vis-à-vis those after interaction with galena. The flotation recovery of sphalerite, beyond 1 h of interaction with T. thiooxidans cells is not affected but galena is totally depressed in the presence of T. thiooxidans cells, in the pH range 5-11. The differential flotation tests on a synthetic mixture of galena and sphalerite reveal that sphalerite can be selectively floated from galena in the presence of T. thiooxidans.

  • 38.
    Sharma, P.K.
    et al.
    Luleå tekniska universitet.
    Rao, Hanumantha
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Forssberg, Eric
    Natarajan, K.A.
    Indian Institute of Science, Bangalore.
    Surface chemical characterisation of Paenibacillus polymyxa before and after adaptation to sulfide minerals2001Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 62, nr 1-4, s. 3-25Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A heterotroph Paenibacillus polymyxa bacteria is adapted to pyrite, chalcopyrite, galena and sphalerite minerals by repeated subculturing the bacteria in the presence of the mineral until their growth characteristics became similar to the growth in the absence of mineral. The unadapted and adapted bacterial surface have been chemically characterised by zeta-potential, contact angle, adherence to hydrocarbons and FT-IR spectroscopic studies. The surface free energies of bacteria have been calculated by following the equation of state and surface tension component approaches. The aim of the present paper is to understand the changes in surface chemical properties of bacteria during adaptation to sulfide minerals and the projected consequences in bioflotation and bioflocculation processes.The mineral-adapted cells became more hydrophilic as compared to unadapted cells. There are no significant changes in the surface charge of bacteria before and after adaptation, and all the bacteria exhibit an iso-electric point below pH 2.5. The contact angles are observed to be more reliable for hydrophobicity assessment than the adherence to hydrocarbons. The Lifschitz--van der Waals/acid--base approach to calculate surface free energy is found to be relevant for mineral--bacteria interactions. The diffuse reflectance FT-IR absorbance bands for all the bacteria are the same illustrating similar surface chemical composition. However, the intensity of the bands for unadapted and adapted cells is significantly varied and this is due to different amounts of bacterial secretions underlying different growth conditions.

  • 39.
    Sivamohan, R.
    Luleå tekniska universitet.
    Computation and interpretation of the flow characteristics of thin films-oscillating surface1990Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 28, nr 1-2, s. 45-58Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A type of non-stationary surface found in slime gravity concentration includes oscillating surfaces and symmetrically reciprocating surfaces. It is the purpose of the present work to compute the flow characteristics of a thin film flowing on an oscillating surface (ex. Bartles Mozley concentrator (Burt and Ottley, 1974)) in various settings of the involved parameters. A concentrator like the Bartles Mozley unit oscillates (does not revolve) in a circular orbit transverse to the plane of the separating surface. The desired oscillation can be provided by means of a mass connected to the concentrator and rotatable about an axis perpendicular to the separating surface. The circular orbital diameter of the oscillating surface is determined by the concentrator's weight and that of the moment of inertia of the rotating mass.

  • 40.
    Sivamohan, R.
    Luleå tekniska universitet.
    Problem of recovering very fine particles in mineral processing1990Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 28, nr 3-4, s. 247-288Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This review puts together the available basic knowledge relevant to the problem of very fine particles and analyses the various surface-based methods. The greater part of this vast literature is of a basic, fundamental nature. An acute need to do more research on the problem of very fine particles from an applied angle is explicit. Considerations of the significance of what has been practically observed with a qualitative theoretical approach may be defined as an applied approach. Such an approach will enable an understanding of why there are lower size limits for various processes and a base for further developments. Aggregation of very fine particles by hydrophobic association, the use of oil as a collector extender, column flotation, and the physical and chemical characterization of the surface composition and heterogeneity are the areas in surface-based methods identified for future research

  • 41.
    Sivamohan, R.
    et al.
    Luleå tekniska universitet.
    Cases, J.M.
    CRVM/CNRS, Vandouevre-les-Nancy.
    Dependence of shear-flocculation on surface coverage and zeta potential1990Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 28, nr 3-4, s. 161-172Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The dependence of shear-flocculation on surface coverage and zeta potential is elucidated using a model system of fluorite/scheelite/oleate. The experiments carried out were (1) shear-flocculation, (2) oleate adsorption/abstraction, (3) flotation of the shear flocs, (4) zeta potential, and (5) turbidity. At a sufficiently high constant shear both an increase in surface coverage and a decrease in zeta potential lead to an increase in the amount of shear flocculating. Manipulation of these two factors permits the turbidity to be reduced from as high as 450 NTU (Θ(surface coverage) = .5; ζ (zeta potential) = -40 mV) to as low as 40 NTU (Θ= 1.2; ζ = -29 mV) in the case of scheelite. With fluorite, turbidity drop is from 120 NTU (Θ= 1; ζ= -40 mV) to 20 NTU (Θ= 1.5; ζ= -19 mV). A close relationship exists between the turbidity measurements and the amount of shear flocculating in percentage. The total flotation of the shear flocs is possible at apparent surface coverages corresponding to a partly formed bilayer

  • 42.
    Sivamohan, Rajaratnam
    et al.
    Luleå tekniska universitet.
    Forssberg, Eric
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    A review of the literature on intermediate and fine particle gravity concentration1985Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 15, nr 3, s. 155-Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    Once again, after a lapse of about 50 years, there is widespread recognition of the importance of understanding and improving the treatment of particles by gravity concentration. An attempt is made here, therefore, to analyze the literature on intermediate and fine particle gravity concentration comprehensively and critically, in order to bring the current stage into perspective. The areas covered are sluicing, spiral concentration, tabling and slime gravity concentration. The underlying mechanisms of the above unit processes, interrelationships among the involved variables, development and design of the relevant equipment and also their application, are discussed. The behavior of the particles in sluicing, spiral concentration and tabling are examined in detail on the basis of the fundamental knowledge available in mineral processing and fluid and particulate dynamics.

  • 43.
    Sivamohan, Rajaratnam
    et al.
    Luleå University of Technology.
    Forssberg, Eric
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Principles of sluicing1985Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 15, nr 3, s. 157-171Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The theoretical background of the mechanism of concentration in the sluice is analyzed in detail by broadly categorizing the involved mechanisms into two separate, different actions; vertical stratification in the inhomogeneous flowing suspension and the same in the moving dilated bed, beneath the former.The significance of the many design and operational variables and their interrelationships are then examined together with the modelling of the cone variables. The cone's application is also discussed.The design aspects of certain forms of sluices are analyzed to show how theoretical and operational considerations should be knitted to achieve an improved performance. Failure to obey such considerations is certain to make any sluice unpopular as is the case of Lamflo sluice.

  • 44.
    Sivamohan, Rajaratnam
    et al.
    Luleå University of Technology.
    Forssberg, Eric
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Principles of spiral concentration1985Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 15, nr 3, s. 173-181Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The different stages of concentration are discussed. The significance of design and operational variables and their interrelationships are examined. The areas where spiral concentrators are applicable are presented.

  • 45. Sivamohan, Rajaratnam
    et al.
    Forssberg, Eric
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Principles of tabling1985Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 15, nr 4, s. 281-295Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The mechanism of concentration on the shaking table is discussed and a fresh attempt is made to obtain the theoretical model describing the velocity of a fluid in depth and time when in contact with a symmetrically reciprocating surface.The significance of the many design and operational variables and their interrelationships are examined. The various areas where the shaking table plays its role are then considered.The relevant features of micropanner, superpanner and the subsequent macropanner and pulsepanner are also treated since they all, like the shaking table, have the differential motion in common.

  • 46.
    Sivamohan, Rajaratnam
    et al.
    Luleå University of Technology.
    Forssberg, Eric
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Recovery of heavy minerals from slimes1985Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 15, nr 4, s. 297-314Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Development of various slime gravity equipment is traced and the merits and demerits of these are discussed and compared.The significance of the design and operational variables and their interrelationships are examined. Emphasis is placed upon the necessity to selectively modify the particle surfaces in order to achieve selective aggregation in conjunction with selective dispersion, in slime gravity concentration. The significance of the deck roughness and the insignificance of the viscosity under the conditions which would normally prevail in slime gravity processes are noted.The possibility of having slime gravity circuits for feeds with a top size of about 45–53 μm only is stressed and selected examples of plant flowsheets are given.

  • 47.
    Stener, Jan
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Carlson, Johan
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Sand, Anders
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Pålsson, Bertil
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Internal flow measurements in pilot scale wet low-intensity magnetic separation2016Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 155, s. 55-63Artikel i tidskrift (Refereegranskat)
    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.

  • 48.
    Su, Fenwei
    et al.
    Luleå tekniska universitet.
    Rao, K. Hanumantha
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Forssberg, Eric
    Samskog, Per-Olof
    The influence of temperature on the kinetics of apatite flotation from magnetite fines1998Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 54, nr 3, s. 131-145Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The influence of pulp temperature on the kinetics of apatite flotation from magnetite fines was studied using Atrac (fatty acid type) as collector and sodium silicate as dispersant at pH 8.5–9.0. The batch flotation tests were conducted in a specially designed temperature controlled flotation cell. A modified first-order model, incorporating two rate terms describing fast and slow-floating components, was applied to evaluate the flotation kinetics. The estimation of the model parameters was made by a non-linear least squares fitter program which is based on the Levenberg–Marquardt algorithm. Results indicate that increasing temperature from 10°C to 40°C decreases the phosphorous content in magnetite concentrate but with a simultaneous loss of magnetite recovery. At temperatures below 30°C, an increase in pulp temperature results increasing flotation rate of fast-floating particles and has a marginal effect on slow-floating particles. Above 30°C, the flotation rate of fast-floating particles decreases with increasing pulp temperature. Sodium silicate has a positive effect for increasing the phosphorous recovery and decreasing the phosphorous content in the magnetite concentrate at 20°C for all the levels of collector dosages. In the absence of sodium silicate, collector is active for both apatite and magnetite flotation. The higher selectivity between apatite and magnetite with an acceptable content of phosphorous in the magnetite concentrate is obtained at a moderate dosage of about 400 g/t sodium silicate. The optimum flotation conditions are: 50 g/t collector dosage, 350–400 g/t dispersant dosage, pH 8.5–9 and pulp temperature 25–30°C.

  • 49.
    Subrahmanyam, T.V.
    et al.
    Departamento de Geologia, CCE/UFRN, Campus Universitario, 59.072, Natal.
    Forssberg, Eric
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Fine particles processing: shear-flocculation and carrier flotation: a review1990Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 30, nr 3-4, s. 265-286Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Shear-flocculation/flotation and carrier flotation are methods by which fine mineral values are aggregated and then recovered by flotation. The aggregates formed have better floatabilities. Without prior treatment ahead of flotation, significant quantities of fines are lost in tailings. An overview of the problems associated with fine particles is presented. Like froth flotation, the mechanisms of shear-flocculation and carrier flotation are governed by physical, chemical and geometrical variables. The present paper deals with the effects of these variables on shear-flocculation and carrier flotation, based on a detailed literature review

  • 50.
    Subrahmanyam, T.V.
    et al.
    Geologia, Laboratory of Mineral Processing, UFRN, Natal.
    Forssberg, Eric
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Froth stability, particle entrainment and drainage in flotation: a review1988Ingår i: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 23, nr 1, s. 33-53Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The froth and its stability, the entrainment and the drainage of particles in flotation were long before recognised as important factors which affect recovery and grade. A too stable froth is difficult to handle but, on the other hand, an unstable froth is least desirable. Therefore, a froth of correct stability is of utmost importance. However, the question is whether this phenomenon is related to the frothing properties of a frother or to the physical, chemical and geometrical conditions of a system! The entrainment and drainage of particles in flotation are concerned with the pulp/froth phases. The present paper deals with the current aspects on froth stability, particle entrainment and drainage, based on a detailed literature review.

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