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Willis Forsling - One of the best experts on this subject based on the ideXlab platform.
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Role of dextrin in the selective flotation of fluorite
2012Co-Authors: G. Bhaskar Raju, K. Hanumantha Rao, Willis ForslingAbstract:Dextrin and related polysaccharides are generally used as depressants/ dispersants in various mineral processing operations. Interaction of dextrin on Calcium Minerals both in the presence and absence of oleate was studied in the present investigation. The mechanism of dextrin adsorption at mineral / water interface was investigated by adsorption, contact angle and zeta potential measurements. The role of dextrin in the separation of fluorite by flotation has been discussed.
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Surface Complexation of Calcium Minerals in Aqueous Solution.
Journal of colloid and interface science, 2000Co-Authors: Willis Forsling, Allan HolmgrenAbstract:Abstract The complexation of Alizarin Red S (ARS) at the surface of hydrous fluorite particles has been investigated by means of potentiometric titrations, adsorption experiments, and ζ-potential measurements in 0.1 mol dm −3 KCl ionic medium at 25.0°C, as well as by UV/visible specular reflectance, FT-IR, and FT-Raman spectroscopy. Chemical reaction models describing the equilibria of ARS (HA 2− ) at the aqueous fluorite surfaces (≡ X ) have been established as follows:[formula] Experimental data were evaluated using the computer program FITEQL on the basis of a constant capacitance model for the electric double layer. Surface complexation mechanisms involving the R–SO 3 − , R–β-OH, and R–α-OH active groups of the ARS molecule are proposed to describe coordination to the fluorite surface.
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surface complexation of Calcium Minerals in aqueous solution iii ion exchange and acid base properties of hydrous fluorite surfaces
Journal of Colloid and Interface Science, 1995Co-Authors: Willis ForslingAbstract:Abstract The acid-base properties of hydrous fluorite surfaces and ion exchange reactions between surface lattice ions of F- and OH- ions in bulk solution have been investigated. The measurements were performed as potentiometric titrations with varied solid concentrations in 0.1 mol dm-3 KCl medium at 25.0°C using a glass electrode for -log[H+] and a fluoride ion selective electrode for -log[F-]. The experimental data could be explained by a model that assumes the surface equilibria(≡CaOH12≡F ⇔ ≡CnOH≡F + H+logβs-1100 (int) = -9.5 ± 0.1≡CaOH+2≡F + H+ ⇔ ≡CaOH+2≡FHlogβs-1100 (int) = 4.4 ± 0.1≡CaOH+2≡F + H+ + H2O+ ⇔ ≡CaOH≡OH + 2H+ + F-logβs-210-1(int) = -20.3 ± 0.1The equilibrium constants were evaluated using the computer program FITEQL assuming a constant capacitance model for the electric double layer.
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Surface hydration of aqueous Calcium Minerals as studied by Fourier transform Raman and infrared spectroscopy
Spectrochimica Acta Part A: Molecular Spectroscopy, 1994Co-Authors: Allan Holmgren, Willis ForslingAbstract:Rapid hydration reactions of several Calcium Minerals are studied using Fourier transform (FT) Raman and infrared (IR) spectroscopy. Oleate adsorption over aqueous synthetic fluorite, calcite and g ...
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surface complexation of Calcium Minerals in aqueous solution 1 surface protonation at fluorapatite water interfaces
Journal of Colloid and Interface Science, 1991Co-Authors: Willis Forsling, Paul W. SchindlerAbstract:The amphoteric properties of hydrous fluorapatite surfaces have been investigated. The measurements were performed as potentiometric titrations in 0.1 M NaCl medium at 25°C using a glass electrode. The experimental data could be explained by a model that assumes the surface equilibria PO−+H+=POH logβs101(int.)=6.6±0.1(3σ) CAOH2+−H+=CAOH logβs-101(int.)=-9.7±0.1(3σ) The equilibrium constants were evaluated using the computer program FITEQL by Westall (Report 82-01, Department of Chemistry, Oregon State University, Corvallis, 1982), assuming a constant capacitance model for the electric double layer. The acidity constants result in a value of log[H+]pzc = −8.15, which shifts to log[H+]pzc = −7.13 upon exposure to atmospheric carbon dioxide.
Paul W. Schindler - One of the best experts on this subject based on the ideXlab platform.
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surface complexation of Calcium Minerals in aqueous solution 1 surface protonation at fluorapatite water interfaces
Journal of Colloid and Interface Science, 1991Co-Authors: Willis Forsling, Paul W. SchindlerAbstract:The amphoteric properties of hydrous fluorapatite surfaces have been investigated. The measurements were performed as potentiometric titrations in 0.1 M NaCl medium at 25°C using a glass electrode. The experimental data could be explained by a model that assumes the surface equilibria PO−+H+=POH logβs101(int.)=6.6±0.1(3σ) CAOH2+−H+=CAOH logβs-101(int.)=-9.7±0.1(3σ) The equilibrium constants were evaluated using the computer program FITEQL by Westall (Report 82-01, Department of Chemistry, Oregon State University, Corvallis, 1982), assuming a constant capacitance model for the electric double layer. The acidity constants result in a value of log[H+]pzc = −8.15, which shifts to log[H+]pzc = −7.13 upon exposure to atmospheric carbon dioxide.
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Surface complexation of Calcium Minerals in aqueous solution: 1. Surface protonation at fluorapatite—water interfaces
Journal of Colloid and Interface Science, 1991Co-Authors: Willis Forsling, Paul W. SchindlerAbstract:The amphoteric properties of hydrous fluorapatite surfaces have been investigated. The measurements were performed as potentiometric titrations in 0.1 M NaCl medium at 25°C using a glass electrode. The experimental data could be explained by a model that assumes the surface equilibria PO−+H+=POH logβs101(int.)=6.6±0.1(3σ) CAOH2+−H+=CAOH logβs-101(int.)=-9.7±0.1(3σ) The equilibrium constants were evaluated using the computer program FITEQL by Westall (Report 82-01, Department of Chemistry, Oregon State University, Corvallis, 1982), assuming a constant capacitance model for the electric double layer. The acidity constants result in a value of log[H+]pzc = −8.15, which shifts to log[H+]pzc = −7.13 upon exposure to atmospheric carbon dioxide.
Ingrid M Weiss - One of the best experts on this subject based on the ideXlab platform.
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Metabolites empowering Minerals
Nature Chemical Biology, 2011Co-Authors: Ingrid M WeissAbstract:Amorphous mineral phases play important roles in the skeletons of many organisms, but the molecular basis for species-specific control is still under debate. The demonstration that energy-rich metabolites such as phosphoenolpyruvate stabilize amorphous Calcium carbonate (ACC) in crayfish inspires speculation about Calcium Minerals in emerging metabolisms.
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Biomaterials: Metabolites empowering Minerals
Nature chemical biology, 2011Co-Authors: Ingrid M WeissAbstract:Amorphous mineral phases play important roles in the skeletons of many organisms, but the molecular basis for species-specific control is still under debate. The demonstration that energy-rich metabolites such as phosphoenolpyruvate stabilize amorphous Calcium carbonate (ACC) in crayfish inspires speculation about Calcium Minerals in emerging metabolisms.
Lev Filippov - One of the best experts on this subject based on the ideXlab platform.
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Synergistic adsorptions of Na2CO3 and Na2SiO3 on Calcium Minerals revealed by spectroscopic and ab initio molecular dynamics studies.
Chemical science, 2019Co-Authors: Yann Foucaud, Inna V. Filippova, Lev Filippov, Odile Barres, Michael Badawi, Sébastien LebègueAbstract:The synergistic effects between sodium silicate (Na2SiO3) and sodium carbonate (Na2CO3) adsorbed on mineral surfaces are not yet understood, making it impossible to finely tune their respective amounts in various industrial processes. In order to unravel this phenomenon, diffuse reflectance infrared Fourier transform and X-ray photoelectron spectroscopies were combined with ab initio molecular dynamics to investigate the adsorption of Na2SiO3 onto bare and carbonated fluorite (CaF2), an archetypal Calcium mineral. Both experimental and theoretical results proved that Na2CO3 adsorbs onto CaF2 with a high affinity and forms a layer of Na2CO3 on the surface. Besides, at low Na2SiO3 concentration, silica mainly physisorbs in a monomeric protonated form, Si(OH)4, while at larger concentration, significant amounts of polymerised and deprotonated forms are identified. Prior surface carbonation induces an acid–base reaction on the surface, which results in the formation of the basic forms of the monomers and the dimers, i.e. SiO(OH)3− and Si2O3(OH)42−, even at low coverage. Their adsorption is highly favoured compared to the acid forms, which explains the synergistic effects observed when Na2SiO3 is used after Na2CO3. The formation of the basic form on the bare surface is observed only by increasing the surface coverage to 100%. Hence, when Na2CO3 is used during a separation process, lower Na2SiO3 concentrations are needed to obtain the same effect as with lone Na2SiO3 in the separation process.
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The role of a fatty alcohol in improving Calcium Minerals flotation with oleate
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2019Co-Authors: Lev Filippov, Inna V. Filippova, Zineb Lafhaj, Daniel FornasieroAbstract:Abstract The adsorption mechanism of collector mixtures and the implication for mineral flotation are discussed in light of the results of a quantitative study of the flotation of fluorapatite and calcite with mixtures of fatty alcohol and oleate collectors. It was found that the recovery of fluorapatite and calcite floated with oleate improved considerably after addition of the fatty alcohol. With oleate alone, the low mineral flotation was attributed to a patchy oleate surface coverage and oleate dimers but with the collector mixture it was shown that the fatty alcohol co-adsorbs with oleate on the mineral surface and in a much larger quantity than when it was used alone. Spectroscopic analyses reveal that the amount of oleate adsorbed remains similar when added alone or in mixtures, which implies that the co-adsorption of the fatty alcohol is responsible for the improved mineral flotation. Replacement of oleate dimers with fatty alcohol-oleate complexes at the mineral surface may also explain the increase mineral hydrophobicity and flotation.
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Effect of Calcium Minerals reactivity on fatty acids adsorption and flotation
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2018Co-Authors: Inna V. Filippova, Lev Filippov, Zineb Lafhaj, Odile Barres, Daniel FornasieroAbstract:Abstract The separation between Calcium Minerals such as apatite and calcite by flotation relies on the use of long chain fatty acid collectors. Oleic acid, and its salt, is the main fatty acid collector and many studies have reported on the mechanisms of its interaction with Calcium at the mineral surface and in solution, and on the oleic acid species present at the mineral surface. Although collector adsorption and mineral flotation depend mainly on solution pH and collector concentration, other factors such as mineral crystallinity and impurity affect mineral dissolution, influence collector adsorption and may explain the different flotation results reported in the literature on the same Minerals. In this study the flotation of two calcites, with different degrees of purity, and one apatite was compared and related to the amount and type of collector adsorbed on the mineral surface, and to the reactivity of these Minerals (acid-base interaction and dissolution). The results obtained in this study indicate that Calcium dioleate (or dilinoleate) is the species present on the Minerals surface at pH 9 and its amount increases with collector addition and Calcium mineral dissolution, which results in a higher flotation of the Calcium Minerals. The influence of Calcium site density and impurity in the Minerals on flotation was also discussed.
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New reagent formulations for selective flotation of scheelite from a skarn ore with complex Calcium Minerals gangue
Minerals Engineering, 2018Co-Authors: Lev Filippov, Inna V. Filippova, Yann Foucaud, Michael BadawiAbstract:Abstract The approach using synergistic effects of the blend of carboxylic collectors was applied to process the Tabuaco tungsten skarn ores (Portugal) by flotation. However, a very complex mineral composition with high amounts of the fluorite (>10%) and apatite (3–5%), as well as the presence of more than 40% of vesuvianite, a silicate of Calcium, implied that such separation is highly challenging. In this work, the influence of sodium silicate and sodium carbonate on the selective flotation of scheelite has been investigated. A study of depressants dosage allowed to reach a selective flotation of scheelite from Calcium Minerals at 1125 g/t, except from fluorite. The use of sodium carbonate with sodium silicate showed synergistic effects, increasing the WO 3 grade from 6.6% to 11.2% without impacting the recovery. Collector formulations were created in the laboratory by mixing the commercial fatty acids, in which oleic and linoleic acid predominated, in various proportions with rosin acids while the ratio between oleic and linoleic acids was kept constant. The tungsten recovery increased significantly, up to 98%, with the amount of rosin acids in the mixture while the concentrate grade decreased from 16% WO 3 grade to 10.5% WO 3 grade impacting the selective flotation of scheelite from an ore with 0.9% WO 3 grade. The optimal ratio of fatty and rosin acids was then experimentally set to 5/1-6/1. An unprecedented increase of the flotation selectivity between scheelite and fluorite was obtained when the saturated acids were introduced in the formulation. The concentrate grade reached 27% WO 3 grade for the same ratio between anionic reagents. Thus, the new reagent formulation allowed to obtain a tungsten concentrate after only one cleaner stage without additional use of thermal treatment or activating heavy metals salts or specific depressants.
Allan Holmgren - One of the best experts on this subject based on the ideXlab platform.
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Surface Complexation of Calcium Minerals in Aqueous Solution.
Journal of colloid and interface science, 2000Co-Authors: Willis Forsling, Allan HolmgrenAbstract:Abstract The complexation of Alizarin Red S (ARS) at the surface of hydrous fluorite particles has been investigated by means of potentiometric titrations, adsorption experiments, and ζ-potential measurements in 0.1 mol dm −3 KCl ionic medium at 25.0°C, as well as by UV/visible specular reflectance, FT-IR, and FT-Raman spectroscopy. Chemical reaction models describing the equilibria of ARS (HA 2− ) at the aqueous fluorite surfaces (≡ X ) have been established as follows:[formula] Experimental data were evaluated using the computer program FITEQL on the basis of a constant capacitance model for the electric double layer. Surface complexation mechanisms involving the R–SO 3 − , R–β-OH, and R–α-OH active groups of the ARS molecule are proposed to describe coordination to the fluorite surface.
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Surface hydration of aqueous Calcium Minerals as studied by Fourier transform Raman and infrared spectroscopy
Spectrochimica Acta Part A: Molecular Spectroscopy, 1994Co-Authors: Allan Holmgren, Willis ForslingAbstract:Rapid hydration reactions of several Calcium Minerals are studied using Fourier transform (FT) Raman and infrared (IR) spectroscopy. Oleate adsorption over aqueous synthetic fluorite, calcite and g ...
