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David A. Beattie - One of the best experts on this subject based on the ideXlab platform.
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Influence of solution conditions and polymer chemistry on the adsorption behaviour of anionic dispersants onto Chalcocite in aqueous media
Chemical Engineering Journal, 2011Co-Authors: David A. Beattie, Jonas Addai-mensahAbstract:Abstract The adsorption behaviour of two polymeric dispersants (Cyquest 3223: sodium acrylate/acrylamide co-polymer and P80: sodium allyl sulfonate/maleic acid co-polymer) onto Chalcocite mineral particles has been investigated as a function of solution pH (5, 7 and 9) and different oxidative environments. The dissociation of both polymers in aqueous solutions in the pH range 2–10 was quite similar, commencing at pH 2 and finishing at ∼pH 7, where the polymers became fully ionised, reflecting maximum negative charge. Strong pH-dependent adsorption onto negatively charged Chalcocite at pH 7 and 9 was observed, the behaviour consistent with polymer binding through a chemical complexation mechanism. Furthermore, the plateau adsorption density was ∼80% greater under air or O2 gas saturation, than under N2 gas saturation and ∼25% higher for P80 than Cyquest 3223. Unlimited polymer adsorption propensity was displayed at pH 5, with no polymer remaining in solution irrespective of initial polymer concentration. The polymer adsorption behaviour is rationalized in terms of dissolved Cu(II) metal ion mediation. Both lower pH and stronger oxidative environment (oxygen or air saturation) facilitated Chalcocite oxidation, Cu(II) leaching and hydrolysis at Chalcocite particle–solution interface. These subsequently fostered Cu(II)-polymer (carboxylic acid and sulfonate groups) complexation and adsorption, the extent of which was greatly attenuated under weak dissolution conditions of N2 purging and high pH. Langmuirian polymer adsorption behaviour was displayed at pH 7 and 9, implying substantially homogeneous Chalcocite surface adsorption sites.
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the influence of polymeric dispersants on sericite Chalcocite particle interactions in aqueous media
Chemical Engineering Journal, 2009Co-Authors: Jonas Addaimensah, David A. BeattieAbstract:Abstract Unexpected sericite–Chalcocite mineral particles’ hetero-aggregation occurs under aqueous processing conditions where both minerals display negative zeta potentials. In this study, the use of anionic co-polymers (carboxylate- versus sulphonate-substituted) as dispersants to suppress the hetero-aggregation behaviour was investigated in the pH range 5–9. Both polymers showed strong substrate and pH-dependent adsorption and electrokinetic potential characteristics onto both minerals. The adsorption propensity was considerably higher onto Chalcocite than sericite particles and dramatically accentuated at pH 5 for the former due to leached electropositive Cu(II) species’ surface activation effect. At high polymer dosages (>1.5 g kg −1 solid) leading to plateau adsorption density, the magnitude of both mineral particles’ zeta potential increased to a maximum. Furthermore, the adsorbed polymer layer dominated the interfacial chemistry that showed subtle mineral phase and pH dependency. The concomitant particle interactions reflected a marked reduction of dispersion shear yield stress and the suppression of sericite–Chalcocite particulate adsorption. Electro-steric repulsive forces are believed to be responsible for the dispersing mechanism. Both polymers displayed similar, high dispersing efficacy at dosages >1.5 g kg −1 solid for sericite–Chalcocite mix dispersions, regardless of the pH.
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sericite Chalcocite mineral particle interactions and hetero aggregation sliming mechanism in aqueous media
Chemical Engineering Science, 2009Co-Authors: Jonas Addaimensah, David A. BeattieAbstract:Abstract Attractive particle interactions which lead to hetero-aggregation or “sliming” of gangue and valuable mineral particles are encountered in a number of hydrometallurgical and flotation processes. Sliming leads to poor recovery of the valuable, hydrophobic minerals and high recovery of hydrophilic gangue particles in flotation concentrates. In the present work, the influence of interfacial chemistry and dispersion conditions on particle interactions which underpin the mechanism of hetero-aggregation between sericite and Chalcocite particles was investigated in the pH range 5–9 at 23 °C. Hetero-aggregation is shown to occur under aqueous dispersion conditions where the fluid shear rate was high and the individual Chalcocite and sericite particles were negatively charged, as shown by the electrokinetic potential data. Continuous flow particulate adsorption and rheological studies revealed that the hetero-aggregation behaviour was strongly pH and oxidative environment dependant. Sliming was greater at lower than higher pH and under air saturation than N 2 gas purge. The unexpected hetero-aggregation is ascribed to Chalcocite (Cu(I) 2 S) surface oxidation and dissolution which accentuated with decreasing pH and Cu (II) ion hydrolysis effect. Specific adsorption of Cu (II) complexes onto the mix minerals’ surfaces had a striking impact on the interfacial chemistry, reflecting significantly enhanced dispersion shear yield stress. The attractive particles’ interactions are believed to be due to a combination of Cu(II)-mediated mechanisms including: electrostatic-charge patch attraction, van der Waals attraction, adsorbed ion–particle bridging, surface nucleation and cementation. Sliming mitigation was demonstrated by the use of N 2 gas and higher pH, as evidenced by markedly lower sericite–Chalcocite dispersion shear yield stress and greatly reduced particulate adsorption behaviour.
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The influence of polymeric dispersants on sericite–Chalcocite particle interactions in aqueous media
Chemical Engineering Journal, 2009Co-Authors: Jonas Addai-mensah, David A. BeattieAbstract:Abstract Unexpected sericite–Chalcocite mineral particles’ hetero-aggregation occurs under aqueous processing conditions where both minerals display negative zeta potentials. In this study, the use of anionic co-polymers (carboxylate- versus sulphonate-substituted) as dispersants to suppress the hetero-aggregation behaviour was investigated in the pH range 5–9. Both polymers showed strong substrate and pH-dependent adsorption and electrokinetic potential characteristics onto both minerals. The adsorption propensity was considerably higher onto Chalcocite than sericite particles and dramatically accentuated at pH 5 for the former due to leached electropositive Cu(II) species’ surface activation effect. At high polymer dosages (>1.5 g kg −1 solid) leading to plateau adsorption density, the magnitude of both mineral particles’ zeta potential increased to a maximum. Furthermore, the adsorbed polymer layer dominated the interfacial chemistry that showed subtle mineral phase and pH dependency. The concomitant particle interactions reflected a marked reduction of dispersion shear yield stress and the suppression of sericite–Chalcocite particulate adsorption. Electro-steric repulsive forces are believed to be responsible for the dispersing mechanism. Both polymers displayed similar, high dispersing efficacy at dosages >1.5 g kg −1 solid for sericite–Chalcocite mix dispersions, regardless of the pH.
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Sericite–Chalcocite mineral particle interactions and hetero-aggregation (sliming) mechanism in aqueous media
Chemical Engineering Science, 2009Co-Authors: Jonas Addai-mensah, David A. BeattieAbstract:Abstract Attractive particle interactions which lead to hetero-aggregation or “sliming” of gangue and valuable mineral particles are encountered in a number of hydrometallurgical and flotation processes. Sliming leads to poor recovery of the valuable, hydrophobic minerals and high recovery of hydrophilic gangue particles in flotation concentrates. In the present work, the influence of interfacial chemistry and dispersion conditions on particle interactions which underpin the mechanism of hetero-aggregation between sericite and Chalcocite particles was investigated in the pH range 5–9 at 23 °C. Hetero-aggregation is shown to occur under aqueous dispersion conditions where the fluid shear rate was high and the individual Chalcocite and sericite particles were negatively charged, as shown by the electrokinetic potential data. Continuous flow particulate adsorption and rheological studies revealed that the hetero-aggregation behaviour was strongly pH and oxidative environment dependant. Sliming was greater at lower than higher pH and under air saturation than N 2 gas purge. The unexpected hetero-aggregation is ascribed to Chalcocite (Cu(I) 2 S) surface oxidation and dissolution which accentuated with decreasing pH and Cu (II) ion hydrolysis effect. Specific adsorption of Cu (II) complexes onto the mix minerals’ surfaces had a striking impact on the interfacial chemistry, reflecting significantly enhanced dispersion shear yield stress. The attractive particles’ interactions are believed to be due to a combination of Cu(II)-mediated mechanisms including: electrostatic-charge patch attraction, van der Waals attraction, adsorbed ion–particle bridging, surface nucleation and cementation. Sliming mitigation was demonstrated by the use of N 2 gas and higher pH, as evidenced by markedly lower sericite–Chalcocite dispersion shear yield stress and greatly reduced particulate adsorption behaviour.
Anna Zdziennicka - One of the best experts on this subject based on the ideXlab platform.
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Influence of ethyl xanthate on the wettability and surface free energy of synthetic Chalcocite
Powder Technology, 1998Co-Authors: Anna Zdziennicka, Bronisław Jańczuk, Wiesław WójcikAbstract:Abstract Contact angles of apolar and polar liquids were measured on unoxidized and oxidized surfaces of synthetic Chalcocite and on Chalcocite surfaces covered with potassium ethyl xanthate film formed from aqueous solutions at different concentrations. Then, using the obtained contact angle values, the Lifshitz—van der Waals component and electron—acceptor and electron—donor parameters of the Lewis acid—base component of the surface free energy of Chalcocite and Chalcocite covered with ethyl xanthate (EX) film were calculated. It was found that the surface free energy of Chalcocite originated from apolar and polar intermolecular interaction and that covering the Chalcocite surface with ethyl xanthate changed its surface free energy and its components. It was also found that the changes of the surface free energy as a function of the ethyl xanthate concentration from which the films were formed were larger for oxidized than for unoxidized Chalcocite. This probably results from the polar character of oxidized Chalcocite being higher than that of unoxidized Chalcocite and from the difference between the amounts of sulfur present on the unoxidized Chalcocite/EX film surface and on the oxidized Chalcocite/EX film surface.
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Determination of surface-free energy components of synthetic Chalcocite from contact angle measurements
Powder Technology, 1993Co-Authors: Bronisłlaw Jańczuk, W. Wojcik, Anna ZdziennickaAbstract:Abstract Measurements of the contact angle for water, glycerol, ethylene glycol, diiodomethane, bromoform and 1,1,2,2-tetrabromoethane on Chalcocite, copper oxide, copper hydroxide, copper sulfate and sulphur were made. Using the ‘geometric mean’ and van Oss et al. approaches, the dispersion and nondispersion — or Lifshitz-van der Waals, electron-acceptor and electron-donor components of the surface-free energy — of the studied solids were determined and compared with those calculated from zeta potential measurements. On the basis of the results obtained it was found that the surface-free energy of the solids studied in this work originated from apolar and polar intermolecular interactions. As concentration of the hydroxyl group on Chalcocite surface is increased, so the polar interactions are increased.
Jonas Addai-mensah - One of the best experts on this subject based on the ideXlab platform.
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Influence of solution conditions and polymer chemistry on the adsorption behaviour of anionic dispersants onto Chalcocite in aqueous media
Chemical Engineering Journal, 2011Co-Authors: David A. Beattie, Jonas Addai-mensahAbstract:Abstract The adsorption behaviour of two polymeric dispersants (Cyquest 3223: sodium acrylate/acrylamide co-polymer and P80: sodium allyl sulfonate/maleic acid co-polymer) onto Chalcocite mineral particles has been investigated as a function of solution pH (5, 7 and 9) and different oxidative environments. The dissociation of both polymers in aqueous solutions in the pH range 2–10 was quite similar, commencing at pH 2 and finishing at ∼pH 7, where the polymers became fully ionised, reflecting maximum negative charge. Strong pH-dependent adsorption onto negatively charged Chalcocite at pH 7 and 9 was observed, the behaviour consistent with polymer binding through a chemical complexation mechanism. Furthermore, the plateau adsorption density was ∼80% greater under air or O2 gas saturation, than under N2 gas saturation and ∼25% higher for P80 than Cyquest 3223. Unlimited polymer adsorption propensity was displayed at pH 5, with no polymer remaining in solution irrespective of initial polymer concentration. The polymer adsorption behaviour is rationalized in terms of dissolved Cu(II) metal ion mediation. Both lower pH and stronger oxidative environment (oxygen or air saturation) facilitated Chalcocite oxidation, Cu(II) leaching and hydrolysis at Chalcocite particle–solution interface. These subsequently fostered Cu(II)-polymer (carboxylic acid and sulfonate groups) complexation and adsorption, the extent of which was greatly attenuated under weak dissolution conditions of N2 purging and high pH. Langmuirian polymer adsorption behaviour was displayed at pH 7 and 9, implying substantially homogeneous Chalcocite surface adsorption sites.
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The influence of polymeric dispersants on sericite–Chalcocite particle interactions in aqueous media
Chemical Engineering Journal, 2009Co-Authors: Jonas Addai-mensah, David A. BeattieAbstract:Abstract Unexpected sericite–Chalcocite mineral particles’ hetero-aggregation occurs under aqueous processing conditions where both minerals display negative zeta potentials. In this study, the use of anionic co-polymers (carboxylate- versus sulphonate-substituted) as dispersants to suppress the hetero-aggregation behaviour was investigated in the pH range 5–9. Both polymers showed strong substrate and pH-dependent adsorption and electrokinetic potential characteristics onto both minerals. The adsorption propensity was considerably higher onto Chalcocite than sericite particles and dramatically accentuated at pH 5 for the former due to leached electropositive Cu(II) species’ surface activation effect. At high polymer dosages (>1.5 g kg −1 solid) leading to plateau adsorption density, the magnitude of both mineral particles’ zeta potential increased to a maximum. Furthermore, the adsorbed polymer layer dominated the interfacial chemistry that showed subtle mineral phase and pH dependency. The concomitant particle interactions reflected a marked reduction of dispersion shear yield stress and the suppression of sericite–Chalcocite particulate adsorption. Electro-steric repulsive forces are believed to be responsible for the dispersing mechanism. Both polymers displayed similar, high dispersing efficacy at dosages >1.5 g kg −1 solid for sericite–Chalcocite mix dispersions, regardless of the pH.
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Sericite–Chalcocite mineral particle interactions and hetero-aggregation (sliming) mechanism in aqueous media
Chemical Engineering Science, 2009Co-Authors: Jonas Addai-mensah, David A. BeattieAbstract:Abstract Attractive particle interactions which lead to hetero-aggregation or “sliming” of gangue and valuable mineral particles are encountered in a number of hydrometallurgical and flotation processes. Sliming leads to poor recovery of the valuable, hydrophobic minerals and high recovery of hydrophilic gangue particles in flotation concentrates. In the present work, the influence of interfacial chemistry and dispersion conditions on particle interactions which underpin the mechanism of hetero-aggregation between sericite and Chalcocite particles was investigated in the pH range 5–9 at 23 °C. Hetero-aggregation is shown to occur under aqueous dispersion conditions where the fluid shear rate was high and the individual Chalcocite and sericite particles were negatively charged, as shown by the electrokinetic potential data. Continuous flow particulate adsorption and rheological studies revealed that the hetero-aggregation behaviour was strongly pH and oxidative environment dependant. Sliming was greater at lower than higher pH and under air saturation than N 2 gas purge. The unexpected hetero-aggregation is ascribed to Chalcocite (Cu(I) 2 S) surface oxidation and dissolution which accentuated with decreasing pH and Cu (II) ion hydrolysis effect. Specific adsorption of Cu (II) complexes onto the mix minerals’ surfaces had a striking impact on the interfacial chemistry, reflecting significantly enhanced dispersion shear yield stress. The attractive particles’ interactions are believed to be due to a combination of Cu(II)-mediated mechanisms including: electrostatic-charge patch attraction, van der Waals attraction, adsorbed ion–particle bridging, surface nucleation and cementation. Sliming mitigation was demonstrated by the use of N 2 gas and higher pH, as evidenced by markedly lower sericite–Chalcocite dispersion shear yield stress and greatly reduced particulate adsorption behaviour.
Jonas Addaimensah - One of the best experts on this subject based on the ideXlab platform.
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the influence of polymeric dispersants on sericite Chalcocite particle interactions in aqueous media
Chemical Engineering Journal, 2009Co-Authors: Jonas Addaimensah, David A. BeattieAbstract:Abstract Unexpected sericite–Chalcocite mineral particles’ hetero-aggregation occurs under aqueous processing conditions where both minerals display negative zeta potentials. In this study, the use of anionic co-polymers (carboxylate- versus sulphonate-substituted) as dispersants to suppress the hetero-aggregation behaviour was investigated in the pH range 5–9. Both polymers showed strong substrate and pH-dependent adsorption and electrokinetic potential characteristics onto both minerals. The adsorption propensity was considerably higher onto Chalcocite than sericite particles and dramatically accentuated at pH 5 for the former due to leached electropositive Cu(II) species’ surface activation effect. At high polymer dosages (>1.5 g kg −1 solid) leading to plateau adsorption density, the magnitude of both mineral particles’ zeta potential increased to a maximum. Furthermore, the adsorbed polymer layer dominated the interfacial chemistry that showed subtle mineral phase and pH dependency. The concomitant particle interactions reflected a marked reduction of dispersion shear yield stress and the suppression of sericite–Chalcocite particulate adsorption. Electro-steric repulsive forces are believed to be responsible for the dispersing mechanism. Both polymers displayed similar, high dispersing efficacy at dosages >1.5 g kg −1 solid for sericite–Chalcocite mix dispersions, regardless of the pH.
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sericite Chalcocite mineral particle interactions and hetero aggregation sliming mechanism in aqueous media
Chemical Engineering Science, 2009Co-Authors: Jonas Addaimensah, David A. BeattieAbstract:Abstract Attractive particle interactions which lead to hetero-aggregation or “sliming” of gangue and valuable mineral particles are encountered in a number of hydrometallurgical and flotation processes. Sliming leads to poor recovery of the valuable, hydrophobic minerals and high recovery of hydrophilic gangue particles in flotation concentrates. In the present work, the influence of interfacial chemistry and dispersion conditions on particle interactions which underpin the mechanism of hetero-aggregation between sericite and Chalcocite particles was investigated in the pH range 5–9 at 23 °C. Hetero-aggregation is shown to occur under aqueous dispersion conditions where the fluid shear rate was high and the individual Chalcocite and sericite particles were negatively charged, as shown by the electrokinetic potential data. Continuous flow particulate adsorption and rheological studies revealed that the hetero-aggregation behaviour was strongly pH and oxidative environment dependant. Sliming was greater at lower than higher pH and under air saturation than N 2 gas purge. The unexpected hetero-aggregation is ascribed to Chalcocite (Cu(I) 2 S) surface oxidation and dissolution which accentuated with decreasing pH and Cu (II) ion hydrolysis effect. Specific adsorption of Cu (II) complexes onto the mix minerals’ surfaces had a striking impact on the interfacial chemistry, reflecting significantly enhanced dispersion shear yield stress. The attractive particles’ interactions are believed to be due to a combination of Cu(II)-mediated mechanisms including: electrostatic-charge patch attraction, van der Waals attraction, adsorbed ion–particle bridging, surface nucleation and cementation. Sliming mitigation was demonstrated by the use of N 2 gas and higher pH, as evidenced by markedly lower sericite–Chalcocite dispersion shear yield stress and greatly reduced particulate adsorption behaviour.
Wiesław Wójcik - One of the best experts on this subject based on the ideXlab platform.
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Influence of ethyl xanthate on the wettability and surface free energy of synthetic Chalcocite
Powder Technology, 1998Co-Authors: Anna Zdziennicka, Bronisław Jańczuk, Wiesław WójcikAbstract:Abstract Contact angles of apolar and polar liquids were measured on unoxidized and oxidized surfaces of synthetic Chalcocite and on Chalcocite surfaces covered with potassium ethyl xanthate film formed from aqueous solutions at different concentrations. Then, using the obtained contact angle values, the Lifshitz—van der Waals component and electron—acceptor and electron—donor parameters of the Lewis acid—base component of the surface free energy of Chalcocite and Chalcocite covered with ethyl xanthate (EX) film were calculated. It was found that the surface free energy of Chalcocite originated from apolar and polar intermolecular interaction and that covering the Chalcocite surface with ethyl xanthate changed its surface free energy and its components. It was also found that the changes of the surface free energy as a function of the ethyl xanthate concentration from which the films were formed were larger for oxidized than for unoxidized Chalcocite. This probably results from the polar character of oxidized Chalcocite being higher than that of unoxidized Chalcocite and from the difference between the amounts of sulfur present on the unoxidized Chalcocite/EX film surface and on the oxidized Chalcocite/EX film surface.