On the mechanism of the flotation of oxides and silicates |
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| Affiliation: | 1. Mining and Metallurgy Institute, Bor Mineral Processing Department, Zeleni Bulevar 35, Bor, Serbia;2. University of Belgrade, Faculty of Mining and Geology, Department of Applied Computing and System Engineering, Djusina 7, Belgrade, Serbia;1. Graduate Program in Bioinformatics, Seoul National University, Seoul, Republic of Korea;2. School of Chemical and Biological Engineering, Seoul National University, Seoul, Republic of Korea;3. Graduate Program in Brain Science, Seoul National University, Seoul, Republic of Korea;4. School of Computer Science and Engineering, Seoul National University, Seoul, Republic of Korea;5. Biological and Agricultural Engineering, University of Arkansas, Fayetteville, AR, USA;6. Bio/Nano Technology Laboratory, Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, AR, USA;7. Electrical and Computer Engineering, University of Memphis, Memphis, TN,USA;8. Graduate Program in Cognitive Science, Seoul National University, Seoul, Republic of Korea;1. Far East Geological Institute, Far East Branch of Russian Academy of Sciences, 159 Prospect 100 let Vladivostoku, Vladivostok 690022, Russia;2. School of Engineering, Far Eastern Federal University, 8 Suhanova St., Vladivostok 690950, Russia;3. Department of Earth Sciences, University of Adelaide, SA 5005, Australia;4. School of Earth Sciences and Resources, China University of Geosciences Beijing, 29 Xueyuan Road, Beijing 100083, China;1. College of Resource and Environmental Engineering, Wuhan University of Technology, Wuhan 430070, China;2. School of Resources and Safety Engineering, Wuhan Institute of Technology, Wuhan 430205, China;3. School of Mines and Engineering, Mining and Mineral Processing Engineering Department, Taita Taveta University, Voi, Kenya |
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| Abstract: | The mechanism of flotation of oxide and silicate minerals was established long ago as being due to the electrostatic attraction between the charged surface and the charge of the collector. What is less well established is the mechanism of the charging of the mineral surface. Most researchers have postulated that the adsorption of H+ is the cause. However, the adsorption model and its derivatives (such as the amphoteric and multisite-adsorption models), do not successfully describe the data for the zeta potential as a function of pH. In particular, these adsorption models have the following features that are not observed: (i) they are symmetrical about the point of zero charge, whereas the data is asymmetrical, (ii) they have an inflection at the pKa values, leading to an asymptotic approach to the point of zero charge, whereas such an inflection is not observed, and (iii) they only fit the data in its extremes, that is, when the pKa values differ by orders of magnitude, or are very close to one another. An alternative mechanism of charging is proposed here that is based on the dissolution of ions from and deposition of ions onto the mineral surface. It is shown that this model (a) fits the data, (b) is consistent with the thermodynamic model for reversible interfaces, (c) is consistent with the thermodynamics of the overall reaction and its solubility, (d) indicates reasons for the ageing of surfaces and (e) displays the observed features of zeta potential measurements as a function of pH, that is, it is pseudo-Nernstian and asymmetrical in nature. Application of the proposed theory is discussed for the flotation of quartz and corundum. |
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| Keywords: | Flotation Mechanism Electrostatic mechanism Zeta potential Surface charging |
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