Effect of Physisorption of Collector on Activation of Flotation of Sphalerite
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MINERAL DRESSING
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Effect of Physisorption of Collector on Activation of Flotation of Sphalerite T. G. Gavrilovaa and S. A. Kondrat’eva* a
Chinakal Institute of Mining, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630091 Russia *e-mail: [email protected] Received March 12, 2020 Revised March 15, 2020 Accepted May 29, 2020
Abstract—The studies into the mechanism of activation of sphalerite flotation by ions of heavy metals show that neither ion exchange nor electrochemistry explain the experimental facts, namely, activation of flotation of copper mineral by lead ions, activation of sphalerite flotation by zinc, or flotation in the presence of non-conducting surface layer with silver or mercury. The authors put forward the hypothesis of activation due to the effect of physisorption of a collector in elementary event of flotation. It is possible to activate froth flotation by the products of nonstoichiometric interaction between xanthate and ions of some heavy metals. The influence of the scope of deviation from the stoichiometric relation of concentrations of xanthate and activation metal salt on the collectability of the interaction products is described. The activation efficiency of the interaction products is estimated using the criterion of ‘surface flow thickness’ of the film of collector derivatives at the gas–liquid interface. Keywords: Flotation, activation, ion exchange and electrochemistry, heavy metal ions, physisorption. DOI: 10.1134/S1062739120036738
INTRODUCTION
At present, there are two mechanisms for activating sphalerite. According to the first mechanism, it is assumed that sphalerite is activated by copper in acidic medium due to ion exchange of cations Zn2+ for Cu2+ in a ratio of 1:1 [1–4]. In neutral and alkaline media, copper is deposited in the form of hydroxides and, due to their instability, copper cations Cu+ replace zinc cations in crystal lattice of sphalerite. Adding xanthate to sphalerite suspension with a modified surface layer leads to the formation of copper xanthate, which has much lower solubility product in comparison with zinc xanthate. As a result, the collector is more firmly attached to the mineral surface. One of the first works on flotation of sphalerite using heavy metal salts, with ion exchange considered as a working mechanism is described in [1]. In [5], an extensive list of probable flotation activation metals was studied and some parallelism between the effectiveness of metal as an activator and insolubility of its sulfide was revealed, but the question whether the solubility of activation metal sulfide determines the activation process was not answered. Thallium, whose sulfide has a higher solubility than zinc sulfide, activates f
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