Abstract
In this study, the flotation performances of ethoxycarbonyl thionocarbamate (ECTC), dialkyl thionocarbamate (DATC) and xanthate copper sulfide collectors are compared by the structure-reactivity relationship using generalized perturbation theory and density functional calculation at the B3PW91/6-31G(D) level. The electron-donating power of xanthates is strong and, therefore, xanthates can strongly react with metal cation on the surfaces of copper and iron sulfide minerals through the formation of normal covalent bonds. This explains the poor selectivity of xanthates and also the high pH levels (above 13) required for the flotation separation of copper/iron sulfide minerals. DATC’s are more selective for copper sulfide flotation, particularly against gangue iron sulfides. Although less powerful than xanthates, DATCs can perform copper/iron flotation separation at lower operating pH (commonly at pH levels below 11.5). ECTCs use an ethoxycarbonyl replacing an alkylN-substituent in DATCs. The presence of the ethoxycarbonyl group effectively changes the functional group of collector from -C(=S)NH- to -C(=S)NHC( = O)-. The strong electron-withdrawing ethoxycarbonyl group adjacent to the C=S group decreases the electron density of the sulfur atom, which improves ECTC’s selectivity against iron sulfide minerals at slightly alkaline conditions. The lowest unoccupied molecular orbit (LUMO) of ECTC, which is constituted by the pz-orbit of every atoms in the conjugate -O-C(=O)-N-C(=S)-O- group and which is pleased with accepting richly d-orbital electrons (feedback electrons) from the (t2g)6(eg)3Cu(II) or t6e4Cu(I) configuration of copper cation on the surfaces of copper sulfide minerals, resulted in the formation of dative π-bond. The iron atom, which has a (t2g)6Fe(II) or (t2ga)3(ega)2 Fe(III) configuration on the surfaces of iron sulfide minerals (Fe(III) is the predominant composition at alkaline conditions), has difficulty in offering its d-orbital electrons (feedback electrons) to ECTC’s LUMO. ECTC collectors are powerful for copper sulfide minerals and very selective against iron sulfides, which has been further confirmed by UV spectra and bench-scale and industrial-scale flotation tests.
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References
Basilio, C.I., 1989, “Fundamental Studies of Thionocarbamate Interactions with Sulfide Minerals,” Ph.D. Thesis, Virginia polytechnic institute and state university, Blacksburg, Virginia.
Boulton, A., Fornasiero, D., and Ralston, J., 2000, “Depression of iron sulphide flotation in zinc roughers,” Minerals Engineering, Vol. 14, No. 9, pp. 1067–1079.
Fairthorne, G., Fornasiero, D., and Ralston, J., 1996, “Solution properties of thionocarbamate collectors,” International Journal of Mineral Processing, Vol. 46, No. 1–2, pp. 137:153.
Fairthorne, G., Fornasiero, D., and Ralston, J., 1997, “Interaction of thionocarbamate and thiourea collectors with sulphide minerals: a flotation and adsorption study,” International Journal of Mineral Processing, Vol. 50, No. 4, pp. 227–242.
Frisch, M.J., Trucks, G.W., Schlegel, H.B., et al., 1998, Gaussian 98, Revision A.9. Gaussian, Inc., Pittsburgh Pennsylvania, USA.
Fu, Y-L., and Wang, S.S., 1989, “Neutral Hydrocarboxycarbonyl Thionocarbamate Sulfide Collectors,” American Cyanamid Company, U.S. Patent RE32827.
Fu, Y-L., Wang, S.S., and Nagaraj, D.R., 1986, “Collectors and Froth Flotation Processes for Metal Sulfide Ores,” American Cyanamid Company, G.B. Patent 2163068A.
Klopman, G., 1968, “Chemical reactivity and paths,” Journal of American Chemical Society, Vol. 90, pp. 223–230.
Liu, G., 2004, “Research on the Comprehensive Utilization for Copper Sulfide Ores with New Collectors,” Ph.D. Thesis, Central South University, Changsha, Hunan, PR. China.
Mielczarski, J.A., and Yoon, R.H., 1991, “Spectroscopic studies of the structure of the adsorption layer of thionocarbamate. 2. On the cuprous sulfide,” Langmuir, Vol. 7, No. 1, pp. 101–108.
Nagaraj, D.R., Lewellyn M.E., Wang S.S., Mingione, PA., and Scanlon, M.J., 1988, “New sulfide and precious metals collector: for acid, neutral and mildly alkaline circuits,” in Proceedings of the XVIth International Mineral Processing Congress, Stockholm, E. Forssberg, ed., Elsevier, Amsterdam, pp. 1221–1232.
Nagaraj, D.R., Wang S.S., and Frattaroli, D.R., 1986, “Flotation of copper sulfide minerals and pyrite with new and existing sulfur-containing collectors,” in Proceedings of the 13th CMMI Congress Metall., Singapore, L.E. Fielding and A.R. Gordon, eds., CMMI and Ausr. Inst. Min. Met., pp. 49–57.
Nagaraj, D.R., and Brinen, J.S., 1996, “SIMS and XPS study of the adsorption of sulfide collectors on pyroxene: a case for inadvert metal in activation,” Colloids and Surfaces A: Physicochemical and Engineering Aspects, Vol. 116, No. 3, pp. 241–249.
Nagaraj, D.R., and Brinen, J.S., 2001, “SIMS study of adsorption of collectors on pyrite,” International Journal of Mineral Processing, Vol. 63, pp. 45–57.
Seryakova, I.V., Vorobiova, G.A., and Glembotskii, A.V., 1975, “Extraction of metals by neutral sulfur-containing extractants. Part I, O-isopropyl-N-ethylthionocarbamate,” Anal Chim Acta, Vol. 77, pp. 183–190.
Shen, W.Z., Fornasiero, D., and Ralston, J., 1998, “Effect of collectors, conditioning pH and gases in the separation of sphalerite from pyrite,” Minerals Engineering, Vol. 11, No. 2, pp. 145–158.
Wang, D., Lin, Q., and Jiang, Y., 1996, Molecular Design of Reagents for Mineral and Metallurgical Processing, Central South University of Technology, Changsha, 1st Edition, pp. 88–110.
Woods, R., and Hope, G.A., 1999, “ASERS spectroelectrochemical investigation of the interaction of O-isopropyl-N-ethylthionocarbamate with copper surfaces,” Colloids and Surfaces A: Physicochemical and Engineering Aspects, Vol. 146, Nos. 1–3, pp. 63–74.
Yoon, R.H., and Basilio, C.I., 1993, “Adsorption of thiol collectors on sulfide minerals and precious metals — a new perspective,” in Proceedings of the XVIIIth International Mineral Processing Congress, Sydney, The Australasian Institute of Mining and Metallurgy, Melbourne, Vol. 3, pp. 611–617.
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Liu, G., Zhong, H. & Dai, T. Investigation of the selectivity of ethoxylcarbonyl thionocarbametes during the flotation of copper sulfides. Mining, Metallurgy & Exploration 25, 19–24 (2008). https://doi.org/10.1007/BF03403381
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DOI: https://doi.org/10.1007/BF03403381