Xanthate adsorption

Figure 4.38 FTIR reflection spectra of ethyl xanthate adsorption on pyrrhotite (pH = 7.0, KEX 5 x 10 mol/L = 297 mV)...

Figure 4.41 presents the FTIR reflection spectra of ethyl xanthate adsorption on marmatite at different pH. The characteristic absorption peaks 1210, 1108, 1025 cm occurred. It has been reported that the characteristic absorption bands of dixanthogen are 1260, 1240, 1020 and 1105 cm and those bands of zinc xanthate are 1030, 1125 and 1212 cm (Mielezarski, 1986 Leppinen, 1990). It is derived from Fig.4.41 that there may exist the mixture of dixanthogen and zinc xanthate because both distinct peaks of dixanthogen and xanthate salt appeares in Fig. 4.41, which further confirms the results from the UV analysis in Fig. 4.36 and Fig. 4.37. It can also be seen from Fig. 4.41 that the intensity of the IR peaks is strong indicating the stronger adsorption of xanthate on marmatite accounting for its good floatability in weak pH media. When pH increased above 7, only a very weak peak appeared in the spectra indicating very weak or no adsorption of xanthate on marmatite accounting for its very poor floatability in alkaline pH media.

The FTIR reflection spectra of ethyl xanthate adsorption on jamesonite are shown in Fig. 4.42. It can be seen that the characteristic absorption bands of lead ethyl xanthate at 1020,1112 and 1206 cm" appeared on the surface of jamesonite, indicating the primary hydrophobic species on jamesonite surface to be lead ethyl xanthate. It is possible that antimony ethyl xanthate was formed on jamesonite surface simultaneity like lead ethyl xanthate. 

Figure 4.44 The effect of pH on FTIR signal intensity of xanthate adsorption on jamesonite and jamesonite flotation recovery...

The FTIR spectra of ethyl xanthate adsorption on marmatite in the presence of 150... 

Finkelstein, N. P., 1999. Addendum to The activation of sulphide minerals for flotation a review. Inter. J. Miner. Process, 55(4) 283 - 286 Fomasiero, D., Montalti, M., Ralston, J., 1995. Kinetics of adsorption of ethyl xanthate on pyrrhotite in situ UV and infiared spectroscopic studies. Langmuir, 11 467 - 478 Forssberg, K. S. E., Antti, B. M., Palsson, B., 1984. Computer-assisted calculations of thermodynamic equilibria in the chalcopyrite-ethyl xanthate system. In M. J. Jones and R. Oblatt (eds.). Reagents in the Minerals Industry. IMM, Rome, Italy, 251 - 264 Fuerstenau, M. C., Kuhn, M. C., Elgillani, D. A., 1968. The role of dixanthogen in xaomthate flotation ofpyrite. Trans. AIME, 241 437 Fuerstenau, M. C. and Sabacky, B. J., 1981. Inter. J. Miner. Process, 8 79 - 84 Fuerstenau, M. C., Misra, M., Palmer, B. R., Xanthate adsorption on selected sulphides in the presence of oxygen. Inter. J. Miner. Process... 

Kowal, A. and Domianowski, A., 1973. Cyclic voltammetry of ethyl xanthate on a natural copper sulphide electrode. Electrocnal Chem. Interf. Electrochem., 46 411 - 420 Laajalehto, K., Nowak P., Pomianowski, A., Suonien, E., 1991. Xanthate adsorption at the PbS/aqueous interface comparison of XPS, infiared and electrochemical results. Colloids Surf., 57 319-333... 

Leppinen, J. 0., Basilio, C. I, Yoon, R. H., 1989. In-situ FTIR study of ethyl xanthate adsorption on sulphide minerals under conditions of controlled potential. Int. J. Miner. Process, 26 259 - 274... 

Natarajan, K. A., Riemer, S. C., Iwasaki, I., 1984. Influence of pyrrhotite on the corrosive wear of grinding balls in magnetite ore grinding. Inter. J. Miner. Process, 13(1) 73-81 Nesbitt, H. W., Bancroft, G. M., Pratt, A. R., Scaini, M. J., 1998. Sulfur and iron surface states on fractured pyrite surfaces. American Mineralogist, 83 1067 - 1076 Neeraj, K. M., 2000. Kinetic studies of sulphide mineral oxidition and xanthate adsorption. Doctor thesis of Virginia Polytechnic Institute and State University. A Bell Howell Company UMI dissertation Services... 

Grano, S. R., Prestidge, C. A., and Ralston, J. (1997) Solution interaction of ethyl xanthate and sulfite and its effect on galena flotation and xanthate adsorption, Int. J. Miner. Process., 52(2-3), 161-186. 

The type of the oxidation product on galena is independent of the chemical environment during preparation. Rao152) measured the adsorption heat of K amyl xanthate (KAX) on unactivated and Cu2+-activated pyrrhotite (FeS) and compared his results with heats of the reaction between KAX and Fe2+ or Cu2+ salts. With the unactivated mineral, the interaction involves a chemical reaction of xanthate with Fe2+ salts present at the interface (i.e. not bound to the crystal surface). The adsorption enthalpy is identical with the formation of Fe2+ amyl xanthate FeS04 + 2 KAX —> FeX2 + K2S04, and -AH = 97.45 kJ/mol Fe2+). As revealed from the enthalpy values and the analysis of anions released into the solution, the interaction of xanthate with Cu2+-activated pyrrhotite consists of xanthate adsorption by exchange for sulfate ions (formed by an oxidation of sulfides) at isolated patches (active spots), and by further multilayer formation of xanthate. The adsorption heat of KAX on pyrrhotite at the initial pH 4.5 was - AH (FeS unactivated) = 93.55 kJ/mol Fe2+ and - AH (FeS activated) = 70.03 kJ/mol Cu2+. 

K. C. Pillai and V.Y. Young,/. Colloid Interface Sci 103 103 (1985). X-ray photoelectron spectroscopy study of xanthate adsorption on pyrite mineral surfaces. 

Talonen, P., Sundholm, G., Floate, S., and Nichols, R.J. (1999) A combined in situ infrared spectroscopy and scanning tunnelling microscopy smdy of ethyl xanthate adsorption on Au(lll). Physical Chemistry Chemical Physics, 1,... 

Table 7.4. Sensitivity of in situ and ex situ IR spectroscopic techniques in studies of xanthate adsorption...

The ex situ studies of xanthate adsorption under chemically controlled conditions have been conducted by transmission [487-489] and DRIFTS [375-377, 385, 386, 480, 484, 490-495] on powdered sulfides, by ATR on thin polycrystalline synthetic films of PbS [496-498] and single-crystal sphalerite [499], and by IRRAS on sulfide and metal plates [327, 329, 330, 481, 482, 500],... 

Obviously, to define the reactions that occur in such a complex electrochemical system, the surface species must be identified. The first IR SEC investigation of xanthate adsorption as a function of increasing potential was performed by Leppinen et al. [513, 514] in 1988. Below, the contribution of this and subsequent work to a microscopic understanding of the anodic processes on the natural sulfides will be discussed. The spectra presented were obtained in deaerated 0.05 M sodium tetraborate buffer (pH 9.2) unless otherwise indicated. The potentials were converted in the SHE scale. 

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