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Reaction mechanism of gold dissolution with bromine

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Abstract

The dissolution of gold with elemental bromine was studied by using a rotating disc technique. The main parameters studied were bromine and bromide concentrations, stirring speed, pH, and temperature. The effect of various salts, manganese, and hydrogen peroxide was also examined. The dissolution kinetics of gold with Br2 and NaBr mixture is complex. The reaction mechanism is a function of solution composition, which determines the kind of adsorbing species. For an excess concentration of bromide ions, the rate expression is Rate = (2k cl7 k al6)1/2 K 15 [Br −3 ] and for an excess concentration of bromine, the rate expression is Rate = (2k c27 k a29)1/2 [Br−]1/2 {K25 [Br2]3/(1 +K 25 [Br2]3)}1/2

Gold in bromine solutions dissolves according to electrochemical/chemical (EC) mechanisms. The electrochemical component of the mechanism is responsible for the formation of AuBr2. In the chemical component of the mechanism, this monovalent gold bromide disproportionates into gold and stable AuBr −4 , which reports into solution. With respect to pH, there are two characteristic dissolution regions. In the pH range of 1 to 7, gold dissolution rates were insensitive to pH. Above pH 7, gold dissolution rates decreased with increase of pH.

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Abbreviations

j:

flux, moles/cm2s

A:

surface area, cm2

R:

universal gas constant

C:

concentration of lixiviant, moles/cm3

D:

diffusion coefficient, cm2/s

υ:

kinematic viscosity, cm2/s

ω:

angular velocity, rad/s

T:

temperature

[Br−]:

bulk concentration of bromide ions

[Br −3 ]:

bulk concentration of tribromide ions

[Br2]:

bulk concentration of bromine

[HOBr]:

bulk concentration of hypobromous acid

[BrO−]:

bulk concentration of bromite ion

Kd:

dissociation, hydrolysis, and complexation

Kh:

equilibrium constants, respectively

F:

Faraday’sconstant

K:

equilibrium constant

Em:

mixed potential

kai, k′ai :

rate constants for the forward and reverse directions, respectively, of the anodic process given by Reaction [i]

kci, k′ci :

rate constants for the forward and reverse directions, respectively, of the cathodic process given by Reaction [i]

Za :

total number of electrons transferred in the anodic half-cell reaction

θ:

fraction of total available surface sites occupied by adsorbed Br −3

θc :

fraction of total available surface sites occupied by adsorbed Br2

SCE:

standard calomel electrode

References

  1. C.A. Shaeffer: United States Patent No. 267,723, 1882.

  2. B.C. Hinman: United States Patent Nos. 545,890 and 545,891, 1895.

  3. H.R. Cassel: United States Patent Nos. 732,706, 1903, and 732,709, 1903.

  4. C.G. Fink and G.L. Putnam: United States Patent No. 2,283,198, 1942.

  5. R.H. Sergent and K.N. Thanstrom: United States Patent No. 4,637,865, 1987.

  6. R.H. Sergent:Randol Gold Forum 88, Scottsdale, AZ, Jan. 23–24, 1988, Randol International Ltd., Golden, CO.

    Google Scholar 

  7. A. Dadgar:Precious Metals ’s89, M.C. Jha, S.D. Hill, and M. El Guindy, eds., TMS, Warrendale, PA, 1989, pp. 227–40.

    Google Scholar 

  8. A. Dadgar:J. Met., 1989, December, pp. 37–41.

  9. B. Pesic and R.H. Sergent:EPD Congress ’s90, D.R. Gaskell, ed., TMS, Warrendale, PA, 1990, pp. 355–91. 355–91.

    Google Scholar 

  10. B. Pesic and R.H. Sergent:J. Met., 1991, December, pp. 35–37.

  11. G.I.Z. Kalocsai: United States Patent No. 4,684,404.

  12. V.G. Levich:Physicochemical Hydrodynamics, Prentice Hall, Englewood Cliffs, NJ, 1962.

    Google Scholar 

  13. W.M. Latimer:The Oxidation States of the Elements and Their Potentials in Aqueous Solutions, Prentice Hall, Englewood Cliffs, NJ, 1952.

    Google Scholar 

  14. L. Farkas and M. Lewis:J. Am. Chem. Soc, 1950, vol. 72, pp. 5766–67.

    Article  Google Scholar 

  15. H.A. Liebhafsky:J. Am. Chem. Soc, 1934, vol. 56, pp. 1500–05.

    Article  Google Scholar 

  16. R.O. Griffith, A. McKeown, and A.G. Winn:Trans. Faraday Soc, 1932, vol. 28, pp. 101–07.

    Article  Google Scholar 

  17. D.H. Evans and J.J. Lingane:J. Electroanal. Chem., 1963, vol. 6, pp. 1–10.

    Google Scholar 

  18. B.I. Peshchevitskii, V.P. Kazakov, and A.M. Erenburg:Zh. Neorg. Khim., 1963, vol. 8, pp. 853–59.

    Google Scholar 

  19. G. Milazzo and S. Caroli:Tables of Standard Electrode Potentials, John Wiley, New York, NY, 1978.

    Google Scholar 

  20. A.J. Bard, R. Parsons, and J. Jordan:Standard Potentials in Aqueous Solutions, Marcel Dekker, New York, NY, 1985.

    Google Scholar 

  21. K.J. Vetter:Electrochemical Kinetics, Academic Press, New York, NY, 1967.

    Google Scholar 

  22. G.P. Power and I.M. Ritchie:J. Chem. Educ., 1983, vol. 60 12, pp. 1022–26.

    Article  Google Scholar 

  23. G.P. Power and I.M. Ritchie:Electrochim. Acta, 1981, vol. 26 (8), pp. 1073–78.

    Article  Google Scholar 

  24. G.P. Power and I.M. Ritchie:Electrochim. Acta, 1982, vol. 27 (1), pp. 165–69.

    Article  Google Scholar 

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Authors and Affiliations

  1. Department of Metallurgical Engineering, College of Mines, University of Idaho, 83843, Moscow, ID

    Batric Pesic (Professor)

  2. Great Lakes Chemical Corporation, 47906, West Lafayette, IN

    Rodney H. Sergent (Business Manager-Commercial Development)

Authors
  1. Batric Pesic
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  2. Rodney H. Sergent
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Pesic, B., Sergent, R.H. Reaction mechanism of gold dissolution with bromine. Metall Trans B 24, 419–431 (1993). https://doi.org/10.1007/BF02666424

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