Journal of Mining Science

, Volume 34, Issue 4, pp 325–332 | Cite as

Specifics of the sulfuric-acid processing of galena concentrates in the presence of nitrous acid

  • T. I. Markovich
  • A. B. Ptitsyn
Physical and Chemical Principles of Ore Dressing


  1. 1.

    Nitrous acid has a catalytic effect on the sulfuric-acid decomposition of galena. With oxygen at atmospheric pressure, the presence of even small quantities of HNO2 in the solution (0.01 M) at room temperature increases the degree of oxidation of lead sulfide twofold.

  2. 2.

    The solid products of the oxidation of PbS (PbSO4 and S) form a dense film on the surface of the reacting particles, which leads to a decrease in the reaction rate. The kinetic curves are parabolic in form.

  3. 3.

    The rate of oxidation of galena depends on the initial concentration of sulfuric acid in the solution. The order of the reaction with respect to H2SO4 is close to unity (0.99).

  4. 4.

    The apparent activation energy of the process is 12.8 kJ/mole.

  5. 5.

    A change in the rate of mixing of the reaction mixture has almost no effect on the degree of decomposition of galena.


The process of the sulfuric-acid oxidation of galena, catalyzed by nitrous acid, occurs in the intradiffusional regime and can be satisfactorily described by the Ginstling—Braunstein equation. This, equation reflects the fact that the reaction rate depends on the completeness of the reaction due to the changing thickness of the layer of solid product that is formed. The dependence is described by the equation for different temperatures and different concentrations of sulfuric acid in the solution: {fx331-1} where α is the fraction of galena oxidized to the sulfate; CH2SO4is the initial concentration of sulfuric acid, moles/liter; T is temperature, K; τ is time, sec.


Apparent Activation Energy Galena Lead Sulfide Trivalent Iron Lead Sulfate 
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© Plenum Publishing Corporation 1998

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  • T. I. Markovich
  • A. B. Ptitsyn

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