ISSN 1070-4272, Russian Journal of Applied Chemistry, 2008, Vol. 81, No. 6, pp. 1074!1077. + Pleiades Publishing, Ltd., 2008.
Original Russian Text + V.V. Patrushev, S.V. Ostanova, A.V. Chubarov, S.V. Drozdov, 2008, published in Zhurnal Prikladnoi Khimii, 2008,
Vol. 81, No. 6, pp. 1036!1038.
Behavior of Silver Sulfide in the System
V. V. Patrushev, S. V. Ostanova, A. V. Chubarov, and S. V. Drozdov
Institute of Chemistry and Chemical Technology, Siberian Branch, Russian Academy of Sciences,
Received November 2, 2007
Abstract-Behavior of silver sulfide in the system Ag
O was studied at 25, 55,
and 80oC using the method of the simplex-lattice experiment design. The quantitative dependences of
S oxidation on the concentrations of the acid and Fe
were determined. The isoconcentration
diagrams were obtained.
The main amount of silver is extracted from
complex ores and concentrates in which silver is in
the form of silver sulfide, argentite, one of the most
widespread minerals. Argentite is contained in grav-
itational and flotation concentrates produced in
processing of gold- and silver-containing ores and,
in particular, lead-zinc ores, and in secondary raw
Hydrometallurgical procedures for recovery of
silver, including that in the form of silver sulfide,
employ cyanide [1, 2], thiocyanate , thiourea ,
and thiosulfate solutions. However, it is neces-
sary to use in such cases oxidizing agents, e.g., O
, which involves additional expenditure.
A technology for processing of sulfide lead-zinc
ores and concentrates and, in particular, those from
the Gorevo deposit with the use of nitric acid and
iron(III) nitrate solutions has been developed.
The behavior of silver sulfide in systems of this
kind has not been studied.
Nitric acid is a strong oxidant (-
0.80 V) and, therefore, it oxidizes silver sulfide
without introduction of any additional oxidizing
agent into a system. However, it is of interest to
study the effect of Fe
additives on the process of
argentite oxidation. This is due to the composition
of technological solutions, because, in most cases,
the concentration of Fe
ions is appreciable when
nitrate acid-salt solvents are used for processing of
silver-containing ores and concentrates.
To obtain information about the oxidation of
silver sulfide in complex systems with various min-
eral forms in industrial processing of silver-con-
taining ores and concentrates, we studied Ag
O systems with a high content
of silver. The silver sulfide synthesized was identi-
fied by X-ray phase analysis. The behavior of Ag
in the systems under study was judged from the var-
iation of the total silver concentration in solution
and from the composition of insoluble precipitates.
The concentration of silver in solution was deter-
mined by titration analysis and atomic-absorption
spectrophotometry [6, 7], and that of HNO
titration analysis . The mathematical data pro-
cessing was carried out by the method of simplex-
lattice experiment design .
The experiments were performed in thermo-
stated cells at 25 + 0.1, 55 + 0.1, and 80 + 0.1oCin
the course of 2 h, with mechanical stirring at s : l =
1 : 5. Preliminary experiments demonstrated that
making longer the time of contact of phases does
not change the silver concentration in solution.
After the completion of the experiments, the solu-
tion was analyzed for the content of silver and ni-
tric acid. The solid phase was filtered and washed
with water and ethanol to remove the solution,