Russian Journal of Applied Chemistry, 2013, Vol. 86, No. 6, pp. 807−810.
Pleiades Publishing, Ltd., 2013.
Original Russian Text © O.G. Gromov, Yu.A. Savel’ev, G.B. Kunshina, E.P. Lokshin, S.A. Mastyugin, V.T. Kalinnikov, 2013, published in Zhurnal Prikladnoi
Khimii, 2013, Vol. 86, No. 6, pp. 864−868.
AND INDUSTRIAL INORGANIC CHEMISTRY
Manufacturing Metallic Silver from Its Chalcogenides
O. G. Gromov
, Yu. A. Savel’ev
, G. B. Kunshina
, E. P. Lokshin
S. A. Mastyugin
, and V. T. Kalinnikov
Tananaev Institute of Chemistry and Technology
of Rare Elements and Mineral Raw Materials, Apatity, Russia
JSC “Uralelectromed,” Verkhnyaya Pyshma, Russia
Received May 16, 2013
Abstract—The decomposition of silver selenide and sulﬁ de to metallic silver and chalcogen containing oxygen
compounds by sintering with an equimolar mixture of sodium nitrate and nitrite was examined. It was found that
100% recovery of silver in a metal phase is reached at 5% excess of sodium nitrate and nitrite and a time of the
isothermal exposure at 375 °C 1 hour or half an hour at 400°C.
The technology of processing of copper electro-
lytic slime provides the recovery of silver, selenium,
gold and metals of platinum group in the flotation
concentrate.  The main phase component of this
concentrate is silver selenide, one of the hardly
oxidized chalcogenides. Its oxidative stability region
extends up to 1 V in an acidic medium and 0.2 V
in alkaline. Therefore, developing a simple method of
decomposition of silver selenide to metallic silver and
selenium-containing compounds, which are suitable
for the subsequent recovery of selenium, is of practical
interest. This way may be sintering of silver selenide
with oxygen-containing compounds of alkali metals at
a relatively low temperature.
In  metallic silver was produced form silver sulﬁ de
by mixing a silver salt with sodium carbonate, which was
taken with a 100% excess to the stoichiometric amount,
and sintering the mixture at 600–650°C for 1–3 hours,
cooling the cake in the heating oven to 100°C, grinding
and processing it with water followed by separation of sil-
ver precipitate from the mother liquor containing sodium
sulﬁ de and unreacted sodium carbonate. The recovery of
silver did not exceed 99.5%.
In  metallic silver was obtained form silver com-
pounds including silver sulﬁ de by mixing a silver salt
with potassium hydroxide or sodium hydroxide taken in
an amount of 120–150% of the stoichiometric, pelleting
the mixture at the compaction pressure of 15–25 MPa,
and sintering at 400–500°C by one step for 0.3–1.0 hours
or by two steps for 0.3–0.7 h and 0.4–0.7 h, respectively.
In the one-step sintering the cake was cooled and treated
with water with removal of the silver precipitate. In the
two-step after the ﬁ rst step the cake was air cooled to
room temperature, ground, and re-pelleted, and then
sintered again and treated with an aqueous separation
of the silver precipitate. The method provides a silver
recovery of 99.65–99.98% in the one step sintering, and
100%, in the two-stage. Disadvantages of this method are
the increased sintering temperature, the need for pelleting
a mixture of original components, elevated consumption
of alkaline reagent, two step process of sintering for 100%
In this paper we investigated the decomposition of
silver chalcogenides to metallic silver and chalcogen-
containing oxygen compounds by sintering with an equi-
molar mixture of sodium nitrate and nitrite.
(reagent grade), NaNO