1070-4272/01/7406-0925 $25.00 C 2001 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 74, No. 6, 2001, pp. 925!929. Translated from Zhurnal Prikladnoi Khimii, Vol. 74, No. 6, 2001,
Original Russian Text Copyright + 2001 by Tsymbulov, Tsemekhman.
AND INDUSTRIAL INORGANIC CHEMISTRY
Solubility of Carbon in Sulfide Melts of the System Fe!Ni!S
L. B. Tsymbulov and L. Sh. Tsemekhman
Institut Gipronikel’ OAO, St. Petersburg, Russia
Received February 20, 2001
Abstract-The solubility of carbon in iron-nickel sulfide melts at 1673 K was studied in the entire range
of compositions of the Fe3FeS3Ni
3Ni tetragon. The boundaries of the stratification area were determined
in this system upon its being saturated with carbon. Lines of carbon isosolubility are plotted in the tetragon
field outside the stratification area.
To reduce oxides of non-ferrous metals, various
carbon-containing materials are added to blends when
nickel and cooper-nickel raw materials are smelted
to produce a matte (an alloy of iron, copper, nickel
and cobalt sulfides), with slag depleted of these non-
ferrous metals. These manufacturing processes were
described in detail in .
Carbon dissolves in the sulfide phase formed upon
smelting. Its concentration is determined not only by
the amount of a reducing agent added to a blend, but
also by the content of sulfur in the matte, relative con-
tent of metal components in it, and temperature.
The available published data on the solubility of
carbon in matte melts are extremely scarce and mainly
concern the Fe3S system [8, 9].
The scantiness of the published data is related, on
the one hand, to the absence, until recently, of reliable
procedures for determining the carbon content in sul-
fide products with sufficiently high content of sulfur,
and, on the other, to the conventional opinion that ad-
mixtures (of which the main are oxygen and carbon)
insignificantly affect both the distribution of metals
in a matte3slag system and the physicochemical proc-
esses occurring in further processing of the matte.
However, a trend has appeared recently toward smelt-
ing to obtain mattes with greater metal content, which
is known to make lower the loss of non-ferrous metals
with slag .
It is natural to assume that the carbon content in
such mattes will be higher, and, therefore, its effect
will be stronger. Furthermore, data on carbon solubil-
ity can be also useful for gaining deeper insight into
the structure of sulfide melts.
The initial object of our research was the system
Fe3S3C . It is known from the literature that it
is characterized by separation into the sulfide and me-
tallic phases [8, 9]. We confirmed this once more,
our data on the carbon solubility in both phases be-
ing in good agreement with the data of . This fact
proved the correctness of the selected experimental
technique, which was as follows.
A 30-g portion of powdered iron, nickel, and sul-
fides of these metals was placed in a graphite crucible,
and 5 g of graphite powder was poured above. The
crucible with the blend was placed in an alundum
reactor mounted in a furnace with a graphite heater.
The reactor was heated to 1673 K in an argon atmo-
sphere, and the melt was kept at this temperature for
a specified time (this time was 5 h for stratifying com-
positions and 2 h for homogeneous melts). On com-
pletion of experiment, the crucible was taken out of
the furnace and cooled in an argon flow. The thus
cooled sample was analyzed for the content of iron,
nickel, sulfur, and carbon.
The content of metals and sulfur in the sulfide
phase was determined by chemical methods, that of
sulfur and carbon in the metallic phase-on a CS-444
analyzer ([LECO] production), and that of carbon in
the sulfide phase-on an analyzer of the same make
but upgraded for determining the carbon content at
high sulfur content. The inaccuracy of carbon deter-
mination in the sulfide phase was as follows (wt %):
+0.014 for concentrations 0.0530.10, +0.018 for
0.1030.20, +0.025 for 0.2030.50, +0.09 for 0.5031.00,
The experimental technique is described in more detail in .