ISSN 1070-4272. Russian Journal of Applied Chemistry, 2006, Vol. 79, No. 1, pp. 156 !158. + Pleiades Publishing, Inc., 2006.
Original Russian Text + A.A. Kabanov, 2006, published in Zhurnal Prikladnoi Khimii, 2006, Vol. 79, No. 1, pp. 157!159.
Thermal Stability of Limestone with a Medium Content of Iron
A. A. Kabanov
Astaf’ev State Pedagogical University, Krasnoyarsk, Russia
Received August 24, 2005
Abstract-The thermal stabilities of limestone with varied content of iron are compared. The nature of
the differences observed is discussed.
The properties and thermal stability of limestone
with a high content of iron (0.81 wt %) were consid-
ered in  in comparison with analytically pure
O. Here we compare the thermal
stabilities of limestone with a low content of iron and
of the same analytically pure grade reagent.
Limestone from the Torgashino deposit in Krasno-
yarsk krai was used. After its dispersion, the 0.08-mm
fraction was separated by sieving and kept over P
for five days. Then the preparation was degassed at
200oC for 6 h. This limestone was taken to be the
starting material. The quantitative analysis of the
samples was performed in conformity with GOST
(State Standard) 4530376 and 5382391; a DRON-3
diffractometer served for X-ray diffraction analysis.
Mass-spectrometric measurements were made with an
MI-1305 ionization spectrometer.
Thermal studies were performed in air with a
Q-1500D derivatograph. M1ossbauer spectra were
Fig. 1. X-ray diffraction pattern of the starting limestone. (I) Absorption intensity and (d/n) interplanar spacing. (I) CaCO
(II) goethite FeOOH, and (III) wustite FeO.
measured on an electrodynamic spectrometer based on
an AI-5006-3M-V100 analyzer operating in the con-
stant-acceleration mode. The spectra obtained were
processed on an ES1022 computer. The
in a chromium matrix, with an activity of 0.5 GBq,
served as the source of g-radiation. Kinetic curves
of limestone decomposition were obtained by the
volumetric method at 825+0.5oC, with 0.100-g
weighed portions used. The procedures used were
described in more detail in .
The chemical composition of limestone is the fol-
lowing (wt %): main substance CaCO
93.50, Fe 0.40,
(K + Na) 0.11, Si 1.91, Al 0.20, Mg 0.60, and other
impurities 3.28. The X-ray phase analysis (Fig. 1)
suggested that the starting limestone contains CaCO
in the calcite modification, goethite FeOOH, and
wustite FeO. The content of other crystalline phases is
less than 3.16%.
Additional evidence concerning iron minerals was