1070-4272/03/7607-1045$25.00C 2003 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 76, No. 7, 2003, pp. 1045!1047. Translated from Zhurnal Prikladnoi Khimii, Vol. 76, No. 7,
2003, pp. 1077!1079.
Original Russian Text Copyright + 2003 by Kabanov.
AND INDUSTRIAL INORGANIC CHEMISTRY
Thermal Stability of Limestone
A. A. Kabanov
Krasnoyarsk Pedagogical State University, Krasnoyarsk, Russia
Received November 4, 2002; in final form, February 2003
Abstract-Thermal stability of limestones and effects of various impurities on their stability were discussed.
The thermal stability of limestones and factors af-
fecting it are of scientific and applied interest, because
limestones are widely used in various industries.
A number of interesting effects of impurities on the
thermal stability of CaCO
O samples was estab-
lished earlier , and testing natural limestones
with respect to these effects has become urgent.
In this work, we used limestone from the Solo-
mensk deposit (Kemerovo oblast). Its 3 0.08-mm frac-
tion was sifted after dispersion and kept over P
10 days. Then the sample was degassed at 200oC for
6 h and again kept over P
for no less than 10 days.
The limestone sample thus pretreated was considered
as the starting sample.
The quantitative analysis of the samples was carried
according to GOSTs (State Standards) 4530376 and
5382391. The X-ray analysis was performed on
a DRON-3 diffractometer. The mass spectra were
obtained on an MI-1305 ionization spectrometer.
Thermal measurements were performed in air on a
Q-1500D derivatograph. Magnetic susceptibility was
measured on a pendular magnetic balance with auto-
matic equilibration. The sensitivity of measuring spe-
cific magnetic susceptibility was 10
M1ossbauer spectra were obtained on an electro-
dynamic spectrometer based on an AI-5006-3M-V100
analyzer operating in the constant acceleration mode.
The spectra were processed on an ES-1022 computer.
g-Radiation was emitted by a
Co source of 0.5 GBq
activity in a chromium matrix.
Analytical data for limestone (wt %): main sub-
95.08, Fe 0.81, (K + Na) 0.08, Si 0.52,
Al 0.70, and others 2.81. The X-ray phase analysis
(Fig. 1) shows that the starting sample contained
in the form of calcite, a-Fe
, and ferri-
O. It is
known that the X-ray diffraction patterns of a-Fe
O are identical. Taking into ac-
count the signal intensity and sensitivity of the X-ray
diffractometer, we can conclude that the concentration
of both iron(III) compounds in limestone is 0.10%.
Thermogravimetric analysis shows (Fig. 2) that the
weight of the limestone sample starts to change notice-
ably in air at 130oC. The highest rate of the sample
Fig. 1. X-rray diffraction pattern of the starting limestone:
(I) absorption intensity and (d /n) interplanar spacing.
O, (II) hydrohematite a-Fe
and (III) ferrigaluasite (Fe
T, oC Dm =5mg
Fig. 2. Derivatogram of the starting limestone. m 0.2 g,
dT/dt = 6 deg min
.(T) Temperature and (Dm) weight loss.