Russian Journal of Applied Chemistry, 2012, Vol. 85, No. 10, pp. 1519−1523.
Pleiades Publishing, Ltd., 2012.
Original Russian Text © P.S. Gordienko, V.V. Bagramyan, S.B. Yarusova, A.A. Sarkisyan, G.F. Krysenko, N.V. Polyakova, Yu.V. Sushkov, 2012, published
in Zhurnal Prikladnoi Khimii, 2012, Vol. 85, No. 10, pp. 1582−1586.
AND INDUSTRIAL INORGANIC CHEMISTRY
Effect of Microwave Treatment on the Kinetics of Formation
and Morphology of Calcium Hydrosilicates
P. S. Gordienko, V. V. Bagramyan, S. B. Yarusova, A. A. Sarkisyan, G. F. Krysenko,
N. V. Polyakova, and Yu. V. Sushkov
Institute of Chemistry, Far Eastern Division, Russian Academy of Sciences, Vladivostok, Russia
“Stone and Silicates” Scientiﬁ c-Production Joint-Stock Company, Yerevan, Armenia
Received April 27, 2012
Abstract—It was shown that microwave treatment improves kinetics of formation and morphology of calcium
hydrosilicates obtained from the waste of boric acid production, borogypsum.
Wide spectrum of applications of calcium hydro-
O (CHS) and wollastonite
in various branches of industry is caused by
their valuable physicochemical and technological proper-
ties. At present a stable growth in demand for synthetic
calcium silicates is observed, which is caused by the ap-
preciable extension of ﬁ elds of their application and also
by nonuniform distribution of natural mineral deposits.
At present there are a great number of procedures for
obtaining calcium silicates from various calcium- and
silicon-containing compounds: melt methods of wollas-
tonite preparation, a hydrothermal (autoclave) synthesis
of calcium hydrosilicates, and a synthesis by direct high-
temperature solid-phase reactions. In recent years the
interest to application of microwave heating, including
the application in the synthesis of the above-stated com-
pounds [1, 2], has considerably increased. The microwave
treatment has several advantages over usual methods of
heating condensed media (solids and liquids) including
rapidity and low time lag of heating, absence of contact
of a heated object and a heater, thermal homogeneity of
the whole volume of a material, possibility of selective
heating, and high efﬁ cient factors .
Earlier  the possibility has been shown of obtaining
calcium hydrosilicates and wollastonite from borogypsum
formed as a result of treating datolite with sulfuric acid.
The purpose of the present work was the study the effect
of microwave treatment on the kinetics of formation and
morphology of calcium hydrosilicates prepared from
As raw material for the synthesis of CHS we used the
waste of boric acid production, borogypsum, containing
the following main components (wt %): SiO
34.2, and Fe
2.4. In addition the waste
contains 0.9–2.2 wt % of B
. Borogypsum accounts
for 5–5.5 ton per 1 ton of produced boric acid. The total
borogypsum in the Far East region of Russia makes more
than 50 million ton.
Borogypsum is a light-yellow powdery substance
insoluble in water, рН of its aqueous suspension being
7.4. Main components of borogypsum are calcium sulfate
dihydrate and amorphous silica. The speciﬁ c surface area
of borogypsum under study was 12.9 m
To prepare calcium hydrosilicates, we mixed weighted
samples of borogypsum with a solution of chemically
pure-grade potassium hydroxide in a stoichiometric
relationship. A glass ﬂ ask with a reaction mixture was
placed in a microwave-treatment apparatus supplied by
a mechanical stirrer. The synthesis was carried out at
a power output of microwaves of 600 W and temperature
of 95°С. The reference synthesis was performed under