1070-4272/03/7602-0167 $25.00 C 2003 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 76, No. 2, 2003, pp. 167!170. Translated from Zhurnal Prikladnoi Khimii, Vol. 76, No. 2, 2003,
Original Russian Text Copyright + 2003 by Fakeev, Vasil’eva, Sukhanovskaya.
AND INDUSTRIAL INORGANIC CHEMISTRY
A Study of Calcium Chloride Purification
A. A. Fakeev, L. V. Vasil’eva, and A. I. Sukhanovskaya
State Research Institute of Chemical Reagents and Ultrapure Chemical Substances, Moscow, Russia
Received February 27, 2002
Abstract-Two methods of calcium chloride purification were studied: crystallization from aqueous solutions
and joint precipitation of impurities from aqueous solutions onto inorganic collectors (hydrated aluminum or
zirconium oxides). The purification factors were calculated and a high efficiency of purification of calcium
chloride solutions with hydrated zirconium dioxide as collector was established.
Calcium chloride is widely used in metallurgical,
chemical, chemical-pharmaceutical, aircraft, and coal
industries, in glass manufacture, agriculture, everyday
chemistry, etc. .
In chemical industry, calcium chloride is, along
with calcium nitrate, a key compound for preparing
the most practically important calcium products (cal-
cium carbonate, phosphate, chromate, etc.) .
In recent years, ultrapure calcium compounds (cal-
cium carbonate, fluoride, and phosphate) have found
application in fabrication of optical fibers, single crys-
tals, and luminophores, [3, 4]. This required the de-
velopment of novel methods for thorough purification
of the accessible raw material, calcium chloride.
In the system CaCl
O, compounds of the
following compositions crystallize: CaCl
O, and CaCl
whose solubilities are 42.9, 53.60, 67.20, and 77.32,
and >80 wt %, respectively [1, 5].
The efficiency of crystallization purification of cal-
cium chloride could be estimated from data on phase
equilibria in water3salt systems containing this salt.
However, the relevant data are scarce. The systems
O, where M
is Co(II) [6, 7], Cu(II)
, K , or Mg(11) are of simple eutonic
type at 25oC; those in which M
is Cu(I) , Mn(II)
, Zn , or Cd  are binary compounds. An-
alysis of the data presented suggests that crystalliza-
tion from aqueous solutions is an effective method
for separation of calcium chloride from Co(II), Cu(I),
Cu(II), Mn(II), Zn, Cd, NH
, K, and Mg chlorides.
Crystallization of CaCl
from HCl solutions is
promising, since in this case, the yield of the target
product increases substantially (CaCl
a26328% HCl solution is 4 times lower at 0oC and
twice lower at 15oC than that in H
O ); however,
this process has not been studied. It has been proposed
to purify CaCl
solutions to remove iron ions by treat-
ment with carbonate-containing compounds (ammo-
nium carbonate solution) at 713100oC and pH 437.
A product containing 8 0 10
wt % iron has been ob-
A way to prepare CaCl
phosphors by precipitation
of sparingly soluble sulfide and phosphate impurities,
separation of precipitate, and boiling of the solution
with activated carbon has been described. The quality
of the product obtained has not been reported .
Joint precipitation of impurities with calcium car-
bonate at 60380oC and pH 537 has been proposed
as a method for purification of CaCl
the possibility of using purified solution for preparing
luminophore has been demonstrated [17, 18].
Treatment of CaCl
solutions with complexing
reagents (sodium diethyldithiocarbamate ,
8-oxyquinoline ) is highly efficient in removal
of iron, heavy metals, and other impurities.
Analysis of the above data on CaCl
shows that published data are rather scarce. Promising
among the known purification methods are crystalliza-
tion of CaCl
from aqueous solutions and joint pre-
cipitation of impurities onto inorganic collectors.
The aim of the present study was to analyze the
process of calcium chloride purification.
Two methods of calcium chloride purification were
studied: crystallization from aqueous solutions and