April 19, 1932.
s. B. HEATH
PREPARATION OF A MIXED CALCIUM CHLORIDE
1,854,405
-CALCIUM CHLORATE PRODUCT
Filed March ‘7, 1930
INVENTOR
BY 512mm 6. m
J?mw “aw/M4
ATTORNEY
Patented Apr. 19, 1932
1,854,405‘
stares}, PAT‘, NT‘ FFEQE
SHELDON B. HEATH, 0F MIDLAND, MICHIGAN, ASSIGNOR TO THE DOW CHEMICAL’
PANY, OF IIIIDLAND, MICHIGAN, A CORPORATION OF MICHIGAN
PREPARATION OF A MIIXED CALCIUM CHLORIDE-CALCIUM GHLORATE PRODUCT
Application ?led March 7,
1980. ‘ Serial No. 433,853.
This invention relates to the preparation balances that so introduced, a mixture of
of a product comprising a mixture of crystals crystals of such chloride and chlorate will be
of calcium chloride dihydrate, CaCI‘PQI-IQO, salted out having the same chloride-chlorate
and anhydrous calcium chlorate, Ca(ClO3)2, ratio as existed in the added solution. In
5 such mixed product having particular value case the added water is insu?icient to compen
for use in herbicidal preparations and the sate for that evaporated, crystals of the
like.
equilibrium mixture will also be precipitated
A process for the separation of calcium at the same time. By suitably controlling
chlorate as the dihydrate, Ca(Cl()3)2.2H2O, conditions, however, it is possible to prepare
19 by direct crystallization fromasolutionthere any desired mixture of CaClZQHZO and
of containing calcium chloride is described in Ca( C103)2 crystals by direct crystallization
my co-pending application Serial No. methods. For certain purposes such mixed
424,493 ?led January 30, 1930, such process product is especially to be desired, as in the
being generally applicable to mixed solutions preparation of herbicidal compositions, and
ill)
15 of the two salts wherein the molecular ratio it is an object of the present invention to pro
of chloride to chlorate is greater ‘than
vide a method whereby the aforesaid mixed
product may be prepared in a particularly
1
expeditious manner. The invention, then,
consists of the method hereinafter fully de
1 .
"i9 In the aforesaid process the mixed salt solu scribed and pointed out in the claims, the an_
tion is first concentrated to salt out a portion nexed drawing and following description set~
of the chloride, if necessary, as CaClZQI-LO ting forth but a1 few of the various ways in
and leave a residual solution in which the which the principle of the invention may be
molecular ratio of chloride to chlorate is be
used.
25 tween
'
‘
I
v
-
In said annexed drawing :—
I
The single ?gure is a chart showing curve
2 and
for
the composition of mixed solutions of cal
1
cium chloride‘ and calcium chlorate saturated
The concentrated solution is then diluted, if with respect to CaC12.2H2O at the tempera
so necessary, and cooled to a temperature below tures 80° and 100° (1, respectively.
about 60° to 67° 0., the transition point range
As an illustrative example of the operation
of Cit-(C103) 221-120 to anhydrous Ca(ClO3) 2 of my improved method, I may prepare a
in the presence of a liquid phase containing crystallized mixture of CaCl22H2O and
calcium chloride, to crystallize out the chlo Ca( C103)2 from a solution of calcium chlo
rate as Ca(ClO3)2.2I-I2O. If, instead of di ride and calcium chloride prepared accord
luting and cooling the concentrated solution ing to the known method of absorbing chlo
to crystallize out the chlorate, the solution is rine in milk of lime and having the following
further concentrated by evaporation, a mixed analysis :—
.
product consisting of an approximately equi
4
molecular mixture of CaCbQl-LO and
‘v
I
~
TU
-
80
$5
Per cent
C3012 ________________ __' ___________ __ 25.1
Ca( C103)2 may be salted out directly, while
C3.(ClO3)g____'___v__i ______________ __
6.8
the boiling mother liquor maintains‘ a con
stant composition at any stated temperature
(M010), ____
0.1
____ __'_' __________ __
H20 ______________________________ __ 68.0
until evaporated to dryness. Furthermore,
if a solution containing calcium chloride and
100.0
calcium chlorate in any proportion is intro The composition of this solution is represent~
duced into such boiling mother liquor of con_ ed by the point X on the drawing. The feed
stant composition at a rate such that the wa_ solution is ?rst warmed and subjected to a
ter evaporated and removed as water of preliminary treatment with a reducing
crystallization in the precipitated crystals agent, e. g. sulphur dioxide or sodium bisul
100
1,854,405
2
phite, to remove the small amount of hypo~ 1y between those limits aifords the most con~
chlorite, and the treated solution is ?ltered. venient operating conditions, in that the con—
The clear ?ltrate is then concentrated by centration may be carried out under reduced
such as are easily attainable with
evaporation preferably under reduced pres pressures
sure at a moderate temperature, for instance, usual equipment and the metallic surfaces
100° C. As water is removed by evaporation» exposed to the strong salt solution are not sub
the composition of the solution changes con jected to severely corrosive attack.
tinuously along line XA until a composition Instead of continuing the evaporation of a
represented by point A is reached whereat mother liquor of composition B or the equiva
the solution becomes saturated with respect lent, however, until most or all of the solu
to CaCl22H2O. Continued evaporation is tion is boiled o? to obtain a crystal product
75
then accompanied by salting out of crystals of composition D, which necessarily involves
of CaCl22H2O, the composition of the solu a batch or intermittent mode of operation, the
tion following along curve AB until at point process may be adapted to continuous opera
B the solution becomes saturated with re tion by boiling a body of mother liquor, for
spect to Ca(ClO3)2 and crystals of the latter instance, of equilibrium composition B at a
salt begin to be precipitated together with the convenient temperature, e. g. 100° C., and
chloride crystals. Further evaporation be continuously introducing thereto further
yond this point results in no further change amounts of solution of any available com
in the composition of the solution, and both position, such as represented by X, at a
salts are crystallized out together in the pro su?icient rate that the vaporizable water add
is equal to that boiled oil. Thereby a
portion represented by the equilibrium point ed
mixture
of crystals of CaClZQHZO and
B, the ratio of chloride to chlorate being
Ca(ClO3)2 would be continuously salted out
28
50
inal solution, while the boiling mother liquor
by weight and the water content of the solu
tion being 22 per cent. The molecular ratio
of chloride to chlorate corresponding thereto
would be maintained at substantially constant
volume. The composition of the crystal mix
ture so obtained is represented by the point
is seen to be very nearly
1
1
from the H20 vertex through point X to the
intersection with line DC. Under properly
in the same proportion as present in the orig
E, which is determined by drawing a line ~~
controlled conditions an uninterrupted pro
duction of the crystal mixture may be car
The composition of the crystal mixture salted ried on in this way. The precipitated crystals
out is found by drawing a straight line from may be removed and filtered while hot from
the H20 vertex through point B, and an the mother liquor. When the ?ltered crystals
1
other line from the Ca(ClO3) 2 Wertex to
are cooled to a temperature below about 60° C.
point C representing the composition of the
slight amount of mother liquor adhering
CaCl22H2O, and ?nding the intersection of to the surfaces thereof is absorbed by rehy- "
the two lines, i. e. oint D, which corresponds
to 32 per cent Ca 12, 57.5 per cent Ca(ClO3)2
and 10.5 per cent H2O.
If the concentration is carried out at 80° C.
the solution composition during the salting
out of CaCl22H2O is shown by curve A’ B’,
point B’ representing the composition of the
equilibrium mixture. The mixed salt product
obtained by crystallizing at 80° C. therefore
contains a slightly higher ratio of chloride
to chlorate. Still lower temperatures down
to about 60° C. may be employed, if desired,
but with somewhat less advantage owing to
the higher vacuum required for the evapora
tion. Likewise higher temperatures may be
dration of anyhydrous Ca(ClO3) 2 to the di
hydrated salt Ca(ClO3) 221-120, so that a sen
sibly dry, granular mass is obtained which
possesses free flowing and non-caking char
acteristics.
Similarly a crystalline mixed calcium
chloride-calcium chlorate product of any de
sired composition may be prepared by em
ploying as a feed solution a solution of the
two salts in the same ratio. Likewise the op—
eration may be carried out at any desired
temperature between about 60° C. and the
atmospheric boiling point of a calcium chlo
ride-calcium chlorate solution of equilibrium
composition corresponding to the tempera—
employed for the evaporation and salting out, ture
chosen. The principle governing the
up to the atmospheric boiling point of the foregoing
method of operation remains the
saturated solution, but at such higher tem
same in any case, regardless of the composi~
tion of the feed solution or of the tempera
ture of evaporation within the limits stated
above. A calcium chloride-calcium chlorate
solution
of equilibrium concentration, as re
have been selected for the purpose of illus
tration and are not to be construed as imply ferred to hereinbefore and in the appended
ing any limitation upon the invention, still claims. is a solution saturated with respect
the range of temperatures comprised rough~ to CaCl2.2H2O and Ca(C1O3) 2. The actual
peratures the corrosive action of the strong
salt solutions upon the equipment constructed
of usual materials becomes appreciable.
While the temperatures of 100° and 80° C.
110
H as U!
3
1,854,405
ratio of chloride to chlorate therein varies tially the same proportion as present in such
somewhat with the temperature, but in gen added solution.
eral does not deviate greatly from an equi~
5. The method of preparing a mixed cal
molecular ratio.
cium chloride-calcium chlorate product which
Other modes of applying the principle of comprises concentrating an aqueous solution
my invention may be employed instead of thereof wherein the ratio of chloride to
the one explained, change being made as re chlorate is greater than
gards the method herein disclosed, provided
10
1
the step or steps stated by any of the fol
1
lowing claims or the equivalent of such
stated step or steps be employed.
to crystallize out CaCl22H2O and leave a
I therefore particularly point out and dis mother liquor wherein said ratio is approxi
mately
tinctly claim as my invention :-—
1. The method of preparing a mixed cal
15
1
cium chloride-calcium chlorate product which
II
comprises evaporating an approximately continuing evaporation of the mother liquor
equimolecular solution thereof at a tempera
80
ture above 60° C. to crystallize out a mixture at a temperature above 60° (1, adding there
to a solution of the two salts at such rate as
of CaCl22H2G and Ca(ClO3)2.
2. The method of preparing a mixed cal to maintain a substantially constant volume,
whereby a mixture of CaCl22H2O and
cium chloride~calcium chlorate product which Ca
2 is crystallized out in substantially
comprises concentrating an aqueous solution the (010,)
same
proportion
as present in such added
thereof wherein the ratio of chloride to
solution,
and
separating
the crystals from the
chlorate is greater than
mother liquor.
1
6. The method of preparing a mixed cal—
cium chloride-calcium chlorate product which
1
comprises boiling a solution thereof, wherein
to crystallize out CaCl22H2O and leave a the ratio of chloride to chlorate is approxi
solution wherein said ratio is approximately mately
1
1
1',
I7
separating the crystals and evaporating the at a temperature between about 80° and
residual solution at a temperature above 100° C. and continuously adding thereto a
60° C. to- crystallize out a mixture of solution of the two salts at such rate as to
95
100
CaCl22I-I2O and Ca(ClO3)2 in substantially maintain a substantially constant volume,
the same ratio.
3. The method of preparing a mixed cal
whereby a mixture of CaCl22H2O and
Ca (C103) 2 is crystallized out in substantially
cium chloride-calcium chlorate product which the same proportion as present in such added
comprises concentrating by evaporation at a solution.
temperature between about 80° and 100° C.
105
7. The method of preparing a mixed cal
an aqueous solution thereof wherein the ratio cium chloride-calcium chlorate product which
comprises concentrating by evaporating at a
of chloride to chlorate is greater than
temperature between about 80° and 100° C.
1
1
an aqueous solution thereof, wherein the
ratio of chloride to chlorate is greater than
to crystallize out CaCl22H2O and leave a
1
solution wherein said ratio is approximately
1
1’
I,
to crystallize out CaCl22H2O and leave a
,
separating the crystals and further evaporat
ing the residual solution at the stated tem
,perature to crystallize out a mixture of
mother liquor wherein said ratio is approxi
mately
1
I7
“ CaCl22H2O and Ca(ClO3)2 in substantially continuing evaporation of the mother liquor
the same ratio.
4. The method of preparing a mixed cal
cium chlorlde-calclum chlorate product which
.I comprises boiling a solution thereof of equi—
librium concentration at a temperature above
60° C. and adding thereto a solution of the
120
at such temperature, adding thereto a solu
tion of the two salts at such rate as to main
tain a substantially constant volume, where
by a mixture of ‘JaCLiZHyO and Ca (ClOQa
is crystallized out in substantially the same
proportion as in such added solution, and
two salts at such rate as to maintain the separating the crystals from the mother
65
110
volume of the boiling solution substantially liquor.
constant. whereby a mixture of CaClQQI-PO
Signed by me this 4th day of March, 1930.
and Ga(ClO3)2 is crystallized out in substan
SHELDON B. HEATH.
125
130
CERTIFICATE OF CORREC'i‘lON.
Patent No. 1,854,405.
Granted April 19, 1932; to
SHELDON B. HEATH.
It is hereby certified that error appears in the printed specification of the
above numbered patent requiring correction as follows: Page 1, line 85, for the
word "chloride" read chlorate, and line 86, for "of" read by; and that the said
Letters Patent should be read with these corrections therein that the same may
conform to the record of the case in the Patent Office.
Signed and sealed this 21st day of June, A. D. 1932.
(Seal)
.M. J. Moore,
Acting Commissioner of Patents.