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reamed May 3, 1938 ‘_ ‘
z,116,4i2, 1
UNITEDYSTATES,
PATENT oFFicE '
2,116,423
METHOD OF CBYSTALLIZATION AND CRYS
TALLIZED PRODUCTS
‘Chester L. Baker, Berkeley, Calif., assignor to
Philadelphia Quartz Company of California,
Ltd., Berkeley, Calif., a corporation of Cali
fornia
I
No Drawing. Application January 18, 1933,
Serial No. 652,418
20 Claims. (01. 23-110)
The present invention relates to an improved 551,785, ?led'Juiy 18, 1931, I have disclosed cer
crystallizing process which is particularly‘ appli- tain ways and means for producing stable hy
cable to systems where the solution from which drates of the alkali metal silicates, and the pres—
the substance is to be crystallized is of a sticky
5 or syrupy nature and contains an alkali metal
silicate.
Such solutions though usually super
saturated are difllcult to crystallize. My inven
tion is especially applicable to the production ‘of
crystalline hydrates of alkali silicates, although
10 .I wish it to be understood that the principles in
ent invention, therefore, is somewhat in the na
ture of a modi?cation of or improvement upon U1
the processes therein claimed. In this particular
held the primary object of the present invention
is to produce the desired crystal species by means
of a process in which the necessary control is ex
ercised through regulation of the seeding opera
volved might equally well be used in the producé
tion without particular control of the tempera
tion of mixtures of alkali metal silicates with
tures involved. To state the matter in another
way, I have now found that if a liquid of the ap
proximate composition of the desired hydrate be '
seeded in such an intimate and thorough ‘man
ner as to cause crystallization to proceed from
other materials. ,
-
1 The invention also relates to certain new prod
ucts o'r compositions of‘ matter as will further
appear.
'
The invention, to a large extent, has been de
veloped in connection with the production of so
dium metasilicate, and the present disclosure,
20 therefore, will relate in large measure to such '
material, but, as before stated, it is not-to be lim
ited to this ?eld.
\
'
v In the prior art relating to the alkali metal sili
cates, where crystals, if any, have been produced,
they have been contaminated with supercooled vor
uncrystalnzed liquid to an extent sumcient to re
sult in an unstable end product which, if ground,
has heretofore tended to agglomerate into a solid .
mass di?lcult to handle.
.
1
With the foregoing in mind, the primary ob
ject of the present invention may be said to re
side in the provision of a crystallizing process in
which the solution from which the product is to
be crystallized is so thoroughly and intimately
seeded, i‘. e., where the fool of crystallization are
fool much more numerous than heretofore con
templated, cakes and/or masses can be produced '
in which the conversion from syrupy liquid to
crystalline solid is sui'liciently complete to yield 20
end products which are stable and free-?owing
even if the crystallization takes place at ordinary
,ambient temperatures, which temperatures, of
course, are considerably under the melting tem
peratures of the crystal hydrates involved in the 25
present invention. Furthermore, my invention
contemplates and makes possible a marked de
crease in the time required to convert the solu
tion into crystal form.v
A statement of the more detailed objects of 30
my invention,‘ therefore. may be said to involve ‘
(1) the provision of a method for the production
of crystalline materials by means of which it is -
unnecessary to give any particular consideration
to the control of the temperatures involved so long 35
so greatly multiplied and distributed throughout as the particular compound sought does not melt
- the mass ‘as to result in the production of an ,or decompose; (2) the provision of a method in
which the conversion from syrupy liquid to a crys
end product which is substantially free or uncon
taminated with supercooled or uncrystallizedma . talline solid is more complete than with previous
:3 in
terial so that in granular or divided condition the
processes known to the art; (3) the provision of 40
a method in which the foci of crystallization are
1 enormously multiplied so as to bringall portions
will not tend to agglomerate into solid masses.
_ The new method of promoting crystallization of the liquid into intimate contact with a focus _
product will be stable, dry' and free-?owing‘ and
herein disclosed mayalso be used ‘in connection
with systems which contain constituents other
than‘ those which it is desired to-crystallize, such
as soap for example.
More ‘specifically considered, my invention has
for its object the provision of an improved proc
ess for producing stable hydrates of the alkali
of crystallization; (4) the provision of a method
which results in an end product of ?aked charac 45
ter which will remain dry, stable add free-?ow
‘ ing in storage; (5) the provision of a method
which will result in considerable saving not only
in the cost of manufacture but also in the amount,
of time necessary to arriige at the desired end
metal silicates, notably sodium metasilic'ata. In ‘ product; (6) the provisionoi' a method in which." ~
my prior applications, Serial No. 465,245, (of the transition from liquid to solid form' takes
which the present application‘ is a continuation ' place in a much shorter interval of time than has
in part) ?led July 1, 1930, and issued as Patent been possible heretofore, which feature, of course,
No. 1,898,707 on February 21, 1933 and Serial No. lends itself particularly well to the development
2,110,428
of a continuous manufacturing process; (7) the
provision of a method of the foregoing charac
ter whereby mixtures of crystallized materials
‘maybe prepared, which mixtures are also stable
and substantially free of any tendency to ag
glomerate; and (8) the production of certain new
compositions of matter in stable form. Other
plicable to the production of other alkali metal
silicates‘ in stable crystalline form, as well as to
mixtures of these with other materials, ‘such, for
example, as sodium sesqui-silicate, sodium meta
borate (NaBOzAHzO) etc.
By way'of example sodium sesqui-silicate can
objects and advantages will appear hereinafter I
10
or occur to those skilled in the art.
Various examples of the manner in whch my
improved method can be carried out are as fol’ lows:
I.—Method of producing NazSi0s.5HzO
15
To 5000 grams of a solution of sodium silicate
containing 8.84% NazO- and 28.8% SiO2 are add
ed 1378 grams of caustic soda containing 76%
NazO. The solution is then evaporated until the
total weight is reduced from 6378 grams to 5090
20 grams. This hot liquor shouldv test just under
63° Bé. This solution is allowed to cool to any
convenient temperature below 70° C. It is then
placed on a roll type ink grinding mill and 500
grams of powdered NazSiOa?HzO crystals added.
25 The mass is then ground on the two primary
rolls of the mill for about one minute. The
discharge roll is then moved into place and the
entire mass discharged onto the knife of the, ma
chine. The product will be white in color and
30 quite opaque. Immediately upon cooling it will
become hard ‘and brittle, so that it may be ground
into a dry, free-?owing powder. In case the
evaporated liquid has been cooled to room tem
perature, the mass may be discharged from the
35 mill in the form of a very heavy paste which
solidi?es almost immediately. ‘
' II.—Method of Producing NazSiO3.6'HzO
40
To 4525 grams of a solution of silicate of soda
containing 8.84% NaaO and 28.8% SiO2 is added
. 1245 grams of caustic soda containing 76% NazO.
The solution thus formed. is evaporated until the
total weight is reduced from 5770 grams to 5000
grams. .The liquid is then allowed to cool to
45 any convenient temperature below 62° C. and
I placed on the two primary rolls of an ink grind~
ing mill. 500 grams of crystalline NazSiOaGI-EO
are then added and the mixture ground for one
minute. The third roll of the mill is then moved
50 into place and the mass discharged onto the
knife of the machine. Upon cooling the mass
will become hard and brittle so that it may be
ground to a, dry, free-flowing, granular powder
consisting of crystalline Na2Si03.6HzO.
55
III.—Method of producing Nazsioaszizo
To 4500 grams of a solution of silicate of soda
containing 8.84% M120 ‘and 28.8% SiOz is added
'. 1240 grams of caustic soda containing 76% NazO,
and 410 grams of water. The solution is brought
to a boil and the small amount of water lost by
evaporation replaced, so that the ?nal solution _
has a weight of 6150 grams. This liquid is cooled
to any convenient temperature below 47° C. The
65 mass is then ground for about 1 minute. The
third roll of the mill is then moved into place
and the entire ma‘ss discharged onto the knife
of the machine. The discharged mass will be
white and creamy in consistency. Upon cooling
70 it will become hard and brittle so that it can
be ground'to a dry, free-?owing, granular pow
be produced in the following manner:
IV.-—Meth0d of producing NGaHSiO4.5HzO
To 3300 grams of a solution of silicateof soda 10
containing 8.84% NazO and 28.8% S102 is added
909 grams of caustic soda containing 76% NazO
and the solution thus formed evaporated to a
weight of 3360 grams. This solution should‘ then
test just under 63°Bé. This solution isthen cooled 15
to a temperature of 70° C. or below and 640
grams of caustic soda containing 76% NazO dis—
solved in it. The solution thus formed is allowed
to cool to any convenient temperature below 78°
C. and if necessary 500 grams of crystalline 20
Na3HSiO4.5I-I2O mixed in. The mass is then
placed on the two primary rolls of an ink grind
ing roll mill and ground for one minute. The
third roll' of the mill is then moved into place
and the mass discharged onto the knife of the 25
machine. The discharged mass will be white and '
opaque in color and will almost immediately
harden into a brittle mass capable of being
ground to a dry free-?owing stable granular pow
der. More often, however, the mass will be dis 30
charged from the machine as thin white ?akes
which immediately harden and can be used in
the arts without further grinding.
In the foregoing example the seeding by
the addition of the 500 grams oi’ crystalline
NaaHSlO4.5H'2O may not be necessary because
experience has shown that after a period of cool
ing a number of crystals may sometimes form
spontaneously and these can be satisfactorily dis
persed by the grinding’ operation or its equiva
lent.
My improved process gives rise to an additional
and very important advantage in that it makes
possible a state 01' more intimate relationship be
tween crystals prepared from solutions which 45
crystallize with difficulty and other substances
which modify and/or increase their usefulness.
For example, a mixture of sodium carbonate
and the pentahydrate 01' sodium metasilica’.e may
be made in which the two substances are pres 50
ent, the sodium metasilicate as a crystalline
product while the sodium carbonate appears as
an amorphous solid, although undoubtedly be
ing ?nely crystalline. But the two crystals are
so intimately interlocked that they appear to 55
the eye or even under a low-power microscope
as a homogeneous mass. The same is also true
of mixtures of crystalline alkali metal silicates
and soap and of salt mixtures where two crystal
species are formed concurrently, such as the 60
phosphate silicate mixtures, the silicate meta
borate mixtures and the mixtures of the di?er
ent hydrates of sodium sesquisilicate withthe
hydrates of sodium hydroxide. This intimate re
lationship prevents the possibility of mechanical 65
segregation of the mixed substances and thusv
of one of them acting in any sense independent
of the modifying e?’ect of the other. Caustic
soda, for example, is an extremely corrosive sub
stance, but in such mixtures as here contem 70
plated its corrosive effect is modi?ed by the pres-'
ence of the silicate compound and it is much
der consisting'of crystalline Na2Si03.9H2O.
The foregoingexamples relate to‘ certain of safer to use. Some of the silicate compounds are
v the sodium metasilicates, but it should be under
73
stood that the principles of the invention are 8P
too actively alkaline for certain uses,'as in con
tact with sensitive fabrics or human skin, and 75
3 .
‘ “3,110,423
the presence of hydrates of
thus intimately related exerts a modify!“
‘
ef
in the product being‘at least 90 per cent crys
tallized.
fect quite beyond expectation in; vie'wpof“ the prop
‘ ‘erties ofthe materials separately. '
'1
Insofar as mixtures are concerned, theffollow
ing examples may be taken as typical methods
of procedure:—- .
'
To 5000 grams of a solution of sodium silicate‘ -
containing 8.84% M120 and 28.8% $102 are added
1378 grams of caustic soda containing 76% NazO.‘
The solution is then evaporated until the total
weight is reduced to 5090 grams. The solution is
then allowed to cool to any convenient tempera
'
V.—Method of preparing a mixture of
10
NdapollzHzO and NG2SiO3.9HzO
To 4500 grams of a solution of silicate of soda
containing 8.84% NazO and 28.8% S10: is added
ture below 70° C. and 500 grams of granulated
1240 grams of caustic soda containing 76% NaaO
soap, together with ,500 grams of Na2SlO3.5H2O,
added. The mixture is then ground on the two
primary rolls of an ink grinding roll mill for 15
' ‘and 410 grams of water. The solution is brought
to a boil and the small amount of water lost by
evaporation-replaced so that the ?nal solution
has a weight of 6150 grams. This liquid is cooled
one minute. The third roll is then moved into
place and the mass discharged as a heavy paste.
This mass will harden upon cooling so that it
may be ground into a dry free-?owing granular
and stable powder.
20
-VIII.--Method of preparing a. mixture of
to any convenient temperature below 47° C. To
the liquid is then added 1000 grams of crystalline
20. trisodium
phosphate (NaaP0a12HzO) and 500
grams of ‘crystalline NazSiOailI-IzO. The mix
ture is then placed on the two primary rolls of
25
‘
VIL-Method of preparing a mixture of soap and
NazSiOs.5HzO
NazSz‘OaQHZOT and NaBOzAHzO
an ink grinding roll mill and ground for one
minute. The third roll is then moved into place
and the mass discharged onto the knife of the
machine. The discharged material will be white
and opaque in color and usually in the form of
To'2250 grams of a solution of silicate of soda
containing 28.82% S102 and 8.84% NaaO are 25
added 620 grams of caustic soda containing 76%
NazO and 630 grams of water. The solution
thin white ?akes which become hard and brit1 ' formed is Just brought to a- boil and any water
lost by evaporation replaced.
tle almost immediately. At times the discharged
harden almost immediately and can be ground
to dry free-?owing, non-caking stable granular
powder.
35
The solution is
then cooled to any convenient temperature be
low 55° C. At a temperature above 55° C.
30 mass will come oil as a heavy paste which will
NaBOz.4H2O
.
This ground product is in the form of granules
of interlocking crystals of NaaPOalZI-laO and
Na2SiOa.9HzO, said crystals being interlocked dur
ing growth, being substantially free from super
so’
transforms into NaBOaZI-IzO and since the former
compound is desired, it is necessary to maintain
the temperature below 55° C. To the solution
is then added 1850 grams of borax
' cooled metastable liquid and being, substantially
incapable of mechanical segregation, the compo
40 sition as a whole being at least 90 per cent crystal
lized and having substantially no tendency to
agglomerate into solid masses.
VI .—Method of preparing a mixture of
NazCOs and NdzSiOa?HzO
‘To 5000 grams of a solution of sodium silicate
containing 8.84% Na20 and 28.8% S102 are added
1378 grams of caustic soda containing 76% NaaO.
The solution‘ is then evaporated until the total
weight is reduced to 5090 grams. 2000 grams of
and 390 grams caustic soda containing'76% No.20.
This addition is brought into solution by stirring, 40
care being taken to prevent the temperature rising
above 55?’ C. The massis then placed upon the
two primary rolls of an ink grinding roll mill
and 100 grams of Na2SiOa.9HzO and 100 grams of
NaBO2.4H2O added for seed. The mixture is 45
ground for about one minute and then discharged
from the machine as a white, opaque material
which solidi?es almost immediately‘ to a hard
brittle product which whenground will remain
commercial sodium carbonate are then mixed in
dry, free-?owing and stable upon storage. ‘The
and the mixture allowed to cool to any convenient
temperature below 70° C. 500 grams of
productwill consist of a de?nite mixtureof‘ '
NazSlOaSI-IzO
crystals are then added andv the mixture ground
on the two primary rolls of an ink grinding roll
mill for about one minute. The third' roll is then
moved into place and the material discharged. as
60 a heavy, white, opaque paste which solidi?es upon
cooling, to a hard brittle mass which can be easily ‘
ground to dry free-?owing'granular stable pow
der. The sodium carbonate remains, unchanged
during the above procedure and. it occurs in the
. ‘product in its original state, usually considered
amorphous, but known to be finely crystalline.
The ground product therefore consists of granules
of interlocking crystals of Nil-2C0: and.
NaBOafiHzO
and NazSiOsBHaO.
'
1.
IX.—-Method of preparing a mixture of ‘crystalline.
55
1450 grams oi caustic soda containing 76%
NazO are dissolved in‘5250 grams of a solution of ,
'
silicate of soda containing 28.84% S102 and 8.84% 60
NaaO.
'
-
‘
‘
'
The solution thus formed is evaporated to a '
weight of 5476‘g1'ams and is then cooled to'any
convenient temperature below 30° C.vv 4555 grams
of-caustic soda containing 76% of NazO are then 65.
added and the mixture ground for one minute
on the two primary rolls of an ink‘ grinding roll
- mill. The third roll is then brought into position
> and the mass discharged from the machine as a
thick white opaque paste which hardens within 70
in a dry,» stable, .non-caking free-?owing state, a short period of time into a brittle mass which
said crystals being interlocked during growth, can be easily ground to a ‘granular, free-flowing,
being substantially free from' supercooled me ' stable powder.
tastable liquid and being substantially incapable
Many other mixtures can be made in a similar
75 of mechanical segregation, and the NazSiOaM-IaO 7 way providing proper consideration be given to 75
4
2,116,428
equilibrium characteristics. For example, com
binations or penta or monohydrates or sodium
sesquisilicate vwith hydrates oi’ sodium hydroxide
maybe made.
It should also be noted that certain combina
tions of the hydrates may be produced as stable
mixtures, and by way of example I desire to cite
the following:
X.--Method of producing a mixture of
10
_
NazSiOaSIhO and NGzSiOs.6H2O
To 5000 grams of a solution 01' sodium silicate
containing 8.84% Nazo and 28.8% S10: are added
1378 grams 0! caustic soda containing ‘76% NazO.
15 The solution is then evaporated until the total
weight has been reduced to 5310 grams. This
’ solution is then allowed to cool to any convenient
temperature below 53° C. 250 grams of crystal-1
line NazSiOa.5I-Iz0 together with 25 grams of
20 crystalline NazSiOa?HzO are then stirred in. The
mixture is then ground on the two primary rolls
oi’ an ink grinding roll mill for about one minute.
‘.25
‘The third roll is then moved into place and the
mass discharged onto the knii'e of the machine.
The mass- will be white and opaque in color and
will solidify immediately upon cooling.
'
In all of the foregoing examples it will be noted
as arecommonly used as a breakfast cereal, ex
cept, of course, that these ?akes are white. This
flaked product or any ground or comminuted
form into which the‘ crystallized mass may be
converted by suitable mechanical means .will re
main dry, stable and free-flowing in storage.
One way in which to determine the degree of
transition into crystal‘ form which may result
when practicing the foregoing process is to resort
to the heat of solution test. It is a fact well
known to physical chemists that soluble sub
stances, when dissolved in water, either give oil or
absorb heat, and the quantity of heat thus in
volved is referred to as “heat of solution” and is
expressed in calories per gram molecule. Thus, 15
for example, when one gramv molecule of
MgSO4.7HzO is dissolved in 400 gram molecules
of water, the system "will absorb 3800 gram
calories. On the other hand, one gram molecule
of MgSO4.H2O will give off 13,300 gram calories 20
and one gram molecule of MgSOr will give off
' 20,280 gram calories.
- A similar relationship exists between the heats
of solution for the various hydrates of the alkali
metal silicates, and with particular reference to 25
sodium metasilicate, the values indicated in the
following table have been obtained by dissolving,
that I have described the use 0! a roll type ink
on the one hand, 10 (grams of the crystallized ma
grinding mill for the purpose of grinding the
seeded solution. I wish it to be distinctly under
stood, however, that it is not essential to the
spirit and scope of the invention that a machine
terial‘in 150 grams of water, and on the‘other
hand, 10 grams of the uncrystallized supercooled 30
liquid in 150 grams of water.
- of this type is necessary, as other grinding or
’ subdividing machines such as paint mills, colloid I
Temperature change when Ill) grams of material
are dissolved in 150 grams of water
35 mills or dlsintegrators may very well be em
Crystals
ployed for accomplishing the same purpose. In
Liquid
iact other expedients may be adopted, within the
scope oi’ this invention, for causing the necessarily
NilgSlOLQHjO _________________ _l
—3. 48
i0. 02
—0. 55
ill. 02
thorough and intimate subdivision and distribu
NmSiO1.8H10 _________________ __ —3. 10
N8:SlOl.6HIO.
-_ —2. 25
i0. 02
i0. 02
—0. 53
—0. l5
5:0. 02
:i;0. 02
NmSlO;.5H:O _________________ _ _
=l;0. 02
+0. 14
i0. 02
40 tion of the seed. The factor which is important
is to greatly multiply the foci of crystallization
by comminuting or subdividing the seed, as by
the grinding operation described.
.
Insofar as my present knowledge is concerned,
it would seem that the action involved is a dis
tribution of the seed, together with su?icient
multiplication of the loci of crystallization of
such nature as will serve to bring substantially
all portions of the liquid into intimate contact
with a focus oi’ crystallization, and this in a
reasonably short space of time. The grinding em
ployed in my invention operates to break up, sub
divide or comminute the seed and/or the crystals
as they are formed so that the whole mass crystal
limintothedesiredhydrateinsuchawayasto
substantially preclude, in the end product, the
?raence of supercooled or uncrystallized mother
quor.
'
-- l. 85
35
40
If one examines the table above he will noticev
that in the case of NazSiO3.9H2O the uncrystal
llzed solution lowers the temperature by 0.55° 0.,
whereas the crystallized material lowers the tem 45
perature by 3.48° C. A similar relationship exists
in the case of each material. It will thus be seen
that if a mixture ofv crystals and uncrystallized
solution of the same chemical composition are
used in this experiment a value will be obtained 50
which is less than that given by the uncontami
nated crystals. From the values thus obtained
it is possible to make a rough calculation of the
amount ,of crystalline material in the sample
taken. For example: Should the sample taken
give a temperature lowering of 2.95, the amount
or the crystallized material can be expressed as
-
The uniform dispersal or distribution of the
crystals or crystal fragments may be likened to
the distribution of a pigment in a vehicle to form
paint. _ In any event the‘ distribution should be
- extremely thorough ‘and the number of nuclei
(2.95-—.55)100 =81.8%
3.48— .55
60
In the several examples given above heats of
solution tests of the character just described in
dicated that the degree of crystallization was
should be multiplied to a _very great extent in - upwards of 90% in every instance and generally
65
ranged between 93.5% and 95%.
order to obtain the best results. ‘
,
I I have discovered that the desired result can be
brought about by adding seed crystals or the de
sired hydrate to the uncrystallized solution at
room temperature and grinding and dispersing
.70 this seed in the solution on an ink grinding roll
mill or other grinding device.
Where a roll type grinding mill is employed,
such as‘ the ink grinding mill mentioned in the
examples, it is possible to produce'an end product
7:
of ?aky character very similar to corn ?akes such
vI also wish to point out that in connection
with all of the foregoing examples involving the
speci?c grinding operation described, consider
able latitude is permissible in the grinding time.
For example,.I have conducted a series of tests 70
in which the grinding time was varied from 10
seconds to 5 minutes and the heat of solution
test showed that crystallization was substan
tially the same throughout the entire range.
The criterion, therefore, is the nature of the end 76
51,
2,116,423
product. Intimacy of seed distribution should ‘tion, ?nely grinding the resultingv mixture of vcrystals and solution while simultaneously dis- v
be sufficient to ensure a conversion into crystal
persing the crystals rapidly and uniformly
line form which will result in a dry, stable, free
?owing end product andyas indicated above”, I, throughout said mixture while said mixture is
prefer to ‘operate in a range which will yield a
still in‘ a liquid condition in such manner as to
product which is crystallized substantially 90%
produce a resulting crystallized product substan
tially free from supercooled‘ liquid and capable
of being comminuted to a dry, stable, free-Howe
or more.
.
_
It will be seen, therefore,.that I, ‘have provided
a method for producing crystalline hydrates of s
U) the alkali metal ‘silicates and compositions con
ing powder.
‘
2. The method er claim 1 wherein crystalliza
10
taining the same in which it is unnecessary to ~ tion is initiated by seeding with a quantity of
give any particular consideration to the tempera
sodium metasilicate pentahydrate crystals.
,
3. In the production of a composition of mat
stability and‘character of the end product are ter containing a crystalline hydrate of an alkali
metal silicate,.the method which includes prep 15
15 determined by suitable control of the seeding step
as herein described. The extremely thorough and‘ aration of a solution which corresponds substan
T-intimate manner of seeding the solution ‘which tially to the composition desired, cooling the so
lution to any convenient temperature below the
I have described will yield an end product char
melting point of the crystallinehydrate, initiat
acterized by substantially complete transforma
ing crystallization thereof, ?nely grinding the 20
tion into crystal form. Furthermore, my im
resulting mixture of crystals and solution while
proved process may be used to produce the var
f ture at which crystallization takes place. The
ious alkali metal silicate crystal hydrates in sub- > simultaneously dispersing the crystals rapidly and
stantially pure form, ‘i. e.,‘ uncontaminated with
other hydrates. In other words, the end product
may be characterized by the predominance of
a single hydrate, which fact, in cooperation with
the substantially complete crystallization which
uniformly throughout said mixture ‘while, said
mixture is still in a liquid condition in such man
nerv as to produce a resulting crystallized prod
25
uct substantially free from supercooled liquid and
capable of being comminuted to a dry, stabl
'
takes place, is largely responsible for‘ the dry, free-flowing powder.
4. The method of claim 3‘wherein crystalliza
stable, free-flowing qualities which are so vital
30 to a satisfactory practical and commercial‘ tion. is initiated by seeding with a quantity of 30
the crystalline hydrate desired.
_
article.
.
5. The method of making crystalline hydrates
From the foregoing examples it will‘ also be
seen that the transition from liquid to crystal
form takes place in a much shorter interval of
35 time than has been possible heretofore. This
fact lends itself particularly well to application
of the invention to continuous manufacturing
of alkali metal silicates which includes prepar
ing a solution substantially corresponding to‘ the
composition of a predetermined hydrate, cool‘ 35
ing the solution to any convenient temperature
below the melting point of the said hydrate, ini- I
tiating crystallization, ?nely grinding the result
processes, the economic advantages of which are
' . ing mixture of crystals and solution while simule
very material.
taneously dispersing the crystals rapidly and 40
I should also like to point out that when . uniformly
throughout said mixture while said
the crystals vhave been comminuted; thus estab
lishing the rapid rate of transition, the mass mixture is still in a liquid condition in such man
ner as to produce a resulting crystallized product
may be allowed ,to solidify as a ?lm which will substantially
free from supercooled liquid and
produce an end product in the form of ?akes,
capable of being comminuted to a dry, stable, 45
45 or it may be mechanically atomized to yield a
powder directly without grinding or it may be free-?owing powder.
6. The method of claim 5 wherein crystalliza; '
extruded through suitable apertures to yield ver
tion
is initiated by seeding with a quantity of
micular particles. In short, the process may be
adapted to produce a ?nished product in any the hydrate desired.
[The method of making a definite hydrate 50'
50 one of a great variety of physical shapes adapted
of
sodium metasilicate which includes prepar
tov commercial requirements and all of which are
ing a solution approximately corresponding to
characterized by, the properties of free-?owing the
composition of the desired hydrate, initiating
and stability. This has not heretofore been pos
crystallization, ?nely grinding the resulting mix
sible and results in another advantage, 1. e.,
55 with my process the ?nished article can be pro
duced in particles of predetermined shape and
size.‘
.In practice the advantages of the invention
ture of ' crystals and solution while simultaneous
ly dispersing the crystals rapidly and uniformly
55.
throughout said mixture while said mixture is
still in a liquid condition in such manner as to
produce a resulting crystallized product substan
may be realized even in instances where other tially free from supercooled liquid and capable
60
60 materials may be added for the purpose of modi
of being comminuted to a dry, stable, free-?ow
fying the behavior of the crystals sought. By. ing
powder.
.
~
way of example, for detergent or other purposes,
8. The method of claim 'I wherein crystal
materials such as starch, rosin, mineral or vege
table oils, colloidal silicates and/or other agents lization is initiated by seeding with a quantity
,
65
05 may be introduced where desired to modify the of the desired hydrate.
9. The method of making a de?nite‘ hydrate
behavior of the crystal species without depart
ing from the spirit and scope of the present ‘of sodium metasilicate which includes preparing
_a solution approximately corresponding to the
invention.
I claimt-
-
1. In the production of ‘sodium metasilicate
pentahydrate', themethod which includes pre
paring a solution of the approximate. composie
tion of the said hydrate, cooling the solution to
any convenient temperature below the melting
75 point of the said hydrate, initiating crystalliza
compositionof the desired hydrate, cooling the
solution to any convenient temperature below
the melting point of the said hydrate, initiat
ing crystallization, ?nely grinding the resulting
mixture of crystals and solution while simultane
ously dispersing the crystals rapidly and uniform
ly throughout said mixture while said mixture is 75
' 6
-
2,116,498
still in a liquid condition in such manner as to
produce a resulting crystallized product sub
stantially tree from supercooled liquid and ca
pable of being comminuted to a dry, stable, tree?
?owing powder.
10. The method of claim 9 wherein crystallisa‘
tion is initiated by seeding with a quantity or the
desired hydrate.
11. The method of making a de?nite hydrate
10 01' sodium metasilicate which'includes prepar
ing a solution approximately corresponding to
the composition of the desired hydrate, initiating
crystallization and grinding the mass to subdi
vide the-crystals in such manner as to distribute
15 fool of crystallization so intimately and rapidly
as to result in a dispersal of the order of the
distribution of a pigment in a vehicle to form
paint, whereby the resulting product is at least
90 per cent crystallized.
20
I
12. The method of claim 11 wherein crystal
lization is initiated by seeding with a quantity of
the desired hydrate.
13. The method of preparing a ‘mixture oi’
crystalline trisodium phosphate and crystalline
25 sodium metasilicate which consists in preparing
a liquid mixture calculated to satisfy the water
requirements in the proportions of the two ma- ,
terials as desired in the ?nished product, cooling
the solution to any convenient temperature below
30 the melting point of the crystalline sodium meta
silicate, initiating crystallization, ?nely grinding
the resulting mixture of crystals and solution
I while simultaneously dispersing the crystals rap
‘as
idly and uniformly throughout said mixture while
said mixture is still in a liquid condition in such
manneras to produce a resulting crystallized
product substantially free from supercooled liq
uid and capable of being comminuted to a dry.
stable, free-?owing powder.
40
14. The method of claim 13 wherein crystal
lization is initiated by seeding with a mixture
of crystalline trisodium phosphate and crystal
line sodium metasilicate.
4
15. The method of' preparing a mixture of sodi-'
45 um carbonate and sodium metasilicate pentahy
drate which consists in preparing a solution of
sodium metasilicate pentahydrate, adding sodi
um carbonate in the desired proportiorninitiat
ing crystallization, ?nely grinding the-resulting
mixture 01' crystals and solution while siimiltane
ously dispersing the crystals rapidly and-uni
i'ormly throughout said mixture while said mix
ture is still in a liquid condition in such manner
as to produce a resulting crystallized product
substantially free from supercooled liquid and
capable of being comminuted' to a dry, stable,
tree-?owing powder.
5
16. The method of claim 15 wherein crystal
lizationis initiated by seeding with crystals of
sodium metasilicate pentahydrate.
-
1'1, In“ the production of crystalline composi
tions of matter containing a crystalline hydrate
10
of an alkali‘ metal silicate and another compatible
alkali'metal compound, the process which com
prises preparing aliquid mixture having a com
position substantially corresponding to that of 15
the desired ?nished product, cooling the liquid
mixture to a point below ‘the melting point of
the desired crystalline alkali metal silicate, ini
tiating crystallization, ?nely grinding the mix
ture of crystals and solution while simultane 20
ously dispersing the crystals rapidly and uni
iormly throughout the liquid mixture while said
mixture is still in a liquid condition in such
manner as to produce a resulting crystallized
product substantially free irom supercooled liq 25
non-caking, tree-?owing powder.
uid and capable of being comminuted to a dry,
18. The method of claim 1'7 wherein crystalliza
tion is initiated by the introduction of seed crys
tals into the liquid mixture.
'
19. As a new composition of matter, granules
of interlocking crystals of an alkali metal sili
cate hydrate and sodium carbonate in a dry non
30.
caking, free-?owing state, said crystals being
substantially free from supercooled metastable 35
liquid and being substantially incapable of me
chanical segregation, the alkali metal silicate in
said composition being at least 90 per cent crys
tallized and having substantially no tendency to
agglomerate into solid masses.
40
20. As a new composition of matter, granules
‘
oi’ interlocking crystals of an alkali metal sili
cute-hydrate and Na:PO4.I2HzO in a dry, non
caking, free-?owing state, said crystals being
substantially free from supercooled metastable 45
liquid and being substantially incapable of me
chanical segregation, the composition as a whole
being at least 90 per cent crystallized and hav
ing substantially no tendency to agglomerate into
solid masses.
-
'
60
LBAKIR.
.
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