Note: Descriptions are shown in the official language in which they were submitted.
PHOSPHATE DEICING COMPOSITIOM
Yield o~ the Invention
The present invention is directed to a deicing
composition and a method for utilizing the deicing
composition. More particularly, the present invention is
directed to a deicing composition which comprises a water
soluble salt from the neutralization of superphosphoric
acid and a deicer salt such as NaCll MgC12 and KCl. In
another aspect of the invention, the deicing composition
includes a combination o~ bittern and the water soluble
reaction product from the neutralization of super-
phosphoric acid.
BacX~round of the Invention
Magnesium chloride and alkali metal salts, suchas sodium chloride, are extensively used in very large
quantities on the xoads o~ many countries for snow and ice
removal. The use of MgC12 or sodium chloride has,
however, met with some resistance due to their corrosive
effect on ferrous met~l and deleterious effect on
concrete. Indeed data has been released suggesting that
the cost of the damage associated with the widespread
application of salt is approximately ~ourteen times the
direct cost associated with the application o~ the salt;
D. M. Murray, et al., An Economic Analysis of the
Environmental Impact of Highway Deicina, U.S.
Environmental Protection Agency, Cincinnati, Ohio,
EPA-600/A-76-105 (May 1976). Accordingly, it would be
highly desirable to provide a deicing composition which
deices rapidly, has a reduced level of concrete damage,
such as by scaling the surface of the concrete, and
reduces corrosion of ferrous metallic obj~cts.
Various additives have been proposed for mixing
with salt to aid in inhibiting corrosion caused by the
salt. British Patent No. 1328509 to Bi~hop et al.
describes a composition suitable for use in the inhibition
of corrosion caused by salt, which includes a water-
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surface active agent is various amine compounds. In an
article by E. E. Steed, Road Research Laboratorv, Ministry
o~ Transport, Report LR268-l96s, pol~metaphosphate
inhibitors which require the presence of calcium ions are
described to be effective as a corrosion inhibitor for
brine solutions.
There is a serious need to provide a low cost
deicing composition which reduces corrosion of ferrous
metal, such as oxidative corrosion caused by aqueous
solution~ of MgC12 or alkali metal salts such as NaCl.
Depending on cost, a deicing composition which reduces
such corrosion or rust would be highly desirable for use
on roadways where large quantities of the deicing
composition are required. The present invention is
directed to providin~ a corrosion resistant deicing
composition which is suitable for highway and sidewalk
use.
Accordingly, one of the principle objects of the
invention is to provide a deicing composition which deices
rapidly. Another object of this invention i~ to provide a
deicing composition which causes a reduced level of
corrosion to ferrous metal. A further object of the
invention is to provide a method for deicing. Yet another
important object of this invention is to provide a method
for making a deicing compo~ition by using bittern. Still
another o~ject of this invention is to provide a deicing
composition which causes a reduced level of concrete
surface damage such as scaling.
The term "bittern" refers to the mother liquor
remaining after the evaporation such as by solar
evaporation of seawater to produce sodium chloride.
Seawater and brines from inland lakes have been evaporated
in ponds by the heat of the ~un since earliest times.
Intake or tide ponds are flooded with seawater at high
tide. Brine is transferred by pumping or gravity to a
series of concentrating ponds and finally to the
crystallizing pond~ from which the salt harvesting is done
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by machinery which scrapes the salt from the crystallizing
beds. Some of the bittern remaining after the
crystallization of salt is used for the production of
bromine and compounds of magnesium. However, most bittern
is a waste by-product for which there is no use. Hence,
an important aspect and object of this invention is to
provide a new use for a heretofore useless waste
by-product.
These and other objects of the invention will
become apparent from the following description.
Summar,y~of the Invention
The present invention is directed to a deicing
composition comprising a deicer salt in an amount
effective for deicing a surface with frozen water thereon,
the deicer salt selected from the group consisting of
NaCl, MgC12 and KCl and mixtures thereof and an amount
of water soluble salt from the neutralization of
superphosphoric acid effective for the reduction of
corrosion of ferrous metal by aqueous solutions of deicer
salt. The composition includes an amount of the deicer
salt effective for deicing a surface with frozen water
thereon. Generally, however, the deicer salt comprises
the major amount of the deicing composition.
An important aspect of this invention is
combining the water soluble salt of superphosphoric acid
with MgC12. In this aspect of the invention, the deicer
salt/phosphate combination not only provides for reduced
corrosion of ferrous metal, but reduces the scaling or
deleterious effect aqueous solutions of a deicer salt such
as NaCl have on concrete.
Another important aspect of the invention is a
deicing composition which is a mixture of bittern and the
water soluble salt of neutralized superphosphoric acid.
In this aspect of the invention, the deicing composition
not only is non-corrosive to ferrous metal, it also
reduces the scaling of or deleterious effects on concrete
; usually associated with deicer salts such as NaC1.
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In yet another important aspect of the invention,
the compositions which include ~gCl2 or bittern also
contain added sodium chloride or KCl.
The present invention is also directed to a
method for deicing a surface having frozen water thereon
by applying the deicing composition o~ the invention onto
the surface of the ice.
Detailed Description of the Invention
As used herein "water soluble salt of neutralizPd
superphosphoric acid'l means the reaction product which
results when superphosphoric acid is combined with a
neutralizing agent such as an alkali metal base or a
precursor to a base such as NaOH, Na2CO3 (soda ash or
sodium carbonate) or Na2SiO3 wherein the amount of
base which is used is effective to bring the acid/base
blend to a pH of from about 5.0 to about 9Ø
As used herein, bittern ~olids or solid bittern
is the material which precipitatss out from concentrating
`: 20 ponds of sea water or brinesO Bittern solids comprises
sodium chloride at a level of from about 35% to 70%,
magnesium chloride at a leYel of from about 7% to 35%,
magnesium sulfate at a level of from about 7% to 35%,
calcium chloride at a level of from about 0.1% to 0.3% and
magnesium bromide at a level of from about 0.001% to 0.1%
on an anhydrous basis. Bittern solids generally have a
total solids level of about 50% and includes a high level
of water of hydration.
As used herein, liquid bittern, is the by-product
of seawater and brines is liquid and generally includes
; from abou~ 7 to 8.6 weight percent magnesium ion, from
about 19 to about 22 weight percent chloride ion, from
about 1.0 to 5 weight percent sulfate ion, from about 0.2
to about 2 weight per~ent sodium ion and from about 0.2 to
about 2 weight percent potassium ion. Small ~uantities of
bromine, iron and other soluble salts found ln seawater
also are present. Liquid bittern generally has from about
26% to 36% weight percent total solids.
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Dried liquid bittern is a solid and is formed by
removing moisture from liquid hittern and comprises from
about 0.5 to about 8.0 weight percent NaCl, about 40.0 to
about 50.0 weight percent MgC12, about 2.0 to about 12.0
weight percent MgS04, from about 0.1 to about 0.3 weight
percent CaC12, ~rom about 0.001 to about O.ol weight
percent MgBr2 on an anhydrous basis and a total s~lids
content in the range of fxom 2bout 45 to about 73 weight
percent. Dried liquid bittern includes a high level of
water of hydration.
In the invention dried liquid bittern and bittern
solids may be dried to a moisture level of from about 20%
to about 60% by weight, based upon the weight of the
bittern prior to combining it with the water soluble salt
of superphosphoric acid. The total solids content of the
bittern solids will vary in the range of from about 40 to
about 80 weight percent. Alternatively, the
superphosphoric acid or the water soluble salt of
superphosphoric acid can be mixed with bittern prior to
neutralization (in the case of mixing the acid with the
liquid bittern) and drying. If the superphosphoric acid
is added to the bittern prior to neutralization, the acid
is neutralized in the bittern. The mixture of phosphate
salt and bittern then are dried to a moisture level of
from about 20% to about 60% hased upon the weight of the
bittern. Apparent dryness occurs even when a substantial
amount of moisture is still present in the bittern. The
remaining water is water of hydration and it is important
in the method of the present invention that evaporation
not be severe enough to remove the water of hydration. In
general, evaporation at a temperature of from about 250F
to about 330F at ambient pressure is suitable to provide
the composition of the present invention which includes
bittern. Of course, lower evaporating temperatures can be
used under vacuum conditions.
Liquid bittern as recovered from the solar
evaporation of salt is a brown liquid containing soluble
magnesium sulfateO It may sometimes be desirable, such as
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when the deicing composition is used in a household use,
to produce a whitP colored solid from bittern and to
remove the soluble sul~ates~ Sulfate removal will
eliminate an insoluble residue on the deiced surface. The
brown color is primarily caused by dead algae cells. Such
brown color can be removed by passing the liquid bittern
through a bed of granular carbon. Approximately 0.6
pounds of granular carbon will remove the color from 100
pounds of bittern solids. Sulfates are easily removed
from liquid bittern by addition of a soluble calcium salt
such as calcium chloride. Calcium sulfate is highly
insoluble and replaces the sulfate from the magnesium
sulfate. Calcium sulfate is then removed from the liquid
bittern by filtration. It is preferred, however, that the
organic materials not be removed from the bittern.
As used herein ferrous metal means iron or alloys
of iron, including steel, which undergo corrosion or
oxidation under ambient conditions.
According to the invention, the water soluble
salt of superphosphoric acid used in combination with a
deicer salt selected from the group consisting of NaCl,
MgC12, KCl and mixtures thereof reduces the corrosive
effect on ferrous metal that is usually associated with
aqueous solutions of the deicer salts. The deicer salt
such as MsC12 may be in its hydrated form.
In the aspect of this invention which utilizes
bittern in an amount effective for deicing, the water
soluble salt of superphosphoric acid is used in
combination with liquid, solid dried bittern or bittern
solids. In this aspect of the invention where the deicing
composition includes liquid bittern without added deicer
salt, the deicing composition includes at least about 90
weight percent liquid bittern and at least about 1.0
weight percent salt of superphosphoric acid; preferably
from 90 to 98 weight percent llquid bittern and from 2 to
10~ of the salt of superphosphoric acid.
Where the deicing composition lncludes dried
liquid bittern without added deicer salt, the deicing
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composition comprises at least about 90 weight percent
dried liquid bittern and at least about 1.0 weight percent
of salt of superphosphoric acid; and preferably from about
90 to about 98 weight percent dried liquid bittern and
from 2 to 10 weight percent of the salt of superphosphoric
acid.
WhPre the deicing composition includes bittern
solids or dried bittern solids without added deicer salt,
the deicing composition comprises at least about 90 weight
percent bittern solids or dried bittern solids and at
least about 1.0 weight percent salt of superphosphoric
acid; preferably from about 90 to about 98 weight percent
bittern solids or dried bittern solids and from 2 to 10
weight percent of the salt of superphosphoric acid.
Deicer salt such as sodium chloride or potassium
chloride in amounts effective for deicing may be added to
the deicer composition which includes bittern or magnesium
chloride. The effective ratio of the water soluble salt
of superphosphoric acid to a deicer salt can vary widely,
especially if bittern is present because the amount o~
deicer salt may be reduced to zero if an amount of bittern
effective for deicing is present with the deicer salt in
the composition of the invention. If liquid bittern is
used, deicer salts generally will not be soluble therein,
but the deicer composition may comprise at least about 5%
liquid bittern; at least about 70 weight percent deicer
salt; and at least about 1.0 weight percent of the water
soluble salt of superphosphoric acid; preferably 5 to 25
weight percent liquid bittern; 70 to 90 weight percent
deicer salt; and 2 to 10 weight percent of the water
soluble salt of superphosphoric acid.
Where the deicer composition includes a dried
liquid bittern/deicer salt combination, the deicer
composition comprises at least about 1.0 weight percent
dried liquid bittern; at least ab~ut 1.0 weight percent
deicer salt; at least about 1.0 weight percent of the
water soluble salt os superphosphoric acid; preferably 5
to 30 wei~ht percent dried liquid bittern; preferably 60
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to 93 weight percent deicer salt; and preferably 2 to 10
weiyht percent of the salt of superphosphoric acid.
Where the deicer composition includes solid
bittern or dried solid bittern in combination with deicer
salt, the deicer composition comprises at least about l.o
weight percent solid bittern or dried solid bittern; at
least about 1.0 weight percent deicer salt; at least about
l.o weight percent o~ the water soluble salt of
superphosphoric acid; preferably 5 to 45 weight percent
solid bittern or dried solid bittern; pre~erably 45 to 93
weight percent deicer salt and preferably 2 to 10 wsight
percent of the water soluble salt of superphosphoric acid.
Examples of such compositions include: 75 weight
percent NaCl, 20.7 weight percent dried liquid bittern;
2.2 weight percent Na2SiO3; 1.6 weight percent
superphosphoric acid; 71.~ weight percent NaCl; 20.9
weight percent dried liquid bittern; 4.9 weight percent
Na2CO3 and 2.4 weight percent superphosphoric acid.
The deicing composition of the invention without
bittern contains the water soluble salt of superphosphoric
acid in an amount effective for the reduction of corrosion
of ferrous metal by aqueou6 solution o* deicer salt which
generally is at least from about 1 weight percent and
preferably from about 2 to about 10 weight percent o~ the
deicing composition. The deicing composition also
includes an amount of deicer salt effective for deicing
and generally has at least about 90 weight percent and
preferably from about 95 to about 98 weight percent, based
upon the weight of the composition on a dry basis, of the
deicer salt. Due to the low cost of sodium chloride, in
an important embodiment of this invention, sodium chloride
is a major component or is in the major amount of the
deicing composition, such as at least about 95 weight
percent of the deicing composition. In a preferred aspect
35 of the invention using NaCl in a major amount of the
deicing composition, magnesium chloride hexahydrAte
comprises from about 10 to about 25 weight percent of the
deicing composition. In the latter aspect of the
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invention, the water soluble salt of superphosphoric acid
also is present in an amount effective to reduce the rate
of corrosion o~ ferrous metal by aqueous solutions of
sodium chloride and MgC12. Such amounts result from
mixing from about 0.5 to about 5.0 weight percent
superphosphoric acid based upon the weight of the deicing
composition, with an amount of neutralizing agent as
described above.
Superphosphoric may bP used in its green or
colorless (white) formO When neutralizing the acid with
the base the molar ratio of acid to base is important, the
weaker the base the more base being required to neutralize
the superphosphoric acid to the pH range of from about 5
to about 9. Hence, if Na2SiO3 or Na2CO3 are used
to neutralize the superphosphoric acid, 1.5 more NaSiO3
or 1.3 times more Na2CO3 is required than if NaOH is
used as a baseO
In the aspect of this invention which includes
liquid bittern or any other ingredients in an aqueous
medium, the superphosphoric acid and base may be blended
in the aqueous medium including bittern. After
neutralization of the superphosphoric acid, the water may
be evaporated as desired.
The final deicing composition of the present
invention is provided by blending the deicer salt and
water soluble salt of superphosphoric acid or bittern and
the water soluble salt of superphosphoric acid by
combining the compounds in the desired weight ratio and
blending them until a substantially homogeneous mixture is
obtained.
The resultant mixture which comprises the deicing
composition is applied to a surface coated with ice or
snow by any suitable means, such as by mechanical
spreading. The deicing composition of the present
invention can al~o be aombined with conventional materials
intended to increase traction, such as sand, gravel, and
the like.
The following examples further illustrate various
features of the present invention but are intended to in
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no way limit the scope of the invention which is set forth
in the appended claims.
EXAMPLE I - Corrosion Test
The corrosivity of various deicers was measured
by an alternate immersion corrosion test involving the use
of 2" x 3" S.A.E. 1010 carbon steel panels which werP
degreased in hexane and dried after a methanol rinse. The
steel panels had a 1/4" diametPr hole drilled in the
center and near the top o~ the 2" side. The panels had
numbers stamped in each of them. All panels were weighed
to the nearest tenth of a milligram after drying. Three
percent by dry weight basis of deicer solutions were
prepared in all cases except for plain water. Four panels
were suspended by a rod pushed through the l/41' holes and
separated by segments of rubber tubing. Each assembly was
suspended in the water or 3% deicer solutions such that
the panels were 1/2 immersed. During two 1 hour periods
each work day the panels were suspended in air to achieve
good contact with oxygen. The other 22 hours of each work
day the panels were 1/2 immersed. Over weekends, panels
were 1/2 immersed. At the ~nd of each week, old solution
was removed and replaced with new solution of the same
type. At the end of one month the panels were removed and
the solutions cleaned with 1800 g hot water, 1~0 g of
concentrated hydrochloric acid and 2 g of Rodine 213. The
panels were weighed and the percent protection against
salt induced corrosion was calculated as follows:
% Protection Against Salt Induced Corrosion = 100 x
1- Ava Wt Loss in ~ Sol'n-Ava Wt ~ in Wa~Avg CleanLn~ W~ LLSS
Avg Wt ~ in Salt Sol'n-Avg Wt ~s in Water-Avg Cle~in~ Wt LLSS
The cleaning loss due to the action of the
inhibited cleaning solution alone also is given and it is
obtained by putting panels that were subjected to neither
to water or deicer solutions into the cleaning bath for
the same length of time and sub~ecking them to all other
conditions as panels exposed to either water or deicer.
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P~ts
p~ p~i~n
3% Solution OfSalt Ib~xrd ~nsion
Water 100.0
Sodium chloride O.o
71.8~ NaCl,
2.4% S~pho~horic Acid,
20.9% ~ried Liquid Bittern,
4.9% Sodium C~dx~te 188.1
75.0% NaCl added to the product
of evaporating 2.55 g of g~n
s~Fho6phoric acid and 33.69 g
of liquid bittern to 24.45 g.
0.56 g of sodi~m ~onate were 115.3
added to the 3% sol~tion of the
foregoing evaporated blend to
bring to pH 7.
The protection afforded by use of bittern and a neutralized
superphosphoric acid mixed with salt produced less corrosion
than plain water with carbon steel.
~XAMPL~ Antiscalin~ Test
Antiscaling tests are performed using 5% by
weight solutions of the deicer or plain water. Concrete
samples are prepared using ASTM procedures for determining
the effect of deicing chemicals on concrete. The concrete
was poured into one liter beakers to a 5" depth and
allowed to cure for 28 days. Each deicer was applied to
two beakers to a 1" depth above the concrete surface.
Later in the test, most beakers required that more deicer
solution be applied to maintain the 1" depth because the
liquid penetrates the concrete. At the end of each week
of the 30 day test, old solution was decanted off of each
beaker and new solution was applied. At the end of the 30
day test period, the scaled concrete was poured into a
filter along with the deicer liquid and more scaled
concrete was rinsed vigorously from the surface of the
concrete into the filter. The scaled concrete was rinsed
thorouyhly with water on the ~ilter and then dried in an
oven. The weight of scaled concrete from each beaker was
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then determined and the weights from the two beakers
having the same deicer were averaged. The percent
protection against salt caused scaling was calculated in
the same way as for corrosion in Example I above except
that the average weight of scaled material was substituted
in the equation for average weight loss.
~esults
10 5% Solution Of Salt IXhX~d ~ n~
Plain Water 100.0
NaCl 0.0
71.8% NaCl,
2.4% S~Fh~horic ~cid,
15 20.9% Dried Iiquid Bittern,
4.9% Sodium ~onate 85.5
The composition including NaCl, neutralized superphos-
phoric acid, dried liquid bittern and sodium carbonate
produced considerably less scaling of concrete than caused
by salt alone.
~XAMPLE III - Deicinq Rate
15.0 grams of deicer was spread uniformly on 8" x
8" trays containing 400.0 grams of ice at 15 F. at 2Q, 40
and 60 minute interval~. The melt was poured from the
trays for exactly l.0 minutes and weighed to the nearest
0.1 gram. The melt was returned to the ice and the tray
to the freezer. The results were:
Gra~s ~f ~
20 ~n. 40 Min. 6Q Min.
1. 100% Salt (NaCl) 23.2 44.3 74.9
2. 92.7% Salt, 2.4% s ~ ric acid/
4.9% sodium car ~ ate 19.0 43. 3 73.S
35 3. 71.8% ~t, 20.9% dried liquid bi~n
liguid, 24% s~ hosphoric acid,
4.9% sodium c~*~n~te 25.1 46.1 70.3
- 4. 75.0% ~ t, 25% dried liquid bit~ern
liguid 31.4 49.9 71.6
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Oox~usion:
1. Addition of s~phosphoric acid and sodium c~nate sli~htly
lowered the initial deicing rate of ~ t or salt and dried liquid
bi~n.
2. Ihe t~ deic ~ capacity (60 m~ ) was very sLmilar, tha~
slightly lower.
Although the invention has been described with
regard to its preferred ~mbodiments, it should be
understood that various changes and modifications as would
be obvious to one having ordinary skill in this art may be
made without departing from the scope of the invention
which is set forth in the claims appended hereto.
Various features of the invention are set forth
in the following claims.
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