CA2049722A1 - Phosphate deicing composition - Google Patents

Abstract

ABSTRACT OF THE INVENTION
A deicing composition which includes a deicer and the reaction product from the neutralization of superphosphoric acid.

Description

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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-- 2soluble polyphosphate and a surface active agent. mhe 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 7~

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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: - 4 -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 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 7~

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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g _ 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 ~' 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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Claims (24)

1. A deicing composition comprising a deicer salt selected from the group consisting of NaCl, KC1, MgC12 and mixtures thereof in an amount effective for deicing a surface with frozen water thereon and a reaction product of superphosphoric acid and a base in an amount effective to bring the reaction product to a pH in a range of from about 5 to about 9 to provide a salt of superphosphoric acid, the salt of superphosphoric acid in an amount effective for the reduction of corrosion of ferrous metal by an aqueous solution of deicer salt.

2. A deicing composition as recited in Claim 1 wherein the base is selected from the group consisting of NaOH, Na2CO3, Na2SiO3 and mixtures thereof.

3. A deicing composition as recited in Claims 1 or 2 wherein the deicer salt comprises at least about 90 weight percent of the deicing composition and the salt of superphosphoric acid comprises from about 2 to about 10 weight percent of the deicing composition.

4. A deicing composition as recited in Claims 1 or 2 wherein the deicing salt is NaCl and comprises at least about 95 weight percent of the deicing composition.

5. A deicing composition comprising from about 90 to about 98 weight percent of a deicer salt selected from the group consisting of NaCl, KCl, MyC12 and mixtures thereof, and from about 2 to about 10 weight percent of a reaction product of superphosphoric acid and a base, the base in an amount effective to bring the reaction product to a pH in a range of from about 5 to about 9 to provide a salt of superphosphoric acid, the salt of superphosphoric acid in an amount effective for the reduction of corrosion of ferrous metal by an aqueous solution of deicer salt.

6. A deicing composition as recited in Claim 5 wherein the base is selected from the group consisting of NaOH, Na2CO3, Na2SiO3 and mixtures thereof

7. A deicing composition comprising at least about 90 weight percent based upon the weight of the deicing composition, bittern selected from the group consisting of liquid bittern, dried liquid bittern, bittern solids and mixtures thereof and at least about 1.0 weight percent, based upon the weight of the deicing composition, of a reaction product of superphosphoric acid and a base in an amount effective to bring the reaction product to a pH
in a range of from about 5 to about 9 to provide a salt of superphosphoric acid.

8. A deicing composition as recited in Claim 7 wherein the base is selected from the group consisting of NaOH, Na2CO3, Na2SiO3 and mixtures thereof.

9. A deicing composition as recited in Claims 7 or 8 wherein the bittern is liquid bittern and the composition comprises from about 90 to about 38 weight percent liquid bittern and wherein the composition comprises from about 2 to about 10 weight percent of the salt of superphosphoric acid.

10. A deicing composition as recited in Claims 7 or 8 wherein the bittern is dried liquid bittern and the composition comprises from about 90 to about 98 weight percent dried liquid bittern and wherein the composition comprises from about 2 to about 10 weight percent of the salt of superphosphoric acid.

11. A deicing composition as recited in Claims 7 or 8 wherein the bittern is bittern solids and the composition comprises from about 90 to about 98 weight percent bittern solids or dried bittern solids and wherein the composition comprises from about 2 to about 10 weight percent of the salt of superphosphoric acid.

12. A composition as recited in Claim g wherein the composition further comprises NaCl.

13. A deicing composition comprising a deicer salt selected from the group consisting of NaCl, KCl, MgCl2 and mixtures thereof; bittern selected from the group consisting of liquid bittern, dried liquid bittern, bittern solids and mixtures thereof and from about 2 to about 10 weight percent, based upon the weight of the deicing composition of a water soluble salt of superphosphoric acid.

14. A deicing composition as recited in Claim 13 wherein the bittern is liquid bittern comprising from about 5 to about 25 weight percent of the deicing composition and the deicer salt comprises from about 70% to about 90 weight percent of the deicing composition.

15. A deicing composition as recited in Claim 13 wherein the bittern is dried liquid bittern composition comprising from about 5 to about 30 weight percent of the deicing composition and the deicer salt comprises from about 60 to about 93 weight percent of the deicing composition.

16. A composition as recited in Claim 13 wherein the bittern is bittern solids comprising from about 5 to about 45 weight percent of the deicing composition and the deicer salt comprises from about 45 to about 93 weight percent of the deicing composition.

17. A deicing composition as recited in Claim 16 wherein the bittern solid is dried.

18. A method for deicing a surface having frozen water thereon, the method comprising applyinq a deicing composition comprising a deicer salt selected from the group consisting of NaCl, KCl, MgC12 and mixtures thereof in an amount effective for deicing a surface with frozen water thereon and a reaction product of superphosphoric acid and a base in an amount effective to bring the reaction product to a pH in a range of from about 5 to about 9 to provide a salt of superphosphoric acid, wherein the reaction product of superphosphoric acid is a salt in an amount effective for the reduction of corrosion of ferrous metal by an aqueous solution of deicer salt.

19. A method as recited in Claim 18 wherein the deicer salt comprises at least about 90 weight percent of the deicing composition and the salt of superphosphoric acid comprises from about 2 to about 10 weight percent of the deicing composition.

20. A method for deicing a surface having frozen water thereon, the method comprising applying a deicing composition comprising:
at least about 90 weight percent, based upon the weight of the deicing composition, bittern selected from the group consisting of liquid bittern, dried liquid bittern, bittern solids and mixtures thereof and at least about 1 weight percent, based upon the weight of the deicing composition, of a reaction product of superphos-phoric acid and a base, wherein the reaction product is a salt in an amount effective to bring the reaction product to a pH in a range of from about 5 to about 9 to provide a salt of superphosphoric acid.

21. A method as recited in Claim 18 wherein the composition comprises from about 90 to about 98 weight percent liquid bittern and wherein the composition comprises from about 2 to about 10 weight percent of the salt of superphosphoric acid.

22. A method as recited in Claim 18 wherein the composition comprises from about 90 to about 98 weight percent dried liquid bittern and wherein the composition comprises from about 2 to about 10 weight percent of the salt of superphosphoric acid.

23. A method as recited in Claim 18 wherein the composition comprises from about 90 to about 98 weight percent bittern solids or dried bittern solids and wherein the composition comprises from about 2 to about 10 weight percent of the salt of superphosphoric acid.

24. A method for deicing a surface having frozen water thereon, the method comprising applying a deicing composition as recited in Claim 13, 14, 15, 16 or 17.