FI86074C - Method of de-icing a road surface and de-icing composition useful in the process - Google Patents

Description

1 86074

A method for removing ice from the road surface and the de-icing mixture used in the method

The invention relates to a method for removing ice from a road surface, which method reduces the corrosion of metal parts on the road and which method applies an effective amount of a mixture consisting essentially of a mixture of lignosulfonate and alkali metal and / or alkaline earth metal chloride to a snow or ice covered road surface.

It is generally recognized that the needs of commerce, industry and the general public generally require that traffic flow reasonably safely, even in snow or ice conditions. However, confidence in mechanical methods alone to remove snow or ice is not enough to guarantee the safe and efficient flow of traffic. Today, the only feasible way to maintain a snow-free surface is to use de-icing salts. The main chemical used in de-icing is mainly rock salt or sodium chloride due to its low cost, ease of transport and easy spread.

The price of de-icing salt is deceptively cheap compared to the irreplaceable costs of corrosion for metal guardrails, bridge girders, metal concrete support bars and automobiles. The estimated cost of repairing damaged bridges in America alone is approaching $ 50 billion. Chemical Marketing Reporter, August 27, 1984.

Other chemicals have been used in place of alkali metal or alkaline earth metal chlorides, such as mixtures of urea and calcium formate sprayed with formamide, calcium magnesium acetate, metal sulfates, phosphates, nitrates, amides, alcohols, long chain amines and long chain amines. None of these chemicals has gained worldwide popularity due to their high price, low potency and / or high toxic content.

2,86074

Some work has been done to reduce the corrosivity of chlorine salts of alkaline earth metals applied to road surfaces by using 1 ignosulfonate as one component in the deicer or dust binder. JP Patent 51-12310 discloses the use of a three-part mixture comprising calcium chloride, a small amount of calcium lignosulfonate and calcium hydroxide as a dust binding or antifreeze agent. Without substantial corrosion inhibition, a 1-3% (dry weight) mixture of cesium lignosulfonate and cesium chloride (1ignosulfonate to cesium chloride ratio 1:35) was tested. Some anti-rust effect was observed when calcium hydroxide was combined with calcium chloride. However, when both the cesium lignosulfonate and the cesium hydroxide were mixed with the cesium chloride, a higher anti-corrosion effect was demonstrated, and the JP patent is particularly directed to a combination containing both lignosulfonate and calcium hydroxide together with cesium chlorine. Each of these combinations disclosed in the JP patent contains 1-5% calcium lignosulfonate and also at least equal amounts of calcium hydroxide. Tests have shown that the pH of these solutions is approximately 10 or higher.

The sulphite waste solution has been used for many years as a dust suppressant, applied directly to dirt or gravel roads.

The use of chlorine salts of Al metal metals and alkaline earth metals to prevent dusting is also known. Freight rates often determine whether sulphite waste solution or chloride salts are used in a particular location.

De-icing or dust-binding agents such as sodium chloride, calcium chloride, magnesium chlorine or rock salt, such as in the past, cost the consumer much more corrosion damage than the initial cost of the material. 3 86074

Indicate. Thus, a mixture to alleviate corrosion problems would be a highly desirable advantage in the quality of road surface deicer or dust remover.

It is an object of the present invention to provide a de-icing method in which the materials used are inexpensive and capable of reducing corrosion of the metal in the road.

The aim is to prevent corrosion of steel or aluminum road surfaces, canes and beams, as well as cars. In addition, the aim is that the de-icing mixture used has anti-slip properties.

According to the invention, there is thus provided an de-icing process which is less corrosive to metal in the roadway and comprises adding a mixture to the road surface consisting of a mixture of lignosulphonate and alkali metal and / or alkaline earth metal chloride in a dry lignosulphate to metal chloride ratio of about 1:15 to about 2: 1 and wherein the pH is from about 4.5 to about 8.5.

The invention also relates to an de-icing composition which now has a reduced corrosion effect on metal parts in the roadway and which consists essentially of a lignosulphonate and a metal chloride which is either an alkali metal chloride or a mixture of an alkali metal chloride and an alkaline earth metal chloride. The mixture is characterized in that the ratio of the dry weights of lignosulfonate to said metal chloride in the mixture is from about 1:25 to about 15: 1 and that the pH of the mixture is from about 4.5 to about 8.5. According to a preferred embodiment of the invention, the lignosulfonate consists of a sulphite waste solution and that this sulphite solution and the metal chloride are applied to the road surface as a solution. In another embodiment of the invention, a non-slip agent may be added to the waste sulfite solution-chloride salt mixture.

4,86074

The de-icing mixture according to the invention is characterized in that, in addition to de-icing, it also acts as a dust-binding agent.

In accordance with the present invention, it has been found that where the use of chloride salts of alkali or alkaline earth metals as de-icing or dust-binding agents is appropriate, the corrosivity of metal road barriers, bridges, concrete scaffolding and automobiles can be significantly reduced by adding sulfite waste solution.

The pH of the compositions of this invention is substantially neutral and therefore does not cause corrosion due to low or high pH. For example, aluminum may corrode at relatively high basic pHs.

The effectiveness of chloride metal salts in facilitating de-icing of driveways is partly due to their low cost, their ability to perforate frozen surface, allowing normal traffic to break ice slabs and break them easily and evenly on the road surface. Today, several salts are used,. containing sodium chloride, calcium chloride, magnesium chloride, calcium chloride or mixtures thereof. These are often used in mineral form, such as rock salt. Everything can be used in this invention. The most commonly used on roads are sodium chloride and magnesium chloride and ‘·· they are popular substances in the practice of this invention.

Sulphite waste solution is an ideal additive because it is easy to obtain, effective corrosion reducer, relatively low cost and generally non-toxic. A sulphite waste solution is a waste product of sulphite pulp mills in which wood or other vegetable materials are treated to separate cellulose or wood chips from the solution. Such processes are, of course, well known. The main component of the factory-produced sulfite waste solution is lignosulfonate and has generally been found to be present in amounts ranging from about 40% to about 70% or more of the total dry weight, with the residue consisting of carbohydrates and other organic and inorganic mixtures. In addition to the sulphite waste solution obtained from the sulphite cellulose process (ie without substantial removal or other evaporation residues), sulphite waste solutions fermented to convert at least some of the carbohydrates to alcohol or protein by-products (vanified are also contemplated for use in this invention and are included in the term sulfite waste solution used herein.

The sulfite waste solution contains 1ignosulfonate as salts of magnesium, calcium, sodium, potassium or ammonia and the weight ratios referred to herein are relative to the salt.

It has been found that, in general, an effective lower limit of the sulphite waste solution ratio (dry weight) to the metal dichloride salt provides a ratio of about 1:25 (dry weight) between the lignosulfonate and the metal chloride salt. When the upper limit is exceeded by about 15: 1, it begins to lose the benefits of using combinations of ingredients. Ratios of from about 1:25 to about 15: 1 can be used to remove both ice and dust, but when used on ice, ranges from about 1:15 to about 2: 1 are preferred, and ranges from about 1: 8 to about 3: 2 are particularly preferred. When binding dust, ranges of about 1: 4 to about 2: 1 are often preferred for best results. In each case, the ratio refers to the dry weight of the lignosulfonate salt in the sulfite waste solution relative to the dry weight of the metal dichloride salt.

: * The pH of the compositions of this invention is approximately neutral. It has a pH of about 4.5 to about 8.5, and mixtures with a pH of about 5 to 8 are particularly popular. The mixtures often provide the desired pH themselves, but if necessary the pH can be adjusted to 6,86074. Any base can be used to adjust the pH upwards. Because the pH of many sulfite waste solutions tends to be slightly acidic, downward adjustment of the pH occurs less frequently, but can be easily accomplished using mineral acid. The pH described herein is the pH determined when the mixtures of this invention are dissolved in water to provide a total solids content of 10% by weight in solution.

When a sulfite waste solution is used, it can be mixed either in solution or dried with either a solid or in solution metal chloride salt (with subsequent drying, if appropriate) to provide the liquid or solid mixtures of this invention. While this aspect of the invention relates to the application of mixtures of materials to a surface, the invention also relates to the separate application of each ingredient to a road surface, either as a solution or as a solid.

Since the ingredients are essentially a physical mixture, any mixing device can be used. In addition, additives such as a non-slip agent may also be added during mixing. Conventional anti-slip agents include sand, limestone, crushed coke and the like. Often, the sulfite waste solution is essentially the only non-corrosive additive added to the chloride salt.

For dust binding on roads and in dry areas, the application of substances together with the solution is usually used. The substances can be applied in liquid form, some can be applied in solid form while others are applied in solution, or the substances can be applied in solid form and then the surface can be wetted.

Because ice stores moisture, application of the mixture to frozen roads or roads threatened by freezing can be performed in either liquid or solid form. most often

II

> «7 86074 salt mixtures are applied in solid conditions under ice conditions. However, such use does not preclude the possibility of applying either or both substances in liquid form, as the case may be.

The amount of material applied to the road surface varies greatly depending on the purpose (e.g., dust binding or freezing) and the severity of the conditions. Diluted brine tends to corrode more, apparently because more oxygen is dissolved in the diluted brine and therefore the total amount of sulfite waste solution in the solution on the road is a corrosion reducing factor. When quite a lot of water (e.g. thick ice or snow) is expected, then there is relatively more sulfite waste solution in the proportions of the ingredients and / or higher spreading rates may be desirable. However, the proportion and / or amount to be applied is easy for a professional or dol1 a.

When an anti-slip agent is present, for example, sand, limestone, crushed coke and the like, the mixture can be mixed to provide an aqueous slurry of the anti-slip agent. Alternatively, a dry mixture of sulphide waste and anti-slip agent can be prepared and stored until needed for use with the metal chloride salt. The dry mixture can be prepared simply by mixing dry solids or by applying a sulfite solution to the anti-slip agent and then drying the mixture. The dried mixture can again be applied to the surface separately or as an additional mixture with the metal or organic salt, and the substances can be applied in any desired combination of solution and solid form.

The present invention is further illustrated by the following various examples. These examples are included for illustrative purposes and are not intended to limit the scope of the invention.

In these examples, the pH was adjusted with the metal cation oxide and hydroxide to correspond to the metal of the metal oride so that the pHs maintained for each example were substantially the same to provide a basis for comparison.

Example 1

Magnesium chloride solutions were made using the following concentrations of fermented calcium sulfite waste solution (CaSSL) and magnesium chloride. The original CaSSL was fermented with Saccharomyces cerevisiae (yeast) to produce alcohol, and the fermented CaSSL contained about 75% calcium lignosulfonate (dry solids base). The pH was adjusted to approximately neutral with MgOr. Corrosion ratios were determined using a 1966 Magma Corporation Model 1170 Corrater® Corrosion Ratio Meter, made of mild steel, then aluminum alloy 5454.

% By weight of total solution

Corrosion ratio, ^ μm /

MgCl ^ Launched Final. year

CaSSL-suspense. pH Aluminum Mild steel .50 7.4 35.5 145 5 5 6.8 20.3 76.2 - 5 10 6.6 20.3 5 15 6.8 20.3 60.9 10 0 6.5 50 .8,206 10 5 7.1 12.7 53.3 10 10 6.8 12.7 43.2 10 15 6.6 10.2 0 5 7.5 12.7 73.6

Example 2

The same solutions used in Example 1 were left at ambient temperature for 25 days, each of which was immersed in a sealing ring made of mild steel. The weight loss of the sealing rings was determined.

Weight Ϊ of total solution 9 86074 Started Final Mild steel

MgCl 2 CaSSL suspension. pH. Average weight loss per day mg% 5 0 7.4 8.0 5 5 6.8 4.4 5 10 6.6 4.0 5 15 6.8 6.6 10 0 6.5 6.0 10 5 7 , 1 4.4 10 10 6.8 4.8 10 15 6.6 4.4 0 5 7.5 5.7

Example 3

MgCl -1 solutions were made and left to stand overnight before testing on mild steel 1966 Magma Corporation Model 1170 Corrateri 11 a ®. The effect of dilution on the corrosivity of the solution is shown.

:% By weight of total solution After fermentation Final. Mild steel

MgCl 2 CaSSL suspension. pH. Corrosion ratio (^ μm / year) 1 ·. «« 4 5.7 33.0 5 2 6.3 50.8 '! · .. 2.5 1 6.7 86.3, V: 1.25 0.5 6.9 188 0.625 0.25 7.0 328 • ♦ * 10 86074

NaCl solutions were made and the pH was adjusted similar to the above solutions. As these data show, more dilute solutions result in greater corrosion.

% By weight of total solution After fermentation Final. Mild steel

NaCl CaSSL suspension. pH. Corrosion ratio (μm / year) 10 4 5.7 63.5 5 2 6.3 76.2 2.5 1 6.7 152 1.25 0.5 6.9 2540 0.625 0.25 7.0 371

CaCl solutions were made and the pH was again adjusted to the above examples:

% By weight of total solution After fermentation Final. Mild steel

CaCl 2 CaSSL suspension. pH. Corrosion ratio (μm / year) 10 4 5.7 38.1 5 2 6.3 38.1 2.5 1 6.7 91.4 1.25 0.5 7.0 152 0.625 0.25 7.0 188

Example 4

Solutions of 2.9% MgCl 2 were made. The pH was adjusted with dilute MgO slurry. Samples were left to equilibrate overnight, then tested on Magma Corporation's Model 1170 • ®

Corraterilla. Sealing rings made of mild steel were placed in the solutions for 30 days and the weight loss was determined.

Il

% By weight of total solution 11,86074 Fermented Final Mild steel

MgCl 2 CaSSL suspension. pH. Corrosion ratio (μm / Average weight loss per day mg mg 2.9 0 7.3 168 12.6 2.9 0.5 6.9 150 4.9 2.9 1.0 7.1 73.6 3.0 2.9 1.5 7.4 52.0 2.9 2.9 5.0 7.4 53.3 2.4

Example 5

Sodium chloride was made into a solution and the pH was adjusted very well with dilute NaOH and left to stand overnight.

Weight-esta of total solution Launched Final Mild steel

MgCl CaSSL suspension. pH. Corrosion ratio (μm / year) 5 0 7.0 267 5 2 6.3 76.2 :: 10 0 7.0 172 10 4 5.7 63.5 20 0 7.0 63.5

Example 6 A soft solution of MgCl 2 solutions comprising fermented CaSSL or unfermented sodium sulfite waste solution (NaSSL); the corrosion ratio of steel was measured for corrosivity.

Unfermented NaSSL contained about 65% sodium lignosulfonate.

% By weight of total solution 12 86074 To ferment Unfermented pH Alum.met. 24 day NaSSl alloy 5454 mild steel M g Cl 2 CaSSL suspension. corrosion ring suspension. ratio weight loss ^ μm / year mg% 5 10 0 6.6 20.3 4.1 5 0 10 7.0 12.7 4.0

Example 7 The corrosivity of fermented CaSSL-containing calcium chloride solutions was measured in 24-day experiments.

Weight% of total solution Fermented pH Mean. weight loss CaCl 2 CaSSl suspension. in color (mg%) 5 0 6.1 8.6 5 5 5.8 4.7

Example 8

See Example 4 for instructions.

% By weight of total solution

Corrosion ratio Fermented pH Corrater® MgC 1 ^ CaSSl suspension of mild steel. ^ um / year avg. weight loss per day mg% 8.6 0.0 7.5 91.4 6.5 8.6 0.5 7.4 15.2 2.5 8.6 1.0 7.3 15.2 2.0 8.6 1.5 7 , 1 15.2 2.0 13 86074

Example 9 The corrosivity of fermented CaSSL-containing calcium chloride solutions was measured for corrosion after adjusting the pH with CaO.

Weight% of total solution Fermented pH Corrosion ratio

CaCl 2 CaSSl suspension. ^ um / year) 5.0 0.25 6.3 63.5 5.0 1.0 7.1 60.9 5.0 2.0 8.1 38.1 0.625 0.25 7.0 188 0.625 2.0 7.0 45.7

Example 10

The corrosivity of the sodium chloride and fermented CaSSL solutions was measured after adjusting the pH with 1% sodium hydroxide.

Weight-esta of total solution Fermentation rate Corrosion ratio

NaCl CaSSl suspension. um / year) 2 / 5.0 0.0 7.0 267 5.0 0.25 8.1 119 5.0 1.0 7.1 93.9 5.0 2.0 6.3 76.2 2.5 1.0 6.6 152 2.5 2.0 7.0 63.5 ·: **: 0.625 0.25 7.0 371!.! 0.625 2.0 7.0 53.3 and 86074

The data gathered above indicate that a significant reduction in corrosivity can be achieved by adding a sulfite waste solution. Example 4 illustrates that a 1/6 proportion of the sulfite waste solution placed in a 2.9% MgCl 2 solution gives a 60% reduction in weight loss due to corrosion compared to a saline solution without a sulfite waste solution. Larger amounts of sulfite waste solutions further reduce corrosion. Example 8 shows that adding 1/17 of the sulfite waste solution to 8.6% MgCl showed a 60% reduction in corrosion weight loss compared to the same test mixture without sulfite residue. In Example 10, a proportion as low as 1/20 of the sodium sulphide waste solution added to 5 NaCl solution shows an effective reduction in corrosivity of 147 μm / year compared to the same test mixture without sulfite waste solution (corrosion ratio was more than halved). Examples 1 and 2 also show that the fermented calcium sulphite waste solution itself causes somewhat more corrosion than many sulphite waste solution mixes.

Since modifications of the present invention will be apparent to those skilled in the art, it is intended that the present invention be limited only by the appended claims.

Claims (14)

1. A method of de-icing a road surface to reduce corrosion of metal parts located on the roadway, in which method on a snow or icy roadway surface is applied an effective amount of a composition consisting essentially of a mixture of a lignosulfonate and a alkali metal and / or alkaline earth metal chloride, characterized in that the dry weight ratio of lignosulfonate to metal chloride in the composition is from about 1:15 to about 2: 1 and that the composition has a pH from 4.5 to 8.5. Process according to claim 1, characterized in that the lignofulphonate and the metal chloride are supplied in dry form. Method according to claim 1, characterized in that the lignosulfonate consists of a spent sulfite liquor and that the sulfite liquor and the metal chloride are applied to the road surface in solution. Method according to claim 1, characterized in that anti-glidants are also present in the mixture. . 5. A method according to claim 1, characterized in that ... said ratio is from about 1: 8 to about 3: 2. Method according to claim 1, characterized in that the pH of the mixture is from about 5 to 8. Process according to claim 1, characterized in that the metal chloride is sodium chloride. . Process according to claim 1, characterized in that the metal chloride is magnesium chloride. Method according to claim 1, characterized in that the lignosulfonate is fermented calcium sulphite liquor. 18 86074 10. A process according to claim 1, characterized in that the lignosulfonate consists of spent sodium sulfite liquor obtained from the sulfite process. 11. Deicing composition having a reduced corrosion effect on metal parts found on the roadway and consisting essentially of lignosulfonate and a metal chloride which is either an alkali metal chloride or a mixture of an alkali metal chloride and an alkaline earth metal chloride, characterized the ratio of dry weights of lignosulfonate to said metal chloride in the composition is from about 1:25 to about 15: 1, and that the composition has a pH from about 4.5 to about 8.5. Dispensing composition according to claim 11, characterized in that the alkali metal chloride is sodium chloride and said ratio of dry weights of lignosulfonate to sodium chloride ranges from about 1:15 to about 2: 1. Disposal composition according to claim 11, characterized. that the alkali metal chloride is sodium chloride, that the alkaline earth metal chloride is magnesium chloride and that the ratio of lignosulfonate to the mixture of sodium chloride and magnesium chloride is from about 1:15 to about 2: 1. Dispensing composition according to claim 12, characterized in that said ratio is from about 1: 8 to about 3: 2. A deicing composition according to claim 13, characterized in that said ratio is from about 1: 8 to about 3: 2.