Compositions: coating or plastic – Coating or plastic compositions – Alkali metal silicate containing
Reexamination Certificate
2000-02-16
2002-06-25
Jones, Deborah (Department: 1775)
Compositions: coating or plastic
Coating or plastic compositions
Alkali metal silicate containing
C106S600000, C106S602000, C106S603000, C106S606000, C405S266000, C405S270000, C405S275000, C427S426000, C427S427000, C252S088100
Reexamination Certificate
active
06409818
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to the covering of bulk salt piles stored outdoors. More particularly, the invention relates to covering bulk salt piles or mounds which are stored outside or outdoors where the salt is waiting to be spread as a deicing composition and where the cover for the salt is a foamed concrete which will easily break up into particulate matter which will spread along with the deicing composition.
BACKGROUND OF THE INVENTION
Millions of tons of deicer salt in the form of sodium chloride, calcium chloride and magnesium chloride is applied in many countries to roads, bridges and sidewalks during the cold winter season to melt ice and snow. Sodium chloride is most commonly used, but all of these salts have to be stored and be ready for transport and spreading at indeterminate times depending upon the weather. Storing deicing salts, such as sodium chloride, outdoors exposed to the elements, however, creates problems. Rain and snow will wet the salt which will solubilize to some extent and then form a hard crust which will cause spreading problems. Rain, snow and wind also will erode the piles. This causes several problems.
The salt pile will spread and require more area for storage. Also the water from the rain and snow will solubilize a portion of the salt and it will be lost as a part of a brine type of run off. But even more important, the aqueous solution of salt which forms the run off is an environmental problem which can contaminate surface water and ground water and will be detrimental to surrounding vegetation.
To solve the aforedescribed problems salt piles have been covered with tarpaulins. In some cases, structures have been built to house the salt, such as “beehive” shaped structures often seen by the roadsides in the northern American Midwest. These solutions, however, are not without drawbacks. The tarpaulins are expensive, heavy and difficult to move. They are also subject to inadvertent ripping and tearing by earth moving equipment loading salt onto spreader trucks. The structures used to house salt are expensive and also prone to inadvertent damage during the movement of the bulk salt.
It is an object of this invention to provide an easy way to cover bulk salt stored outdoors so that it will be protected from rain, snow and wind.
It is an object of this invention to reduce brine run-off from bulk salt stored outdoors.
It is yet another object of this invention to provide a cover for a bulk salt pile or mound that will retain the integrity of the salt pile or mound.
These and other objects, advantages, features and characteristics of the present invention will become more apparent upon consideration of the following description and appended claims.
SUMMARY OF THE INVENTION
The present invention is directed to a foamed composition and method for forming an inexpensive, semi-permanent cover layer over deicing salt which is stored outdoors in large bulk mounds or piles. The cured foamed cover layer protects the salt from moisture, wind and other erosive elements so that the salt can be stored outdoors for extended periods of time without experiencing agglomeration of the salt particles from moisture, erosion or deterioration of the salt mound and without experiencing the deteriorating effects of the elements. The cured foamed cover layer protects the salt by forming a continuous coating over the exposed surface of the salt mound or pile and eliminates or substantially eliminates brine water run off from the pile that would otherwise occur as a result of moisture from the elements solubilizing and then transporting dispersed or solubilized salt from the bulk salt pile. Moreover, the invention has the additional advantage of allowing easy recovery of the salt after some of the salt pile has been removed. As it becomes desirable to remove a volume of salt from beneath the cured foamed cover layer, a portion of the cover layer may be broken and removed as necessary to expose the salt and provide access for its removal. In this way, the remaining portion of the cover layer may be left on the salt until it is desired to remove more of the salt. A cover layer then may be reapplied to cover any areas of the salt pile that are exposed as a result of removing salt from the pile.
Broadly, the cured foamed cover layer formed by the method of the invention comprises cured cement, and in an important aspect, cured concrete which has been foamed with a foaming agent, without any other organic polymeric material which will form a polymeric coating or layer except an optional water resistant/repellant additive. The cured foamed cover layer, which provides a water resistant foamed coating over the salt mound, is of a thickness which is effective for maintaining the integrity of the salt mound for at least a year when exposed to the outdoor elements and which is effective for minimizing passage of moisture to the salt for at least that time. The cured foamed cover composition is brittle and readily broken into particulates which can be spread with the particulate salt, but the cured cover or layer is effective for providing a cover layer over the salt that is a continuous, hardened coating which generally protects the salt from water and keeps the integrity of the mound or pile of bulk salt comprising sodium chloride, calcium chloride, magnesium chloride and mixtures thereof. The cured foamed cover has a density of not more than about 1.6 gram/cm
3
, and in an important aspect, it has a density in the range of from about 1.4 to about 0.9 gram/cm
3
and a strength in the range of from about 28 to about 8 as measured on a Ametex-Accru-Force Cadet Force Gauge as available from Ametek using 0.5 cm chisel.
The cured foamed cover composition is entirely compatible with the end use of the deicing salt. As the deicing salt is used, an amount of the cured cover will be crushed and intermixed with the salt without deleterious effect to the salt. Indeed, the crushed cover will enhance some aspects of the use of the deicing salt because its particles will enhance traction over ice and snow.
In an important aspect, the method of the invention includes applying a foamed cover composition which in its cured form comprises a blend of foaming composition, aggregate, cement and water on the salt mound (especially sodium chloride in the form of rock salt). The cured foamed cover composition comprises from about 2 to about 14 weight percent cement, based upon the weight of the cement, aggregate and other solid components. The amounts of foaming composition, aggregate and water in the uncured foamed cover composition are effective to provide the cured foamed cover composition with a density of from about 1.6 to about 0.9 gr/cm
3
and a strength of from about 28 to 8. The aggregate also should not be too fine (not greater than about 10 U.S. standard mesh) to assure that the cover will not be too hard and stay brittle so that the salt can be readily accessed without damage to moving equipment such as front loaders. Larger aggregate causes the concrete to break too easily since the aggregate dimensions will approach or exceed the thickness of the concrete layer. Also keeping the size of the aggregate to not greater than 10 mesh, but not less than 300 mesh (except for fly ash which could have a particle size which is finer than 300 mesh), provides a cover which can be reduced to particulates which are in a size such they can be spread with spreader equipment along with the salt on surfaces with ice and snow. In an important aspect the aggregate is selected from the group consisting of sand, fly ash, silica and mixtures thereof. In general, the cured foamed cover composition will comprise from about 2 to about 14 weight percent cement, from about 97.6 to about 70 weight percent aggregate and from about 0.4 to about 6 weight percent foaming composition.
In an important aspect, the pile or mound of salt is permitted to shift or settle, such as from about 3 to about 7 days before the foamed cover composition is applied to the salt. Thereafter, the foamed cover
Cargill Incorporated
Fitch Even Tabin & Flannery
Jones Deborah
Stein Stephen
LandOfFree
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