Hydraulic and earth engineering – Earth treatment or control – Chemical
Reexamination Certificate
2002-09-03
2004-05-04
Lagman, Frederick L. (Department: 3673)
Hydraulic and earth engineering
Earth treatment or control
Chemical
C405S258100, C405S302600, C404S076000, C252S088100, C106S244000, C106S900000
Reexamination Certificate
active
06729805
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field
The invention is in the fields of methods and compositions for treating earth surfaces, such as dirt and gravel roads and parking lots, to reduce dust from and erosion of such surfaces.
2. State of the Art
Dust control on exposed earth surfaces is a continuing problem. Surfaces such as dirt roads and dirt parking lots generate substantial dust when driven over by a vehicle and can generate dust in windy weather conditions. Erosion from vehicle use and from weather conditions, such as rain, snow, or wind, also are problems for such surfaces. Surfaces such as construction sites and tailing disposal sites have similar problems, particularly in windy conditions.
There are various prior art ways of dealing with the dust problems. One way is to spray water onto the problem earth surfaces to eliminate dust. However, this is very wasteful of the water used and is labor intensive as the surface has to be maintained in a damp condition and damp surfaces dry quickly in many areas.
In some instances, petroleum products, such as diesel fuel, have been used to spread on earth surfaces to reduce dust and erosion. However, such products have been found to cause contamination of water supplies so is now outlawed in most areas. Chemicals such as magnesium chloride, re-claimed asphaltic materials, resins, lignins, lignin sulfonates, lecithin and its derivatives, and various other materials have and are being used in various circumstances, but have associated problems of contamination, only short term effectiveness because it is washed away with rain or is worn away through use, questionable effectiveness, or expense.
Vegetable oil has been tried but has similar problems to other prior art materials in that it is easily washed away by water so is effective after application only until the next rain.
SUMMARY OF THE INVENTION
According to the invention, it has been found that a fatty acid containing grease or oil, referred to herein as a fatty acid containing material, such as rendered grease and/or used vegetable oil, creates a long lasting and cost effective material to apply to earth surfaces to reduce dust from and erosion of such surfaces. While vegetable oil is only temporarily effective for dust control because it is easily washed away by water so is easily washed away by rain, used vegetable oil and rendered animal grease, or mixtures thereof, which contain fatty acids and surprisingly do not wash away with water, are very effective for not only long lasting dust control, but erosion control also. It has been found that such product appears to bind to and penetrate into the top layer of earth forming the surface and binds the particles forming the surface and top layer together to form a dust resistant and water repellent, relatively hard surface that appears to last indefinitely.
While I previously believed that the fatty acid containing material needed to be mixed with water, with at least one of the ingredients, preferably the fatty acid containing material, at an elevated temperature, so that upon mixing, an emulsion or semi-emulsion product is formed, see my copending application, now U.S. Pat. No. 6,443,661, incorporated herein by reference, I have now found that such mixing with water is unnecessary and that applying the fatty acid containing material directly to the surface works well. The mixing with water to form an emulsion or semi-emulsion is not necessary. Further, with such emulsions or semi-emulsions, or with the straight fatty acid containing material, it is not necessary to have the fatty acid containing material at an elevated temperature depending upon the temperature of the surface to which it is applied and the temperature of the surrounding air. However, an emulsion or semi-emulsion can still be used and is very effective. In addition, I have found that if an emulsion is used, the drying time necessary to form a relatively hard and water resistant surface can be reduced by including a binding material such as lignin, magnesium chloride, and/or calcium chloride in the emulsion or semi-emulsion. Lignins, magnesium chlorides, and calcium chlorides are currently used on roads and other surfaces for dust control, but remain water soluble when applied to the road or other surface so wash off with water, such as with rain or snow fall. The useful life of a road coating of such material in a usually dry climate is generally no more than three to six months, and less in a wet climate. With the fatty acid containing material, the lignin, magnesium chloride, or calcium chloride is coated with the fatty acid material which has been found to make it water resistant giving it much longer life.
The fatty acid containing material may come from various sources. Used vegetable oil may come from sources such as fast food outlets where it has been used for cooking food such as french fries or from industries such as potato chip or other snack food factories. The rendered grease will generally come from an animal rendering plant, and may be tallow or similar products. The presently preferred fatty acid containing material is a mixture of used vegetable oil and animal fat available from animal rendering plants and referred to as Yellow Grease. Most animal rendering plants collect used vegetable oil, mix it with animal fat to create the Yellow Grease which is used on or as animal feed.
The described fatty acid containing material generally has an unpleasant odor. Therefore, when using the fatty acid containing material, it is generally preferred to deodorize the material. A masking scent may be added to the material before it is applied to the surface. It has been found, however, that when lignin is used in the emulsion or semi-emulsion, a masking scent is not necessary as the lignin masks the odor.
Where the fatty acid containing material alone is applied to the surface, the material should be at least about 85° F. when applied with a surface temperature of at least about 90° F. and an air temperature of at least about 60° F. and preferably above about 80° F. If surface temperatures are below those given, it is preferable to heat the fatty acid containing material to a higher temperature before application. The same holds true for an emulsion or semi-emulsion.
With an emulsion or semi-emulsion, as indicated in my prior patent cited above, the product needs to remain in the emulsion or semi-emulsion state only until the product is applied to the surface to be treated. The mixing of the product can take place in advance of application and kept in a tank or drum, or can take place in a tank such as the tank of a truck which applies the material with a spray bar, or may be mixed as the ingredients are pumped together from separate tanks for application through a spray bar or nozzle. If desired, an emulsifying agent may be added. Such agent is generally mixed with the water prior to mixing with the fatty acid containing material. Use of the emulsifying agent appears to allow a lower fatty acid containing material to water ratio and more uniform spreading of the product on an earth surface.
When using an emulsion or semi-emulsion with lignin, magnesium chloride, and/or calcium chloride, the lignin, usually in the form of lignol sulfonate, magnesium chloride, and/or calcium chloride, will make up about 10% to about 40% of the emulsion or semi-emulsion, the fatty acid containing material will make up between about 30% and about 75%, preferably about 50%, and water will make up the remaining amount, usually between about 10% and about 50%, preferably between about 20% to about 30%. If an emulsifying agent is used, such agent may make up to about 1% of the emulsion or semi-emulsion. The fatty acid containing material may be heated prior to mixing with the other ingredients, but while it was previously thought that heating to a temperature between about 130° F. to about 215° F. was preferred, it has been found that the fatty acid containing material will mix satisfactorily at about 85° F. The water, and if liquid, the lignin, the magnesium chloride, or the calcium
Lagman Frederick L.
Mallinckrodt Robert R.
Mallinckrodt & Mallinckrodt
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