Classifying – separating – and assorting solids – Sifting – With heating or cooling
Reexamination Certificate
2001-11-14
2003-06-10
Walsh, Donald P. (Department: 2856)
Classifying, separating, and assorting solids
Sifting
With heating or cooling
C209S239000
Reexamination Certificate
active
06575303
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to controlling the operation of equipment for processing materials to produce a product which includes aggregate materials and a volatile component. More particularly, the invention relates to an integrated system for controlling the operation of processing equipment based upon an analysis of the weight ratios of different sizes of aggregate materials to the total quantity of aggregate materials remaining after the volatile component has been removed. A preferred embodiment of the invention relates to an integrated system for controlling the operation of an item of processing equipment based upon an analysis of the ratio of the amount of the volatile component contained in a sample of the product to the total weight of the sample of the product. The invention is useful, for example, especially in its preferred embodiment, in controlling the relative composition of the components of hot mix asphalt.
BACKGROUND AND DESCRIPTION OF THE PRIOR ART
Sampling of various aggregate materials is commonly required in the construction, mining and other industries to insure that the materials meet the required specifications for quality, composition, and/or gradation. Samples of products containing aggregate materials may be taken at various stages during the processing or manufacturing thereof for analysis to insure that the proper particle sizes of aggregate materials are being produced. During rainfall and other adverse weather conditions, it may be difficult to analyze the particle sizes of a product containing aggregate materials to insure that the proper particle sizes of the aggregate materials are being produced. In addition, when a product includes a volatile component other than water, such as the asphalt cement in a hot mix asphalt product, it is also desirable to sample the product for analysis to insure that the desired proportion of asphalt cement to the aggregate component of the product meets a predetermined standard, such as for example, 3-5% by weight.
Samples of products containing aggregate materials and a volatile component, such as for example, wet aggregate materials and hot mix asphalt, may be taken from conveyors, trucks, barges, railcars or other transport devices, or from product stockpiles, silos, or other storage facilities. Such samples may be taken manually or automatically, and they may be taken from quantities of products produced by batch or continuous processes.
It is common for producers of products containing aggregate materials to sample their product at several stages, including the shipping stage. In addition, the purchaser will almost always sample at least a portion of the incoming shipments before unloading them to insure that they are acceptable. Products containing aggregate materials that are hauled by truck are usually sampled by hand shoveling a sample portion from various locations in the product load in the truck bed, in order to obtain a representative sample. Because the aggregate in the product may segregate by size as it is being loaded and hauled, however, hand sampling in this way makes it difficult to obtain a representative sample. It is generally necessary to remove a portion of the surface material from several locations in the truck bed in order to obtain a sample portion from therebeneath. However, when the aggregate product is bituminous paving material such as hot mix asphalt, its surface temperature may be as high as 250-300° F., which makes hand sampling at least uncomfortable and potentially dangerous. Furthermore, a worker who is charged with the responsibility of obtaining a hand sample from a hot mix asphalt truck will not likely be willing and may not be able to spend the time to take sample portions from various locations on the load in the truck bed to insure that he gets a representative sample. Nevertheless, the standard practice for sampling bituminous paving mixtures from truck transports is to take several portions of a sample from each truck using a flat-bottom scoop or a square-nose shovel.
ASTM Designation D 979-96 specifies that at least three approximately equal increments should be taken from each truck load of bituminous paving materials sampled. Various state highway departments impose additional requirements on the sampler of asphalt concrete, in an effort to insure that representative samples are obtained. For example, the Georgia Department of Transportation Sampling Procedure GSP-15 specifies that hand samples may be taken only after the “cone” of material in the bed of the truck is first shoveled off to a depth such that the resulting flat area is at least 60% as wide as the truck and at least six inches deep. Wyoming Department of Transportation Sampling Procedure 830.0 requires that for smaller trucks, a sample area must be prepared by removing the top 2-4 inches from each quarter of the load, while for larger trucks, at least two transverse trenches must be excavated across the load in the truck bed. The sample is then removed by pushing the shovel into each cleared area or trench at a 45° angle. Illinois Department of Transportation Sampling Procedure 4.7.1 requires that an equal amount of material is to be taken from locations approximately one foot below the top of each pile in the truck bed, at quarter points around the pile's circumference. Mississippi Department of Transportation Field Testing Procedure TMD-11-77-00-000 requires that at least three samples be taken from specified locations in the truck after first removing the top 2-3 inches of material at each sample point. All of these-procedures require that the sampler work for a significant period of time in the bed of the truck atop the load of hot mix asphalt. Complying with such procedures is uncomfortable and may be dangerous, which makes proper sampling problematic.
Once a sample of product comprised of various aggregate materials and a volatile component (which may be water) is obtained, analysis is often required to insure that the materials meet the required specifications for composition and/or gradation. Many such products include mixtures or blends of components having various particle sizes. Thus, for example, certain coal and coke products and industrial catalytic powders are sold having various particle sizes in specified ranges by weight. Crushed stone products that are used in the construction of roadways may also include mixtures or blends of several particle sizes in various specified ranges, depending on the anticipated use. Several such crushed stone products, as well as sand and/or other aggregates and other additives, including asphalt cement as a volatile component, are combined in specific weight percentages in the manufacture or processing of bituminous paving mixtures.
It is known that the particle size distribution in a quantity of aggregate materials may be determined more-or-less automatically. Thus, for example, U.S. Pat. No. 3,439,800 of Tonjes, U.S. Pat. No. 5,059,310 of Fischer et al. and U.S. Pat. No. 5,222,605 of Pogue describe methods and devices for automatically determining the proportionate amounts of various particle sizes of such a product. Such methods and devices, however, do not contemplate control of equipment such as a rock crusher that is employed in the processing or manufacturing of the product which includes aggregate materials and a volatile component.
Finally, heating devices have been used to facilitate the sampling and analysis of products which include aggregate materials. Such heating devices remove the combustible components of a product which includes aggregate material. By heating the product to a level sufficient to burn off the combustible components, the heating devices effectively isolate the aggregate materials contained in the product for more accurate sampling and analysis of the aggregate material distribution. Examples of such prior art heating devices are contained in U.S. Pat. No. 5,081,046 of Schneider, U.S. Pat. No. 6,000,935 of Regimand, et al., U.S. Pat. No. 4,276,093 of Pickermann and U.S. Pat. No. 6,054
Barrett Michael E.
Brock J. Donald
Collins R. Ronald
Heeszel Gary P.
Jakob Herbert E.
AI Enterprises, Inc.
Chambliss Bahner & Stophel P.C.
Rodriguez Joseph C
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