Abstract:
The aggregate processing system is a substantially closed onshore system that provides significant improvement in economy by substantially eliminating the spread of dust and dirt and/or the partial filling of the berth with sediment during the offloading of aggregate materials from a bulk cargo ship. The system includes one or more extractors that draw the bulk aggregate material from the hold(s) of the ship by entraining the aggregate in a stream of water and air. The aggregate is automatically cleaned during this step, and passes to a separating hopper where the sand and water settle out and the clean gravel is transferred to surface transport. The sand and water pass to a settling tank, where the sand is recovered for use and the water is recycled for continued use.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates generally to handling systems for raw materials used in the construction industry, and particularly to an aggregate processing system for simultaneously cleaning and transferring gravel and stone aggregate from a cargo ship to onshore processing and transport facilities. 
         [0003]    2. Description of the Related Art 
         [0004]    Aggregates comprising gravel, sand, stone, and similar materials are used throughout the world as ingredients in various construction materials, such as concrete, asphalt paving, and the like. Any given project may require many tons of such material. Hundreds of such projects may be underway at any given time. Virtually all such projects require that the completed structure meet certain standards of quality, which demand that the aggregates and other materials used be clean and free of undesirable foreign matter. Accordingly, there is high demand for large quantities of clean, high quality aggregate material. 
         [0005]    Aggregates are mined from deposits of gravel and sand in numerous locations throughout the world. Such deposits are seldom located convenient to the construction site where they are needed, and thus require transportation from the mining site to the construction site. Moreover, the aggregate material nearly universally contains a great deal of foreign matter (dirt, vegetation, etc.) when it is mined, which must be removed from the aggregate in order to provide the high quality required for most construction projects. The aggregate must be further separated according to particle size and material, i.e., sand and gravel. While these two materials are commonly used together in the making of concrete and other poured and cast construction materials, the quality of the completed mix requires that the aggregate be mixed in specific ratios to one another. Thus, a loose undetermined mix of sand, gravel, and other materials is not suitable for use in the manufacture of most cast and poured construction materials. 
         [0006]    In accordance with the above needs, various apparatus and systems have been developed in the past for mining, cleaning, separating, and transporting aggregate materials. These various systems and apparatus generally handle only one, or at best two, of the required steps in the process of recovering the aggregate materials from the mining site to delivering the processed aggregate to the construction site. Moreover, many such systems and apparatus cannot provide aggregate processing on the large scale needed for rapidly handling multiple tons of such material, as is the case when offloading bulk aggregate material from a bulk cargo ship. In such cases, it is important that the material be offloaded as rapidly as possible, in order to minimize the down time for the ship. 
         [0007]    Aggregates are conventionally offloaded from the ship by means of the shipboard handling apparatus of the ship. This conventional offloading procedure is not concerned with the fallout of extraneous materials, e.g., dust, dirt, etc., from the operation. Accordingly, the buildup of dust and dirt in the port, and even the surrounding environs outside the port proper, is a chronic problem requiring effort and expense for cleanup. Much of the residual sand and dirt from such an open offloading operation ends up in the water where the cargo ship is berthed for the operation. It will be seen that this results in the partial filling of the berth with sediment after some period of time, thus necessitating the periodic dredging of the berth at some expense. 
         [0008]    Thus, an aggregate processing system solving the aforementioned problems is desired. 
       SUMMARY OF THE INVENTION 
       [0009]    The aggregate processing system is a substantially closed system that precludes the substantial escape of dust, dirt, and extraneous matter during the process of offloading aggregate material from a cargo ship. The apparatus of the system is onshore, with the exception of the units temporarily and removably inserted into the hold(s) of the ship for withdrawing the aggregate material therefrom. 
         [0010]    The aggregate processing system includes one or more hydropneumatic units that are inserted into the hold(s) of the aggregate cargo ship to withdraw the aggregate from the hold(s). These devices are powered by large volumes of air and water from an onshore air compressor and tank and an onshore water tank and pump system. The stream of air and water entrains the aggregate material in the stream to draw the material from the hold(s). This forms a slurry of aggregate gravel, sand, and other materials with the water and air. The slurry is then ducted from the ship to an onshore separation hopper through a closed tube(s). The large amount of water used to form the slurry automatically washes the aggregate simultaneously with the offloading operation. 
         [0011]    The onshore separation hopper is a passive device having an internal screen that allows the sand and smaller particles to pass therethrough, along with the water. Air is vented from the system at this point. The washed gravel aggregate remains atop the screen, where it is passed to ground transportation vehicles (e.g., dump trucks, railroad hopper cars, etc.). 
         [0012]    The water and residual material that has passed through the screen of the separation hopper is then ducted to a settling tank, where the heavier material settles out of the water passively due to gravity. The clean sand is captured in the bottom of the settling tank for use in the manufacture of concrete or other building materials. The relatively clean water is pumped back to the water tank for reuse in mixing with air for the further entrainment and removal of aggregate from the ship. 
         [0013]    This closed system results in greater economy due to the constant recycling of the water used in the system, as well as the recovery of sand and other materials from the gravel aggregate. These recovered materials, particularly sand, have economic value. Moreover, the capture of sand and other materials obviates the previous problems of sand and dust residue in the port and surrounding areas, as well as obviating the need and associated expense of periodically dredging the dockside berths where aggregate cargo ships berth to offload their materials. 
         [0014]    These and other features of the present invention will become readily apparent upon further review of the following specification and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is a schematic diagram of a first embodiment of an aggregate processing system according to the present invention, illustrating various features thereof. 
           [0016]      FIG. 2  is a schematic diagram of a second embodiment of an aggregate processing system according to the present invention, illustrating further features thereof. 
       
    
    
       [0017]    Similar reference characters denote corresponding features consistently throughout the attached drawings. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0018]    The aggregate processing system is adapted for the largely automated, large scale handling of bulk aggregates, such as gravel, from ship to shore. The system includes a series of steps for offloading such materials from the bulk cargo ship, cleaning the aggregate, separating the aggregate into at least two sizes or grades, and delivering the aggregate material to ground transportation for delivery. The water used in the offloading and cleaning steps is recycled for economy. 
         [0019]      FIG. 1  of the drawings provides a schematic view of a first embodiment of the aggregate processing system  10 . The system  10  is permanently installed as a fixed, stationary onshore installation on a dock D or the like, where it may be operated for the removal, cleaning, grading, and transfer of aggregate from a ship S to ground transport units T (trucks, as shown, or alternatively, rail cars). 
         [0020]    Initially, one or more hydropneumatic aggregate ejectors  12   a,    12   b,  along with their aggregate suction bits  14   a  and  14   b,  are positioned to extend into the hold(s) H 1 , H 2  of the ship S once the ship has been docked. The assemblies, comprising the ejectors  12   a  and  12   b  and their suction bits  14   a  and  14   b,  operate by entraining the aggregate material in jets of high volume, high velocity air and water to form a slurry of aggregate and water, which is then ejected upward from the hold of the vessel to an onshore hopper for further processing. Corresponding high volume water delivery ducts or lines  16   a,    16   b  are extended from the valve  18  of a high volume water supply tank  20  permanently installed onshore on the dock D. 
         [0021]    Corresponding high volume air delivery ducts or lines  22   a,    22   b  are extended from the respective valves  24   a  and  24   b  (a single valve may be provided having both air delivery lines  22   a  and  22   b  extending therefrom, as in the two water lines  16   a  and  16   b ) of a permanently installed high volume compressed air tank  26  on the dock D. Aggregate slurry transfer ducts or lines  28   a  and  28   b  are extended from the corresponding aggregate ejectors  12   a  and  12   b  to a permanently installed onshore aggregate passive separation hopper  30  on the dock D. The various water, air, and aggregate ducts  16   a,    16   b,    22   a,    22   b,    28   a,  and  28   b  are laterally closed tubular structures to preclude the escape of water, air, and/or aggregate therefrom during operations. These components  12   a  through  16   b,    22   a,    22   b,    28   a,  and  28   b  are stored on the dock D with the other components of the system  10  when not in use. 
         [0022]    Air is supplied to the compressed air tank  26  by a large, high volume air compressor  32 . Air used in the system is not recycled, but is drawn in by the air compressor  32  and passed through the system via the air tank  26  and the closed air supply duct or line  22   a  (and  22   b,  if a second aggregate ejector and suction bit assembly are used) to the assembly or assemblies, and thence out with the aggregate slurry through the closed aggregate slurry transfer duct or line  28   a  (and  28   b,  in the case of a second ejector and suction bit assembly) to the hopper  30 . 
         [0023]    However, the water used in the system is preferably recycled, for economy. The water is initially collected in a sand and water separation tank  34  and drawn from that tank by a high volume pump  36  installed in a water return line or duct  38  that extends to the water tank  20 . The water then flows through the closed water delivery line or duct  16   a  (and  16   b,  if a second ejector and suction bit assembly is used) to the aggregate ejector  12   a  (and optionally  12   b ) and its suction bit  14   a  (and optionally  14   b ) to entrain the gravel aggregate and other matter in the hold and wash it outward through the slurry transfer duct or line  28   a  (and optionally  28   b ) to the aggregate separation hopper  30 . 
         [0024]    The hopper  30  is a passive unit, i.e., it contains no powered machinery to separate the aggregate into different sizes or grades of material. Rather, the hopper  30  includes a separator screen  40  therein that allows the water and smaller particles of sand and the like to flow therethrough, while retaining larger gravel and stones thereabove. It will be seen that two or more progressively smaller mesh screens or separators  40  may be installed within the hopper  30  to grade the aggregate slurry into a number of different sizes. The graded aggregate, having been cleaned as a result of the water used to extract the aggregate from the ship S, then travels outward from the hopper  30  to waiting ground transportation T via one or more delivery chutes  42 . 
         [0025]    The water (and fine sand, as noted above) passes through the screen(s) or separator(s)  40 , and exits the hopper  30  through a closed sand and water return line or duct  44  that extends from the hopper  30  back to the sand and water separation tank  34 . The tank  34  is also a passive separation device. Sand settles to the bottom of the tank  34  due to gravity, where it may be removed at the end of the aggregate offloading operation for drying and use. The relatively clean water in the upper portion of the tank  34  is again drawn from the tank  34  through the closed water return line or duet  38  by the pump  36  and recycled through the system, as described above. 
         [0026]    The aggregate processing system  100  illustrated schematically in  FIG. 2  is very similar to the system  10  of  FIG. 1 . While the relative positions of many of the components are different in  FIG. 2  in comparison to  FIG. 1 , the two systems  10  and  100  differ essentially only in the positioning of the water delivery duct or line  16   a  (and optionally  16   b , when two ejectors  12   a,    12   b  and suction bits  14   a,    14   b  are used). In  FIG. 2 , the water supply or delivery duct or line  16   a  extends from the high volume water tank  20  to the top of the aggregate suction bit  14   a,  rather than to the ejector  12   a,  as in  FIG. 1 . The optional second ejector and suction bit assembly  12   b,    14   b  in the hold H 3  of the ship S also has its water delivery duct  16   b  connected to the top of the suction bit  14   b  in  FIG. 2 . Each of the water delivery ducts  16   a,    16   b  includes its own valve  18   a,    18   b,  although the two lines or ducts may branch from a single connector and valve  18 , as in  FIG. 1 , if so desired. 
         [0027]    The remaining components illustrated schematically in  FIG. 2  are equivalent to those correspondingly numbered components shown in  FIG. 1 , but it will be seen that the relative locations of the high volume air tank  26 , the compressor  32 , and the passive separation hopper  30  have been reversed in  FIG. 2  relative to their positions in  FIG. 1 . However, the system  100  of  FIG. 2  operates essentially identically to the system  10  of  FIG. 1 . Relatively clean water flows from the sand and water separation tank  34  to the water tank  20  via the pump  36  and water return line or duet  38 . The water is then delivered to the upper portion(s) of the aggregate suction bit(s)  14   a  (and  14   b ) by closed duct(s)  16   a  (and  16   b ). Air is provide by the compressor  32  to the compressed air tank  26 , from which it is delivered to the ejector(s)  12   a  (and  12   b ) by closed air supply or delivery duct(s)  22   a  (and  22   b ). The aggregate slurry, comprising aggregate materials pumped from the hold(s) H 1  (and H 3 ) of the ship S and mixed with water and air, as described above, is pumped to the aggregate passive separation hopper  30  by the slurry transfer duct(s)  28   a  (and  28   b ). The washed and cleaned gravel aggregate is delivered from the hopper  30  to waiting transports T by the delivery chutes  42 . Water and finer sand and the like falls through the screen(s) or separator(s)  40  to pass to the sand and water separator tank  34 , where the sand and fine particles settle out to the bottom of the tank. The relatively clean water is then drawn from the tank  34  by the pump  36  to be recycled through the system. 
         [0028]    The closed ducts and lines used throughout the system, along with the water used, essentially eliminate the spread of dust and dirt resulting from other open systems. The water used in the system is recycled, thus greatly reducing expense, and is also used to wash the aggregate material, thus increasing its commercial value and eliminating unwanted finer contaminants from the washed gravel and stone. Moreover, the finer sand particles that are removed from the gravel have some commercial value. The system serves to recover such materials, rather than flushing them overboard from the ship where they contaminate the dockside berth and require periodic dredging. Accordingly, the present aggregate processing system provides numerous efficiencies in operation that are not achieved by earlier systems used in the large scale offloading and processing of aggregate materials. 
         [0029]    It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.