Abstract:
Systems and methods are disclosed for disposing of aggregate material in the mine caverns from which these materials were originally obtained. In an apparatus for combining aggregate material, for example, chat or tailings, with water, an emulsion is formed. The water is drawn from the cavern, through a casing. The emulsion is pumped back into the cavern below ground level, through another casing, the pumping at pressures that overcome the forces of the water in the cavern and create turbulence in the water, such that the emulsion spreads throughout the cavern, at a good angle of repose, to maximize the amount of material disposed of.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application is related to and claims priority from commonly owned U.S. Provisional Patent Application Ser. No. 60/858,560, entitled: System and Method for Aggregate Disposal, filed Nov. 13, 2006, the disclosure of which is incorporated by reference herein. 
     
    
     TECHNICAL FIELD 
       [0002]    The disclosed subject matter is directed to systems and methods for waste disposal, and more particularly, to systems and methods for safely disposing of chat and tailings for underground storage. 
       BACKGROUND 
       [0003]    Lead and zinc production involved crushing and grinding the mined rock to standard sizes and separating the ore. The remaining material or by product of this ore separation is known as “chat” or “tailings.” While some of the chat or tailings was deposited into the mine shafts once the mines were exhausted or abandoned, most of the chat and tailings were left behind in piles of leftover rock. For example, these “chat” and “tailings” piles cover over 40,000 acres in Cherokee County, Kansas, Ottawa and Craig Counties in Oklahoma, and Jasper County, Missouri, making it some of the most environmentally blighted land in the United States. 
         [0004]    These wastes were also a source of contamination. Lead, zinc, and cadmium from the chat and tailings leached into the shallow ground water, contaminating local wells, and runoff moved contaminants into nearby streams and rivers. Wind also blew fine metal-bearing dust (from chat and tailings piles and roads made of chat and tailings) into the air, spreading the contamination to nearby non-mined areas. 
         [0005]    It was attempted to dispose of the chat and tailings by depositing it back into the mines. However, the biggest problem faced was that the caverns in the mines were filled with water, that was contaminated. Simply dumping the chat and tailings  10  back down the mine casings (shafts)  12  into the caverns  14 , formed between the mine roof  14   a  and the mine floor  14   b , that either were or over time filled with water, did not spread the chat and tailings  10  in a volume efficient manner. Rather, the chat and tailings accumulated in a conical pile  15 , as shown in  FIG. 1 . 
         [0006]    As a result most of the space in the caverns  14 , between the mine roof  14   a  and the mine floor  14   b , was not filled (as shown in  FIG. 1 ). Also, raw chat plugged the casings quickly. The chat was typically not screened for large particles, hindering the dumping process. Moreover, the chat and tailings just dumped into the casing  12  in this manner, as shown in  FIG. 1 , and eventually returned above the ground surface  16  in the form of toxic dust. 
         [0007]    Additionally, the chat and tailings can not be put in large holes and ditches on the ground surface and buried therein, as the rock table is too close to the ground surface. Accordingly, there is simply not enough over burden to facilitate such a process. 
         [0008]    With additional reference to the mine cavern  14 , the total depth of the mine, from the surface  16  to the mine floor  14   b  is represented by the arrows labeled D T . The depth through the dirt/rock strata  18 , from the surface  16  to the mine roof  14   a  is represented by the arrows labeled D M , and the mine cavern height, from roof  14   a  to floor  14   b  is represented by the arrows labeled H M . 
       SUMMARY 
       [0009]    The disclosed subject matter provides systems and methods for returning the materials of chat and tailing piles back underground, and typically back to the caverns of the former mines from which the ores were removed, in a long-term, pollution free and environmentally safe manner. The systems and methods disclosed provide for the movement of large amounts of chat and tailings in a cost effective manner. For example, this allows for the land above the mines to be reclaimed. 
         [0010]    The disclosed subject matter is directed to systems and methods for disposing of aggregate material in the mine caverns from which these materials were originally obtained. In an apparatus for combining aggregate material, for example, chat or tailings, with water, an emulsion is formed. The water is drawn from the cavern, through a casing. The emulsion is pumped back into the cavern below ground level, through another casing, the pumping at pressures that overcome the forces of the water in the cavern and create turbulence in the water, such that the emulsion spreads throughout the cavern, at a good angle of repose, to maximize the amount of material disposed of. 
         [0011]    The disclosed methods and systems employ separators, to render the chat and tailings, such that they can be blended into a homogeneous material, such as an emulsion, that is pumped under pressure, back into the underground caverns for safe disposal and storage. Additionally, the water used for the methods is the same water presently in the caverns, and therefore, avoids using and contaminating fresh water. These systems and methods also include methods for flowing emulsified chat or tailings, such that it can be deposited into the caverns, so as to flow through the voids, maximizing the amount of material that can be deposited in the caverns. 
         [0012]    The disclosed subject matter is directed to a method for disposing of aggregate material. The method includes, obtaining aggregate material, and combining the aggregate material with water to form an emulsion. The emulsion is then pumped into a cavern below ground level at pressures that overcome the forces of the water in the cavern and create turbulence in the water, such that the emulsion spreads throughout the cavern. 
         [0013]    There is also disclosed a system for disposing of aggregate material. The system includes an apparatus for combining aggregate material, for example, chat or tailings, with water to form an emulsion, and a pump. The pump acts on the emulsion, to pump it into a cavern below ground level at pressures that overcome the forces of the water in the cavern and create turbulence in the water, such that the emulsion spreads throughout the cavern. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    Attention is now directed to the drawings, where like numerals or characters indicate corresponding or like components. In the drawings: 
           [0015]      FIG. 1  is a diagram of a mine cavern showing the present storage of chat or tailings; 
           [0016]      FIG. 2A  is a diagram of a system in accordance with the disclosed subject matter; 
           [0017]      FIG. 2B  is a diagram of the system of  FIG. 2A , shown in an exemplary operation; and, 
           [0018]      FIG. 3  is a diagram of a mine showing the results of the exemplary operation of  FIG. 2B . 
       
    
    
     DETAILED DESCRIPTION 
       [0019]      FIG. 2A  shows the disclosed subject matter as a system  20  both above and below the ground surface  22 . The system  20  includes multiple components for processing the chat or tailings, emulsifying it, and causing it to flow in such a manner that emulsified material can fill a maximum amount of space in the underground caverns. 
         [0020]    The system  20  includes an aggregate bin  30 , or other storage container, with scalper bars  32 , for the removal of large pieces, such a boulders, roots, and the like from the chat and tailings piles. The bin  30  also includes a gate  34 , that when released, opens the bin  30  and allows material to flow onto a first conveyer  40 . 
         [0021]    The first conveyer  40 , is, for example, a standard conveyer belt system, and includes a screening unit  44 . The screening unit  44  is, for example, a shaker screen, for example, of an approximately half-inch size, to create material that is suitable to be flowable, for example, in an emulsion or slurry, as detailed below. 
         [0022]    There is a second conveyer  50 , that receives material from the screening unit  44 . The belt of this conveyer  50  typically includes an electronic weighting system. There is a hopper  54 , that receives material from the second conveyer  50 . The hopper  54  includes a gated proportioning mechanism  56 . 
         [0023]    A water line  60  runs under the hopper  54  at the gated proportioning mechanism  56  (with an opening into the water line  60  whose size may be set manually), to receive the aggregate. The water line  60  originates in an irrigation or first pump (P 1 )  61 , that is typically submersible, as shown in a water source  62 . The water source  62  is, typically underground (through a layer or layers of strata  90 , hereinafter “strata layer”, such as dirt, rock and the like), and for example, in an underground cavern  64  of the former mine. The water is obtained from the water source  62 , as the pump (P 1 )  61  pumps the water through the water line  60  (for example, an approximately six inch internal diameter pipe), that extends through the casing  65   a  to the gated proportioning mechanism  56 . The pump  61  (P 1 ) may be, for example, a 1000 gallon per minute (gpm) deep well irrigation 40 horsepower (hp) pump. 
         [0024]    The water line  60 ′ extends from the hopper  54  to a pump unit  70 . This pump unit  70  includes a second pump (P 2 )  72 , powered by motor (M)  73 . A pipe  76  (for example, 12 inches in internal diameter) extends from the pump (P 2 )  72 , into a mine casing (shaft)  65   b , for example, typically to depths proximate the last solid layer of rock prior (of the strata  90 ) to at least proximate the cavern  64 . The mine casing  65   b , is, for example, typically common to the underground cavern(s)  64 . The pump (P 2 )  72  pulls emulsion or slurry (chat or tailings mixed with water) from the grated proportioning mechanism  56  and pushes it down the casing  65   b , through the pipe  76 . There may be a bore hole  65   x  intermediate the casing  65   b  and the cavern  64 , depending on the strata, dirt, rock, etc., for example, as shown in  FIG. 3 . The casing  65   b  alone, and with the bore hole  65   x , if necessary, form the down hole  88 . The second pump (P 2 )  72  is, for example, a 12″ by 10″ sand pump, powered by a motor (M)  73 , that is, for example, an N-14 400 horsepower diesel engine, available from Cummins Engines. This pump (P 2 )  72  pumps at pressures from approximately 15-30 pounds per square inch (psi). 
         [0025]    Turning also to  FIGS. 2B and 3 , an exemplary operation of the system  20  is detailed. Initially, chat or tailings  80 , from chat or tailings piles are dumped into the aggregate bin  30 , by a loader  82 . The chat or tailings  80   a  passes through the scalper bars  32 , to remove large materials, such as boulders, tree roots and the like. The gate  34  is opened, such that the sifted chat or tailings is received on the first conveyer  40 . The first conveyer  40 , delivers the chat or tailings  80   b , to the screening unit  44 , where it is again sorted to be of an approximately half-inch size, to create material that is suitable to be flowable. The now sorted chat or tailings  80   c  is received on a second conveyer  50 , that delivers it to the hopper  54 . 
         [0026]    The chat or tailings  80   d  (also known as aggregate) flows downward, by gravity to the gated proportioning mechanism  56 , where it enters the water line  60  (as shown by the broken line bent arrow  84 ). The water for the water line  60  is delivered from the pump (P 1 )  61 , that moves the water in the direction of the thin arrows  85 . The aggregate  80   d  combines with the water in the water line  60 , as the aggregate  80   d  flows into the water at speeds sufficient to create an emulsion or slurry  80   e  (the speed in which the aggregate flows to combine with the water is based on the speed of the second conveyer  50 —the speed of the conveyer  50  also influenced by the air temperature and other atmospheric conditions, and the size of the opening of the gated proportioning mechanism  56 ). The emulsion or slurry  80   e  flows along a path indicated by the thick arrows  86 . 
         [0027]    The pressure from the water (first) pump (P 1 )  61 , coupled with the suction from the second pump (P 2 )  72  moves the emulsion or slurry  80   e  (in the water line  60 ′) into the second pump (P 2 )  72 . The second pump  72  (P 2 ) pumps the emulsion  80   e , for example, into the pipe  76  for delivery to the mine cavern  64 . The pumping is at pressures of up to 30 psi, and, for example, at pressures of at least approximately 20 psi, in order to overcome the resistance of the water in the cavern  64  (any resistance from any ground water in the down hole  88  is negligible). 
         [0028]    Turning also to  FIG. 3 , the action of the pump (P 2 )  72  is such that it forces the emulsion or slurry to move at a relative high velocity, for example, approximately 80-140 tons of chat or tailings per hour. This speed of movement causes a spreading action of the emulsion  80   e  as it enters the cavern  64 . The spreading action, resulting from the high pumping speeds, also creates turbulence in the water of the cavern  64 , allowing for further spreading of the emulsion  80   e . The complete spreading action is shown by the broken lines  92 , and is such that the emulsion  80   e  is completely spread over the maximum volume of the cavern  64 , at a good angle of repose, for example, at least a 1.5:1 to 3.5:1 slope on the sides. 
       EXAMPLE 1 
       [0029]    A system in accordance with  FIGS. 2A and 2B  was built on 170 acres of mined land on the West edge of Commerce Okla.  FIG. 3  shows a land profile, representative of the mined land of the aforementioned site. As shown in  FIG. 3 , the mined land had a water level, approximately 12-20 feet below the ground surface  22 . The total depth of the mine (D T ) was approximately 180 to 235 feet. The depth to the mine cavern (D M )  64  was approximately 150 to 195 feet. The height of the mine cavern (H M )  64  was approximately 30 to 40 feet. The depth of the dirt/rock strata layer(s)  91   a  (D L1 ), formed of dirt and shale, was approximately 100 to 120 feet, and the depth of the rock strata layer(s)  91   b  (D L2 ), formed of solid rock, for example, bedrock, was approximately 150 to 195 feet. The cavern  64  was full of water. 
         [0030]    A casing  65   b  was made (drilled) to accommodate a 12 inch internal diameter pipe  76 , that extended from the pump (P 2 )  72 , through the dirt and shale portion  91   a , as was an approximately 11 inch bore hole  65   x  continuing from the dirt and shale portion  91   a  through the solid rock portion  91   b  to the cavern. The pipe  76  was extended to the rock portion  91   b  of the strata layer  90 . 
         [0031]    The irrigation pump (P 1 )  61  pumped water at approximately 1000 gallons per minute and combined with the aggregate delivered through the hopper  54 . The second pump (P 2 )  72  pumped at pressures averaging at least 20 psi. The resultant emulsion  80   e  was delivered at a relative high velocity, for example, approximately 120 tons of chat or tailings per hour, to the mine cavern  64  (also filled with water), between the mine ceiling  64   a  and mine floor  64   b . The deposited emulsion  80   e  settled at an angle of repose having a slope of approximately 3:1. 
         [0032]    While the system  20  has been shown and described for chat or tailings, for example, from zinc or lead, this is exemplary only. The system  20  and methods for its use can also be used with other mined aggregates, or other aggregates, such a coal, dirt (e.g., contaminated soil) and the like. 
         [0033]    While preferred embodiments have been described, so as to enable one of skill in the art to practice the disclosed subject matter, the preceding description is intended to be exemplary only. It should not be used to limit the scope of the disclosed subject matter, which should be determined by reference to the following claims.