Abstract:
A hanging chute with a rib cage is described. In accordance with one embodiment of the invention, a chute constructed from flexible wear material with a rib cage to reinforce the chute. In particular, several ribs are dispersed throughout the length of the flexible sheet for support. A flexible sheet has a reinforced edge with varying thicknesses to accommodate different weight loads and abrasive conditions. Furthermore, the chute has interlocking edges for ease of constructing long lengths from a series of shorter sections. These shorter sections are easier to transport to a processing plant or other site where the chute is to be installed. Preferably the chute is easily maintainable and can incorporate wear inserts for additional wear resistance.

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 12/399,230, filed 6 Mar. 2009, entitled “Hanging Chute,” which is a continuation of U.S. patent application Ser. No. 11/668,335, filed 29 Jan. 2007, entitled “Hanging Chute,” which has been issued as U.S. Pat. No. 7,513,352. The above applications are incorporated by reference herein. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to the field of mining and material handling, and in particular to a chute for conveying mining materials. 
     2. Description of Related Art 
     From high rises to highways, drainage pipes to railroad beds, houses to hospitals, the aggregate, cement, concrete and mining material industries provide the glue and buildings blocks of modern life. For example, we use them to build our schools and commercial buildings because concrete and aggregate products will not burn. Also, water purification systems are made from concrete products because they are clean and easy to maintain. At the same time, these products are natural and reusable. Sand, crushed stone, gravel, cement, and water in all of their combinations and forms are natural resources and part of the earth. Low in cost, natural aggregates are a major contributor to and an indicator of the economic well being of a nation. 
     It is important to note that more than three billion tons of aggregate were produced in the United States (U.S.) in 2004 with a value of approximately $16 billion, contributing $37.5 billion to the U.S. Gross Domestic Product. Every $1 million in aggregate sales creates 19.5 jobs, and every dollar of industry output returns $1.58 to the economy. Also, about ten tons of aggregate per person are used annually in the U.S. Every mile of interstate highway uses 38,000 tons of aggregate and about 400 tons of aggregate is used to build the average home. 
     Mining materials also have an amazing variety of other uses. Imagine our lives without wallboard and roofing tiles or without paint, glass, plastics, and medicine. When ground into powder, limestone is used as an important mineral supplement in agriculture, medicine and household products. Mining materials are also being used more and more to protect our environment. Soil erosion-control programs, water purification, and reduction of sulfur dioxide emissions generated by electric power plants are just a few examples of such uses. 
     Even after these materials are extracted and utilized, the job still is not finished. For example, what was once the bottom of a rock quarry can become a golf course, school, theme park or shopping center. Furthermore, these natural mining materials are a major basic raw material used by construction, agriculture, and industries. Mining industries employ complex chemical and metallurgical processes. 
     Carefully managing these valuable and limited resources is essential for the environment, economy, and future of a nation. For this reason, mining material producers, industry service providers and equipment suppliers are continually procuring ideas and innovations to help with the industry. 
     The mining industry utilizes a variety of methods to excavate such natural resources. These methods are dependent upon the geologic characteristics of the natural deposit. Open-pit mining and quarrying are commonly used. Other deposits require mining underground. Sand and gravel deposits above the water table are excavated with bulldozers, front-end loaders, tractor scrapers, and draglines. Deposits below the water table, including stream and lakebed deposits, may be excavated with draglines or from barges using hydraulic or ladder dredges. Mining and quarrying stone generally require drilling and blasting, after which the rock is then transported to a processing facility on trucks and conveyors. 
     Processing plants are generally constructed on the site of extraction. Processing of mined or quarried rock requires primary and possible secondary crushing, depending on the sizes of mining material needed. After crushing, the crushed stone, sand and gravel usually are sorted to size, moved by conveyors to bins or stockpiled. 
     Chutes associated with these processing steps are subjected to a great deal of wear and tear, not only by the impact and abrasion resulting from movement of the ore and other fluent material but also by the impact of other machinery or equipment. Impact and wear of the chutes will, over a period of time, result in significant deterioration. Another contributing factor to such deterioration is exposure of the chutes to the liquid components of mining materials. 
     One approach has been to weld liners of steel to the chutes. This is an expensive procedure requiring significant labor and hoisting machinery. Furthermore, chutes in a significant state of deterioration or chutes of certain types of materials are often not amenable to repair utilizing this approach. Use of steel or other metal liners also adds significant weight to the chute, which is undesirable. 
     Attempts have been made to coat chutes with plastic or elastomer materials; that is, a bond is created between the plastic and the chute material over the entire extent. This causes difficulties due to the difference in coefficients of expansion of the two materials. Furthermore, any break in the coating will result in the underlying chute material coming into contact with liquid or other types of processing materials, thus causing corrosive or abrasive wear that will over time significantly deteriorate the quality and strength of the chute. This same result can, of course, occur even when steel liners or plates are affixed to chutes. And it almost goes without saying that the various attempts to protect in these processing plant chutes result in permanent alteration of the chutes. That is, the various liners and coatings become integral parts of the chutes, rendering further repair even more difficult, if not impossible. 
     U.S. Pat. No. 5,035,313, “Telescopic chute for a mixer truck,” issued Jul. 30, 1991 to Smith discloses a dispensing chute for attachment to a mixer truck comprising a plurality of telescopically mounted sections. The chute sections are in the form of interlocking open top curved metal sections having replaceable plastic liners affixed to interior portions of the metal sections. 
     U.S. Pat. No. 4,054,194 “Discharge chute for concrete mix,” issued Oct. 18, 1977 to Davis discloses a conveying chute for freshly mixed concrete made with cross members at each end of the chute connected by two outer longitudinal members on opposite sides of the chute. It also has a bottom member between the cross members along the bottom of the chute. The chute includes a metal mesh reinforced polyurethane liner fastened to the cross members at each end of the chute by sets of bolts and nuts. 
     Existing concrete chutes used with aggregate transport vehicles or with stationary processing mining material and mixing plants, are typically made of steel with and without reinforcing members. Such chutes are heavy and difficult to manipulate. Also, chutes associated with aggregate transport are subject to a great deal of wear and tear not only by the impact and abrasion resulting from the movement of the aggregate or other fluent materials, but also by the impact of other machinery and equipment. In response to such conditions, chutes have been developed that have a liner attached in the chute to ameliorate the abrasion and impact conditions experienced by the chute during their use. 
     These devices typically will bolt or otherwise fasten the liner to the chute in order to maintain the liner within the chute throughout the chute&#39;s operational positions. Problems continue to exist; however, in that the fasteners wear as the ore moves over the fasteners, and the fasteners are subject to corrosion and rust either from the ores&#39; chemical composition or from the process fluids. 
     Other liners have been laminated to the chute in order to avoid the wear and corrosion of hardware described above. However, the laminated liners, experience different thermal expansion characteristics which causes stress and cracks that allows aggregate and other fluent materials to attack the chute. Also, laminated liners cannot be easily replaced or repaired and typically a new chute is required. Other chutes composed of materials other than metal and with or without liners have also been used. However, such chutes are not as resilient to the conditions they are exposed to and further cracking and breaking requires replacement of the entire chute. 
     A need exists for a lightweight but strong chute for use with processing plants in the mining material industry. Elastomers such as rubber and urethane are better suited than other plastics, metals, or other materials, because of their resistance to abrasion, elasticity, and because of their relatively low weight. Urethane is also of special interest due to its particularly smooth surface. U.S. Pat. No. 4,362,231, “Chute for Transporting Timber,” issued Dec. 7, 1982 to Meyer utilizes polyurethane material to construct the chute. 
     The present invention provides a solution to these needs and other problems, and offers other advantages over the prior art. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention is related to an apparatus that solves the above-mentioned problems. In accordance with one embodiment of the invention, a chute constructed from urethane wear material within a rib cage for support is described. In particular, several ribs are dispersed throughout the length of the chute for support of the flexible urethane wear sheet. A flexible sheet has a reinforced edge with varying thicknesses to accommodate different weight loads and abrasive conditions. Furthermore, the chute has interlocking edges for ease of constructing long lengths from a series of shorter sections. These shorter sections are easier to transport to a processing plant or other site where the chute is to be installed. Another feature is that the flexible sheet is formed such that it may be installed in the rib cage in a tool less manner without need for fasteners. Preferably, the chute is easily maintainable and can incorporate wear resistant inserts such as ceramics for additional wear resistance. 
     Additional advantages and features of the invention will be set forth in part in the description which follows, and in part, will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a processing plant with chutes in place to transport mining material in accordance with one aspect of this invention. 
         FIG. 2  illustrates a side view of a hanging chute in accordance with one aspect this invention. 
         FIG. 3  is a perspective view of one overlapping urethane sheet in accordance with one aspect of this invention. 
         FIG. 4  is a bottom view of a featured urethane sheet in a relaxed flat condition accordance with one aspect of this invention. 
         FIGS. 5 ,  6  and  7  are end views of three different embodiments of an upper ridge of the urethane sheet that fits over a top rib of a rib cage and engages a lid surface in accordance with various aspects of this invention. 
         FIG. 8  is a perspective view of a hanging chute incorporated into a processing plant in accordance with one aspect of this invention. 
         FIG. 9  illustrates a perspective view of a feed end in accordance with one aspect of this invention. 
         FIG. 10  illustrates another perspective view of a discharge end with a chute cap in accordance with one aspect of this invention. 
     
    
    
     Throughout the drawings, the same reference numerals indicate similar or corresponding features or functions. 
     DETAILED DESCRIPTION 
     In  FIG. 1  an example of the invention, a hanging chute  100 , is shown incorporated into a processing plant  150 . It will be understood by those skilled in the art that chutes transport material from one piece of equipment in a processing plant  150  to another. It will further be understood by those skilled in the art that significant dust generation may result if chutes are not designed properly. The chutes should be large enough to avoid jamming of material and reduce fugitive material escape. 
     Turning now to  FIG. 2 , a side view of the hanging chute  100  is shown. The hanging chute  100  has an upper ridge  120  that fits over a top rib  152 . This engagement of the upper ridge  120  with the top rib  152  ensures that material will not seep out of the chute. The hanging chute  100  also has ribs  130  that engage to a flexible sheet  124 . These ribs  130  are dispersed throughout the length of the flexible sheet  124  at various intervals to form a rib cage. It will be understood by those skilled in the art that the flexible sheet  124  may alternatively be constructed from a material or composite consisting of polyurethane, polyethylene, high density polyethylene, polypropylene, glass reinforced plastics, polyethylene terephthalate, and polyestrene. However, in the preferred embodiment of the invention, the flexible sheet  124  should be constructed from urethane. This is because urethane is flexible and lighter and therefore easier to transport and install. Furthermore, urethane is also more resistant to wear and tear that occurs from the transport of materials through chutes in the processing plant  150 . In the alternative, various forms of rubber may be used to form the flexible sheet  124 . It will be understood by those skilled in the art that rubber is often better suited for “grizzly” type chutes where large bulk material needs to be moved. 
     Looking again at  FIG. 2 , the hanging chute  100  also has a lower ridge  122  that acts as a latching mechanism to hold flexible sheet  124  in place. Alternatively, lower ridge  122  may also be configured to act as a spacer to help shape the flexible sheet  124 . It will be understood by those skilled in the art that a mining material conduit  132  is incorporated into the hanging chute  100  to transfer material into other hanging chutes  100  or other equipment in the processing plant  150 . 
       FIG. 3  illustrates a perspective view of one overlapping sheet  124  in accordance with this invention. It will be understood by those skilled in the art that when fine material and lumps are mixed in a product stream, the chute depth should be at least three times the maximum lump size to avoid jamming or overflow. Furthermore, the chute should be designed so that material falls into the flat bottom  145 . The flexible sheets  124  are placed in an overlapping position to one another so as to prevent material from escaping the product stream.  FIG. 3  depicts the shape taken by the flexible sheet  124  once it is installed in rib cage  130 . 
     A sloping bottom  144  with a flat bottom  145  and radius corner  143  is also shown. The sloping bottom  144  greatly reduces plugging of the chute by preventing material and lumps from gathering unnecessarily. It will be understood that the sloping bottom  144  can be in a U-shape form as normally found in the art or any variation thereof. The sloping bottom is adjacent to a urethane wall  154  and a point of inflection  156 . The flat bottom  145  depicted in  FIG. 3  is beneficial in resisting sliding abrasion since the flowing ore is distributed over a greater surface area than in a U-shaped chute. Radius corner  143  directs flow toward the flat bottom  145  and helps resist build up of sticky materials. 
     Wherever possible, material flowing through the hanging chute should fall onto the sloping bottom  144  of the flexible sheets  124  to reduce dust and noise generation, absorb impact of incoming material, reduce wear and abrasion of chute surfaces, and reduce the height of material fall. Abrupt changes of direction must be avoided to reduce the possibility of material buildup, material jamming and dust generation. Having the sloping bottom  144  prevents this backflow of the mining material stream. 
       FIG. 4  is a bottom view of a flexible sheet  124  in accordance with one aspect of the invention. The flexible sheet  124  is constructed with rib channels  148  that engage the ribs  130 . The rib channels  148  are molded into the flexible sheet  124  during construction to plan the location of the ribs  130 . The flexible sheet  124  also shows the upper ridge  120  and lower ridge  122 . A reinforced edge  128  is shown on the flexible sheet  124 . This reinforced edge  128  also helps reduce wear and abrasion of the hanging chute  100 . The reinforced edge  128  may be reduced or increased in thickness depending on the material to be moved. For instance, if a slurry type of material needs to be moved, the reinforced edge  128  may be thinner for reduced weight. However, if large aggregate material needs to be moved, then the reinforced edge  128  may be thicker for increased reduction of wear and tear. 
     In  FIGS. 5 ,  6 , and  7 , end views of three different embodiments of an upper ridge  120  of the flexible sheet  124  that fits over a top rib  152  of a rib cage and engages a lid surface  160 . The lid surface  160  may be placed on an open side of the hanging chute  100  (see  FIG. 10 ). The lid surface  160  covers the stream of material and prevents deflecting debris similar to the chute cap  138 . The lid surface  160  may be constructed from materials similar to that of the flexible sheet  124 . The flexible sheet  124  also has a lower ridge  122  that acts as a latching mechanism to hold flexible sheet  124  in place against the rib cage. In  FIG. 5 , an overhanging edge  164  has been added to the upper ridge  120  such that they collectively form a channel into which the top rib  152  is placed. In  FIG. 7 , a snap fit female connector  168  has been added to the upper ridge  120  that matingly fits a reciprocal male connector  172  formed along the length of the top rib  152 . Similarly, a female connector  170  has been added to lid surface  160  that matingly fits a male connector  172 . Together these connectors provide a toolless connection of the flexible sheet  124  to the ribs  130  and an optional lid surface  160  to the ribs. It will be appreciated by those skilled in the art that other forms of lid surface, upper ridge, and top rib engagement may be provided without departing from the scope and spirit of the present invention. 
     In alternative embodiments of the invention, a wear insert  162  (un-shown item in bottom of chute) can also be incorporated into the reinforced edge  128  for increased reduction of wear and tear. Some examples of wear inserts  162  may be ceramics, carbides, chrome iron or other high wear compounds. It will be understood by those skilled in the art that the modular nature of the chute allows strategic placement and replacement in a simplified manner. 
     Moreover, in preferred embodiments, the flexible sheet  124  has interlocking edges  158  that aid in connecting the flexible sheets  124  together. This makes transfer, assembly, and disassembly of the hanging chute  100  easier. It will be understood by those skilled in the art that the interlocking edges  158  utilize male and female connections, but may be as simple as overlapping joints. Replacement or repair has been difficult in the past due to the welded or bolted metal sheets that were used in the construction of the chutes. The use of interlocking edges  158  minimizes the problem of replacement and repair by reducing labor, time, and increasing safety of the laborers. 
       FIG. 8  is a perspective view of a hanging chute  100  incorporated into a processing plant  150  in accordance with one aspect of this invention. In a preferred embodiment of the invention, the reinforced edge  128  appears on a lower surface  166  of the hanging chute  100 . The upper ridge  120  and the lower ridge  122  are shown again in detail. Several ribs  130  engage the flexible sheet  124  at various intervals  148  (see  FIG. 4 ) and secure the hanging chute to processing plant  150  and resist moving with the material flow. It will be understood by those skilled in the art that aggregate conduits  132  are shown in  FIG. 8  to further demonstrate the flow of material. The reinforced edge  128  is shown at a lower surface of the hanging chute  100 . This reinforced edge  128  helps absorb heavy impact on the chute when materials drop from the conduits  132 . In most applications, the combination of the flexible sheet  124 , reinforced edge  128 , sloping bottom  144 , and the various ribs  130  are sufficient to absorb the heavy impact on the chute  100 . Alternatively, the flexible sheet  124  may have internal steel rods  163  molded into the sheet  124  to further stabilize the apparatus. 
     It will be understood by those skilled in the art that the mining and material handling industries move a great variation in weight and size of substances. Accordingly, the flexible sheet  124  may be thinner in zone  154  to conserve costly wear resistant material in this low wear zone. Meanwhile, the reinforced edge  128  can be constructed with a thicker cross section to accommodate higher wear rate or impact absorption. The cross sections joining these two may have a variable thickness to accomplish the proper curved corners  143 . 
       FIG. 9  illustrates a perspective view of the hanging chute&#39;s feed end  136 . The flexible sheet  124  is shown attached to the end rib  126  by use of fasteners  140 . The fasteners  140  are attached to fastener holes  134  on the end rib  126 . It will be understood by those skilled in the art that fasteners  140  can be nut and bolt combinations, nails, pins or any common fastener found in the art. The reinforced edge  128  is shown again on the lower surface of the hanging chute  100 .  FIG. 9  illustrates feed end  136  without a chute cap  138 . Support rib structure incorporates a bolting flange on ends  126  to allow modular construction and installation of rib structure to accommodate different lengths of carrier frames. 
     Turning now to  FIG. 10 , the discharge end  137  is shown with a chute cap  138 . The chute cap  138  is, in preferred embodiments, constructed from material similar to the flexible sheet  124 . The chute cap  138  is attached to the tail end  136  with fasteners  140 . It will be understood by those skilled in the art that the chute cap  138  can be constructed from plastics or metals. The object of the chute cap  138  is to prevent back spill and dust emission from the tail end of the hanging chute  100 . Additionally, debris may be deflected off the interior surfaces of the hanging chute  100  and thrown at an undesirable trajectory. Having a chute cap  138  prevents such occurrences. Furthermore, a snap spout  132  may be attached to the discharge end  137  with or without fasteners  140 . It will be understood by those skilled in the art that a snap spout  132  is a separate molded piece of equipment that may be cylindrical in shape. 
     The foregoing merely illustrates the principles of the invention. It will thus be appreciated that those skilled in the art will be able to devise various arrangements which, although not explicitly described or shown herein, embody the principles of the invention and are thus within its spirit and scope. Although the hanging chute  100  is utilized in this description with mining industries, the invention may also be utilized in various material handling industries. For example, the hanging chute  100  and all of its embodiments may be incorporated into agricultural systems to move farm produce, grains, meat, and waste. Furthermore, the hanging chute  100  may be incorporated into delivery of materials from the dock to assigned space, removing empty crates, returning crates at end for re-crating, and delivering materials back to dock for carrier loading. These and other features will be evident to one of ordinary skill in the art in view of this disclosure, and are included within the scope of the following claims.