Storage bunker
THIS INVENTION concerns a storage bunker for substantially dry and loose materials such as shreaded paper waste, and provides a receptacle in which the material may be stored and at least partially compacted and withdrawn when required for further handling and disposal. 
     Many devices are known for storing materials such as shreaded paper waste. These include a storage bin having a number of conveying screws at its base operating in different directions to keep the material in motion and preventing it from bridging at the bottom of the bin. Another device is a storage silo with a tapering hopper at its base and having a number of screw conveyors projecting into the waste to discharge it from the silo. A further known device comprises a scraper conveyor which collects material and deposits it into a bunker having screw conveyors at the base for discharging the material. 
     The principal disadvantage with these kinds of known storage facility is that they include no means for compacting the material thus to maximise the storage capacity. 
     An object of the present invention is to provide a storage bunker which is capable of storing and compacting large volumes of materials. 
     According to the present invention there is provided a storage bunker for substantially dry and loose materials such as shreaded paper waste, comprising a receptacle having its longitudinal axis or major dimension generally horizontal, means for feeding material to the bunker at one end thereof, means within the bunker for feeding accumulated material therein towards the other end, further means within the bunker in a base region thereof for conveying compacted material forwardly towards said one end at which the material is discharged from the bunker by further conveying means. 
    
    
     An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 
     FIG. 1 is a partially-sectioned elevation of a storage bunker made in accordance with the invention; and 
     FIG. 2 is a vertical section along line II--II of FIG. 1. 
    
    
     The bunker comprises a receptacle generally indicated at 10 and being typically some 40 meters long and about 6 meters high internally. An input conveyor 11 carries materials such as shreaded paper waste to be stored and compacted into a chute 12 containing a pivotable and reciprocating distributor flap 13 which spreads the material substantially evenly across a plate 14 which extends longitudinally over the top of the bunker 10 to form a ceiling thereto. A scraping and levelling conveyor 15 having a number of spaced upstanding flights 16 are driven forwardly in the direction of arrow 17 by a pair of driven chains 18. The flights 16 serve to drive the material forwardly on plate 14 which, due to the restricted height between the plate and a fixed top 20, causes the material to assume a substantially constant depth. 
     At 21, the plate 14 is broken to permit access to the interior 22 of the bunker, and at this point the material is deposited by gravity into the bunker. Accumulated material within the bunker fills to a height at which it is driven backwards along the bunker by the return run of flights 16. Thus compaction takes place to a level of between 11/2-1 to 4-1. 
     Continuously or intermittently, substantially the whole body of material within the bunker is carried forwards by a belt plate conveyor 25 forming a floor to the bunker interior 22, towards the discharge end, the material being &#34;stripped&#34; off the compacted mass thereof by the bottom run of an inclined toothed conveyor belt 26 moving in the direction of arrow 27, this conveyor serving to define a wedge-like front end of the bunker space. The material stripped from the bunker by conveyor 26 may be deposited onto a troughed conveyor 28 or any other suitable means for transferring the material from the output end of the bunker to, say, an incinerator or pelleting press. 
     It will be seen from FIG. 2 that the side walls 29 of the bunker diverge towards its base thus ensuring that material will always descend towards belt plate conveyor 25. 
     The conveyor 25 may be driven intermittently or continuously and at variable speed depending upon the required dischage rate. Similarly, the speed at which conveyor flights 16 are driven may be varied during operation to control the feed rate to the bunker. For this purpose, proximity devices may be provided at spaced positions along the bunker and throughout its height thus to control the input and output of materials. 
     Liquor sprays may be incorporated close to material input point 21 to control the condition of the material entering the bunker. 
     It is expected that a bunker having the dimensions mentioned above will be capable of containing some 25 to 35  tons of material by virtue of the compaction provided. Drive motors for conveyors 11, 15, 25 and 26 may be of a low horsepower rating since none drives more than a light load. The system is, therefore, inexpensive to operate and maintain.