APPARATUS FOR HANDLING DUSTY MATERIAL IN A DUST-FREE MANNER

Abstract: A loading spout (1) for free flowing particulate material, said spout comprising an inner tube (2, 3) and a shorter outer tube (13) mounted through bearing means (6) so as to be rotatable about and concentric with the inner tube (2, 3) with the inner tube (2, 3) extending beyond both ends of the outer tube (13), drive means (5, 10, 12) to rotate the outer tube (13), at least one helical flight (17) on the outer tube (13) where the flight comprises an outer flight portion (20) extending outwardly from the outer tube (13) and an inner flight portion (18) extending across the annular space (19) between the inner and outer tubes and terminating closely adjacent the outside of the inner tube, and discharge openings (21) in the wall of the inner tube within the outer tube whereby material can exit the inner tube into said annular space into the path of the flight inner portion (18).

Description: APPARATUS FOR HANDLING DUSTY MATERIAL IN A DUST-FREE MANNER This invention provides apparatus for bulk handling free flowing particulate dusty materials such as wheat, fly ash, cement, clinker, alumina and the like. Such materials are frequently delivered by means of gravity feed pipes into hoppers, the holds of ships and in other locations which involves free fall of the material from the end of the feed pipe to the top of a pile of material. With materials of the above type this manner of material handling will result in the generation of large quantities of dust which is a health and explosion hazard. A number of devices have been tried hitherto with a view to minimising the problem of dust. Some such devices have comprised a loading bell with an associated dedusting unit, spouts with spindle gates, spouts with paddle gates, baffle plate constructions and spout connections to covered hatches with excess air withdrawal. All of the above systems suffer with one or more drawbacks including rapid wear, inefficiency, heavy weight, difficult loading procedures and standardisation problems and these problems have limited the use of the devices. As a result of studies made by the inventor it has been established that in order to overcome dust problems it is essential that the discharge end of the spout be immersed during the discharging process in the pile of material discharged and that the extent of immersion be substantially constant, preferably automatically adjusted, as the pile of discharged material increases. In addition, the characteristics of low wear, acceptable weight, simplicity and efficiency are desirable. The present invention has been devised to address all of the above requirements. Broadly stated the present invention can be said to provide a loading spout for free flowing particulate material, said spout comprising an inner tube and a shorter outer tube mounted through bearing means so as to be rotatable about and concentric with the inner tube with the inner tube extending beyond both ends of the outer tube, drive means to rotate the outer tube, at least one helical flight on the outer tube where the flight comprises an outer flight portion extending outwardly from the outer tube and an inner flight portion extending across the annular space between the inner and outer tubes and terminating closely adjacent the outside of the inner tube, and discharge openings in the wall of the inner tube within the outer tube whereby material can exit the inner tube into said annular space into the path of the flight inner portion. More specifically the invention can be said to provide a loading spout for free flowing particulate material, said spout comprising an outer tube with an upper mounting end and a lower outlet end, an inner tube disposed within the outer tube with an annular space therebetween, the inner tube has an upper inlet end which extends beyond the mounting end of the outer tube and a lower discharge end which extends beyond the outlet end of the outer tube, bearing means connecting the mounting end of the outer tube to the inner tube to allow rotation of the outer tube around the inner tube, drive means to rotate the outer tube around the inner tube, at least one helical flight on the outer tube with an outer portion of the flight around the outside of the outer tube and an inner portion of the flight on the inside of the inner tube and extending across the annular space between the inner and outer tubes and terminating closely adjacent the outside of the inner tube and discharge openings in the wall of the inner tube lying within the outer tube whereby material can exit the inner tube into said annular space into the path of the flight inner portion. A presently preferred embodiment of the present invention will now be described with reference to the accompanying illustration which is a schematic cross-sectional elevation of the loading spout provided by this invention. The loading spout of the invention is intended to be at the end part of a conveying system for discrete material. The loading spout is indicated l in the drawing and comprises an inner tube with an upper part 2 and a lower part 3 coupled together by bolts through mating flanges on the parts 2 and 3. This arrangement allows ready separation of the tube parts for servicing or replacement of the part 3 when it becomes worn. The tube part 2 can be circular or square or other cross-sectional shape and would typically be coupled at its upper end to a feed pipe fed by a conveyor. At the lower end of the tube part 2 there is a bearing flange 4 and a slew ring gear 5 is rotatably coupled to the bearing flange 4 by a bearing 6. The ring gear 5 is coupled to a slew collar 7 including a mounting flange 8 and preferably strengthening gussets 9. Whilst a ball type bearing 6 is illustrated it is to be understood that the ball bearing could be replaced by a low friction sleeve type bearing. The slew ring gear 5 is in mesh with a pinion 10 on the drive shaft 11 of a drive unit 12. The drive unit 12 includes an electric motor, as illustrated, but alternatively the motor may be a hydraulic motor or an internal combustion motor. The drive unit 12 is directly or indirectly sensitive to the reaction torque resulting from the loading on the ring gear 5. If an electric motor is used it is preferably of the variable voltage-variable frequency (W.VF) constant speed variable torque type. There is an outer tube 13 disposed concentrically around the inner tube 2,3. The outer tube 13 has a mounting end provided with a mounting flange 14 and the flange 14 is coupled to the mounting flange 8 of the slew collar by bolts and nuts 15 allowing the outer tube 13 to be readily demounted for service or replacement when it becomes worn. The outer tube 13 has a lower outlet end 16 and it is to be noted that the inner tube extends upwardly beyond the outer tube mounting end and below the outer tube outlet end 16. There is a helical flight 17 on the tube 13 with an inner flight portion 18 occupying the annular space between the inner tube part 3 and the outer tube 13 and lying closely adjacent the outer surface of the inner tube part 3. There is a matching outer flight portion 20 extending outwardly from the outside of the outer tube 13. It is to be understood that this is representative and more than one flight could be mounted on the tube 13 as design circumstances may require. The design requirements are discussed later herein. The inner tube part 3 has openings 21 in its wall, the function of the openings 21 will be described later. For the purpose of explanation the inclined side of a stockpile of material M is illustrated and it will be noted that the free ends of the tubes 3 and 13 both extend into the stockpile material M. The loading spout assembly just described is supported by a hoisting arrangement (not shown) whereby the loading spout can be raised so as reduce the penetration of the tubes 3 and 13 into the stockpile. The hoisting arrangement is also used to lower the loading spout to . a starting elevation at the commencement of a loading operation. In an operational sequence and assuming that there has been some discharge into a bin or like holder so as to create a stockpile M as illustrated, the following would occur. The material M would be fed into the pipework feeding into the tube part 2, as by a conveyor or the like. The material would fall by gravity through the tubes 2,3 and 13 and contribute to the stockpile M and at the same time the outer tube 13 would be rotated at a calculated speed by the drive unit 12. The rotation of the tube 13 and its helical flight 17 is in an anti-clockwise direction, that is, the underface of the flight 17 is dragged over the surface of the material M in a compacting sense. As the stockpile increases in height the end 16 of the rotating tube 13 will be buried deeper and deeper in the material M. This will cause an increase in the frictional resistance to the tube 13 rotating and this in turn will increase the torque loading on the drive unit 12. The increase torque loading on the drive unit 12 is allowed to increase to a level where a sensor associated with the drive unit 12 registers a torque value equal to predetermined maximum level. The sensor will then activate the hoisting arrangement and the loading spout will be elevated until the torque level falls to a predetermined minimum level. The hoisting movement would then be terminated. The process is repeated until the discharge of material through the loading spout is completed. It is to be noted that during the whole operation the outlet end of the tube part 3 and the end 16 of the tube 13 will lie below the top surface of the stockpile thereby preventing the creation of and circulation of dust. During the operation outlined above a condition will be reached where the M passing though the tube parts 2 and 3 will 'choke', that is, the material will no longer flow from the open end of the tube 3. When this condition occurs the material M commences to !0 discharge radially from the tube part 3 through the openings 21 and onto the upper surface of the flight portion 18. Because of the rotation of the tube 13 and vibration in the system and the effects of gravity the material will progress down the inclined upper face of the flight portion 18 and discharge into the stockpile through the annular space 19 between the tubes 3 and 13. It is to be understood that different materials have different characteristics, such as slump angle, 0 particle size, fluidity, and for this reason an apparatus as before described would be designed for a particular material. Design aspects likely to be effected by the characteristics of the material to be handled would be, the helical pitch of the flight 17, the relative dimensions of the flight portions 18 and 20, the diameter of the tube 13 (and thus the annular space 19), the size and distribution of the openings 21 and the length of the projection of the tube part 3 beyond the end 16 of the tube 13. The speed of rotation of the tube 13 would be designed around the above factors and the range of torque variation between maximum and minimum would be determined in the knowledge of the characteristics of the material being handled. If the apparatus was to be used to load material requiring components with characteristics different from those in place on the loading spout, conversion is simple. The bolts 15 would be removed and the tube 13 would be removed. The bolts securing the tube part 3 to the tube part 2 would be removed and the tube part 3 would be removed. This would be followed by replacement by a matched pair of tubes 3 and 13 for the different material. The foregoing is a description of a presently preferred embodiment of the invention. It is to be understood that changes can be made to the members herein described and illustrated without departing from the inventive concept as set forth in the following claims.

Claims: CLAIMS : 1. A loading spout for free flowing particulate material, said spout comprising an inner tube and a shorter outer tube mounted through bearing means so as to be rotatable about and concentric with the inner tube with the inner tube extending beyond both ends of the outer tube, drive means to rotate the outer tube, at least one helical flight on the outer tube where the flight comprises an outer flight portion extending outwardly from the outer tube and an inner flight portion extending across the annular space between the inner and outer tubes and terminating closely adjacent the outside of the inner tube, and discharge openings in the wall of the inner tube within the outer tube whereby material can exit the inner tube into said annular space into the path of the flight inner portion. 2. A loading spout for free flowing particulate material, said spout comprising an outer tube with an inner tube mounted upper mounting end and a lower outlet end, an inner tube disposed within the outer tube with an annular space therebetween, the inner tube has an upper inlet end which extends beyond the mounting end of the outer tube and a lower discharge end which extends beyond the outlet end of the outer tube, bearing means connecting the mounting end of the outer tube to the inner tube to allow rotation of the outer tube around the inner tube, drive means to rotate the outer tube around the inner tube, at least one helical flight on the outer tube with an outer portion of the flight around the outside of the outer tube and an inner portion of the flight on the inside of the inner tube and extending across the annular space between the inner and outer tubes and terminating closely adjacent the outside of the inner tube and discharge openings in the wall of the inner tube lying within the outer tube whereby material can exit the inner tube into said annular space into the path of the flight inner portion. 3. A loading spout as claimed in claim 2 wherein the said flight inner portion is wider than said flight outer portion. 4. A loading spout as claimed in claim 2 or claim 3 wherein said drive means includes a gear drive comprising a ring gear fixed to said outer tube and a meshing pinion gear on a rotatable drive shaft of a drive motor. 5. A loading spout as claimed in any one of claims 2 to 4 wherein said inner tube comprises an upper part and a removable lower part with a connection therebetween which lies within the outer tube and adjacent the mounting end thereof. 6. A loading spout as claimed in any one of claims 2 to 5 wherein the outer tube at its mounting end includes a collar which is coupled to said inner tube through said bearing means and which is fastened to said outer tube by removable fastenings. 7. A loading spout as claimed in any one of claims 2 to 6 where said drive means is torque sensitive and includes control means for the operation of lifting means for said loading spout, whereby said loading spout is elevated when a predetermined high torque condition is detected and the elevation is discontinued when a subsequent predetermined low torque condition is detected. 8. A loading spout as claimed in claim 7 where the drive means includes an electric motor of the variable voltage-variable frequency constant speed variable torque type.

Inventors: MAYER HANS PHILIPP, MAYER, HANS, PHILIPP
Applicants: MAYER HANS PHILIPP, MAYER, HANS, PHILIPP
Application year: 1992
Main classification: B65G69
IPC codes: B65G69