ZA200505597B - A conveyor belt cleaning mechanism - Google Patents

Description

THIS INVENTION relates to a conveyor belt cleaning system.

It is well known in relation to various industries, including particularly also in relation to aluminium smelters where aluminium is manufactured, to displace raw materials and bulk materials with the aid of a conveyor belt arrangement. Fine product particles, herein merely referred to as dust particles, of the material being conveyed, are known to attach themselves to the conveyor belt on which they are conveyed, either because the particles are damp or because of electrostatic charges that act between the particles and the conveyor belt. When a conveyor belt travels along its return path, dust particles can drop from the belt and this constitutes not only a pollution hazard, but results in substantial losses of the material being conveyed.

It is thus an object of this invention to provide a conveyor belt cleaning system that can serve to at least ameliorate the above problems.

South African Patent 2000/3313 discloses a conveyor belt dust separator unit that cooperates with a vacuum suction unit, the dust separator unit being located, in use, immediately beyond the location where a conveyor belt, having dust particles attached thereto, initiates its return path. The dust separator unit effectively separates the dust particles from the conveyor belt, while the vacuum suction unit provides for separated dust particles to be contained by being displaced along a suction line that leads to the suction unit. It is hence required to separate the dust particles from the air in which they p are suspended while displaced along the suction line, and then to reintroduce the dust particles back onto the conveyor belt line for downstream processing. Dust separation and reintroduction of dust particles onto a conveyor belt line, also present various problems, particularly because of the dust particle quantities involved and because the process has to be continuous. lt is thus also an object of this invention to provide a conveyor belt cleaning system that provides for effective dust particle separation and reintroduction of dust particles onto a conveyor belt line.

According to the invention there is provided a conveyor belt cleaning system, which includes a conveyor belt dust separator unit for separating dust particles from a conveyor belt, the dust separator unit defining a passage formation into which dust particles separated from a conveyor belt can pass; a vacuum suction unit connected in air communication with the passage formation defined by the conveyor beit dust separator unit via an air suction line, for displacing dust particles suspended in air from the conveyor belt dust separator unit through the suction line towards the vacuum suction unit; a cyclone separator connected in line with the air suction line for separating dust particles suspended in air displaced through the suction line from the air and collecting the separated dust particles in a storage compartment of the separator; a multi-stage filter system connected in line with the air suction line between the cyclone separator and the vacuum suction unit, the filter system having a storage compartment for collecting dust particles filtered from air passing through the filter system and incorporating a reverse pulse filter system for separating dust particles collected on filter elements of the filter system, to be collected in the storage compartment of the filter system; and feed means that permits feeding of dust particles collected in the storage compartment of the cyclone separator and in the storage compartment of the filter system, respectively, onto a conveyor belt line.

The conveyor belt dust separator unit of the conveyor belt cleaning system may include a pair of blades that are held in a substantially parallel, spaced configuration with respect to one another, the blades each defining an operative front end and an operative rear end and two sides along which the space defined between the blades are blocked to define a segment of the passage formation defined by the dust separator unit between the blades, extending from the front ends to the rear ends thereof, the blades having an operative width at least at the front ends thereof that permit the blades to extend across the entire width of the conveyor belt of a conveyor belt arrangement with which the conveyor belt cleaning system is to be used; and mounting means for mounting the conveyor belt dust separator unit on a conveyor belt arrangement in a location in which the blades of the dust separator unit are disposed in an operative configuration with respect to the conveyor belt of the arrangement, in which the front ends of the blades substantially touch the conveyor belt.

The front end of each blade of the pair of blades of the conveyor belt dust separator unit particularly defines a continuous linear edge, although it is envisaged also that the front end of the operative leading blade of the pair of blades may define a comb-type configuration with a series of spaced teeth extending across with width of the blade, while the front end of the operative trailing blade defines a continuous linear edge. The reference to a leading blade and a trailing blade clearly refers to the direction of displacement of a conveyor belt of a conveyor belt arrangement with respect to the conveyor belt dust separator unit when mounted in its operative configuration with respect to the conveyor belt arrangement.

Further according to the invention, the conveyor belt dust separator unit may include a brush element that is located operatively between the blades of the pair of blades and that can act on a conveyor belt of a conveyor belt arrangement on which the conveyor belt dust separator unit is operatively mounted, for agitating dust particles and brushing dust particles form the conveyor belt of the conveyor belt arrangement, for the passage of the dust particles into the passage formation defined by the dust separator unit, during use of the conveyor belt cleaning system. The brush element particularly is in the form of a nylon/brass brush that can serve also to eliminate static charges acting between a conveyor belt and dust particles to be separated therefrom.

The mounting means of the conveyor belt dust separator unit may include an adjustment arrangement for adjusting the position of the pair of blades of the dust separator unit with respect to the belt of a conveyor belt arrangement on which the dust separator unit is operatively mounted. It is envisaged in this regard that the blades will be exposed to wear and the adjustment arrangement will thus provide for the blades to be continuously positioned in a position in which the front ends thereof substantially touch the conveyor belt of a conveyor belt arrangement on which the dust separator unit is operatively mounted.

The conveyor belt cleaning system of the invention also may include a second equivalent conveyor belt dust separator unit, the two dust separator units being operatively positioned, in use of the conveyor belt cleaning system, to act on opposite sides of the conveyor belt of a conveyor belt arrangement at locations immediately beyond the location where the conveyor belt initiates its return path.

The vacuum suction unit of the conveyor belt cleaning system of the invention may comprises a side channel blower/motor unit having a safety cartridge filter that can serve to filter air entering the vacuum suction unit along the suction line thereof. In addition, the vacuum suction unit may have an exhaust side that includes a vacuum relief valve that is rendered operative, during use of the cleaning system, in response to the suction line being blocked. Still further, the vacuum suction unit may have an exhaust side that’includes an inlet filter cartridge at the inlet end thereof and that serves to prevent particles from entering this exhaust side in the event of upstream filtering of dust particles having failed, during use of the cleaning system. The inlet filter cartridge may be of a type that operatively acts to provide for shutdown of the suction unit in response to a differential pressure switch associated therewith sensing a differential pressure across the cartridge reaching a predetermined level, during use of the cleaning system. The vacuum suction unit still further may be associated with a vacuum gauge for measuring the vacuum in the suction line.

The cyclone separator of the conveyor belt cleaning system of the invention may comprises a conventional-type cyclone separator within which centrifugal forces serve to separate dust particles from the airline passing through the unit, the cyclone separator providing in the order of 99% dust particle separation efficiency.

Further according to the invention, the multi-stage filter system of the conveyor belt cleaning system may comprise a unit having a tangential material inlet, a dust particle storage compartment, a conical central discharge and an upper chamber housing the filter elements of the filter unit. The reverse pulse filter system may be a system known in the trade as an “Air Shock” filter (registered trade mark), hence comprising an electronically controlled automatic reverse jet cleaning system that provides for fine dust particles collecting on filter elements to be periodically pulse jetted into the storage compartment of the filter unit, during use of the cleaning system.

Still further, the filter elements of the multi-stage filter may be side mounted into a filter frame, each filter element being effectively isolated and sealed for separating the “dirty” side of each filter element from the “clean” side of each filter element.

The feed means of the conveyor belt cleaning system may include, in association with each of the storage compartment of the cyclone separator and the storage compartment of the filter unit, a discharge arrangement located along a discharge line leading from the storage compartment to a conveyor belt, onto which collected dust particles can be

Lo a J y discharged. Each discharge arrangement may include a set of pinch discharge valves that can alternately open and close to permit dust particles to enter a zone between them from a storage compartment and then to pass from the said zone onto a conveyor belt.

It will be understood that the exact configuration of the conveyor belt cleaning system of the invention is greatly variable, the final configuration of the system being determined by the operating requirements of the system in relation to the use thereof. The invention extends also to such variations of a conveyor belt cleaning system, which still incorporate the essential principles of the invention as hereinabove defined.

The invention extends also to a conveyor belt arrangement which includes at least one conveyor belt cleaning system, in accordance with the invention, as part thereof.

Further features of the invention are described hereafter with reference to an example of a conveyor belt cleaning system which is described hereafter with reference to the accompanying diagrammatic drawings. In the drawings:

Figure 1 illustrates schematically in diagram form the configuration of a conveyor belt cleaning system, in accordance with the invention:

Figure 2 shows in three dimensions the configuration of a conveyor belt dust separator unit forming a part of the system as shown in Figure 1;

Figure 3 shows an exploded three-dimensional view of the conveyor belt dust separator unit of Figure 2;

Figure 4 illustrates in" three dimensions the location of two conveyor belt dust separator units, as shown in Figure 2, in their operative configuration with respect to a conveyor belt of a conveyor belt arrangement; and

F

Figure 5 shows an exploded, diagrammatic, three-dimensional view of part of the conveyor belt cleaning system as illustrated in Figure 1.

Referring initially to Figure 1 of the drawings, a conveyor belt cleaning system, in accordance with the invention, is designated generally by the reference numeral 10.

The conveyor belt cleaning system 10 is shown in an operative configuration with respect to a conveyor belt arrangement that includes a conveyor belt 12 at the end of its conveyor path where it passes over conveyor belt rollers 14 and initiates its return path, i.e. at the location 16 as shown. it must be appreciated in this regard that the conveyor belt arrangement is a conventional arrangement as is commonly used, for example, in aluminium smelters, the conveyor belt arrangement thus including a support structure (not shown) that supports the conveyor belt rollers of the arrangement on which the conveyor belt 12 is displaced. This is not described in further detail herein.

The conveyor belt cleaning system 10 includes a top conveyor belt dust separator unit 18 and a bottom conveyor belt dust separator unit 20, that act on the conveyor belt 12 on opposite sides thereof immediately downstream from the location 16, where the return path of the conveyor belt 12 initiates. The configuration of the conveyor belt dust separator units, 18 and 20, are described in more detail hereafter, the conveyor belt dust separator units, 18 and 20, serving particularly to separate dust particles that have attached themselves to the conveyor belt 12, as a result of being damp or because of electrostatic charges acting between the dust particles and the conveyor belt.

Each conveyor belt dust separator unit 18, 20, defines a passage formation which is connected in communication with a vacuum suction unit 22 via a suction line 24, thus providing for dust particles separated from the conveyor belt 12 to be displaced, while suspended in air, along the suction line 24, towards the vacuum suction unit 22.

The suction line 24 has a cyclone separator 26 located in line therewith, the cyclone separator providing for the separation of dust particles and air passing through the suction line, separated dust particles being collected in a storage compartment 28 linked to the cyclone separator 26. It is envisaged that the cyclone separator will be a high efficiency separator, e.g. in the order of 99% efficient, in relation to the separation of dust particles and air, remaining dust particles and air continuing along the suction line 24 towards a multi-stage filter system 30 which is located between the cyclone separator 26 and the vacuum suction unit 22. The multi-stage filter system provides for the separation of dust particles still contained within the suction line from air, the filter unit also including a storage container 32 within which separated dust particles can be collected. The operation of the multi-stage filter system 30 is described in more detail hereafter. It is envisaged that air passing from the multi-stage filter system 30 will be substantially clear form dust, this air hence passing to the vacuum suction unit 22 from which the air is discharged to the atmosphere, via an exhauster 23 of the unit 22.

The conveyor belt cleaning system 10 includes further, in association with each of the storage containers, 28 and 32, a set of pinch discharge valves 34, the valves being operable as described hereafter in order to provide for the discharge of separated dust particles onto a conveyor helt line 36 for onward processing. It will thus be understood that the vacuum belt cleaning system firstly will serve to prevent dust particle pollution resulting from dust particles separating from the conveyor belt 12, having initiated its return path, while it serves- also to substantially reduce material losses as a result of dust particles being “lost”.

Referring now also to Figures 2 and 3 of the drawings, each conveyor belt dust separator unit 18, 20 includes a housing 40 which carries a pair of blades, the blades including an operative leading blade 44 and an operative trailing blade 42, both the blades defining a substantially continuous linear blade edge. The housing 40 serves to define an enclosed passage formation commencing between the blades, 42 and 44, leading from the front ends of the blades towards the rear ends thereof. The passage formation is connected in communication with a flexible pipe 48 (see Figure 4) that forms a part of the suction line 24, in the operative configuration of the conveyor belt dust separator units. The leading blade 44 may also define a comb-like structure having teeth separated by gaps between them (not shown in detail in the drawings).

Each conveyor belt dust separator unit 18, 20 includes also mounting brackets 52 that can support the dust separator unit in its required configuration with respect to a conveyor belt arrangement, as described more clearly hereinafter with reference to

Figure 4 of the drawings, the mounting brackets 52 carrying the housing 40 via suspension elements 54 and auxiliary brackets 50 that are secured to the housing, providing essentially an adjustable coupling between the mounting brackets 52 and the auxiliary brackets 50. Adjustment rods 56 can act on the above arrangement for adjusting the position of the blades of the dust separator unit with respect to the belt of a conveyor belt arrangement, as is clearly apparent from Figure 3 of the drawings.

Each conveyor belt dust separator unit 18, 20 includes also a brush element in the form of a nylon/brass brush 58 that is held in a spaced configuration between the two blades 42 and 44, the overall construction of each conveyor belt dust separator unit being rendered clearly apparent by the exploded view of the components and parts thereof as is shown particularly in Figure 3 of the drawings.

Referring now also to Figure 4 of the drawings, the operative location of the conveyor belt dust separator units, 18 and 20, are illustrated in more detail therein, the mounting of each unit to the conveyor belt support structure of the conveyor belt arrangement via the mounting brackets 52 not being illustrated in detail. It will be understood that with the mounting brackets 52 fixedly located, the adjustment rods 56 can serve to adjust the location of each dust separator unit with respect to the conveyor belt, thus ensuring that the blades of the dust separator units remain in a position in which they substantially touch the conveyor belt. The brush 58 serves to agitate dust particles attached to the conveyor belt and being disposed between the blade 44 and the blade 42, the suction of the vacuum suction unit 22 serves to separate the dust from the belt. The brush serves also to release the static charge of the conveyor belt.

The mounting arrangement between the mounting brackets 52 and auxiliary brackets 50, i.e. the arrangement of the suspension elements 54, particularly permit adjustment of the positioning of the dust separator units, which will be necessary from time to time as a result of wear occurring on the blades of the dust separator units during use thereof. It is particularly preferred that the blades must remain in a position in which they substantially touch the conveyor belt.

Referring now particularly to Figure 5 of the drawings, the cyclone separator 26 is connected in line with the suction line 24 in a configuration in which dust laden air tangentially enters the separator, centrifugal forces acting on dust particles resulting in the dust particles separating from the air and dropping into the storage container 28, while remaining air centrally exits from the separator 26 via an outlet 60 as illustrated.

The cyclone separator is essentially of a conventional type and its configuration and mode of operation therefore is not described in any further detail herein.

Air exiting from the cyclone separator also enters the outer housing 61 of the multi- stage filter system 30 tangentially, resulting in a substantial portion of dust particles still suspended in the suction line to drop into the storage compartment 32 as a result of centrifugal forces acting thereon, the remaining air and dust particles travelling upwards within the filter system 30 towards a filter casing 62 that carries filter elements 64, the filter elements being side mounted into the casing 62 in a configuration in which they are effectively isolated and sealed, for separating the “dirty” side of each filter element from the “clean” side of each filter element. The condition of the filter elements is monitored by a differential pressure gauge and switch.

The multi-stage filter system includes also an air filter regulator and a reverse pulse filter system which is automatically controlled and which provides for reverse air jets to displace fine dust particles collected on the filter elements along a reverse path into the storage compartment 32, thus permitting continuous use of the filter unit, insofar as the filter elements are effectively kept clean. A manhole plate 66 permits inspection of the interior of the filter casing 62, which is required to ensure the continuous effective operation of the multi-stage filter system 30.

Air exiting from the multi-stage filter system 30 is then displaced towards the vacuum suction unit 22, particularly via an air cleaner 68 that includes a primary filter cartridge and a safety filter cartridge, thus ensuring that dust particles cannot enter the suction unit. The suction unit particularly is a channel blower/motor unit, with the filter arrangement serving as a safety arrangement to protect the vacuum suction unit in case upstream filtering’ of dust particles has failed. Shutdown of the suction unit particularly will occur in response to a differential switch associated therewith sensing a differential pressure across the filter cartridges reaching a predetermined level.

The two sets of pinch discharge valves 34 particularly control the discharge of dust particles collected onto a conveyor belt line 36, operation of these valves being controlled so that opening and closing thereof occur alternately, the valve closer to each storage compartment opening while the other valve is closed, to permit collected dust particles to be displaced under gravity into the space between the two valves, whereafter the valve closest to the compartment closes and the other valve opens, permitting dust particles to fall onto the conveyor belt line 36. By having at least one of each pair of valves continuously closed, interference with the air displacement clearly will not occur, i.e. there will be no tendency for air to be sucked into the suction line via the path defined along the line along which the pinch discharge valves 34 are located.

The conveyor belt cleaning system of the invention includes also, in line with the suction line in a location near the conveyor belt dust separator units 18, 20, knife gate valves 70 that can be manually opened and closed, thus providing for isolation of the dust separator units and the remainder of the system, as a result of malfunctioning of the system. The knife gate valves 70 are also used to balance the airflow, particularly to accommodate the variable dust load on the top and bottom side of the conveyor belt and to provide for just the right amount of suction.

It will be understood that the operation of the conveyor belt cleaning system of the invention will be associated with suitable electronic controls and control circuitry that will provide for the effective continuous operation of the system, the control circuitry particularly controlling operation of the pinch discharge valves 34 and of the reverse jet cleaning system associated with the multi-stage filter system 30, which are required in order to permit continuous operation of the cleaning system, which is essential in relation to the use thereof. The controls and control circuitry also serve to protect the system, insofar as shut-down may be required in the case of malfunctioning within the system, e.g. the suction line becoming blocked, or the like.

The vacuum belt cleaning system, however, is considered a reliable system that is economically operable for dealing with dust particles attaching to conveyor belts, wherever the problem as described above may occur. It will be appreciated that the exact configuration of the conveyor belt cleaning system is greatly variable, while still incorporating the essential components and parts as defined and described above, as well as the principles of the system as defined and described above. The invention accordingly extends to all such different configuration systems which still incorporate these essential components and parts and the said principles.

Claims (21)

1. A conveyor belt cleaning system, which includes a conveyor belt dust separator unit for separating dust particles from a conveyor belt, the dust separator unit defining a passage formation into which dust particles separated from a conveyor belt can pass; a vacuum suction unit connected in air communication with the passage formation defined by the conveyor belt dust separator unit via an air suction line, for displacing dust particles suspended in air from the conveyor belt dust separator unit through the suction line towards the vacuum suction unit; a cyclone separator connected in line with the air suction line for separating dust particles suspended in air displaced through the suction line from the air and collecting the separated dust particles in a storage compartment of the separator; a multi-stage filter system connected in line with the air suction line between the cyclone separator and the vacuum suction unit, the filter system having a storage compartment for collecting dust particles filtered from air passing through the filter system and incorporating a reverse pulse filter system for separating dust particles collected on filter elements of the filter system, to be collected in the storage compartment of the filter system; and feed means that permits feeding of dust particles collected in the storage compartment of the cyclone separator and in the storage compartment of the filter system, respectively, onto a conveyor belt line.

2. A conveyor belt cleaning system as claimed in Claim 1, in which the conveyor belt dust separator unit includes a pair of blades that are held in a substantially parallel, spaced configuration with respect to one another, the blades each defining an operative front end and an operative rear end and two sides along which the space defined between the blades are blocked to define a segment of the passage formation defined by the dust separator unit between the blades, extending from the front ends to the rear ends thereof, the blades having an operative width at least at the front ends thereof that’permit the blades to extend across the entire width of the conveyor belt of a conveyor belt arrangement with which the conveyor belt cleaning system is to be used; and mounting means for mounting the conveyor belt dust separator unit on a conveyor belt arrangement in a location in which the blades of the dust separator unit are disposed in an operative configuration, with respect to the conveyor belt of the arrangement, in which the front ends of the blades virtually touch the conveyor belt.

3. A conveyor belt cleaning system as claimed in Claim 2, in which the front end of each blade of the pair of blades defines a continuous linear edge.

4. A conveyor belt cleaning system as claimed in Claim 2, in which the front end of the operative leading blade of the pair of blades defines a comb-type configuration with a series of spaced teeth extending across the width of the blade and in which the front end of the operative trailing blade defines a continuous linear edge.

5. A conveyor belt cleaning system as claimed in any one of Claims 2 to 4, in which the conveyor belt dust separator unit includes a brush element that is located operatively between the blades of the pair of blades and that can act on a conveyor belt of a conveyor belt arrangement on which the conveyor belt dust separator unit is operatively mounted, for agitating dust particles and brushing dust particles from the conveyor belt of the conveyor belt arrangement, for the passage yr of the dust particles into the passage formation defined by the dust separator unit, during use of the conveyor belt cleaning system.

6. A conveyor belt cleaning system as claimed in Claim 5, in which the brush element is in the form of a nylon/brass brush that can serve to eliminate static charges acting between a conveyor belt and dust particles to be separated therefrom.

7. A conveyor belt cleaning system as claimed in any one of Claims 2 to 6, in which the mounting means of the conveyor belt dust separator unit includes an adjustment arrangement for adjusting the position of the pair of blades of the dust separator unit with respect to the belt of a conveyor belt arrangement on which the dust separator unit is operatively mounted.

8. A conveyor belt cleaning system as claimed in any one of the preceding claims, which includes a second equivalent conveyor belt dust separator unit, the two dust separator units being operatively positioned, in use of the conveyor belt cleaning system, to act on opposite sides of the conveyor belt of a conveyor belt arrangement at locations immediately beyond the location where the conveyor belt initiates its return path.

9. A conveyor belt cleaning system as claimed in any one of the preceding claims, in which the vacuum suction unit comprises a side channel blower/ motor unit having a safety cartridge filter that can serve to filter air entering the vacuum suction unit along the suction line thereof.

10. A conveyor belt cleaning system as claimed in any one of the preceding claims, in which the vacuum suction unit has an exhaust side that includes a vacuum relief valve that is rendered operative, during use of the cleaning system, in response to the suction line being blocked.

. . i

11. A conveyor belt cleaning system as claimed in any one of the preceding claims, in which the vacuum suction unit has an exhaust side that includes an inlet filter cartridge at the inlet end thereof and that serves to prevent particles from entering this exhaust side in the event of upstream filtering of dust particles having failed, during use of the cleaning system.

12. A conveyor belt cleaning system as claimed in Claim 11, in which the inlet filter cartridge operatively acts to provide for shut-down of the suction unit in response to a differential pressure switch associated therewith sensing a differential pressure across the cartridge reaching a predetermined level, during use of the cleaning system.

13. A conveyor belt cleaning system as claimed in any one of the preceding claims, in which the vacuum suction unit is associated with a vacuum gauge for measuring the vacuum in the suction line.

14. A conveyor belt cleaning system as claimed in any one of the preceding claims, in which the multi-stage filter system comprises a unit having a tangential material inlet, a dust particle storage compartment, a conical central discharge and an upper chamber housing the filter elements of the filter unit.

15. A conveyor belt cleaning system as claimed in any one of the preceding claims, in which the reverse pulse filter system comprises an electronically controlled automatic reverse jet cleaning system that provides for fine dust particles collecting on filter elements to be periodically pulse jetted into the storage compartment of the filter unit, during use of the cleaning system.

16. A conveyor belt cleaning system as claimed in any one of the preceding claims, in which the filter elements of the multi-stage filter system are side mounted into a filter frame, each filter element being effectively isolated and sealed for separating the “dirty” side of each filter element from the “clean” side of each filter element,

17. A conveyor belt cleaning system as claimed in any one of the preceding claims, in which the feed means includes, in association with each of the storage compartment of the cyclone separator and the storage compartment of the filter unit, a discharge arrangement located along a discharge line leading from the storage compartment to a conveyor belt, onto which collected dust particles can be discharged.

18. A conveyor belt cleaning system as claimed in Claim 17, in which each discharge arrangement includes a set of pinch discharge valves that can alternately open and close to permit dust particles to enter a zone between them from a storage compartment and then to pass from the said zone onto a conveyor belt.

19. A conveyor belt arrangement which includes at least one conveyor belt cleaning system as claimed in any one of Claims 1 to 18.

20. A conveyor belt cleaning system substantially as described in the specification with reference to and as illustrated in the accompanying drawings.

21. A conveyor belt arrangement substantially as described in the specification with reference to and as illustrated in the accompanying drawings. DATED THIS 11™ DAY OF JULY 2005 ADAMS & ADAMS APPLICANTS PATENT ATTORNEYS