HOPPER PROTECTION AND LEVEL MONITORING

Field of the Invention

The present invention relates to protecting, and monitoring a level of material in, a hopper.

Background of the Invention

In various types of mining, ore bearing rocks are stockpiled in or on one or more hoppers that feed the rocks onto underlying conveyors which in turn transport the rocks to a remote location for subsequent processing or handling. The rocks which are often massive and very hard are dropped from an elevated conveyor to form and feed the stockpile. If a hopper is empty or near empty the dropped rock can damage the hopper or the underlying conveyor. It is therefore preferably that the hopper is filled to a minimum level with rocks to dissipate the energy of subsequently dropped rocks thereby protecting the hopper and conveyor.

Visually detecting the level of material in the hopper may not always be possible or straight forward because the stockpile may visually obscure one or more of the hoppers. For example, when there are three or more hoppers in a row, one or more of the middle hoppers may not be able to be seen. It is possible that one or more of the middle hoppers will empty first, but this will be unknown because the height of the surrounding bulk material obscures any view of the middle hopper(s).

While the present invention was developed having regard to the handling of ore, embodiments of the invention are not limited to application in mining and may be applicable to other industries requiring the handling of bulk materials.

Summary of the Invention

One aspect of the invention provides a method of protecting a hopper from impact damage from bulk material in a bulk material handling facility where bulk material is dropped to the hopper from a bulk materials feeder and the bulk material is removed from a lower end of the hopper, the method comprising:

processing sensor signals from one or more sensors supported on the hopper which receives the bulk material, the or each sensor signal being indicative of whether or not material in the hopper substantially covers or overlies the respective sensor in the hopper, to determine a level of bulk material in the hopper; and operating the bulk materials handling facility in a manner dependant on the determined level of bulk material in the hopper .

Operating the bulk materials handling facility may comprise operating the bulk materials facility to maintain a minimum level of bulk material in the hopper.

Operating the bulk materials handling facility may comprise controlling the bulk materials feeder to vary a position from where the bulk material is dropped when the level of material in the hopper passes a designated level.

Operating the bulk materials handling facility may comprise controlling a feed rate of the bulk material dropped from the feeder.

Operating the bulk materials handling facility comprises controlling a rate of removal of bulk material from the lower end of the hopper.

Operating the bulk materials handling facility comprises trigging an alert when the level of material in the hopper passes a designated level.

The method may comprise positioning a plurality of the sensors so as to be spaced apart and at substantially the same height in the hopper.

The method may comprise positioning a plurality of the sensors at a plurality of differing heights in the hopper.

The method according may comprise providing the or each sensor as a light detecting sensor.

The method may comprise providing a light source positioned to illuminate an inside of the hopper and wherein the light sensor produces the signal on the basis of light from the light source which enters the light sensor from inside the hopper.

The method may comprise providing the sensors in respective fasteners which attach wear plates to an inside surface of the hopper.

A further aspect of the invention may provide a hopper for receiving bulk material comprising: a sensor positioned in the hopper; the sensor being arranged to produce a signal indicative of whether there is material in the hopper that covers the sensor.

The sensor may comprise a light conductor and a light detector wherein the light conductor provides a communication path for light to the light detector, the light conductor positioned to be covered or overlaid by material in the hopper when the level of material is above the position of the sensor.

The light detector may produce the signal indicative of light passes from open air through the light conductor to the light detector.

The hopper may comprise a light source arranged to transmit light through the light conductor to an inside of the hopper and wherein the signal is produced based on a portion of light from the light source reflected back to the sensor from inside the hopper.

The hopper may comprise one or more wear plates on an inside of the hopper and wherein the sensor is incorporated in a fastener used to fasten one of the wear plates to the hopper.

A further aspect of the invention may provide a system for monitoring a level of material in a hopper comprising; a hopper for receiving bulk material; an sensor positioned at a designated height in the hopper, the sensor arranged to produce a signal indicative of whether there is material in the hopper that covers the sensor; and a processor for determining whether a level condition of material in the hopper is met based on the signal.

The sensor may comprise a light conductor and a light detector, the light conductor providing a communication path for light to the light detector, the light conductor positioned to be covered or overlaid by material in the hopper when the level of material is above the position of the sensor.

The light detector may produce the signal indicative of light passes from open air through the light conductor to the light detector.

The system may comprise a light source arranged to transmit light through the light conductor to an inside of the hopper and wherein the signal is produced based on a portion of light from the light source reflected back to the sensor from inside the hopper.

Alternately or additionally the system may comprise a flood light source which is arranged to illuminate inside of the hopper.

Alternately or additionally the system may comprise a modulated light source for illuminating inside of the hopper.

In an embodiment the processor is configured to trigger an alert when the level of material in the hopper passes a designated height.

In an embodiment the processor is configured to control an apparatus which affects the level of material in the hopper when the level of material in the hopper passes a designated height.

In an embodiment the processor is configured to control an apparatus for filling the hopper with material when the level of material in the hopper passes a designated height.

In an embodiment the processor is configured to control an apparatus for emptying the hopper of material when the level of material in the hopper passes a designated height.

According to a further an aspect of the present invention there is a method of monitoring a level of material in a hopper comprising: obtaining one or more sensor signals from one or more sensors

positioned within the hopper which receives bulk material, the or each sensor signal being indicative of whether or not material in the hopper substantially covers the respective sensor in the hopper; and determining whether a level condition is met based on the one or more sensor signals.

In an embodiment determining whether a level condition is met comprises determining whether the material in the hopper is above or below a specified level in the hopper.

In an embodiment the method comprises positioning a plurality of the sensors so as to be spaced apart and at substantially the same height in the hopper.

In an embodiment the method comprises positioning a plurality of the sensors at a plurality of differing heights in the hopper.

In an embodiment taking the or each sensor reading comprises detecting the presence or absence of ambient light or flood light striking the respective sensor.

In an embodiment the method comprises projecting light towards the or each sensor, wherein taking the reading from the or each sensor comprises determining whether the projected light is received by a detector of the sensor.

In an embodiment the projected light is received by the detector when the sensor is not covered by material.

In an embodiment the method comprises projecting light through the sensor such that it is reflected onto a detector of the sensor when the sensor is covered with material.

According to an aspect of the present invention there is a hopper for receiving bulk material comprising: a sensor positioned in the hopper; wherein the sensor is arranged to produce a signal indicative of whether there is material in the hopper that covers the sensor.

In an embodiment the sensor comprises a hardened exterior portion which is resistant to wear from material handled by the hopper.

In an embodiment the sensor comprises a light conductor that conveys light to a light detector, wherein the light conductor is arranged to be covered by material in the hopper when the level of material is above the position of the sensor.

In an embodiment the sensor comprises a light detector arranged to produce the signal according to whether light passes from open air through the light conductor to the light detector.

In an embodiment the sensors comprise a light source arranged to project light through the light conductor so that the signal is produced based on whether light passes to open air from the light source.

In an embodiment the sensors comprise a light detector arranged to produce the signal according to whether light is reflected on to the light detector by material covering the sensor.

According to an aspect of the present invention there is a system for monitoring a stockpile comprising: a hopper for receiving at least a portion of a stockpile; a sensor positioned at a designated height in the hopper, the sensor arranged to produce a signal indicative of whether there is material in the hopper that covers the sensor; and a processor for determining whether a level condition is met based on the signal.

According to an aspect of the present invention there is a method of monitoring a stockpile comprising: positioning one or more sensors in a hopper which receives at least a portion of the stockpile; taking one or more sensor readings from the one or more sensors, the or each sensor reading being an indication of whether or not material of the stockpile substantially covers the respective sensor in the hopper; and determining whether a level condition is met based on the signal.

According to an aspect of the present invention there is a method of installing a level monitoring system in a hopper comprising: positioning a sensor at a designated height in the hopper, the sensor arranged to produce a signal indicative of whether there is material in the hopper that covers the sensor, such that when used one or more sensor signals are obtained from the sensor, the sensor signal being indicative of whether or not material in the hopper substantially covers the respective sensor in the hopper so that a determination as to whether a level condition is met can be made based on the signal.

According to an aspect of the present invention there is a sensor for installing into a hopper comprising: means for generating a signal when installed for use, the signal being indicative of whether or not material in the hopper substantially covers the respective sensor in the hopper so that a determination of whether a level condition is met can be made based on the signal.

Brief Description of the Drawings

In order to provide a better understanding of the present invention embodiments will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 shows a cross sectional view of a stockpile monitoring system according to an embodiment of the present invention;

Figure 2 shows a cross sectional view of a sensor of the monitoring system of Figure 1 , which has been installed in a hopper according to an embodiment of the present invention;

Figure 3 shows the sensor of Figure 2 having been uncovered due to a drop in the height of bulk material in the hopper; and

Figure 4 is a schematic block diagram of a stockpile monitoring system according to an embodiment of the present invention.

Description of Exemplary Embodiments

Figure 1 shows a mineral handling facility 10 comprising a surface 12 upon which bulk material in the form of ore is deposited to form a stockpile 14. A plurality of hoppers 30, 40 and 44 each open at their respective upper ends onto the surface 12 and feed ore from the stockpile 14 onto respective underlying conveyors. Specifically hopper 30 feeds conveyor 34, hopper 40 feeds conveyor 42 and hopper 44 feeds conveyor 46.

A full stockpile 14 is shown by phantom line 16. When the rate of feed onto the stockpile is the same as the accumulative rate of feed from the hoppers to the conveyors, and assuming a substantially uniform fee rate for each hopper, the stockpile will approximately maintain the profile 16. However, when the accumulative rate of feed onto the conveyors is higher than the replenishment rate of the stockpile 14, the stockpile 14 diminishes and may form mounds 18 and 20. In this embodiment the mound 20 in the middle part of the stockpile 14 is smaller than to the outer mound 18, for example because conveyor 34 has been running more, or a at greater rate, than conveyors 44 and 46. The shape of mound 20 is peaked due to it being topped up by ore from a feeder 48. Mounds 18 are in or above respective hoppers 40 and 44, while mound 20 is in or above the hopper 30. Depending on the location of a control room in the facility 10 and/or due to the height of mounds 18, the height of mound 20 may be obscured from view of a controller of the handling facility 10.

In the embodiment in Figure 1 the mound 20 has diminished to an extent that its envelope 22 lies inside the hopper 30 and exposes an inside surface at an uppermost portion 58 of the hopper 30. The envelope is the portion of the mound that is projects into the air and thus does not contact a side wall of the hopper (or other containing structure). If the mound 20 diminishes further, a greater portion of the inside surface of the hopper 30 will be exposed, and the level or height of the mound 20 will reduce. The greater the exposed portion of the inside surface of the hopper 30 the greater the risk of damage by subsequently dropped material. The ultimate position is that the mound 20 is diminished to nothing leaving the entire inside surface of the hopper 30 as well as the underlying conveyor 34 exposed. If material were now to be dropped by the feeder 48 from directly above the hopper 30, one or both of the hopper 30 and conveyor could be damaged to the extent of requiring repair incurring not

only maintenance costs but potentially greater cost in lost production time.

With a view to reducing the risk of damage to and protecting a hopper, a monitoring system 100 (see Fig 4) is provided. The system 100 may monitor the entire facility 10, i.e. each of hoppers 30, 40 and 44. However for ease of description, system 100 is described in the present embodiment in relation to hopper 30 only. Thus in this embodiment the hopper monitoring system 100 comprises one or more sensors, and in this example, sensors 50, 52, 54 and 56 installed in the hopper 30. Sensors 50 and 52 are at substantially the same level and spaced apart from one another. The sensors 50 and 52 will be exposed when the mound 20 is diminished to an extent that its envelope drops to below the level of the sensors 50 and 52. Sensors 54 and 56 are at the same level as each other and spaced apart but located below sensors 50 and 52. In this example they are still covered by the mound 20.

The sensors 50, 52, 54 and 56 are arranged to produce a signal indicative of whether there is material in hopper 30 that covers or otherwise overlies the respective sensor. Accordingly readings from the sensors 50, 52, 54 and 56 can be used to determine the degree of exposure, if any, of the inside surface of the hopper. As a corollary to this, readings from the sensors 50, 52, 54 and 56 can be used to determine whether the envelope 22 of the mound 20 passes a specified level (by dropping or rising) at which one or more of the sensors are revealed or covered.

Figure 2 shows sensor 50 in more detail. The hopper 30 comprises side wall 62 which is lined by wear plates 60. The wear plates 60 sacrificially wear instead of the side wall 62. The sensor 50 is incorporated within a fastener used to hold the wear plate 60 to the side wall 62. This embodiment of the fastener comprises a head 70 and threaded shaft 72, and is secured in place by a nut 74. The shaft 72 passes through a hole in the side wall 62. The head 70 sits within a recess of the wear plate 60 so as to be flush with a surface 32 of the wear plate 60. In one embodiment, the head 70 is hardened so as to be resistant to wear. The head 70 may be hardened to at least the hardness of the wear plate 60.

Extending through the head 70 and the shaft 72, is a light transmission medium taking the form in this embodiment of an optical conductor 76, such as a clear

plastic rod. The optical conductor 76, at an end proximal the head 70, is flush with the surface 32; and, at an opposite end proximal the nut is optically coupled to an optical detector unit 78 which is able to detect light passing down the optical conductor 76. The optical detector unit 78 converts the light into a signal, which may be conveyed by a lead 80 elsewhere for processing. The light detector unit 78 may comprise any suitable photodetector.

It can be seen in Figure 2 that the sensor 50 is covered by the bulk material of mound 20. Thus no or little light is able to pass through the optical conductor 76 from the end adjacent the inside surface 32 of the hopper 30. The signal from the light detector unit 78 is representative or indicative of the amount of light entering the conductor 78 and thus of the degree of exposure, or conversely cover, of the inside surface of the hopper 30.

In contrast, in Figure 3, the level of the bulk material of mound 20 has dropped so as to expose the optical conductor 76. Thus the signal produced by the light detector unit 78 will be different to that produced for Fig 2 and will be representative of the inside surface 32 of the hopper 30 being exposed or uncovered from the bulk material.

The system 100 may be able to determine whether or not the optical conductor 76 is covered by material in the hopper 30 a number of ways. In one example, the light detector unit 78 can sense ambient light, flood light or projected modulated light which enters the optical conductor 76 and is conducted through the optical conductor 76 onto the detector unit 78. In this example the system 100 may include a corresponding flood light source or modulated light source which illuminate the inside of the inside of the hopper. Modulated light may be used to distinguish background light and can be demodulated by, for example, filtering, after detection by the detector unit 78.

Alternatively, light can be directed through the optical conductor 76 form an end adjacent the unit 78 and emitted from the end adjacent the head 70. When material covers the optical conductor 76, some of the emitted light will be reflected back down the optical conductor 76. The amount of light reflected off material covering the sensor 50 is measured by the unit 78. The light may be provided by a suitable light source, such as a LED which produces light at a wavelength suitable for reflection by the material for in the stockpile 14. In this

case, when the optical conductor 76 is covered, some of the light will be reflected back and can thus be detected. When the optical conductor 76 is uncovered, no or less light will be reflected back. The absence or reduction in of reflected light can is representative of the sensor 50, and thus the adjacent portion of the inside surface of the hopper 30, being uncovered. This embodiment can be employed when there is little ambient light, for example if the hoppers are operated at night. In a further embodiment, the system 100 may operate in a dual mode manner having a first mode without using the light source and a second mode using the light source. Switching between the first and second modes can be controlled in a number of ways, for example, by a timer circuit or measuring ambient light at a place not obscured by the stockpile.

In one embodiment a number of sensors positioned around the inside wall of the hopper 30 can vary, for example, only one sensor 50 may be employed. In some instances it may be preferable to have a number of sensors at the same height (e.g. 50 and 52) so that if one of the sensors detects that the drop in the surface 22 has revealed the sensor, this will be detected as early as possible, even though the envelope 22 may be uneven and not all of sensors at the same height may be revealed.

Furthermore, other sensors may be positioned at different heights (eg 50 and 54). In this case the sensors may be used to detect the level of material within the hopper 30, such that as progressively lower sensors are uncovered the progressive drop in the level of material in the hopper and thus the degree of exposure of the inside surface of the hopper, can be determined. Conversely, if sensors are progressively covered then it can be determined that the height of the material has increased and the degree of exposure decreased. The expressions "height of material in (or within) the hopper" and "level of material in (or within) the hopper" are intended to denote the height or level of material contacting the inside surface of the hopper. This corresponds with the level of the base of the envelope 22 of a mound in the hopper. Due to the nature of the bulk material it forms a mound when stockpiled. The peak of the mound may be above an upper edge of the hopper but the base of the envelope 22 is below the upper edge of the hopper thereby leaving a portion of the inside surface of hopper uncovered or exposed. This is illustrated in Figure 1 with mound 20.

In one particular arrangement the sensors may be helically positioned around

the hopper wall. More than one helix of sensors may also be provided on the wall of the hopper 30.

Each sensor need not be formed within a fastener. However, when the sensors are formed in a respective fastener, it is envisaged that sensors will be positioned at appropriate securing points of the wear plates 60 to the inside of the hopper 30.

In some embodiments the sensor may operate as a wear sensor as described in WO2006/081610, WO 2007/128068 or AU 2007906615, the contents of which are incorporated herein by reference.

The lead 80 may be connected to a processor for monitoring the sensors. Instead of wired leads 80 from each of the sensors, the sensors may be wirelessly connected to the processor.

Referring to Figure 4, the hopper level monitoring system 100 is shown, as comprising, in addition to the sensors 50, 52, 54, 56: a processor 102, memory 104 and an output 108. The system 100 may also comprise a mass storage device, such as hard disk drive 106. The output may be connected to one or more of a display 110, an audio device, such as a speaker 112, a controller 114 of a driver motor of the conveyor 34 and/or a controller 116 of a drive motor of a conveyer of the feeder 48.

In one configuration, the processor 102 may be controlled by appropriate instructions of a computer program, which is stored in the memory 104 or some other suitable storage medium. The computer program may be loaded into the memory 102 from the hard disk drive 106. In an embodiment, when the computer program is executed, the processor 102 is controlled such that when one of the sensors is revealed an alert is generated and sent to the output 108. This may indicate to an operator that the conveyor 34 should be switched off or slowed so as to prevent a further drop in the height of the mound 20. The alert may be displayed on display 110 or information may be provided to the operator in some other way, such as by a sound emitted from speaker 112. Alternatively or additionally the alert may be a signal that automatically controls the controller 114 of the conveyor 34.

Furthermore, the processor 102 may be controlled by the computer program so that when the sensors are covered, an alert is produced by the output 108 indicating to the operator to restart or speed up the conveyor 34. Alternatively the processor 102 may be controlled by the computer program so that when the sensors are covered, a control signal is provided from the output 108 to the controller 114 for restarting or speeding up the conveyor 34.

In an embodiment, the signal can be used to control the controller 116 to control the output from the feeder 48, by either turning off or turning on the feed or altering the feed rate according to the level of material in the hopper 30. Alternatively the position of the feeder 48 may be moved so as to deposit further bulk material elsewhere on the stockpile 14 in a manner that will not damage the hopper 30. Such movement may be lateral to the stockpile, that is left or right on the page of Figure 1 or it may be in a longitudinal direction, that is, into or out of the page of Figure 1 , or in some other direction.

Furthermore, the alert can cause an audio/visual alarm to be triggered, to draw the level of the stockpile to the attention of an operator.

As indicated previously, hoppers 40 and 44 may also be installed with sensors which are monitored by the processor in a similar fashion. The processor 102 may also control conveyors 42 and 46 so as to automate the stockpile feed and removal process.

Modifications and variations as would be apparent to a skilled person are intended to fall within the scope of the present invention. In particular, persons skilled in the art will appreciate that features of the above embodiments can be used to form further embodiments.

In particular, while the above example refers to three hoppers, there will often different numbers of hoppers in practice and even a single hopper can be obscured if the stockpile is substantially larger than it. Further the hoppers can be arranged in other configurations, for example in an array.