WO1999014572A1

WO1999014572A1 - Selective sampling of bulk materials

Info

Publication number: WO1999014572A1
Application number: PCT/AU1998/000759
Authority: WO
Inventors: Alan Huth
Original assignee: Gladstone Port Authority
Priority date: 1997-09-16
Filing date: 1998-09-16
Publication date: 1999-03-25
Also published as: AUPO922697A0

Abstract

Sampling apparatus comprises a sample ladle (1) which is able to be positioned in a horizontal (x, y) plane intersecting a stream of falling material, by orthogonal linear drive units (2, 3). The ladle (1) is pivotally mounted, and is normally retracted to an inclined position under a shroud (6). A third linear drive unit (12) is connected to the ladle (1) by a linkage (13). Upon activation of the linear drive unit (12), the sample ladle (1) is pivoted into a vertical orientation at which the ladle mouth is aligned with an opening in the shroud, enabling the ladle to receive a sample of the falling material. The third linear drive unit (12) then retracts the ladle beneath the shroud (6), and the orthogonal drive units (2, 3) move the ladle outside the falling stream of material to a discharge compartment (8), where the contents of the ladle are discharged by inversion.

Description

SELECTIVE SAMPLING OF BULK MATERIALS

THIS INVENTION relates to a method and apparatus for selective sampling of bulk material. In particular, the invention is directed to a method and apparatus for taking samples from a falling stream of particulate or powdered material at selected locations in the stream, as distinct from known falling stream samplers which generally utilise a cutter or sampling bucket which sweeps across or through the stream when taking the sample.

BACKGROUND ART It is often necessary to obtain a sample from bulk material, for testing or other purposes. For example, when loading bulk material such as a coal or other material into the hold of a ship for transport to a purchaser, samples of the material stream are taken for analysis, so that both the coal supplier and the purchaser can ascertain the properties of the material to be transported.

There are known devices for sampling streams of bulk materials. However, the known devices have a number of inherent disadvantages. For example, the known devices sweep across or through the falling stream of material, and collect a relatively large quantity of product. Since only a small quantity is required for laboratory analysis, the remainder has to be returned.

The known devices are relatively large, requiring a large volume space for installation. The large size of the sampler also results in higher initial capital costs. Furthermore, the material on the conveyor belt must conform within a given profile to allow the use of a cross belt sampler, therefore imposing added design requirements on the conveyor system upstream of the sampler.

The known falling stream samplers incorporate a cutter which sweeps across or through the falling stream, sampling the material. Hence, the retrieved sample may not reflect the true nature of the material.

It is an object of the present invention to provide an improved sampling system for bulk materials .

It is a particular object of this invention to provide an improved sampling system for bulk materials, in which samples can be obtained from a falling stream of material at various selected locations within the material stream.

SUMMARY OF THE INVENTION

In one broad form, the invention provides sampling apparatus for obtaining a sample from a stream of material, the apparatus including a sampling device which can be selectively opened and closed, positioning means for positioning the sampling device in the stream of material at a selected location, and sampling means for temporarily opening the sampling device to enable it to receive a sample of the material stream at that location.

Throughout this specification, including the claims, references to opening and closing the sampling device are to be interpreted as including uncovering and covering an opening in the sampling device, respectively. In other words, the sampling device can be effectively closed by covering or shielding its opening. Similarly, the sampling device can be effectively opened by removing any cover or shield from the opening. Preferably, the invention is used to obtain a sample from one or more selected location (s) in the stream of material, and the positioning means is used to position the sampling device at the selected location (s) . The positioning means typically comprises a pair of orthogonally orientated drive units adapted to position the sampling mechanism at a selected (x, y) location in a horizontal plane within a material stream falling in the vertical (z) direction. The drive units may suitably be linear drive units comprising servo motors with threaded drives.

In a preferred embodiment, the sampling device comprises a pivotally-mounted receptacle which, in its non-sampling position, is orientated at an inclination to the vertical. The sampling device also comprises a cover which effectively closes the sample receptacle at this orientation.

The sampling means suitably comprises another drive unit which pivots the sample receptacle out from under the cover so that it is effectively open, thereby enabling the sample receptacle to be filled by the falling stream of material.

Advantageously, the positioning means is also able to move the sampling device to a discharge chamber associated with the sampling apparatus, whereat the sampling means inverts the receptacle to discharge its contents into the chamber.

In the preferred embodiment, the operation of the sampling apparatus is controlled by a control circuit which suitably includes a programmed logical controller or other programmable electronic device. Multiple samples can be taken automatically under the control of the control circuit. In another form, the invention provides a method of obtaining a sample at a selected location in a stream of material, comprising the steps of providing a sampling receptacle having an opening which can be opened and closed, positioning the sampling receptacle at the selected location in the stream of material with its opening effectively closed, and temporarily opening the sampling receptacle to thereby collect a sample of material stream at the selected location.

In order that the invention may be more fully understood and put into practice, a preferred embodiment thereof will now be described with reference to the accompanying drawings .

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic sectional view of the sampling apparatus of the preferred embodiment with the sampling receptacle at a first position,

Fig. 2 is a schematic plan view of the sampling apparatus of Fig. 1,

Fig. 3 is a schematic elevation of the sampling apparatus of Fig. 1 with the sampling receptacle at a second position, and

Fig. 4 is a schematic plan view of the sampling apparatus of Fig. 3.

DESCRIPTION OF PREFERRED EMBODIMENT

The sampling apparatus of the preferred embodiment is mounted, in use, to a frame 10 attached to a chute 11 through which a stream of material falls. Typically, the material is coal, fine ores, mineral products, grain or other particulate or powdered material .

The sampling apparatus comprises a receptacle, in the form of a sample ladle 1, and a mechanism for positioning the sample ladle 1 in a horizontal (x-y) plane intersecting the stream of falling material, shown cross-hatched in Fig. 2.

In the preferred embodiment, the positioning mechanism comprises two linear drive units 2, 3 supported by the frame assembly 10. The drive units are supported by rollers 9 that travel on the frame assembly 10. Each drive unit 2, 3 comprises a servo motor acting on a respective threaded rod, the rods being orientated orthogonally to each other in the x-y plane. Each drive unit also has an associated position feedback device 5, 4 for transmitting the x-y coordinates of the sample ladle 1 to a control circuit (not shown) .

The positioning mechanism is also able to transport the sample ladle 1 to a discharge chute or compartment 8 for emptying.

To prevent cross-contamination of the sample, the sample ladle 1 remains shielded except when taking or discharging a material sample . In the illustrated embodiment, the sample ladle is pivotally mounted, and is normally inclined at an angle α to the vertical as shown in Fig. 1. At that position (the "closed" position) , the top opening of the ladle 1 is covered or closed by an arcuate cover or shroud 6. The shroud 6 has an aperture or cutting orifice 7 therein, which aligns with the opening of the sample ladle 1 when the ladle 1 is orientated vertically.

The sampling apparatus also comprises a third linear drive unit, known as the tippler activator 12, which is connected to the pivotally mounted ladle 1 by a suitable linkage 13. Typically, the linkage 13 comprises a straight bar having one end connected to the tippler activator 12 and its other end pivotally connected to an angled link which, in turn, is pivotally connected to the sample ladle 1. The angled link enables the sample ladle to be inverted into the discharge chamber 8.

The tippler activator 12 is able to "snap tilt" the sample ladle 1 from beneath its shroud 6 into a vertical orientation at which the ladle opening is aligned with the cutting orifice, and then retract the ladle 1 under the shroud 6. Thus, other than when it is at the discharge compartment 8 , the sample ladle remains shielded except for the brief period when it is uncovered or "opened" by aligning its opening with the cutting orifice 7. During this period, it takes a sample from the falling stream of material.

The sampling apparatus is suitably controlled by an electronic control circuit (not shown) which typically incorporates a programmed logic circuit (PLC) or other electrically equivalent circuit.

When not in use, the sample ladle 1 is normally left in an inverted orientation over the discharge compartment 8. This prevents dust settling in the sample ladle 1. Upon initiation of a sampling routine, the PLC activates the tippler drive 12 which retracts the linkage 13 and raises the sample ladle 1 to an inclined position whereat its opening is closed by the shroud 6, as depicted in Fig. 1.

The "cross travel" linear drive unit 2 then positions the sample ladle 1 at the desired "y" position in the flow stream 15 at which a sample is to be taken. The digital position feedback device 5, associated with the cross travel linear drive unit 2, provides a feedback signal to the PLC to enable the PLC to halt the cross travel drive 2 at the correct position.

The "plunger" linear drive unit 3 moves the sample ladle 1 to the desired "x" position in the free falling product stream 15. The digital position feedback device 4, associated with the plunger drive 3, provides a position feedback signal to the PLC to enable it to halt the plunger drive 3 at the correct x position. Once the sample ladle 1 is located at the desired sampling position within the product stream 15, the tippler activator 12, in combination with the snap tilt linkage 13, rapidly tilts the sample ladle out from under the shroud 6 to a vertical orientation aligned with the cutting orifice 7. The cutting orifice 7 preconditions the product stream, straightening and slowing it prior to entering the sample ladle 1. If desired, a vertical tube may be located above the cutting orifice to assist in the preconditioning of the product stream.

Typically, only a small sample is required from the fast flowing material stream. The tippler activator 12 leaves the sample ladle 1 in its "open" position below the cutting orifice 7 only momentarily as filling of the sample ladle is almost instantaneous. The tippler activator 12 and snap tilt linkage 13 then quickly retract the sample ladle 1 back under the shroud 6 , in 7. Sampling apparatus as claimed in claim 1, further comprising a discharge chamber, the positioning means being adapted to move the sampling device to the discharge chamber, and the sampling means being adapted to discharge the contents of the sampling device into the chamber.

8. Sampling apparatus as claimed in claim 1, wherein the positioning means is adapted to position the sampling device successively at several selected locations.

9. Sampling apparatus as claimed in claim 1, further comprising an electronic control circuit for controlling the apparatus of the positioning means and the sampling means. 10. A method of obtaining a sample at a selected location in a stream of material, comprising the steps of providing a sampling receptacle having an opening which can be opened and closed, positioning the sampling receptacle at the selected location in the stream of material with its opening effectively closed, and temporarily opening the sampling receptacle to thereby collect a sample of material stream at the selected location. 11. A sampling method as claimed in claim 10, further comprising the step of positioning the sampling receptacle at a discharge chamber remote from the stream of material, and discharging the contents of the sampling receptacle into the discharge chamber. 12. A method as claimed in claim 10, further comprising the step of positioning the sampling receptacle successively at selected locations in the material stream, and obtaining separate samples of the material stream at the selected locations. 13. A method as claimed in claim 10, wherein the sampling receptacle is moveable between a non-sampling positioning at which its opening is covered, and a sampling position at which its opening is exposed, and The foregoing describes only one embodiment of the invention and modifications which are obvious to those skilled in the art may be made thereto without departing from the scope of the invention. For example, the sample ladle may be provided with a cover or other closure which is momentarily removed or opened while the sample ladle is in the material stream. The cover may be a flip-top lid, a rotating cover with an aperture therein, or any other suitable closure which can be selectively opened and closed.

Furthermore, the orthogonal linear drive units may be replaced by any other suitable actuator (s) or mechanism (s) , for positioning the sampling receptacle, and opening and closing the receptacle. For example, the positioning mechanism can comprise a telescoping arm moveable angularly in a horizontal plane intersecting the stream of material .

Claims

CLAIMS :

1. Sampling apparatus for obtaining a sample from a stream of material, the apparatus including a sampling device which can be selectively opened and closed, positioning means for positioning the sampling device in the stream of material at a selected location, and sampling means for temporarily opening the sampling device to enable it to receive a sample of the material stream at that location.

2. Sampling apparatus as claimed in claim 1, wherein the sampling device includes a pivotally-mounted receptacle with an opening at its top, the receptacle being moveable by the sampling means between a sampling orientation and a non-sampling orientation.

3. Sampling apparatus as claimed in claim 2, further comprising a shielding member having an opening therein, and wherein in its non-sampling orientation the sampling receptacle is orientated at an inclination to the vertical and its opening is effectively closed by the shielding member, and in its sampling position the sampling receptacle has its opening substantially aligned with the opening in the shielding member.

4. Sampling apparatus as claimed in claim 2, wherein the sampling means comprises a drive unit for pivoting the sampling receptacle between its non-sampling and sampling positions, the drive unit being connected to the receptacle by a linkage arm assembly.

5. Sampling apparatus as claimed in claim 1, suitable for use with a material stream falling in a vertical direction, the positioning means including a pair of orthogonally orientated drive units adapted to position the sampling device at a selected location in a horizontal plane intersecting the material stream.

6. Sampling apparatus as claimed in claim 5, wherein each drive unit is a linear drive unit comprising a servo motor with a threaded drive mechanism.

7. Sampling apparatus as claimed in claim 1, further comprising a discharge chamber, the positioning means being adapted to move the sampling device to the discharge chamber, and the sampling means being adapted to discharge the contents of the sampling device into the chamber.

9. Sampling apparatus as claimed in claim 1, further comprising an electronic control circuit for controlling the apparatus of the positioning means and the sampling means.

10. A method of obtaining a sample at a selected location in a stream of material, comprising the steps of providing a sampling receptacle having an opening which can be opened and closed, positioning the sampling receptacle at the selected location in the stream of material with its opening effectively closed, and temporarily opening the sampling receptacle to thereby collect a sample of material stream at the selected location.

11. A sampling method as claimed in claim 10, further comprising the step of positioning the sampling receptacle at a discharge chamber remote from the stream of material, and discharging the contents of the sampling receptacle into the discharge chamber.

12. A method as claimed in claim 10, further comprising the step of positioning the sampling receptacle successively at selected locations in the material stream, and obtaining separate samples of the material stream at the selected locations.

13. A method as claimed in claim 10, wherein the sampling receptacle is moveable between a non-sampling positioning at which its opening is covered, and a sampling position at which its opening is exposed, and wherein the step of opening the sampling device comprises temporarily moving the sampling receptacle from its non- sampling position to its sampling position.

14. Sampling apparatus for obtaining a sample from a stream of material, the sampling apparatus including a receptacle having an opening which can be selectively covered and uncovered, positioning means for positioning the sampling receptacle at a selected location in the stream of material, and sampling means for remotely uncovering the opening of the sampling receptacle temporarily to enable it to receive a sample of the material stream.