AU641791B2 - Improvements in sampling - Google Patents

Description

39491 AWT:LLP/01I Regulation 3.2

AU~STRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

*0 0 see 0 *0000 0 so lose: 00Na:00 of, Applicant: 21XM.NORP PTY LTD ActuhM Inventor: BEVAN PHILLIP QUINN Address for Service: COLL1SON CO.,i 17 King William Street, Adelalde, S.A. 5000 Invention Title: IMPROVEMENTS IN SAMPLING Details of Associated Provlslonp, Applications: Austraiian Patenti Application No: PK1 519 dated 2nd August 1990 The followingj statement Is a full description of this invention, including the best method of performing ft known to us: This invention relates to improvements in sampling and more particuJarly to sampling of mineral materials for analysis.

It is known to use rotary sample cutters in production applications where there is a continuous flow of material through the sampler and it is desired to select a certain proportion of that material for routine analysis. Other methods of continuous sample selection are also known such as buckets which travel across a conveyor line and are intended to collect a certain amount of material on each pass and the like, In the rotary sample collectors a rotary cutter is rotated through a sample flow and for given sample flow and cutter shape and same amount of material will be selected from the flow per unit time regardless of the speed of rotation of °the cutter. The actual volume of sample captured by the cutter is constant 1 5 because the plan view dimensions of the cutter inlet are fixed. If the user wants to vary the percentage of material divided from a sample flow it is necessary to also alter the dimensions of the inlet.

The actual number of cuts through a sample flow per unit time is actually important in mineral analysis to assure that the sample obtained is as bias free •tas practical. For instance a cutter which passes through a stream of material 00 flow one hundred times in one minute will collect a more representative S"sample of the whole than a cutter which oniy passes through once in a minute S. even though the same amount of material has been collected. In other words the actual percentage split will be constant regardless of the number of cuts because the total residence time in the stream remains the same regardless of .o °speed but the bias of the sample will change with the number of cuts.

SO' 0 It is desirable therefore that a cutter have variable speed operation in mineral sample preparation to ensure that the cutter speed can be adjusted to give an unbiased sample particularly with samples of lesser quantities.

This present invention, however, is directed towards batch applications where it is more important to ensure an unbiased sample regardless of the size of the batch of material to be analyzed. In other words, in laboratory sample division the aim is to divide a relatively fixed percentage of materql from the infeed and that this percentage must be as representative of the whole as possible, that is, the sample must be unbiased.

Further the quantity of batch being presented to the sampler is also important in mineral analysis to ensure that the sample obtained is as bias free as possible. Obviously if there is only a very small amount of material to be sampled then the flow rate of material to the cutter should be slowed down as much as possible to allow the stream to be presented to the rotating cutter for as long a time period as possible. Alternatively the number of cuts through the sample should be increased.

1 0 It is the object of this invention to provide a method and meansfor sampling of mineral materials or other materials which can be varied depending upon batch size or other batch characteristics. Batch characteristics may include volume of batch, weight of batch, particle size or the like.

In one form therefore the invention is said to reside in a sampling device comprising sampling means to select a proportion of material as a sample .9o.

:i from a flow of the material wherein the proportion of material selected and/or 0: :the method of selection of material is dependant upon a physical 9 .characteristic of the material, the device includ!ng means to determine the 2 0 quantity of that physical characteristic, means to determine the proportion of sample to be selected based on the determination and/or to determine the 9 method of selection based on that physical characteristic and means to vary the sampling means to select the sample from the flow of material.

The device according to this invention may be manually operated or have 00. some form of semi-automatic or fully automatic operation.

9 The physical characteristic which may be determined may be the mass of materLl or the volume of material or the particle size or the composition.

3 0 Therefore the sample before it enters the sampling device may be weighed or have a size analysis or be measured by some form of volume measuring apparatus.

The means to select a proportion of the flow is in general a riffle and may in 3 5 one preferred form be a rotary sample cutter. Such a rotary sample cutter may have a cutter opening which cuts through a flow of sample while rotating through a full circle of 3600 or may have a cutter opening which reciprocates 7 for instance through 1800.

The sample cutter may have a cutter opening which varies in shape with radial distance from the centre of rotation of the cutter and such a shape may be selected trapezoidal, or having convex, concave or saw tooth shape side walls.

As discussed earlier to obtain an unbiased sample particularly of a smaller quantity of material there is advantage in making more smaller cuts into the sample and hence in one preferred embodiment of the invention the means to 1 0 vary the means to select a proportion of the flow of material is by varying rotational speed of the cutter through 'the sample flow.

WO The means may alternatively be a different number of cutters so that in a given

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ooo time twice as many cutters pass through the flow of material. Such cutters may 090 1 5 each extend different distances from the centre of rotation of the rotary cutter.

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Alternatively the difference in cut may be provided by a change to the stream of material to the cutter. This may be by adjusting the actual flow rate of material or may be by positionrng of the injection of flow of material to the cutter so that different size sample is collected per rotation of the rotary woo* sample cutter.

The means to determine the proportion of sample to be selected based upon the measurement of the physicai characteristic may be some form of computation equipment which may riave a look-up table so that for a certain size of sample a proportion of the material to be selected will be indicated.

In an alternative form the invention may be said to reside in a rotary sample cutter including a rotary cutter adapted to be rotated into a stream of material to select a proportion of the material and means to vary the radial position of the stream of material with respect to the axis of rotation of the rotary cutter to vary the amount of material selected per rotation of the cutter wherein the positioning of the stream is in proportion to a measurement of a physical characteristic of the material.

As before the variation in position may be manual or automatic. The measurement of the physical characteristic such as mass, volume or particle size may be done immediately before the sample selection in an inlet hopper or earlier at the inlet to a sample preparation machine.

In a further form the inven tion is said to reside in a method of sampling a batch of material for analysis c, -nrising the steps of determining the quantity of a physical characteristic of the sample, determining what sample size is necessary based upon that measurement of the physical characteristic and selecting that sample by means of varying a sample selector extending into a batch of the flowing material.

1 0 In one preferred embodiment therefore there may be a vibratory feeder which feeds a sample of material into the rotational path of a rotary cutter and the position of the vibratory feeder ejection point with respect to the rotary cutter may be varied to change the proportion af bias of the sample collected.

1 5 Preferably the sample selector is a rotary cutter and there is a vibratory feeder which feeds the batch of material into the rotational path of the rotary cutter and the position of the vibratory feeder ejection point with respect to the rotary cutter may be varied to change the proportion of the sample collected from the batch, The operating principle is that the whole vibrating feeder will be wheel 4 3 mounted or similarly mounted to allow its movement of its discharge point relative to the cutter inlet. Such a movement may be actuated by an air cylinder or similar.

The change in selection characteristics may be more accentuated by varying the shape of the cutter inlet at dferent distances from its centre of rotation. By 3 3 this means as the feeder is moved in or out then a different size of sample cutter will present itself. It can be quite clearly seen that changing the position of the stream directly changes the adjacent physical dimensions of the cutter inlet and therefore the volume of sample which would be accepted by the cutter on each revolution. In the case of a very small volume of sample therefore the feeder would be moved in towards the rotational point of the rotational cutter where the volume as the cut would be decreased consistent with the total volume of sample available. The shape of the cutter opening may be selected from a wide range of shapes depending upon the variation in sample selection desired. For instance the cutter opening may be shaped such that there is a linear relationship between the amount of sample collected 6 or the percentage split as the feeder moves in and out.

Cutter shapes could include trapezoidal, or having convex, concave or saw tooth shape side walls.

Multiple cutters may also be used.

An alternative method by which variation in sample selection may be provided may be providing multiple cutters but having these extending different radial 1 0 differences so that as the feeder moves into the centre of rotation of the cutter more cutters will be presented to the sample selector. This will cause a more dramatic change in the performance of the sample selector as the feeder takes oi •up positions closer and closer to the centre of rotation.

°aao o• 1 5 In essence by this invention there is provided an automatic sample divider *i preferably of a rotating kind which first weighs or determines some other .physical characteristic of the material available and then uses this weight or other physical characteristic to determine which feeder outlet setting, feeder speed and cutter speed to select to obtain a desired sample. It may be that only one of these may be varied but it may be possible to vary more than one in some cases. It may be desirable for instance to provide a certain degree of calibration to suit each individual application to which it is installed.

a The sample divider according to this invention may be a device which stands alone or may be part of a larger automatic batch preparation and analysis machine. In such a case the determination of the physical characteristic may not be done immediately before the actual sampling takes place but may be determined when the sample is first fed into a large machine and it may go through several other operations before proceeding to sample selection.

This then generally describes the invention but to assist with understanding of the invention reference will now be made to the accompanying drawings which show prefared embodiments of the invention.

In the drawings: FIG. 1 shows a cutaway view of a first embodiment of rotary sample collector with variable feeder position, FIG. 2 shows a partial plan view of the embodiment shown in FIG. 1, FIG. 3 shows a range of cutter openings of rotary sample cutters with different shape cutters, and FIG. 4 shows a cutaway view of a alternative embodiment of rotary sample collector.

Now looking more closely at the drawings and in particular the embodiment o• :shown in FIGS. 1 and 2 it will be seen that a cylindrical enclosure 1 has a rotary shaft 2 driven by a motor 3 through a belt 4. The shaft 2 includes a sample cutter 5 which extends radially out from the shaft 2. The sample cutter 1 5 has an opening which is substantially trapezoidal. A hopper 10 is used to hold •i a sample to be divided and means not shown is used to weigh the amount of o 4.sample in the hopper Based upon the amount of material in the hopper 10 a vibratory feeder tray 12 is moved radially in or out with respect to the shaft 2 by means of the °opneumatic ram 13 on track 14. The nozzle 15 of the feeder tray 12 is S: positioned a different radial distance out from the shaft 2 so that the cutter presents a different portion of the cutter to the flow from the feed nozzle o Sample which is not selected by the cutter 15 passes out through the duct 16 at the bottom of the hopper 1 and sample which is selected passes out through the hollow shaft 17 into collector 18 and out duct 19.

a Where the sample is very small then it may be desirable to vary the speed of Sthe motor 3 so that a more unbiased sample is selected. As discussed earlier the actual quantity of sample selected by changing the speed of the motor for a fixed position of the feed nozzle 15 is the same but a less biased sample or more unbiased sample will be collected by a higher rotational speed.

As an alternative the angle of the feeder chute 12 may be varied by means not shown so that the feed actually occurs at a lower rate. Alternatively changing the speed of vibration of the vibratory feeder will change the rate of feed of material to the sample cutter and hence the proportion of sample collected.

8 Now looking at FIG. 3 it will be seen that a range of sample cutter opening is proposed.

As shown in FIG. 3A the sample cutter opening merely comprises a trapezoidal shape with increasing width with increasing radial distance from the shaft 30. This shape will give only a small difference in size of sample with further distance from the shaft.

As shown in FIG. 3B the sample cutter opening merely comprises a 1 0 trapezoidal shape with decreasing width with increasing radial distance from the shaft 30. This shape will give a reduction in size of sample with further distance from the shaft.

The sample cutter opening shown FIG. 3C has four cutting segments 31,32, let" 1 5 33 and 34 which extend different radial distances out from the central shaft The position of the feed chute may be adjusted therefore so that onli, sample 0°1 cutter 32 selects any feed but with movement of the cutter towards the centre of rotation progressively cutter 33, cutter 34 and cutter 31 are introduced into the flow of material from the feeder so that a greater proportion of the sample is collected per rotation. This in fact gives a stepwise reduction on sample size sores: with increasing distance from the shaft •O..4 The sample cutter opening shown FIG. 3D has concave sid-es viewed from the 2 inside of the cutter and this will mean that an increased proportion of sample is collected as the feed nozzle moves radially inward towards the shaft.

The sample cutter opening shown FIG. 3E has convex sides viewed from the inside of the cutter and this will mean that a reduced proportion of sample is collected as the feed nozzle moves radially inward towards the shaft.

An alternative method of varying the proportion of sample collected is by means of different cutter shapes and while this may not be a change which can be affected automatically different cutters may be used for different types of samples.

The opening of the cutter as shown in FIG. 3F is a sawtooth or stepped opening. In this arrangement eight discrete steps are provided as a sample feeder moves out from the shaft. Rather than a continuous change in sample selection a stepped change in selection may be easier to programme into an automatic system and the position of a feeder nozzle to feed into such a cutter may be easier to control.

FIG. 4 shows a furthe bodiment of a sampling device in which a rotating sample cutter 40 hk, an opening 41 which has sawtooth sides 42 of the type shown in Figure 3F. The sample cutter is rotated on shaft 43. In this embodiment the feeder tray 44 is constrained by means not shown to move in a series of steps so that a number of discrete sample sizes may be collected.

1 0 Collected sample is dispensed through duct 45. Variation in sample bias is also possible by variation of the rotational speed of the shaft 43.

Generally according to this invention there is provided a sample divider or sample cutter that is capable of making the required adjustments to the cutter 15 or feeder speed or position as it is running by sensing the mass of material or other characteristic in the Infeed hopper.

Throughout this specification various indications have been given as to the scope of the invention but the invention is not limited to any one of these but may reside in two or more of these combined together. The examples are given for illustration only and not for limitation.

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Claims (21)

1. A sampling device comprising sampling means to select a proportion of material as a sample from a flow of the material wherein the proportion of material selected and/or the method of selection of material is dependant upon a physical characteristic of the material, the device including means to determine the quantity of that physical characteristic, means to determine the proportion of sample to be selected based on the determination and/or to determine the method of selection based on that physical characteristic and means to vary the sampling means to select the sample from the flow of material.

2. A sampling device as in claim 1 wherein the device is manually operated or has some form of semi-automatic or fully automatic operation.

3. A sampling device as in claim 1 or claim 2 wherein the physical i" characteristic which is determined Is selected from the mass of material, the volume of material, the particle size or the composition.

4. A sampling device as in any one previous claim wherein the means to :,to select the sample is a rotary sample cutter,

5. A sampling device as in claim 4 wherein the rotary sample cutter has a cutter opening which varies with radial distance from its centre of rotation thereby giving a different proportion of sample when cutting through sample .flows at different radial distances from Its centre of rotation.

6. A sampling device as in claim 4 or claim 5 wherein the rotary sample cutter has a cutter opening which cuts through a flow of sample while rotating 3 0 through a full circle of 360°.

7. A sampling device as in claim 4 or claim 5 wherein the rotary sample cutter has a cutter opening which cuts through a flow of sample while reciprocating through 1800

8. A sampling device as in any one previous claim wherein the means to vary the sampling means is means to vary the rotational speed of the cutter _,tfA' 4 through the flow of material.

9. A sampling device as in claim 1 wherein the proportion of material selected is varied by a variation of the flow rate of the stream of material to the sampling means.

10. A sampling device as In claim 1 wherein the proportion of material selected is varied by positioning of the flow of material to the sampling means with respect to the sampling means such that a different size sample is collected.

11. A sampling device as in claim 10 wherein there is a vibratory feeder which feeds the flow of material to the sampling means and the position of an ejection point of the vibratory feeder with respect to the sampling means may be varied to change the proportion of the sample collected. S 12. A sampling device as in claim 6 wherein the shape of the cutter opening is selected from trapezoidal, or having convex, concave or saw tooth shape a. side walls.

13. A sampling device as in claim 4 wherein there are multiple cutters in the sampling means and each cutter of the multiple cutters extending different radial distances from the centre of rotation.

14. A rotary sample cutter incuding a rotary cutter adapted to be rotated into a stream of material to select a proportion of the material and means to vary the radial position of the stream of material with respect, to the axis of roiation of the rotary cutter to vary the amount of material selected per rotation of the gs cutter wherein the positioning of the stream is in proportion to a measurement of a physical characteristic of the material.

15. A rotary sample cutter as in claim 14 wherein the variation in position of the stream of material Is selected from manual or automatic.

16. A rotary sample cutter as in claim 14 wherein the measurement of the physical characteristic selected from mass, volume or particle size is done in an inlet hopper.,

17. A method of sampling a batch of material for analysis comprising the steps of determining the quantity of a physical characteristic the batch, determining what sample size is necessary based upon that measurement of the physical characteristic and selecting that sample by means of varying a sample selector extending into the batch of the flowing material.

18. A method of sampling a batch of material as in claim 17 wherein the sample selector is a rotary cutter and there is a vibratory feeder which feeds the batch of material into the rotational path of the rotary cutter and the position of the vibratory feeder ejection point with respect to the rotary cutter may be varied to change the proportion of the sample collected from the batch.

19. A method as in claim 18 wherein the rotary cutter has the shape of the o. cutter inlet different at different radial distances from its centre of rotation. *a A method as in claim 19 wherein the shape of the cutter opening is 1 5 selected from trapezoidal or having convex, concave or saw tooth shape side walls. o a

21. A method as in claim 18 wherein there are multiple cutters in the sample selector each cutter of the multiple cutters extending different radial distances from the centre of rotation.

22. An automatic sample divider Including a rotating sample cutter which first weighs or determines a physical characteristic of the material available *o and then uses this weight or other physical characteristic to determine which feeder outlet setting, feeder speed and cutter speed to select to obtain a desired sample. S23. A sampling device substantially as hereinbefore described with reference to and as illustrated by the accompanying drawings.

24. A method of sampling a batch of material substantially L. hereinbefore described with reference to and as illustrated by the accompanying drawings. Dated this 23th day of July 1991 QUINNCORP PTY. LTD. By their Patent Attorneys, COLLISON CO. (36-d ABSTRACT A sample collection device which uses a rotary cutter cutting into a stream of sample material. The proportion of a sample collected as a total and per cut is determined sppendent upon a physical characteristic such as weight or particle size. The speed of rotation and/or the position or shape of the cutter may be varied. s* 00 0 V eO e o I S* O0 9 0 1 9'