EP0329865A1

EP0329865A1 - Improvements in particle separators

Info

Publication number: EP0329865A1
Application number: EP88300607A
Authority: EP
Inventors: Reginald Vernon Dutschke
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-08-11
Filing date: 1988-01-26
Publication date: 1989-08-30
Also published as: AU7677287A

Abstract

A particle separator (1) which uses differences in kinetic energy to achieve separation. Particles of different size or density are accelerated by being placed on a belt (4;20) or passed between pinch rollers (30,31) so that they are all projected at the same speed.

Differences in size or density cause particles to travel different distances to be collected in different hoppers (11-14). In some instances a light cross current of air (41;46) may be used to remove dust or other light material. The separator can be used, for example, for grain separation.

Description

This invention relates to improvements in particle separators.
In many industries there is a requirement for the separation of particles which are perhaps of much the same size but of different specific gravities or of much the same mass but different specific gravities. It is the object of this invention to provide a method and an apparatus for the separation of heterogenous particulate material.
An example of such an industry is in the agricultural industry where it is desirable to separate grain which may be of various sizes from husks, straw, small pebbles or stones, soil particles or weed seeds in the process of harvesting to make the product more saleable.
The invention is not restricted to particulate material separation in the agriculture industry but may be used for any other sort of particulate material for instance separation of minerals from gangue or such like.
Australian Patent Specification No 240399 describes "An Apparatus for Classifying Materials" which used acceleration of the particles by means of an air stream and then projection of the particles and associated air stream into a chamber where separation occurs due to differences in velocity of the particles. The use of an air stream even at low velocity, however, induces turbulence and separation can be seriously effected and also an air stream does not accelerate all the particles equally, hence when the particles enter the separation chamber they will not have the same velocity necessarily and hence will not always travel the required distance for efficient separation.
It is the object of the present invention to provide a more efficient means of accelerating the various particles equally so that a cleaner separation or classifying may be achieved.
In one form therefore the invention is said to reside in a method of separating heterogenous particulate material comprising the steps of accelerating by mechanical means the particulate matter to a fixed speed and projecting the particulate material into air so that particles of different mass or different density within the particulate material are projected different distances and collecting different fractions of the projected material at different distances from the point of projection.
It will be noted that the important feature of the present invention is that there is provided a method by which the particulate material is mechanically accelerated to the fixed speed and hence all particles in the stream are travelling at the same speed at the moment of projection. As indicated above, it is known to accelerate such materials in an air stream and then project into void or chamber but this method has the problem that air turbulence caused by the air which is used to accelerate and move the particulate material can cause separation problems. In a preferred form of the present invention the mechanical means to accelerate the particles may comprise a continuous belt passed over a pair of rollers at least one of which is driven to cause the belt to travel at constant linear speed.
Alternatively the mechanical means may further include at least one idler roller driven by the surface of the belt and with the particulate material being placed on the belt to pass between the idler roller and the belt before being projected. By this means the particulate material on the belt may be smoothed into a substantially uniform layer therefore enabling more particles to be uniformly accelerated.
In an alternative embodiment the mechanical means to accelerate the particulate matter may include a pair of pinch rollers between which the particulate material is passed.
In a further preferred form the angle of projection of the particulate material may be varied to alter the characteristics of projection of the particulate material.
There may be further included in the method the step of passing a current of air transverse or substantially transverse to the direction of projection of the particulate material to separate therefrom light materials.
For instance in the separation of grain, chaff and the like may be separated by a gentle air flow transverse to the direction of projection of the particulate matter. Such an air-flow may be up or down or sideways with respect to the direction of projections.
Collection of the different fractions at different distances from the point of projection may be achieved by a series of bins or in a series of hoppers at different distances with uppermost facing open mouths to collect the various fractions as they are projected.
In some preferred embodiments three fractions may be collected with first and third fractions being of substantially pure concentration of that fraction and the middle fraction being still much of a mixture with this middle fraction being recycled for further separation.
In an alternative form the invention may be said to reside in a method of separation of heterogenous particulate material comprising the steps of mechanically accelerating the particulate material and projecting it substantially horizontally or slightly upwards into air and subsequently passing the projected stream of particulate material through a zone of cross current air to remove fine dust, chaff and the like and collecting the projected material other than the dust or chaff in at least one bin arranged in the path of the projected stream. There may be provided a collection duct before the separated chaff or other light materials.
In a further form the invention may be said to reside in a heterogenous particulate material separator comprising a mechanical particulate matter projection means and a plurality of collecting receptacles for particulate matter projected by the projections means the receptacles being positioned at variable distances from the projection means.
In one form of this embodiment of the invention the particulate material projection means may comprise a continuous belt passing over a pair of rollers and onto which belt a stream of particulate material may be directed to be carried on and accelerated by the belt.
Such a projection means may also include at least one idler roller driven by the upper surface of the belt and positioned so that the stream of particulate material passes between the idler roller and the belt.
An alternative mechanical projection means may comprise a pair of pinch rollers between which the particulate matter is projected. Such a pair of pinch rollers may include resilient peripheral surfaces so that damage to the particulate matter being passed through does not occur.
There may be further provided with the particulate matter separator of the present invention means to provide an air current transverse to the direction of projection of the particulate material.
Such an air current transverse to the direction of projection may be vertically up or vertically down in respect to the direction of projection or at a slight angle to the direction of projection and may be used to collect light material s such as dust and chaff from the projected materials. Some form of collecting hood may be provided on the opposite sides of the particulate matter stream to the air-supply means so that dust or chaff or light material can be collected.
In one preferred form of the invention there may be provided a single cross current air producing fan which by means of air directors and ducts may be adapted to either direct air down through the stream of projected material or up through the stream of projected material so that depending upon the type of material to be separated efficient dust removal material may be provided.
It has been found for instance that in separating dust and the like from very light grain materials such as clover it is advantageous to have a downwards directed cross-current air stream but with heavier grains such as wheat and barley grains it is desirable to have an upwards directed cross-current air stream.
In a preferred form of the invention the angle of projection may be varied so that different separations may be obtained for different types of materials. The angle of separation may be anywhere from horizontal to vertical but it is preferable from horizontal to 45 degrees to the horizontal.
The collecting receptacles positioned at various distances from the projection means may be provided by a series of baffles positioned at different distances away from the point of projection with the spaces between the baffles comprising the receptacles. The baffles may be varied in longitudinal position and height depending upon the type of material to be separated and the different concentrations of the heterogenous particulate material and also depending upon the rate or speed of projection.
In the case of projector using a belt the belt may be of substantial width with a thin wide stream of particulate matter placed thereon by means of a chute and with the belt rotating over the series of rollers substantially the same speed of projection will be impassed to all of the particles of material on the belt.
Generally with the method and apparatus of the present invention particles of greater mass or greater density will be projected further from the point of projection and light materials will be projected a less distance and hence can be separated by spacing collector receptacles at a closer distance.
In one preferred embodiment of the invention in a test for the separation of clover seeds from husks and other trash collected when the clover seeds are collected from the ground material is passed as a thin stream onto an endless belt travelling between two six inch diameter rollers rotating at 150 revolutions per minute such that the heaviest fraction, the desired clover seeds, are projected a distance approximately six feet with the undesirable dust and husks be projected a much shorter distance.
In a further embodiment for the separation of chaff and the like from barley seeds and endless belt travelling between two 215 millimetre diameter rollers rotating at 900 revolutions per minute will impart on the seeds a projection speed of approximately 10 metres per second but because of the greater mass of such particles the projection distance for the heaviest particles is approximately 2 metres. Light chaff will be deposited at approximately 0.6 metres and medium size grain at approximately 1.2 metres.
A particulate material separator according to this invention may be incorporated as part of an agricultural harvesting machine such as a combine harvester or may be used a stationary machine for a first stage or later stage seed cleaning.
As indicated above particulate material separator and the method of separating particulate material according to this invention may be used for the separation of chaff and other trash from wheat, barley clover seeds, other cereal seeds, beans and peas and the like or may be used in the mineral separating industry or for instance for purposes such as the cleaning of dried fruit such as sultanas and currants from stalks and the like.
This then generally describes the process and apparatus of the present invention but to more clearly assist with understanding of the invention reference will now be made to the accompanying drawings which are preferred embodiments of the present invention.
In the drawings

Fig. 1 shows a schematic view of a first embodiment of the present invention.
Fig. 2 shows an alternative embodiment of projection means according to this invention.
Fig. 3 shows a further version of a projection means according to this invention.
Fig. 4 shows an upwardly flowing air-current in a material separator according to this invention and,
Fig. 5 shows a downwardly flowing air-current in a material separator of the present invention.

Now looking more closely at the drawings and in particular Fig. 1 it will be seen that the particulate material separator of the present invention comprises generally a projection apparatus 1 and collection region 2. The projection apparatus 1 includes a hopper 3 which provides a thin stream of particulate material onto a continuous belt 4 which passes over rollers 5 and 6 and is maintained in tension by roller 7 which bears onto the top of the belt. The particulate material passes between the roller 7 and the belt on the belt and as the belt is travelling the direction shown by the arrow 8 it is accelerated and moves with the belt at a steady speed until is projected tangentially at the point 9 where the belt 4 passes over the roller 5. The particulate material is projected towards the collection region in a substantially parabolic stream 10 into a series of hoppers 11, 12, 13 and 14. The lightest material travels the shortest distance and falls into hopper 12 while the heaviest material travels the further distance and falls into hopper 14. Intermediate densities or masses fall into hoppers 12 and 13. The hoppers may be emptied continuously or emptied after they fill a certain amount.
Now looking at Fig. 2 it will be seen that the projection apparatus in this embodiment includes a continuous belt 20 passing over rollers 21 and 22 but in this embodiment there are two idler rollers 23 and 24. The belt 20 travels in the direction shown by the arrow 25. The angle 26 of projection of the particulate material from the belt 20 as it passes over roller 22 may be varied by means of raising or lowering the idler roller 24 thereby varying the angle of the belt 20 between the roller 24 and the roller 22 and hence the tangential position on the roller 22 at which the particulate material is ejected.
An alternative form of particulate material projector is shown in Fig. 3. This embodiment includes a lower roller 30 and upper roller 31 to form between them a pinch roller arrangement, each of which is covered by resilient peripheral surface 32. A chute 33 directs material onto the upper face of roller 30 just before it pinches against roller 31 and the pinching position between the two rollers determines the tangential angle of projection. By moving the upper roller 31 in the directions shown by the arrow 24 the tangential joining position of the two rollers 30 and 31 maybe varied and hence this will vary the angle projection of the material as shown by arrow 35.
Fig. 4 shows the projection apparatus 1 as shown in fig. 1 but includes a centrifugal arrangement 40 which provides a cross-current air flow 41 which is substantially transverse to the direction of projection of particulate matter as shown by the shaded area 42. A collection hood 43 is provided with a duct 44 extending away from the hood to draw light particulate materials such as chaff or dust 50 away from the collection area to prevent contamination of the desired fractions of particulate materials.
Fig. 5 shows an alternative embodiment in which the projection apparatus 1 further includes a centrifugal fan apparatus 45 which directs a downwardly directed air flow 46 across the particulate stream 47 and there may be further provided a collection hood 48 to collect dust or chaff or the like 49 collected from the particluate matter stream.
It will be seen that by this invention there is provided an arrangement by which all of the particles of particulate material are enabled to be projected at substantially the same direction and initially the same speed so that separation is achieved by different mass or density of the particles.

Claims

1. A method of separating heterogeneous particulate material comprising the steps of accelerating by a mechanical means (4;20;30,31) the particulate material to fixed speed and projecting the particulate material into air so that particles of different mass or different density of the particulate materials are projected different distances and collecting fractions of the projected material at different distances from the point of projection.

2. A method as in Claim 1 wherein the mechanical means comprises a continuous belt (4;20) passed over a pair of rollers (5,6;20,21) at least one of which is driven to cause the belt to travel at a constant linear speed.

3. A method as in Claim 2 wherein the mechanical means further includes at least on idler roller (7;23,24) driven by the surface of the belt and the particulate material being placed on the belt to pass between the idler roller and the belt before being projected.

4. A method as in Claim 1 wherein the mechanical means includes a pair of pinch rollers (30,31) between which the particulate material is passed.

5. A method as in any of Claims 1 to 4 wherein the angle of projection (26) of the particulate material may be varied.

6. A method as in any of Claims 1 to 5 further including the step of passing a current of air (41;46) transverse or substantially transverse to the direction of projection of the particulate material to separate therefrom light materials.

7. A heterogeneous particulate materials separator (1) comprising a mechanical particulate material projection means and a plurality of collecting receptacles (11-14) for particulate material projected by the projection means, the receptacles being positioned at variable distances from the projections means.

8. A separator as in Claim 7 wherein the particulate material projection means comprises a continous belt (4;20) passing over a pair of rollers (5,6;20,21) and onto which a stream of particulate material may be directed to be carried on and accelerated by the belt.

9. A separator as in Claim 8 wherein the projection means includes at least one idler roller (7;23,24) driven by the upper surface of the belt and positioned so that the stream of particulate material passes between the idler roller and the belt.

10. A separator as in Claim 7 wherein the projection means comprises a pair of pinch rollers (30,31) between which the particulate material is projected.

11. A separator as in any of Claims 7 to 10 further including means (40,43;43,48) to provide an air current transverse or substantially transverse to the direction of projection of the particulate material.

12. A separator as in any one of the Claims 7 to 11 further including means (27;34) to vary the angle of projection of the aprticulate material.