WO2002063943A1

WO2002063943A1 - Seed cleaning apparatus

Info

Publication number: WO2002063943A1
Application number: PCT/AU2002/000166
Authority: WO
Inventors: Kevin John Prater
Original assignee: KASIA NOMINEES Pty Ltd
Current assignee: KASIA NOMINEES Pty Ltd
Priority date: 2001-02-15
Filing date: 2002-02-15
Publication date: 2002-08-22
Anticipated expiration: 2003-08-15
Also published as: AUPR317001A0; AU2003100632A4; AU2003100624A4

Abstract

A seed cleaning apparatus and method for separating a particulate feed material into a plurality of size fractions from which a preferred size fraction may be selected. The apparatus comprises a plurality of elongate, cylindrical scalping screens (12) each having a first end (14) and a second end (16) inclined such that the second end (16) is below the first end (14). Each of the scalping screens (12) is coaxially mounted with and inside of a corresponding elongate, cylindrical cleaning screen (18) forming a screening pair. The cleaning screens (18) each have a first end (20) and a second end (22) also inclined such that the second end (22) is below the first end (20). The second end (16) of each of the scalping screens (12) extends beyond the second end (22) of each of the cleaning screens (18).

Description

SEED CLEANING APPARATUS

Field of the Invention

The present invention relates to a seed cleaning apparatus of the kind used by farmers for separating grain of a preferred size from a feed material comprising grain and trash.

The present invention also relates to a method of separating a preferred size fraction from a particulate feed material.

Background of the Invention

Modern combine harvesters typically include a drum that consists of a rotating barrel with appropriate sized holes for separating the harvested grain from the chaff. The separation achieved by the harvester is generally very coarse and designed to recover as much of the iιarvested=grain as possible. As such, the harvester is unable to distinguish between different grains or sizes of grain and/or seeds from other plants and weeks. There is therefore a need to be able to separate the desired grade of grain from smaller size grain and or other seed and trash or weeds.

For any particular grain being harvested, there exists an optimum size fraction of that grain which attracts a premium price at market. Grain or seed that is less than this particular size fraction is typically undersize due to poor growth or has become shrivelled and is thus not attractive to buyers. Particulate material of a size greater than the preferred size fraction is also unattractive, particularly if such material contains trash such as unwanted grains of other varieties, weeds, insects including caterpillars etc.

Growers who wish to obtain top price for their grain and/or seed need to be able to separate the desired grade of grain of a particular size fraction from other sized grain and/or other seed and trash or weeds.

Screens are employed in many industries for separating material by selection of the size and/or shape of the apertures or holes of the screen. A feed material is introduced on top of the screen. The fraction of that material that is able to pass through the screen is called the undersize fraction. The remaining material retained on top of passes over the screen is called the oversize fraction.

It is also known in various arts to use multiple screens to separate various size fractions, for example when a particular intermediate size fraction is preferred. Typically, however, multiple screens are employed in series or parallel in a side by side or end to end arrangement. In a farming environment however, there is a need for a seed cleaning apparatus to be compact yet still be adapted to allow for an intermediate size fraction to be isolated for future sale.

Throughout this specification, the terms "grain" and "seed" are used interchangeably and the use of either term is not to be taken to imply that the other is intentionally excluded. The term "trash" is intended to cover material other than grain or seed, including sand, dirt, insects, weed etc.

The present invention was developed with a view to providing a seed cleaning apparatus capable of separating a preferred size fraction of first grade seed of an intermediate size from an undersize fraction and an oversize fraction including trash. It is however to be clearly understood that any one of the size fractions separated from the feed material using the device and method of the present invention can equally be chosen as the preferred product of the seed cleaning apparatus.

For the purposes of this specification it needs to be understood the word "comprising" means "including but not limited to" and that the word "comprises" has a corresponding meaning.

Summary of the Invention

According to an aspect of the present invention there is provided a seed cleaning apparatus for separating a preferred size fraction from a particulate feed material, the apparatus comprising:

an elongate, cylindrical scalping screen having a first end and a second opposite end, said scalping screen rotatably mounted at an angle inclined such that the second end is below said first end and is adapted to receive said particulate feed material at said first end and to separate said feed material into a first undersize fraction and a first oversize fraction, wherein said first undersize fraction passes through said scalping screen and said first oversize fraction travels along said scalping screen and out of said second end of said scalping screen; and, an elongate, cylindrical cleaning screen having a first end and a second opposite end co-axially mounted with and outside of said scalping screen to form a screening pair, wherein said second end of said scalping screen extends beyond said second end of said cleaning screen, said cleaning screen adapted to received said first undersize fraction from said scalping screen and separate said first undersize fraction into a second undersize fraction and a second oversize fraction, wherein said second undersize fraction passes through said cleaning screen and said oversize fraction travels along said cleaning screen and out of said second end of said cleaning screen; whereby in use, said particulate feed material is separated into a plurality of size fractions from which the preferred size fraction may be selected.

Advantageously, said screening pair is one of a plurality of screening pairs.

Preferably each of said screening pairs is rotatably mounted on a plurality of rollers fixed along elongate drive shafts extending substantially parallel to each of said cleaning screens and spaced apart at a sufficient distance whereby the cleaning screen is held on the rollers by gravity.

Preferably an outer surface of each cleaning screen sits in rolling contact with said rollers, wherein driving the drive shafts in one direction causes the screening pair to rotate in the opposite direction.

Advantageously, said plurality of screening pairs are mounted side by side and substantially parallel and share at least one drive shaft in common with an adjacent screening pair, wherein the rollers on each drive shaft except the outermost drive shafts are in rolling contact with two of said cleaning screens. According to another aspect of the present invention there is provided a seed cleaning apparatus for separating a preferred size fraction from a particulate feed material, the apparatus comprising a plurality of elongate, cylindrical cleaning screens having a first and a second opposite end, said cleaning screens rotatably mounted at an angle inclined such that said second end is below said first end and adapted to receive said particulate feed material at said first end and separate said particulate feed material into an undersize fraction and an oversize fraction wherein said undersize fraction passes through said cleaning screen and said oversize fraction passes along said cleaning screen and out of said second end; a transfer device for transferring at least one of said fractions from said apparatus; and a drive mechanism adapted to drive said cleaning screens and said transfer device.

Advantageously, at least one of said plurality of cleaning screens is provided with an elongate, cylindrical scalping screen co-axially mounted with and inside of said cleaning screen, said scalping screen comprising a first end and second opposite end and adapted to receive said feed material at said first end and separate said feed material into a first undersize fraction and a first oversize fraction wherein said first undersize fraction passes through said scalping screen to said at least one cleaning screen for further screening and said first oversize fraction passes along said scalping screen and out of said second end.

Preferably each of said cleaning screens is rotatably mounted on a plurality of rollers fixed along elongate drive shafts extending substantially parallel to each of said cleaning screens and spaced apart at a sufficient distance whereby the cleaning screen is held on the rollers by gravity.

Preferably an outer surface of each cleaning screen sits in rolling contact with said rollers, wherein driving the drive shafts in one direction causes the cleaning screens to rotate in the opposite direction. Advantageously, said plurality of cleaning screens are mounted side by side and substantially parallel, and share at least one drive shaft in common with an adjacent cleaning screen, wherein the rollers on each drive shaft except the outermost drive shafts are in rolling contact with two of said cleaning screens.

According to yet another aspect of the present invention there is provided a method for separating a preferred size fraction from a particulate feed material, the method comprising the steps of: separating said feed material into a first undersize fraction and a first oversize fraction by introducing said feed material to an elongate, cylindrical scalping screen having a first end and a second opposite end, said scalping screen rotatably mounted at an angle inclined such that said second end is below said first end and adapted to receive said feed material at said first end, and; separating said first undersize fraction into a second undersize fraction and a second oversize fraction by passing said first undersize fraction through an elongate, cylindrical cleaning screen having a first end and a second opposite end co-axially mounted with an outside of said scalping screen wherein said second end of said scalping screen extends beyond said second end of said cleaning screen, said cleaning screen adapted to receive said first undersize fraction from said scalping screen; whereby said particular feed material is separated into a plurality of size fractions from which the preferred size fraction may be selected.

According to yet another aspect of the present invention there is provided a method of separating a preferred size fraction from a particulate feed material, the method comprising the steps of: separating said feed material into an undersize fraction and an oversize fraction by passing said feed material through at least one of a plurality of elongate, cylindrical cleaning screens having a first end and a second opposite end, said cleaning screens rotatably mounted at an angle inclined such that said second end is below said first end, and adapted to receive said feed material at said first end whereby said undersize fraction passes through said cleaning screens and said oversize fraction passes along said cleaning screens and out of said second end; transferring at least one of said size fractions from said apparatus using a transfer device; and driving said cleaning screens and said transfer device using a single drive mechanism.

Brief Description of the Drawings

In order to facilitate a better understanding of the nature of the invention, a preferred embodiment of the seed cleaning apparatus will now be described in detail, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a front perspective view of a preferred embodiment of a seed cleaning apparatus in accordance with the present invention;

Figure 2 is a close-up perspective view of one of the rotating cleaning screens in the seed cleaning apparatus of Figure 1 ; and,

Figure 3 is a rear view of the seed cleaning apparatus of Figure 1.

Detailed Description of the Invention A preferred embodiment of the seed cleaning apparatus 10 is illustrated in the accompanying drawings and comprises a plurality of elongate, cylindrical scalping screens 12 having a first end 14 and a second end 16 inclined such that the second end 16 is below the first end 14. In the illustrated embodiment, each of said scalping screens is co-axially mounted with and inside of a corresponding elongate, cylindrical cleaning screen 18 forming a screening pair. The cleaning screens have a first end 20 and a second end 22 also inclined such that the second end 22 of the cleaning screen 18 is below the first end 20 of the cleaning screen 18. The second end 16 of each of the scalping screens 12 extends beyond the second end 22 of each of the cleaning screens 18.

In the illustrated embodiment, three of such screening pairs are rotatably mounted side by side in a substantially parallel arrangement above a grain hopper 24 which is mounted on a wheeled chassis 26 of the apparatus 10. It is, however, to be clearly understood that more or less pairs may be used.

Each of the scalping and cleaning screens is provided with an array of apertures in the form of slots or holes adapted to pass undersize material therethrough. The undersize fraction from each of the cleaning screens 18 falls into the hopper 14 where it collects prior to transfer from the apparatus 10.

Particulate feed material is fed into the first end 14 of one or more of the scalping screens 12. The material is then separated into a first undersize fraction and a first oversize fraction. The first undersize fraction passes through the scalping screens 12 into the corresponding cleaning screen 18 of each screening pair. The first oversize fraction from the scalping screens 12 passes along the length of the scalping screen and falls out the second end 16 of the scalping screens 12 into a first collector 28. The first undersize fraction from the scalping screens 12 is further screened by cleaning screens

18. The cleaning screens 18 further separate this first undersize fraction into a second undersize fraction and a second oversize fraction. The second undersize fraction passes through the cleaning screens 18 and into the hopper 14 for collection prior to transfer from the apparatus 10. The second undersize fraction passes along the length of the cleaning screens 18 and falls out the second end 22 of the cleaning screens 18 into a second collector 30.

The second oversize fraction collected in the second collector 30 is directed down towards a first end 34 of a first auger 32 for transferring from the apparatus 10 to a field bin, truck or silo (not shown). Whilst in the preferred embodiment of the present invention an auger is the transfer device used by way of example, it is to be understood that it is within the scope of the present invention for other suitable transfer devices such as flowveyers to be used in place of or in combination with augers to transfer any of the size fractions collected following separation of the particulate material in the seed cleaning apparatus from the apparatus. The apertures formed in the scalping screens 12 are typically of a larger size and/or shape to those of the cleaning screens. It is intended that the particulate feed material that is introduced to the first end 14 of the scalping screens 12 is subjected to two screening steps as it travels through the apparatus 10. The particulate material that is able to pass through the apertures of the scalping screen 12, are further screened by the cleaning screens 18.

In the preferred embodiment of the present invention, the first oversize fraction of the cleaning screens comprises the grain which is of the premium size fraction and is preferred for market. Therefore in use, size and/or shape of the apertures of the scalping screens is chosen to set the upper limit of the preferred size fraction and the aperture size and/or shape of the cleaning screens is chosen to determine the lower limit of the preferred size fraction of material.

The first oversize fraction that passes through from the first end to the second end 16 of scalping screens 12 is collected in the first collector 28 and directed down a chute 38 provided at a lower end 40 of the first collector 28. The chute 38 is provided with a diverter (not shown) which can be moved to a first position in which the contents of the first collector 28 are directed onto the ground, or to a second position in which the contents of the first collector 28 are directed to a first end 44 of the second auger 42.

Each of the cleaning screens 18 is rotatably mounted on a plurality of rollers 48 fixed along two elongate drive shafts 50. The drive shafts 50 extend substantially parallel to each of the cleaning screens 18 and are spaced apart at a sufficient distance from the cleaning screens 18, whereby the cleaning screens 18 are held on the rollers 48 by gravity as illustrated in Figure 3. An outer surface 52 of each cleaning screen 18 sits in rolling contact with the rollers 48 as illustrated in Figure 2, so that when the drive shafts 50 are driven in one direction (say clockwise), the cleaning screens 18 are caused to rotate in the opposite direction (anti-clockwise).

As can be clearly seen in Figure 3, by way of example, in the event that a plurality of cleaning screens/scalping screens are used in combination in a single seed cleaning apparatus 10, each of the cleaning screens 18 share at least one drive shaft 50 in common with an adjacent cleaning screen 18, so that the rollers 48 on each drive shaft 50, except the outermost drive shafts (on the left and right hand sides of the apparatus 10 respectively as illustrated in Figure 3), are in rolling contact with two of the cleaning screens 18. Because each of the cleaning screens 18 simply sit on top of the rollers 48, it is a relatively simply procedure to replace each of the cleaning screens 18 with another cleaning screen 18 having a different sized aperture depending not the particular crop that is being cleaned.

Advantageously, the seed cleaning apparatus 10 also includes a drive mechanism for driving the cleaning screens 18 and the device(s) used to transfer each size fraction from the apparatus using a single drive, in this example engine 54. In the illustrated embodiment, engine 54 is a small 20 horse power petrol engine that supplies all of the power for the apparatus 10. A pair of v-belts 56 are used to couple a double pulley 58 on drive shaft 60 of the engine 54 to a large double pulley 62 mounted at the first end 66 of third auger 64 (not visible). The third auger 64 extends along the full length of the bottom of hopper 24. Whilst in the illustrated embodiment, v-belts and pullies are used for power transmission, it is to be clearly understood to be within the scope of the present invention for other power transmission devices such as chains, synchronous belts or timing belts and sprockets to be used to drive the cleaning screens and/or transfer devices using the single source of power.

In the illustrated embodiment, third auger 64 is driven directly by the engine 54 by means of the double pulley 62 which is fixed to a drive shaft of the third auger 64. Also connected at the first end 66 of the third auger 64 is a sprocket wheel 68 (not visible) that is coupled to a pair of sprockets provided on the two inner most drive shafts 50 respectively via a chain 70 in this example. Again it is to be clearly understood that while a chain and sprocket assembly are the preferred power transmission means in the illustrated embodiment of the present invention, other transmission means such as belting, synchronous belting and v-belting may be used interchangeably with the chain and sprocket assembly and still fall within the scope of the present invention. In the illustrated embodiment, an idler sprocket 72 is provided for adjusting the tension on chain 70. In this way, the innermost drive shafts 50 are driven by the engine 54 via chain 70. Two smaller chains 74 couple the two innermost drive shafts 50 to the two outermost drive shafts 50 in order to indirectly drive the two outermost drive shafts 50 via engine 54 as well. In this way all four drive shafts 50 are -driven in the same direction by the engine 54.

Advantageously, each of the devices for transferring various size fractions of the feed material separated by way of the scalping and/or cleaning screens from the apparatus 10 are also driven by the engine 54 by the clever use of right angle gearboxes respectively fitted to the drive shafts of each transfer means, in this example each auger, at the first or lower end of the respective augers. Thus, for example, as shown in Figure 1 the first auger 32 is fitted with a right angle gearbox 76 at the drive shaft located at the first end 34 of first auger 32. The right angle gearbox 76 is mechanically coupled to the first end 66 of the third auger 64 via another set of double pullies 78 and v-belt 80. Again it is to be clearly understood that while pullies and v-belts have been described in the illustrated embodiment, other power transmission means such as chains and sprocket assemblies could be interchanged therewith and still fall within the scope of the present invention. The second auger 42 is likewise driven by means of a right angle gearbox that is mechanically coupled to the shaft of the first end 66 of the third auger 64 by means of a similar arrangement of v-belts and pullies or other suitable power transmission devices.

It is worth noting that double pulley 78 has two v-belts associated therewith, one of which is used to drive first auger 32 and the other used to drive second auger 42.

A fourth auger 82 is provided at the back end of the apparatus 10 for lifting the feed material into the first end 14 of the scalping screens 12 as can be seen most clearly in Figure 3. A small feed hopper 84 is provided at the back end of the apparatus 10 from which feed pipes 86 corresponding in number to the number of screening pairs transfer the particulate feed material into the first end 14 of the scalping screens 12. The fourth auger 82 is also fitted with a right angle gearbox 88 that is mechanically coupled via a series of pullies 90, v-belts 92 and drive shaft 94 to another right angle gearbox 96. Gearbox 96 is mechanically coupled to one of the outermost drive shafts 50 by way of a chain drive or other suitable power transmission means. In this way, the fourth auger 82 is also driven by the engine 54.

An application of the seed cleaning apparatus will now be briefly described, by way of example, with reference to cleaning of canola seeds. First grade canola seeds are typically of a size fraction whereby the seeds are less than approximately 2.1 to 2.3 mm in diameter, but greater than 1.0 to 1.3 mm in diameter. If the crop has been damaged in some way, or the quality of the crop has been compromised due to, say, poor weather conditions, some of the canola seeds may have become shrivelled and will typically be less than 1.3mm in diameter. During harvesting, both first grade and lower grade canola seeds, as well as unwanted larger grains such as lupin or radish seeds, weed and trash, including caterpillars, insects and pods are mixed up together to form a particulate feed material. This feed material can be fed through the seed cleaning apparatus 10 in order to separate the smaller low quality seed from the first grade seed while also separating larger grain and trash as well. To do this, the cleaning screens 18 are selected with 1.3 mm size apertures, whilst each inner scalping screen 12 is selected with 2.1 mm size apertures.

As the mixture travels along the length of the scalping screens 12, canola seeds less than 2.1 mm in diameter pass through the scalping screens onto the corresponding cleaning screens 12, whereas unwanted larger grain, caterpillars, insects, pods and other trash continue down the length of the scalping screen and fall out the front end into the second collector 24. Meanwhile, the canola seeds that have passed through the scalping screen 12 undergo a second screening step by means of the corresponding cleaning screens 18, which allow the smaller unwanted material, including seeds, rye grass weed and shrivelled canola seeds to pass through into the hopper 14. The first grade seed which is the oversize fraction of the cleaning screens travels along the cleaning screens 18 until it falls out the second end 22 into the first collector 30, from where it can be transferred to a truck or silo via the first auger 32. The unwanted larger grain and trash which is the oversize fraction of the scalping screens can be dumped directly onto the ground, or can be transferred via the second auger 42 to another bin to be used, for example, as animal feed. The smaller unwanted seeds collected in the hopper 24 are transported to the first end 44 of the second auger 42 for transfer to another bin or can be dumped directly on the ground. Different sizes and combinations of cleaning and scalping screens can be used for other types of seed.

Now that a preferred embodiment of the seed cleaning apparatus in accordance with the present invention has been described in detail, it will be apparent that it provides a number of significant advantages, including the following:

(i) The use of scalping screens fitted coaxially within the cleaning screens allows a two step cleaning process for separating good seed from unwanted grain and/or trash;

(ii) By having a plurality of cleaning screens operating in parallel it provides a large surface area for rapid and efficient seed cleaning;

(iii) It employs a single motor to provide all the power for the unit;

(iv) The clever use of right angle gear boxes enables each of the augers to be driven by the same engine; and,

(v) It is simple to operate, robust in design and well suited to use in the field.

Numerous variations and modifications will suggest themselves to persons-skilled in the agricultural machinery arts, in addition to those already described, without departing from the basic inventive concepts. For example, whilst three cleaning screens arranged in a single plain are employed in the preferred embodiment, the number and arrangement of the cleaning screens may be varied depending upon the application. All such variations and modifications are to be considered within the scope of the present invention, the nature of which is to be determined from the foregoing description and the appended claims.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS;

1. A seed cleaning apparatus for separating a preferred size fraction from a particulate feed material, the apparatus comprising: an elongate, cylindrical scalping screen having a first end and a second opposite end, said scalping screen rotatably mounted at an angle inclined such that said second end is below said first end and is adapted to receive said particulate feed material at said first end and to separate said feed material into a first undersize fraction and a first oversize fraction, wherein said first undersize fraction passes through said scalping screen and said first oversize fraction travels along said scalping screen and out of said second end of said scalping screen; and, an elongate, cylindrical cleaning screen having a first end and a second opposite end co-axially mounted with and outside of said scalping screen to form a screening pair, wherein said second end of said scalping screen extends beyond said second end of said cleaning screen, said cleaning screen adapted to received said first undersize fraction from said scalping screen and separate said first undersize fraction into a second undersize fraction and a second oversize fraction, wherein said second undersize fraction passes through said cleaning screen and said oversize fraction travels along said cleaning screen and out of said second end of said cleaning screen; whereby in use, said particulate feed material is separated into a plurality of size fractions from which the preferred size fraction may be selected.

2. A seed cleaning apparatus for separating a preferred size fraction from a particulate feed material according to claim 1, wherein said screening pair is one of a plurality of screening pairs.

3. A seed cleaning apparatus for separating a preferred size fraction from a particulate feed material according to claim 2, wherein each of said screening pairs is rotatably mounted on a plurality of rollers fixed along elongate drive shafts extending substantially parallel to said cleaning screens and spaced apart at a sufficient distance whereby the cleaning screen is held on the rollers by gravity.

4. A seed cleaning apparatus for separating a preferred size fraction from a particulate feed material according to claim 3, wherein an outer surface of each cleaning screen sits in rolling contact with said rollers whereby, in use, driving the drive shafts in one direction causes the screening pair to rotate in the opposite direction.

5. A seed cleaning apparatus for separating a preferred size fraction from a particulate feed material according to any of claims 2 to 4 wherein said plurality of screening pairs are mounted side by side and substantially parallel and share at least one drive shaft in common with an adjacent screening pair, wherein the rollers on each drive shaft except the outermost drive shafts are in rolling contact with two of said cleaning screens.

6. A seed cleaning apparatus for separating a preferred size fraction from a particulate feed material, the apparatus comprising: a plurality of elongate, cylindrical cleaning screens having a first and a second opposite end, said cleaning screens rotatably mounted at an angle inclined such that said second end is below said first end and is adapted to receive said particulate feed material at said first end and to separate said particulate feed material into an undersize fraction and an oversize fraction wherein said undersize fraction passes through said cleaning screen and said oversize fraction passes along said cleaning screen and out of said second end; a transfer device for transferring at least one of said fractions from said apparatus; and a drive mechanism adapted to drive said cleaning screens and said transfer device.

7. A seed cleaning apparatus for separating a preferred size fraction from a particulate feed material according to claim 6, wherein at least one of said plurality of cleaning screens is provided with an elongate, cylindrical scalping screen co-axially mounted with and inside of said cleaning screen, said scalping screen comprising a first end and second opposite end and adapted to receive said feed material at said first end and to separate said feed material into a first undersize fraction and a first oversize fraction wherein said first undersize fraction passes through said scalping screen to said at least one cleaning screen for further screening and said first oversize fraction passes along said scalping screen and out of said second end.

8. A seed cleaning apparatus for separating a preferred size fraction from a particulate feed material according to claim 7, wherein each of said cleaning screens is rotatably mounted on a plurality of rollers fixed along elongate drive shafts extending substantially parallel to each of said cleaning screens and spaced apart at a sufficient distance whereby the cleaning screen is held on the rollers by gravity.

9. A seed cleaning apparatus for separating a preferred size fraction from a particulate feed material according to either one of claims 7 or 8, wherein an outer surface of each cleaning screen sits in rolling contact with said rollers whereby, in use, driving the drive shafts in one direction causes the cleaning screens to rotate in the opposite direction.

10. A seed cleaning apparatus for separating a preferred size fraction from a particulate feed material according to claim 9, wherein said plurality of cleaning screens are mounted side by side and substantially parallel, and share at least one drive shaft in common with an adjacent cleaning screen, wherein the rollers on each drive shaft except the outermost drive shafts are in rolling contact with two of said cleaning screens.

11. A method for separating a preferred size fraction from a particulate feed material, the method comprising the steps of: separating said feed material into a first undersize fraction and a first oversize fraction by introducing said feed material to an elongate, cylindrical scalping screen having a first end and a second opposite end, said scalping screen rotatably mounted at an angle inclined such that said second end is below said first end and adapted to receive said feed material at said first end, and; separating said first undersize fraction into a second undersize fraction and a second oversize fraction by passing said first undersize fraction through an elongate, cylindrical cleaning screen having a first end and a second opposite end co-axially mounted with an outside of said scalping screen wherein said second end of said scalping screen extends beyond said second end of said cleaning screen, said cleaning screen adapted to receive said first undersize fraction from said scalping screen; whereby said particular feed material is separated into a plurality of size fractions from which the preferred size fraction may be selected.

12. A method of separating a preferred size fraction from a particulate feed material, the method comprising the steps of: separating said feed material into an undersize fraction and an oversize fraction by passing said feed material through at least one of a plurality of elongate, cylindrical cleaning screens having a first end and a second opposite end, said cleaning screens rotatably mounted at an angle inclined such that said second end is below said first end, and adapted to receive said feed material at said first end whereby said undersize fraction passes through said cleaning screens and said oversize fraction passes along said cleaning screens and out of said second end; transferring at least one of said size fractions from said apparatus using a transfer device; and driving said cleaning screens and said transfer device using a single drive mechanism.

13. A seed cleaning apparatus for separating a preferred size fraction from a particulate feed material substantially as herein described with reference to and as illustrated in the accompanying drawings.

14. A method of separating a preferred size fraction from a particulate feed material substantially as herein described with reference to and as illustrated in the accompanying drawings.