Patent Description:
Pneumatic conveying systems are used to transfer materials such as particulates, or powders etc. through enclosed pipelines. Air is used as the conveying mechanism, carrying the materials from an inlet to an outlet of the system by transmitting a propulsive force (i.e. a positive pressure) to the material. To function correctly, the pneumatic conveying apparatus requires a pressure differential between the inlet and outlet of the system. The pressure difference is usually provided by a pump on the inlet side of the system.

in an example prior art application, materials are transferred from trucks into storage silos, via a sifter or sieve apparatus. The material is pumped via conveying air from the truck to the silo, via the sifter. However, such systems have a number of significant disadvantages. These disadvantages are addressed in the present invention.

A centrifugal sifter is a type of sifter, which is used to screen, separate, and remove material of different sizes at high rates of efficiency. The sifter contains a drum which is orientated substantially horizontally and comprises a shaft optionally with paddles attached to it, which rotates at high velocity. The material is fed into the drum from an inlet end, usually by a screw shaft. Whilst the material is inside the drum, it is forced to the interior walls of the drum by centrifugal force due to the rotation of the paddles attached to the shaft. The walls of the drum are lined with screens which are perforated with holes. The diameter of the holes determines the size of the material particulates which can pass through the sifter. The material travels along the drum, pushed along by the paddle assembly, until it has either been small enough to pass through the screens, or until it is passed along to the end of the drum to an outlet for oversized material. After the material has passed through the screens, it is gravity fed down a chute where it is reintroduced to the conveying pipeline which terminates inside the silo.

An issue which can arise in the example prior art system described above is that the perforated screens can easily become clogged up due to influxes of material entering the sifting drum. These influxes are caused by the irregular feeding of material from the truck. The truck has little control over the mass flow rate of the material being introduced into the system, due to the nature of the feed-in process. The shape of the truck hopper is mainly dictated by the dimensions of the vehicle, and is not designed for ideal material flow conditions. Large lumps and clumps of material from the truck can block the perforations of the screens, which reduces the efficiency of the sifting drum. The screens may become blocked to the extent that material cannot pass through, resulting in valuable material being fed into the 'oversized material' outlet of the sifter and therefore wasted.

The drum may also overfill, resulting in a lower sifting efficiency. Blocked perforations in the sifter may also cause blockages in the conveying system upstream.

It is an object of at least one aspect of the present invention to obviate or at least mitigate one or more of the aforementioned problems.

It is a further object of at least one aspect of the present invention to provide an improved pneumatic conveying apparatus for separating a range of materials such as particulates and/or powders which are pneumatically conveyed through pipelines.

It is a yet further object of at least one aspect of the present invention to provide an improved pneumatic conveying apparatus which maintains the efficiency of the sifting in a pneumatic conveying system, and which reduces the risk of the sifting becoming blocked due to material mass flow rate fluctuations.

<CIT> is a pressured, close loop, fluid bed combustion system with sizing means for separating fine from coarse grain material using a cyclone separator and a gravity and pressure fed screen.

The present invention provides for apparatus for pneumatically conveying and separating bulk material and corresponding methods as claimed in the accompanying claims.

Embodiments of the present invention will now be described, by way of example only, with reference to the following Figures:.

Generally speaking, the present invention therefore relates to a pneumatic conveying system comprising a cyclonic separator in combination with a cyclonic sifting apparatus which is capable of separating pneumatically conveyed material into oversize powder discharge (e.g. waste material) and fine powder discharge (e.g. valuable product material). This is discussed below in detail.

<FIG> is a representation of a cyclonic feed apparatus <NUM> according to the present invention. As shown in <FIG>, the cyclonic feed apparatus <NUM> is capable of receiving material from a vehicle <NUM>. The vehicle <NUM> contains a transport silo <NUM> which feeds material to a vibration sifter <NUM>. The vibration sifter <NUM>, which is an optional feature, shakes the material to be conveyed and helps to prepare the material to be pneumatically conveyed by breaking down any large clumps of condensed material. This material is then fed to the cyclonic feed apparatus <NUM>. Material then passes through the cyclonic feed apparatus <NUM> which is described in more detail below. The pneumatically conveyed material is then fed into a storage silo <NUM> via, for example, any suitable means such as a static sifter (e.g. a grid) <NUM>.

<FIG> are representations of a further cyclonic feed apparatus <NUM> according to the present invention.

<FIG> and <FIG> show material entering via the direction identified by arrow 'A' into the inlet feed <NUM>. <FIG> also shows the material exiting the cyclonic feed apparatus <NUM> via outlet feed <NUM> along the direction identified by arrow 'B'.

<FIG> show that the cyclonic feed apparatus <NUM> comprises an inlet feed <NUM>. Through the inlet feed <NUM> material may be received from the transport silo <NUM> and optionally the vibration sifter <NUM>. Pneumatically conveyed material is then fed up through a substantially vertically located passageway <NUM>, for example, in the form of a pipe. Located along the substantially vertical passageway <NUM> there is a coarse sieve <NUM>.

The conveyed material is then passed through inlet <NUM> into an upper section of a cyclone separator <NUM>. The cyclone separator <NUM> may have a large volume such as over <NUM>, <NUM> or <NUM> litres. The cyclone separator <NUM> is located substantially vertically along a substantially vertical axis <NUM> of the cyclonic feed apparatus <NUM>. The cyclone separator <NUM> comprises two main sections. The first upper section <NUM> is substantially cylindrical in shape. The lower main section <NUM> is in a funnel form to feed material into the sifting device <NUM>. It should be noted that the size and proportions of the cylindrical and funnel shapes may vary significantly from what is shown in the figures.

Material is fed through the lower main section <NUM> of the cyclone separator <NUM> via an outlet <NUM> into the sifting device <NUM> through an opening <NUM>. The sifting device <NUM> is a centrifugal sifting device. This is described in more detail below.

Material once passed through the cyclonic separator <NUM> and the sifting device <NUM>, then exits the cyclonic feed apparatus <NUM> via an outlet <NUM>.

<FIG> also show that the cyclonic feed apparatus <NUM> comprises a control panel <NUM> which is used to control the apparatus <NUM> and monitor the feed rate and operation of the apparatus <NUM>.

The cyclonic feed apparatus <NUM> also comprises elongate sections <NUM>, <NUM> in the form of skids which allows a fork lift truck to easily lift and manoeuvre the cyclonic feed apparatus <NUM>.

There is also shown a pneumatic control device <NUM> which is used to control the pneumatic feed.

<FIG> also show that there is a conduit generally designated <NUM> which extends from below the sifting device to above the cyclone separator <NUM>. in particular, the conduit <NUM> is in the form of a pipe extending from below a chute <NUM> located below the device <NUM>. The conduit <NUM> comprises a substantially vertical section which may comprise a sieve <NUM>. The conduit <NUM> then extends to above the cyclone separator <NUM> and is then connected to an upper section of the cyclone separator <NUM> via a section of pipe <NUM> and an upper located inlet <NUM>.

The function of the conduit <NUM> is to take the separated air from the cyclone separator <NUM> and reintroduce the air into the pneumatic conveying pipeline, via the outlet <NUM>. This novel process of using the separated air to continue to convey the material after the sifting device <NUM> has many benefits. One such benefits is that there only needs to be one propulsive air source to convey material through the whole system. The air which is used to introduce the material into the cyclonic feed apparatus <NUM>, is the same as the air used to convey the material out of the apparatus <NUM>. This removes any need for additional energy sources within the apparatus to convey the air, thereby making the process more energy efficient.

<FIG> represents part of a further cyclonic feed apparatus <NUM> according to the present invention. The cyclonic feed apparatus <NUM> comprises a cyclone separator <NUM> which comprises an upper section <NUM> and a lower section <NUM>. There is also shown an inlet <NUM> into an upper section of the cyclone separator <NUM>.

Of particular relevance, <FIG> shows a sifting device <NUM>. The sifting device <NUM> is generally a substantially hollow cylindrical member which is located substantially horizontally. The sifting device <NUM> comprises a centrally and substantially horizontally mounted shaft <NUM> which is rotated during use resulting in material being forced to the outside surfaces <NUM>, <NUM> of the sifting device <NUM> via centrifugal forces. Although not shown, outlying and/or protruding members such as paddles maybe located on the shaft <NUM> which assist in the material being stirred and/or rotated. There is also shown a chute <NUM>. Sifted material exits through outlet <NUM>.

<FIG> represents a further cyclonic feed apparatus <NUM> according to the present invention. The cyclonic apparatus <NUM> shown in <FIG> is very similar to the cyclonic apparatus <NUM> shown in <FIG>.

The cyclonic apparatus <NUM> comprises a cyclone separator <NUM> which comprises an upper section <NUM> and a lower section <NUM>. There is also shown an inlet <NUM> into the upper section <NUM> of the cyclone separator <NUM>. Of particular relevance, <FIG> shows a sifting device <NUM>.

The sifting device <NUM> is generally a substantially hollow cylindrical member which is located substantially horizontally. A shaft <NUM> optionally comprising outlying and/or protruding members such as paddles is rotated during use resulting in material being forced to the outside surfaces <NUM>, <NUM> of the sifting device <NUM> via centrifugal forces. There is also shown a chute <NUM>. Sifted material exits through outlet <NUM>.

The cyclonic feed apparatus <NUM> also comprises a coarse screen <NUM> which is used to filter material prior to entering the cyclone separator <NUM>. The coarse screen <NUM> may have a screen range size of about <NUM>- <NUM> or about <NUM>. There is also shown a fine screen <NUM> which secures an air bypass. The fine screen <NUM> may have a screen range size of about <NUM> - <NUM> or about <NUM>.

The air bypass with a cyclone provides that the pneumatically conveyed product has a possibility to be sieved because the airspeed and/or volume fluctuates due to a range of factors such as any one of or combination of the following: pneumatic conveying settings set by a truck driver; air supply; amount of product and a tanker silo on a vehicle; a variety of piping which may be used in different apparatus; and pressure drops anywhere in the systems.

The cyclonic apparatus <NUM>, <NUM> shown in <FIG> and <FIG> may be used in the embodiments shown in <FIG>.

<FIG> is a representation of a partial sectional view of a further cyclonic feed apparatus <NUM> according to the present invention. The cyclonic feed apparatus <NUM> is shown in a partial sectional view which illustrates the travel of pneumatically conveyed material through the apparatus <NUM>. This will now be discussed.

As shown in <FIG>, powder feed material <NUM> is fed into a hopper <NUM>. The powder feed material <NUM> may be fed from a transport silo <NUM> as shown in <FIG>. However, it should be noted that the powder feed material <NUM> may be fed from any location or storage system.

The powder feed material <NUM> is therefore gravity fed via the hopper <NUM> into a cyclone separator <NUM>. The cyclone separator <NUM> will be similar to that shown in <FIG>. As shown in <FIG>, the cyclone separator <NUM> is located substantially vertically. The cyclone separator <NUM> comprises an upper section through which material <NUM> is fed into from the hopper <NUM> and a lower section. inside the cyclone separator <NUM> a vortex of air and particulate material is formed where separation of the material <NUM> may occur. This is discussed in more detail below.

As shown in <FIG>, the material exits the cyclone separator <NUM> along a substantially horizontal path into the sifting device generally designated <NUM>. The material may be fed into the sifting device <NUM> via any suitable means such as a screw shaft.

The sifting device <NUM> has an outer casing <NUM> which may contain an opening in the form of a door which may allow inspection and maintenance of the sifting device <NUM>.

<FIG> also shows that there is a substantially centrally mounted shaft <NUM> which extends substantially horizontally through the sifting device <NUM>. Although not shown, the substantially centrally mounted shaft <NUM> may comprise outlying and/or protruding members such as paddles which may assist in the stirring and/or rotation of the material within the sifting device.

<FIG> also shows that the sifting device <NUM> comprises a substantially horizontally mounted substantially cylindrical sieve <NUM> within which the powder feed material <NUM> is rotated and circulated at a speed of: about <NUM> - <NUM>,<NUM> rpm; about <NUM> - <NUM> rpm or about 500rpm. The speed varies for different sizes of machines and the diameters of rotation involved.

The cylindrical sieve <NUM> comprises a mesh-like structure with a series of small apertures. The apertures in the mesh-like structure may have a cross-sectional diameter of any of the following: about <NUM>; about <NUM>; about <NUM>; about <NUM>; about <NUM>; about <NUM>; about <NUM>; about <NUM>; about <NUM>; about <NUM>; about <NUM>; about <NUM>,<NUM>; or about <NUM>,<NUM>. Alternatively, the apertures may have a cross-sectional diameter of any of the following: about <NUM>- <NUM>,<NUM>; about <NUM> - <NUM>; about <NUM> - <NUM>; or about <NUM> - <NUM>.

The mesh-like structure allows fine particulate material <NUM> to pass through the cylindrical sieve <NUM> and exit as shown as a fine powder discharge <NUM> through an outlet <NUM> located below the sifting device <NUM>.

The cross-sectional size of the fine powder discharge <NUM> particles is selected from any of the following: about <NUM> microns to about <NUM>; about <NUM> microns to <NUM>; or about <NUM> microns to <NUM>.

The fine powder discharge <NUM> is valuable product material. It has been found that the present invention allows the capture of a much greater percentage of fine powder discharge material <NUM> in comparison to prior art systems. This is because fewer 'clumps' of material enter into the sifting device <NUM>, due to the presence of the cyclone separator <NUM>. The cyclone separator <NUM> maintains an almost constant material mass flow rate at its outlet, before being fed into the sifting device <NUM>. The constant mass flow rate received by the sifting device <NUM> prevents the sifting device <NUM> becoming clogged up, and becoming less efficient.

Larger particulate material (e.g. waste material) is retained within the cylindrical sieve <NUM> and exits through an outlet <NUM> as an oversize powder discharge <NUM>. The size of the oversize powder discharge <NUM> particles is larger than the apertures or holes in the cylindrical sieve <NUM>.

<FIG> also shows that the cyclonic feed apparatus <NUM> comprises a release assembly <NUM> which may in some embodiments be a quick release basket assembly. There is also a motor <NUM> which is used to provide rotation to the shaft <NUM> located in the sifting device <NUM>.

Furthermore, there is shown an inspection door <NUM> which may be hinged and quick release to allow easy and quick access. There is also a chute <NUM> which collects the fine powder material which exits as a fine powder discharge <NUM>.

<FIG> is a further cyclonic feed apparatus according to the present invention generally designated <NUM>. The cyclonic feed apparatus <NUM> is similar to the apparatus previously described in <FIG>.

The cyclonic feed apparatus <NUM> comprises a cyclone separator <NUM> which is located substantially vertically. The cyclone separator <NUM> comprises an upper section <NUM> which is substantially cylindrical and a lower section <NUM> which funnels material down into a sifting device <NUM>.

As shown in <FIG>, particulate material enters via an inlet <NUM> into the upper section <NUM> of the cyclone separator <NUM>. Although not shown there may be more than one, two, three or a plurality of inlets feeding particulate material into the cyclone separator <NUM>.

A preferred embodiment is shown in <FIG> where the inlet <NUM> passes the particulate material in a substantially tangential direction into the cyclone separator <NUM> which is substantially cylindrical in shape. The tangential direction is tangential to a central axis extending through the centre of the cyclone separator <NUM>. The tangential direction of the particulate material has been found to be preferred but other directions of input for the material may be used.

The material may be fed at a velocity 'V' into the cyclone separator <NUM> at a range of: about <NUM>/s to <NUM>/s; about <NUM>/s to about <NUM>/s or about <NUM>/s to <NUM>/s. Alternatively, the material may be fed at a velocity 'V' into the cyclone separator <NUM> at a range of: about <NUM>/s; about <NUM>/s; about <NUM>/s; about <NUM>/s; about <NUM>/s; about <NUM>/s; about <NUM>/s; about <NUM>/s; about <NUM>/s; about <NUM>/s; about <NUM>/s or about <NUM>/s.

As shown in <FIG>, the particulate material <NUM> is then caused to rotate in a cyclonic vortex due to the rotation of air within the cyclonic separator <NUM>. They pneumatically conveyed air and particulate material fed into the inlet <NUM> causes the cyclonic vortex rotation of the air and particulate material within the cyclone separator <NUM>. During the cyclonic motion of the particulate material the particulate material is forced to the outer surfaces of the cyclone separator <NUM> in a vortex-like manner.

The particulate material then passes through an outlet <NUM> of the cyclone separator <NUM> and into a substantially horizontally located channel <NUM>. Via the channel <NUM> material is then fed via, for example, a screw shaft, and pneumatically conveyed into the sifter device <NUM>. The screw shaft may be driven by a motor.

As shown in the cross-sectional view in <FIG>, the sifter device <NUM> comprises a substantially longitudinally oriented cylindrical hollow sieve <NUM>. For example, the cylindrical sieve <NUM> may be in the form of a drum. The cylindrical sieve <NUM> comprises a mesh-like structure with a series of small apertures with the cross-sectional diameter. Alternatively, the cylindrical sieve <NUM> may comprise and be lined with a series of screens which are perforated with holes.

The apertures in the mesh-like structure have a cross-sectional diameter of any of the following: about <NUM>; about <NUM>; about <NUM>; about <NUM>; about <NUM>; about <NUM>; about <NUM>; about <NUM>; about <NUM>; about <NUM>; about <NUM>; about <NUM>,<NUM>; or about <NUM>,<NUM>. Alternatively, the apertures have a cross-sectional diameter of any of the following: about <NUM> - <NUM>,<NUM>; about <NUM> - <NUM>; about <NUM> - <NUM>; or about <NUM> - <NUM>.

A screw conveyor <NUM> is shown transferring the material from the outlet <NUM> of the cyclone separator <NUM> along and into the sifter device <NUM>. However, any suitable type of device may be used to assist the transfer of the material into the sifter device <NUM>.

There is also shown a shaft <NUM> which contains a series of outlying and/or protruding members (e.g. paddles) <NUM> which are used to assist in the stirring and/or rotation of the material. The shaft <NUM> is therefore rotated and driven by the motor M whereupon the outlying and/or protruding members (e.g. paddles) <NUM> force the material outwards to the cylindrical sieve <NUM>. This allows the separation of the material to occur under centrifugal forces into smaller and larger particulate material.

There is also shown a chute <NUM>. Sifted material exits through outlet <NUM>.

The mesh-like structure allows fine particulate material <NUM> to pass through the cylindrical sieve <NUM> and exit as shown as a fine powder discharge <NUM> out through an outlet <NUM> from the bottom of the cyclonic feed apparatus <NUM>. The size of the fine powder discharge <NUM> particles is smaller than the size of the apertures in the mesh-like structure.

Larger sized particulate material is retained within the cylindrical sieve <NUM> and exits through an outlet <NUM> as an oversize powder discharge. The size of the oversize powder discharge particles is larger than the size of the apertures in the mesh-like structure in the cylindrical sieve <NUM>. The flowrate of the oversized power discharge particles may depend upon the efficiency of the sieving process, i.e. a higher rate of sieving efficiency = a lower flow rate of oversized particles.

<FIG> also shows that there is a conduit (or passageway) <NUM> connecting the upper section <NUM> of the cyclonic separator <NUM> and the outlet <NUM> from the bottom of the cyclonic feed apparatus <NUM>. There is therefore a flow of air from an opening <NUM> located on an upper surface of the cyclone separator <NUM> along the conduit (or passageway) <NUM> to the outlet <NUM> located below the sifting device <NUM>. This has been found to be pneumatically efficient in conveying the material and air. The additionally conveyed pneumatic air along the conduit (or passageway) <NUM> may therefore collect and assist in transfer of the fine powder discharge <NUM>. This is a specific advantage of the present invention in that there is a highly efficient use of the pneumatically conveyed air in the whole system.

Material exiting from the outlet <NUM> at the bottom of the cyclonic feed apparatus <NUM> may then be collected and continued to be conveyed.

<FIG> is an expanded cross-sectional view of the cyclone separator <NUM> shown in <FIG>. The particulate material <NUM> is shown to be thrown against the sidewalls of the upper section <NUM> of the cyclone separator <NUM> and then funnelled down along into the lower section <NUM> of the cyclone separator <NUM>. Pneumatically fed air and material is tangentially fed via inlet <NUM> into the cyclone separator <NUM> at a sufficient rate to cause a vortex within the cyclone separator <NUM> to allow separation of material to start to occur.

<FIG> clearly shows that the cyclone (i.e. vortex) of air builds a rotating mass of material <NUM> against the sidewalls of the cyclonic separator <NUM>. The material being formed against the sidewalls of the cyclonic separator <NUM> therefore forms, for example, a tubular shape.

A specific advantage of the rotating mass of material <NUM> in the cyclone separator <NUM> is that the rotating mass of particulate material <NUM> has the ability to absorb sudden increases in material feed by adjusting the thickness dimension 'T' and density of the particulate material <NUM> being forced against the inner surfaces of the cyclone separator <NUM>. The dimension 'T' showing the thickness of the tubular shape of particulate material circulating in a cyclone form is shown in <FIG>.

The velocity 'V' of the air and particulate material being fed into the cyclone separator <NUM> has to be sufficiently high to cause the particulate material to spin and form, for example, a substantially tubular shape. The required velocity 'V' of the air and particulate material being fed into the cyclone separator <NUM> changes with different materials but is typically in the range of: <NUM>/s to <NUM>/s; or <NUM>/s to <NUM>/s. As described in reference to <FIG>, after the air has created a cyclone, it exits up through the centre of the cyclone separator <NUM> via the outlet <NUM>.

The apparatus described in the present invention have a number of technical advantages and benefits. The centrifugal sifters described in the present invention use a fine aperture screen to separate material into oversize powder discharge (e.g. waste product) and fine powder discharge (e.g. desired product). A "large" aperture screen can tolerate variations in instantaneous mass flow rate and airflow which occurs inherently in pneumatic conveying systems. The market trend is to use "finer" apertures two separate waste and product. The finer the aperture the less tolerant the screen is of the air and variations of air entering the feeding by pneumatic conveying. The present inventors have found that it is highly advantageous in such situations to use a cyclonic separator (i.e. a cyclonic centrifuge) to smooth out the mass flow by damping the fluctuations in the cyclone body and also by separating the air from the material using the cyclone. It has been found that the combination of these two aspects (i.e. the cyclonic separator and the centrifugal sifter) provides a more stable system with reduced mass flow fluctuations. The flow of separated material and air is then presented to the fine aperture screen of the cyclonic sifter. This allows the centrifugal sifter to pass a larger amount of material than would otherwise be the case in the short residence time the material has in the centrifugal sifter. This results in less waste material (i.e. oversize powder discharge) and more product (i.e. fine powder discharge) being separated even if a finer aperture screen is used in the centrifugal sifter. This is a significant advantage over prior art systems.

The present inventors have therefore found it to be technically advantageous to take a cyclone which is usually used to separate air and material at atmospheric pressure and use it at positive pressure (i.e. above atmospheric pressure) in order to store material in order to dampen the constant variation in mass flow inherent to pneumatic conveying. It has also been found that by using the cyclone at positive pressure provides the further advantage in that positively pressurised air can be reused to pneumatically convey the "product" from the centrifugal sifter to the downstream process. This is shown in <FIG> using the conduit <NUM>. This provides the additional benefit of avoid ing the need for a second pneumatic conveying power source that would otherwise be required. There are clear environmental and commercial benefits in only having the requirement for one pneumatic conveying power source.

As a specific example we now compare using a prior art vibration sifter to separate material such as wheat flour in comparison to the apparatus according to the present invention using the combination of a cyclonic separator and centrifugal sifter as shown in <FIG> and <FIG>.

It has been found that using the combination of cyclonic separator and centrifugal sifter allows smaller mesh widths to be used in the centrifugal sifter, greater throughput is achieved, there is significantly reduced de-agglomeration of the particulate material being conveyed, and a much finer sieving is achievable.

Using a prior art vibration sifter with a mesh size of <NUM>/<NUM> it was compared with the apparatus <NUM> according to the present invention of using a combination of a cyclonic separator <NUM> and cyclonic sifter device <NUM> with a mesh size of <NUM>/<NUM>.

Using the prior art system with a vibration sifter the following was achievable. Capacity wheat flour:.

in comparison, using the present invention combination of the cyclonic separator and a cyclonic sifter the following was achievable:
Capacity wheat flour:.

Using the present invention it was therefore possible to achieve a much higher tonnage rate per hour (i.e. T/hr. ) for the pneumatically conveyed particulate material.

Claim 1:
An apparatus (<NUM>) for pneumatically conveying and separating bulk material comprising:
a vessel (<NUM>) for receiving and separating gas (e.g. air) and bulk material;
at least one material inlet (<NUM>) located on the vessel (<NUM>) for inputting gas (e.g. air) and bulk material into the vessel (<NUM>) and forming a cyclone which separates the gas (e.g. air) and bulk material within the vessel (<NUM>);
a sifting device (<NUM>) for receiving the bulk material from the vessel (<NUM>) wherein bulk material is separated into at least two or more different powder discharges; and
wherein a conduit (<NUM>) connects the vessel (<NUM>) and an outlet (<NUM>) located below the sifting device (<NUM>) which allows a flow of air to travel from the vessel (<NUM>) along the conduit (<NUM>) to the outlet (<NUM>) which assists in the collection and transfer of fine powder discharge (<NUM>),
characterised in that bulk material is separated via centrifugal forces into the at least two or more different powder discharges.