GB2280587A - Preparing pelletised animal feed - Google Patents

Abstract

Pelletised animal feed is manufactured by delivering bulk material from silos 2 having dust extraction outlets 4 from which dust is extracted as material is being delivered into the silo 2. Each silo 2 has an outlet 16 which is of truncated conical shape having opposed flat sidewalls 17 to promote free flow into a weigher 25. Until additional dry ingredients are added at station 40 the mixture cannot be delivered to a premix bin 45. Medicated drugs 49 may also be added to a mixer 46. The mixer 46 cannot be operated until the drugs 49 have been added. <IMAGE>

Description

"A method for manufacturina pelletised animal feed The invention relates to a method for manufacturing pelletised animal feed and in particular to a method for manufacturing medicated animal feed for use in rearing small animals such as piglets and the like.

According to the invention there is provided a method for manufacturing pelletised animal feed comprising the steps of: delivering bulk pulverent or granular loose material to one of a plurality of vertical substantially cylindrical storage silos, each storage silo having an upper end with a bulk feed material inlet and a dust extracting outlet, and a lower end having a bulk material outlet, the outlet being of generally truncated conical shape having sidewall means including flat tapered portions; discharging bulk material from a storage silo through the outlet in free flow along the tapered sidewall portions to a common delivery trough; weighing the bulk material in a weigher; delivering the bulk material to an additive station; preventing delivery of material to the additive station until minor dry ingredients are ready for addition;; adding dry ingredients to the bulk material at the additive station; indicating that the dry ingredients have been added to permit the delivery of a following batch of material from the weigher; delivering the material to a premix bin; adding liquid ingredients to the premix; mixing the material in a mixer; sieving the mixed material to remove oversize; storing the mixed material in a storage press bin; conditioning the material with steam; pressurising the material; pushing the material through a die to form the pressed material into pellets; cooling the pellets;and sieving the pellets.

Preferably the method includes the step of extracting dust from the dust outlet at the upper end of a silo as bulk material is being delivered into a storage silo.

In a particularly preferred embodiment of the invention the method includes the step of recycling dust extracted on delivery of bulk material to the storage silos.

In one embodiment of the invention the method includes the step of preventing the delivery of material into the premix bin until a preceding batch of different material has been emptied from the storage press bin.

In one arrangement the method includes the step of adding drug ingredients to the premix.

Preferably the operation of the mixer is prevented unless the drug ingredients have been added.

Preferably, fines removed during sieving are recycled to the press bin.

In one embodiment of the invention the pellets are cooled by passing them along a cooling belt and passing a stream of air through the pellets.

In a particularly preferred embodiment of the invention a common dust extraction line is connected by means of a flexible connection to the dust extraction outlet of a bulk storage silo during delivery of bulk pulverent or granular loose material into the bulk storage silo.

The substantially flat portion of the storage silo outlet sidewall includes an access hatch and the method includes the step of periodically cleaning at least the outlets of the storage silos.

In one embodiment of the invention prior to delivery of bulk grain material to the storage silos the grain material is delivered to preliminary storage bins and ground to a desired size for delivery to the bulk storage silos.

In a further embodiment of the invention the method includes the step of further sieving the pellets prior to delivery to a packing bin.

In a preferred embodiment of the invention the bulk material is discharged through a silo outlet of generally truncated conical shape having a pair of generally oppositely disposed flat sidewall portions to direct material in free flow through the outlet.

In a particularly preferred embodiment of the invention the method includes the step of sieving the pellets through a static screen to remove dust and fines; and conveying the sieved pellets to one of a plurality of storage bins by means of a belt conveyor.

Preferably bulk material from the storage bins is conveyed by means of a belt conveyor to a lorry.

In a preferred arrangement material from the storage press bin is delivered to one of at least two presses in which the material is conditioned, pressurised and pushed through a die.

Preferably the dies of the presses produce a pellet of substantially uniform diameter, which is typically approximately 2.5mm.

In one embodiment of the invention the dies of the presses are arranged to provide pellets of different lengths from the presses.

The invention also provides pelletised animal feed whenever prepared by a method as claimed in any preceding claim.

The invention will be more clearly understood from the following description thereof given by way of example only with reference to the accompanying drawings in which: Fig. 1 is a schematic view of a method for manufacturing pelletised animal feed according to the invention, Fig. 2 is a top plan view of storage silos used in the method of the invention, Fig. 3 is a perspective view of an outlet end of the storage silos, Fig. 4 is a side elevational view of the storage silos, Fig. 5 is a plan view of the outlet of the storage silos.

Referring to the drawings, the method for manufacturing pelletised animal feed according to the invention comprises the step of first delivering bulk pulverent or granular loose material to one of a plurality of vertical substantially cylindrical storage silos 2. Each storage silo 2 has an upper inlet which is illustrated in Fig. 2 and includes bulk feed material inlets 3 and a dust extracting outlet 4. Dust is extracted from the dust outlet 4 at the upper end of the silo 2 as bulk material is delivered into the storage silo. The extracted dust is delivered along a common dust outlet line (not shown) connected to the individual dust outlets 4 by a flexible connector 10.

Each bulk storage silo 2 has a truncated conical-shaped cuff 15 leading to an outlet 16 of generally truncated conical shape having sidewall means including a pair of generally opposite flat sidewall portions 17. The flat sidewall portions 17 include reinforcement means in the form of angle iron sections 18 and an access hatch 19 which may be removed for cleaning of the silo outlet.

Bulk material from the silo 2 is discharged in free-flow along the tapered sidewall portions to a common delivery trough 20 from which the material is lead to a single weigher 25 which is suspended on a support 26. Load cells 27 are provided between the support 26 and weigher 25 to provide a control signal for monitoring the weight of material delivered into the weigher 25.

Bulk material from the weigher 25 is delivered to an additive station 40 at which dry ingredients are added manually to the bulk material in specific proportions depending on the particular formulation being produced.

Material cannot be delivered to the additive station until an operator indicates that the additives are ready to be added. The delivery of material from the additive station 40 to the next stage is also prevented until the minor dry ingredients have been added. This is achieved by, for example, operating a switch either manually or automatically when the dry ingredients have been added.

The bulk material with the dry ingredients added is then delivered to a premix bin 45 prior to delivery to a screw mixer 46 to which liquid ingredients 48 are added.

Medicated drugs 49 may also be added. The mixer cannot be operated until the operator gives a signal that the drugs have been added.

The mixed material from the mixer 46 is passed over a sieve 50 prior to delivery to a press bin 51. The material from the press bin 51 is delivered on demand to a conditioning station 52 in which the material is conditioned by means of steam and is then delivered to a press roll 53 which pushes the material through a die to form the material into pellets which are typically 2.5mm in diameter.

Preferably a second press is provided which has the same diameter of die but may be arranged to provide pellets of different length than the first press. The second press may also be used as a back up to the first press.

Consequently pellet quality is improved without production downtime in changing dies. Further, in some formulations, particularly for feeding very young animals there is a high milk content and the die must be thin to prevent overheating leading to caramelisation. As the amount of milk is decreased for larger animals the die should be thicker to maintain pellet quality.

The pellets are cooled in a cooler 55, cold air entering the cooler 55 along the line 56 and heated air being extracted by means of a fan 57 through a cyclone 58.

Cooled pellets are delivered to a sieve 60, oversized material from the sieve 60 being extracted for recycling along line 61 and fines from the sieve 60 being recycled to the press bin 51 along the line 63. The sieved pellets may then be passed over a further static screen 65 prior to delivery to one of two storage hoppers 66 which deliver the pellets to a bagging machine 67 on demand.

Alternatively product may be delivered along line 68 for bulk packing 69.

Some bulk grain material is delivered along line 76, not into the main storage silos 2, but rather into preliminary storage silos 70 from which they are delivered as required to a grinding station 72 for pre-grinding the bulk material prior to delivery into the main bulk storage silos 2. Dust generated in the grinding unit 72 is extracted to a dust unit 75 to which dust discharged to the storage silo outlets is delivered along the recycled dust line 76.

Pellets may be diverted prior to packing through a static screen to remove dust and fines and delivered onto a belt conveyor and discharged directly from the belt conveyor through a multiway valve into any one of a number of bins.

The use of a belt conveyor is important in preventing damage to the pellets, maintaining product quality. The bins are also discharged into a lorry using another belt conveyor.

The method for manufacturing pelletised animal feed according to the invention represent significant improvements over other arrangements in a number of important aspects. The granular or pulverent bulk material flows freely through the process with no blockages. The method is optimised both with respect to the number of steps involved and the maximisation of recycling and dust extraction to maintain product quality.

The invention is not limited to the embodiments hereinbefore described which may be varied in both construction and detail.

Claims (20)

1. A method for manufacturing pelletised animal feed comprising the steps of: delivering bulk pulverent or granular loose material to one of a plurality of vertical substantially cylindrical storage silos, each storage silo having an upper end with a bulk feed material inlet and a dust extracting outlet, and a lower end having a bulk material outlet, the outlet being of generally truncated conical shape having sidewall means including flat tapered portions; discharging bulk material from a storage silo through the outlet in free flow along the tapered sidewall portions to a common delivery trough; weighing the bulk material in a weigher; delivering the bulk material to an additive station; preventing delivery of material to the additive station until minor dry ingredients are ready for addition; adding dry ingredients to the bulk material at the additive station;; indicating that the dry ingredients have been added to permit the delivery of a following batch of material from the weigher; delivering the material to a premix bin; adding liquid ingredients to the premix; mixing the material in a mixer; sieving the mixed material to remove oversize; storing the mixed material in a storage press bin; conditioning the material with steam; pressurising the material; pushing the material through a die to form the pressed material into pellets; cooling the pellets;and sieving the pellets.

2. A method as claimed in claim 1 including the step of extracting dust from the dust outlet at the upper end of a silo as bulk material is being delivered into a storage silo.

3. A method as claimed in claim 2 including the step of recycling dust extracted on delivery of bulk material to the storage silos.

4. A method as claimed in any preceding claim including the step of preventing the delivery of material into the premix bin until a preceding batch of different material has been emptied from the storage press bin.

5. A method as claimed in any preceding claim including the step of adding drug ingredients to the premix.

6. A method as claimed in claim 5 including the step of preventing operation of the mixer unless the drug ingredients have been added.

7. A method as claimed in any preceding claim wherein fines removed during sieving are recycled to the press bin.

8. A method as claimed in any preceding claim wherein the pellets are cooled by passing them along a cooling belt and passing a stream of air through the pellets.

9. A method as claimed in any preceding claim wherein a common dust extraction line is connected by means of a flexible connection to the dust extraction outlet of a bulk storage silo during delivery of bulk pulverent or granular loose material into the bulk storage silo.

10. A method as claimed in any preceding claim wherein the substantially flat portion of the storage silo outlet sidewall includes an access hatch and the method includes the step of periodically cleaning at least the outlets of the storage silos.

11. A method as claimed in any preceding claim wherein prior to delivery of bulk grain material to the storage silos the grain material is delivered to preliminary storage bins and ground to a desired size for delivery to the bulk storage silos.

12. A method as claimed in any preceding claim including the step of further sieving the pellets prior to delivery to a packing bin.

13. A method as claimed in any preceding claim wherein the bulk material is discharged through a silo outlet of generally truncated conical shape having a pair of generally oppositely disposed flat sidewall portions to direct material in free flow through the outlet.

14. A method as claimed in any preceding claim including the steps of sieving the pellets through a static screen to remove dust and fines; and conveying the sieved pellets to one of a plurality of storage bins by means of a belt conveyor.

15. A method as claimed in claim 14 wherein bulk material from the storage bins is conveyed by means of a belt conveyor to a lorry.

16. A method as claimed in any preceding claim wherein material from the storage press bin is delivered to one of at least two presses in which the material is conditioned, pressurised and pushed through a die.

17. A method as claimed in claim 16 wherein the dies of the presses produce a pellet of substantially uniform diameter, which is typically approximately 2.5mm.

18. A method as claimed in claims 16 or 17 wherein the dies of the presses are arranged to provide pellets of different lengths from the presses.

19. A method substantially as hereinbefore described with reference to the accompanying drawings.

20. Pelletised animal feed whenever produced by a method as claimed in any preceding claim.