GB2305733A - A fertiliser production process and apparatus - Google Patents

Abstract

Predesired quantities of selected ingredient materials are delivered from feed hoppers 10, Fig 1, onto a conveyor belt 16 of a weighing conveyor 15 at an outlet of each feed hopper and the weight of material on each conveyor belt is sensed and the speed of the conveyor belt 16 is controlled in response to the sensed weight of material for controlling the delivery rate of material from each feed hopper to a transfer conveyor 26 which receives ingredient material discharged from each weighing conveyor. The transfer conveyor 26 delivers the ingredient materials to a mixer (31) (Fig 3) for mixing of the ingredient materials to form a fertiliser. Fertiliser discharged from the mixer is collected in one of a number of holding bins (35). The fertiliser may be bagged and a plurality of bags stacked on a pallet 83, Fig 14, in a tight formation of layers of overlapping bags. The bags are compressed on the pallet 83 and an outer plastics cover 98 is fitted and shrunk over an exterior of the stack of bags to firmly secure the bags on the pallet.

Description

"A Fertiliser Production Process and Apparatus" This invention relates to fertiliser production process and apparatus, in particular for producing granular fertilisers.

The invention is particularly concerned with an improved process and apparatus for the production of high quality fertilisers in a trouble free and efficient manner.

According to the invention, there is provided a process for producing fertiliser comprising the steps: loading a number of granular ingredient materials in associated feed hoppers, delivering predesired quantities of selected granular ingredient material from their feed hoppers onto a transfer conveyor, each ingredient material being discharged from a feed hopper onto a weighing conveyor located at an outlet of the feed hopper and then to the transfer conveyor, each weighing conveyor comprising a conveyor belt driven around support rollers by a variable speed motor, a pair of spaced apart substantially parallel guide walls upstanding at a top surface of the conveyor belt and extending outwardly from the outlet of the feed hopper to a discharge end of the conveyor, forming with the top surface of the conveyor belt a channel for guiding and discharging ingredient materials from the feed hopper for discharge onto the transfer conveyor, continuously weighing the material on the conveyor belt between the outlet of the feed hopper and the discharge end of the conveyor, regulating the speed of the conveyor belt drive motor in response to the sensed weight of material on the conveyor belt for controlling delivery of material to the transfer conveyor to a preset desired rate, delivering ingredient materials from the transfer conveyor through a vibrating sieve, conveying sieved ingredient materials to a mixer downstream of the sieve and mixing the ingredient materials in the mixer to form a fertiliser, and discharging the fertiliser from the mixer into a holding bin selected from a number of holding bins.

In another embodiment, the process further includes the steps of: discharging fertiliser from a holding bin incrementally for filling bags with fertiliser at a bag filling station, conveying each bag in an upright position to a bag sealing station, vibrating the bag as it is being delivered to the bag sealing station for settling fertiliser in the bag, sealing a top of the bag at the bag sealing station, settling fertiliser material in the bag and venting air from the bag through perforations in a side wall of the bag, aligning a number of bags in a desired configuration at a palletising station to form a layer of juxtaposed bags, feeding a pallet from a pallet magazine to the palletising station, loading a number of layers of bags stacked on top of each other on the pallet at the palletising station, delivering a loaded pallet from the palletising station to a covering station, covering the bags on the pallet with a plastics cover, compressing the stack of bags on the pallet at a preset pressure for a preselected time period, and heat shrinking the cover about the bags on the pallet.

Preferably, the process includes delivering each bag from the bag sealing station onto a settling conveyor, the settling conveyor having a number of rectangular section rollers for jogging each bag, thus settling fertiliser material in the bag and venting air from the bag.

In a further embodiment, the process includes loading layers of bags on a pallet by supporting the pallet beneath a pair of roller gates, forming a layer of bags on the roller gates, opening the roller gates and dropping the layer of bags onto the pallet, guiding the bags onto the pallet in a tight configuration by engaging opposite sides of the layer of bags with inwardly biased side pushers and engaging a top of the layer of bags at one end with an overhead pusher bar for firmly guiding bags down onto the pallet when the roller gates open, lowering the pallet and closing the roller gates, similarly forming and loading a plurality of layers of bags stacked on top of each other on the pallet.

Preferably, at the covering station, the process includes the steps of: drawing a flattened plastics tube from a supply reel, engaging and opening a free end of the flattened tube by a set of four grippers disposed in a rectangular spaced-apart orientation on a support frame, the grippers synchronously vertically movable on the support frame between a raised position and a lowered position, forming a seal across the width of the flattened tube spaced-apart from the free end and cutting the tube above the seal to form an inverted cover having a sealed upper end with the lower end opened by the grippers, moving the grippers downwardly on the support frame for drawing the cover downwardly over a loaded pallet, releasing the grippers, returning the grippers to a raised position and engaging the grippers with the free end of the flattened tube.

Most preferably, the stack of bags on the pallet is compressed downstream of the covering station by locating the covered pallet beneath a ram operated overhead platform, moving the platform downwardly by means of rams for engaging a top of the loaded pallet and applying a preset downward pressure to the loaded pallet for a preset period, then retracting the platform.

In a further embodiment, at the cover sealing station, the process includes the steps of: raising the pallet, applying a vacuum to an interior of the cover for drawing the cover closely about the stacked bags on the pallet, passing a rectangular flame ring with inwardly directed flame downwardly encircling the pallet to a lower end of the pallet, heating and shrinking the cover onto the pallet, raising the flame ring vertically in a controlled manner for shrinking the cover about the bags on the pallet, and blowing a charge of air into an interior of the cover for separating the cover from sides of bags on the pallet.

In another embodiment, the process includes the step of perforating the bags at an outlet of the bag sealing station by engaging the bags with a perforating wheel rotatably mounted at the outlet and having a number of radial spikes spaced along a circumference of the wheel to engage and perforate bags guided passed the wheel.

In another aspect, the invention provides apparatus for carrying out the process substantially as herein described.

The invention will be more clearly understood by the following description of some embodiments thereof, given by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a diagrammatic partially sectioned elevational view of weighing apparatus used in a fertiliser production process according to the invention; Fig. 2 is a detail partially sectioned end elevational view of the apparatus shown in Fig. 1; Fig. 3 is a diagrammatic illustration of apparatus used in the process; Fig. 4 is a diagrammatic elevational view of bagging apparatus used in the process; Fig. 5 is a detail plan view of a portion of the bagging apparatus; Fig. 6 is a diagrammatic elevational view of bag handling apparatus used in the process; Fig. 7 is a plan view of the bag handling apparatus shown in Fig. 6; Fig. 8 is a detail elevational view of a portion of the bag handling apparatus; ; Fig. 9a is a detail plan view of palletising apparatus used in the process; Fig. 9b is a plan view of a layer of bags arranged on a pallet by the palletising apparatus; Figs. 10a and lOb are diagrammatic end elevational views of the palletising apparatus; Fig. 11 is an end elevational view of pallet covering apparatus used in the process; Fig. 12 is an elevational view of compression apparatus used in the process; Fig. 13 is a perspective view of pallet cover shrinking apparatus used in the process; and Fig. 14 is an end elevational view of the cover shrinking apparatus shown in Fig. 13.

Referring to the drawings a process and apparatus for producing fertiliser according to the invention will be described.

Referring initially to Figs. 1 to 3 a number of granular ingredient materials are loaded into associated feed hoppers 10. Each feed hopper 10 has an open top 11 for filling the hopper 10 and a tapered lower end 12 for directing ingredient materials in the hopper 10 to an outlet 13.

The outlet 13 is located immediately above a weighing conveyor 15 having a conveyor belt 16 driven around support rollers 17 by a variable speed motor (not shown).

A pair of spaced-apart upstanding parallel guide walls 18 extend outwardly from the outlet 13 to a discharge end 19 of the conveyor 15. It will be noted that the guide walls 18 have a flexible skirt extending along a lower end of each wall 18 thus forming with a top surface 20 of the conveyor belt 16 a channel for guiding and discharging ingredient materials 21 from the hopper 10. As the ingredient materials 21 leave the hopper 10 on the conveyor belt 16 the belt 16 travels over weighing rollers, namely a pair of spaced-apart fixed rollers 22 and an intermediate movable roller 23 located mid-way between the fixed rollers 22. The movable roller 23 is vertically movable and is supported on load cells to weigh material 21 on the conveyor belt 16.Thus the rate of feed of ingredient material 21 from the hopper 10 can be accurately measured and adjusted to a desired feed rate by controlling the variable speed motor driving the conveyor belt 16. Ingredient material 21 discharged from the conveyor belt 16 is guided by a funnel 25 onto a transfer conveyor belt 26. It will be noted that a number of the hoppers 10 and their associated conveyors 15 are arranged in series above the transfer conveyor 26. Thus selected ingredient materials for a fertiliser can be discharged continuously at a controlled rate from a number of the hoppers 10 onto the transfer conveyor 26 which carries the ingredient materials to an elevator 28.

Ingredient materials discharged from an outlet 29 of the elevator 28 pass through a vibrating sieve 30 to remove impurities, the sieved material being directed into a mixer 31.

The mixer 31 comprises a trough 32 mounted on a support frame 33 and having a helical mixer blade rotatable within the trough 32 for thoroughly mixing the ingredient materials as they are moved through the trough between an inlet and an outlet of the mixer 31. Fertiliser discharged from the mixer 31 travels by an elevator 34 to one of a number of holding bins 35. The holding bins 35 comprise a number of bulk storage and distribution bins 36, a bagging storage bin 37 and a bulk bag filling bin 38.

The bin 38 has an outlet chute 39 with a slide valve 40 mounted across the outlet chute 39. The slide valve 40 is ram operated, the ram being connected to a controller 41 which is also connected to a weighing platform 42 disposed directly beneath the outlet chute 39. To fill a bulk bag 43 with fertiliser from the bin 38 the desired amount of fertiliser to be discharged into the bag 43 is keyed into the controller 41. The controller 41 opens the valve 40 fully to rapidly fill the bag 43 with about 99% of the desired weight of fertiliser. The valve 40 is then closed to slowly top up the fertiliser in the bag 43 to the desired weight. Thereafter, the valve 40 is fully closed.

Referring now to Figs 4 to 14, material from the bagging bin 37 is delivered to a bag filling station 45 at which a plastics bag 46 is mounted below a discharge outlet 47 for discharging a metered amount of fertiliser into the bag 46. The bag 46 then travels in an upright position along a vibrating conveyor 48 to settle the granular fertiliser within the bag 46, excluding air from the bag.

Each bag 46 then passes along a slatted conveyor 48a through a bag sealing station 49 in which a top edge 50 of each bag 46 is heat sealed.

Optionally, as each bag 46 leaves the bag sealing station 49 they may be punctured to assist in venting air from the bags 46. As shown in Fig. 5 to puncture each bag 46 a wheel 52 having a number of radial spikes 53 is rotatably mounted at the outlet of the sealing station 49 for engagement with each bag 46 as it leaves the sealing station 49, the spikes 53 puncturing the bag 46. The wheel 52 is movable between an engaged position as shown in Fig. 5 and a retracted disengaged position.

Bags discharged from the sealing station 49 travel up a conveyor 55 for delivery along a settling conveyor 56 (see Fig. 6). The settling conveyor 56 comprises a number of rotating rollers which jog the bags 46 as they travel over the rollers to assist in settling the granular fertiliser within the bags 46 and venting air from the bags 46. The rollers comprise a number of spaced-apart square section rollers 57 followed by a number of generally cylindrical rollers 58 each having one or more ribs 59 on an outer surface of the roller 58 for gently shaking each bag 46 as it passes over the roller 58.

Each bag is then delivered through a bag compressor 60 comprising a pair of spaced-apart conveyors 61, 62 which taper between an inlet end an outlet end for squeezing and settling material in each bag 46 as it passes between the conveyors 61, 62. Downstream of the conveyors 61, 62 each bag passes through a turning station 64. The turning station 64 has a pair of spaced-apart retractable flaps 65. When the flaps 65 are in a raised position as shown in broken outline in Fig. 8 bags pass straight through the turning station 64.However, when it is desired to turn a bag 46 through 900 when a bag 46 locates on support rollers 66 beneath the flaps 65, the flaps 65 come down and engage each side of the bag 46 as shown in Fig. 8 and a rotatable support 69 carrying the flaps 65 rotates through 90" then releases the bag 46 for delivery to a palletising station 72 (Figs. 9 and 10).

At the palletising station 72 a layer of bags is aligned in the configuration shown in Fig. 9b on top of a pair of roller gates 74, 75. When in alignment on the roller gates, the roller gates 74, 75 move apart to drop the bags 46 onto a pallet located immediately below the roller gates 74, 75. Before the roller gates 74, 75 open ram operated side pushers 77 at each side of the roller gates 74, 75 push the bags together. As the roller gates 74, 75 open, an overhead pusher bar 79 engages end bags and guides the end bags downwardly firmly onto the pallet.

Thus the layer of bags 46 is delivered onto the pallet in a tight configuration. When the layer of bags is seated on the pallet the roller gates 74, 75 close and another layer of bags is aligned on the roller gates. This next layer of bags is aligned in the reverse configuration to the previous layer of bags. Thus a number of layers of overlapping bags 46 are stacked on the pallet.

Fig. 10a shows a pallet carrying platform 80 which is vertically slidable by means of rams on a support frame 81 mounted directly below the roller gates 74, 75. A pair of rams 82 locate a pallet 83 against an end stop 84 on the platform 80 when an empty pallet is fed from an associated magazine (not shown) onto the platform 80. This ensures correct alignment of the pallet 83 beneath the roller gates 74, 75. As each layer 85 of bags 46 builds up on the pallet 83 the platform 80 drops a distance equal to the thickness of each layer of bags 46. When a predetermined number of layers of bags have been stacked on the pallet 83, the loaded pallet 83 is conveyed off the platform 80 and a new pallet 83 is located and aligned on the platform 80 which is raised beneath the sliding gates 74, 75 for reception of further bags 46.

Referring to Fig. 11 and Fig. 12, downstream of the palletising station each loaded pallet is delivered to a covering station 90. The covering station 90 has a support frame 91. A pair of reels 92 of a flattened plastic tube 93 are rotatably mounted by rotatable shafts 99a on the frame 91. Associated with each reel 92 is a disc brake comprising a brake disc 99b on the shaft 99a and a complementary brake calliper 99c mounted on the frame 91. With the brake released, plastics tube 93 can be drawn off the reel 92. As soon as the required length of plastics tube for a cover is drawn off, the brake operates to stop rotation of the reel 92 under its own momentum, thus preventing plastics tube 93 uncoiling from the reel until required for the next cover.Only one reel 92 is in use while the other is a back-up reel for use when the first reel is finished, or it may comprise a different plastic tube material. In this way, advantageously downtime due to change-over of reels is minimised. One plastics tube 93 is delivered by feeders 94 to grippers 95 which hold a free end 96 of the flattened tube 93 open in a rectangular configuration. A seal is made across a width of the flattened tube 93 inwardly of the free end and then the plastics tube 93 is cut above the seal to form an inverted cover or bag open at the bottom and the grippers 95 are moved downwardly on the frame 91 to pull the cover 98 down over stacked bags 46 on the pallet 83. It will be noted that the cover 98 is sufficiently long to overhang the pallet 83. The grippers 95 are released and the covered pallet is then delivered to a pressing station 100 (see Fig. 12).

At the pressing station 100 an overhead platform 101 is pressed downwardly by four rams 102 at a preset pressure for a preselected time to further compact the bags 46 on the pallet 83.

The pallet 83 is then delivered to a cover sealing station 110 shown in Figs. 13 and 14. At the sealing station 110 the pallet 83 is raised and a vacuum applied to an interior of the cover 98 to draw the cover 98 down over the bags 46 and pallet 83. A flame ring 112 travels vertically downwardly encircling the palletised load and shrinking the cover 98 to firmly secure the load on the pallet 83. The ring 112 is mounted on a carriage 113 which is vertically slidable on a support frame 114. The ring 112 is moved downwardly around the palletised load to the base of the pallet 83 to shrink free ends of the cover 98 onto the pallet 83 and then is moved slowly upwardly shrinking the cover 98 against the bags 46 on the pallet 83. When fully raised a blast of air is blown inside the cover 98 to separate the cover 98 from the bags and prevent fusing of the hot plastic cover to the bags.The pallet 83 is then delivered onto a turntable 120 for delivery to a dispatch area.

It will be appreciated that the process allows the continuous production of high quality fertilisers in an efficient manner. The ratio and quantity of selected ingredient materials which is critical to product quality can be readily easily controlled and rapidly adjusted if necessary by the manner in which the materials are discharged from the feed hoppers for accurate mixing of ingredient materials. The ingredient materials are evenly dispersed along the transfer conveyor as the feed hoppers are arranged in series above the transfer conveyor to assist in rapid and homogenous mixing of the product. The mixer arrangement allows a continuous stream of material through the mixer, the material being mixed as it passes between the inlet and outlet of the mixer.

The bagged fertiliser is stacked on pal lets in a tight configuration by settling of fertiliser within the bags, venting of air from the bags, the overlapping layer arrangement and controlled stacking of layers of bags on a pallet and compression of stacked layers of bags on a pallet. The cover both protects the bags on a pallet and assists in holding the bags securely on the pallet.

Claims (10)

1. A process for producing fertiliser comprising the steps : - loading a number of granular ingredient materials in associated feed hoppers, delivering predesired quantities of selected granular ingredient material from their feed hoppers onto a transfer conveyor, each ingredient material being discharged from a feed hopper onto a weighing conveyor located at an outlet of the feed hopper and then to the transfer conveyor, each weighing conveyor comprising a conveyor belt driven around support rollers by a variable speed motor, a pair of spaced-apart substantially parallel guide walls upstanding at a top surface of the conveyor belt and extending outwardly from the outlet of the feed hopper to a discharge end of the conveyor, forming with the top surface of the conveyor belt a channel for guiding and discharging ingredient materials from the feed hopper for discharge onto the transfer conveyor, continuously weighing the material on the conveyor belt between the outlet of the feed hopper and the discharge end of the conveyor, regulating the speed of the conveyor belt drive motor in response to the sensed weight of material on the conveyor belt for controlling delivery of material to the transfer conveyor to a preset desired rate, delivering ingredient materials from the transfer conveyor through a vibrating sieve, conveying sieved ingredient materials to a mixer downstream of the sieve and mixing the ingredient materials in the mixer to form a fertiliser, and discharging the fertiliser from the mixer into a holding bin selected from a number of holding bins.

2. A process as claimed in claim 1, further including the steps: discharging fertiliser from a holding bin incrementally for filling bags with fertiliser at a bag filling station, conveying each bag in an upright position to a bag sealing station, vibrating the bag as it is being delivered to the bag sealing station for settling fertiliser in the bag, sealing a top of the bag at the bag sealing station, settling fertiliser material in the bag and venting air from the bag through perforations in a side wall of the bag, aligning a number of bags in a desired configuration at a palletising station to form a layer of juxtaposed bags, feeding a pallet from a pallet magazine to the palletising station, loading a number of layers of bags stacked on top of each other on the pallet at the palletising station, delivering a loaded pallet from the palletising station to a covering station, covering the bags on the pallet with a plastics cover, compressing the stack of bags on the pallet at a preset pressure for a preselected time period, and heat shrinking the cover about the bags on the pallet.

3. A process as claimed in claim 2 which includes delivering each bag from the bag sealing station onto a settling conveyor, the settling conveyor having a number of rectangular section rollers for jogging each bag, thus settling fertiliser material in the bag and venting air from the bag.

4. A process claimed in claim 2 or 3 which includes loading layers of bags on a pallet by supporting the pallet beneath a pair of roller gates, forming a layer of bags on the roller gates, opening the roller gates and dropping the layer of bags onto the pallet, guiding the bags onto the pallet in a tight configuration by engaging opposite sides of the layer of bags with inwardly biased side pushers and engaging a top of the layer of bags at one end with an overhead pusher bar for firmly guiding bags down onto the pallet when the roller gates open, lowering the pallet and closing the roller gates, similarly forming and loading a plurality of layers of bags stacked on top of each other on the pallet.

5. A process as claimed in any of claims 2 to 4, wherein at the covering station, the process includes the steps of: drawing a flattened plastics tube from a supply reel, engaging and opening a free end of the flattened tube by a set of four grippers disposed in a rectangular spaced-apart orientation on a support frame, the grippers synchronously vertically movable on the support frame between a raised position and a lowered position, forming a seal across the width of the flattened tube spaced-apart from the free end and cutting the tube above the seal to form an inverted cover having a sealed upper end with the lower end opened by the grippers, moving the grippers downwardly on the support frame for drawing the cover downwardly over a loaded pallet, releasing the grippers, returning the grippers to a raised position and engaging the grippers with the free end of the flattened tube.

6. A process as claimed in any of claims 2 to 5 wherein the stack of bags on the pallet is compressed downstream of the covering station by locating the covered pallet beneath a ram operated overhead platform, moving the platform downwardly by means of rams for engaging a top of the loaded pallet and applying a preset downward pressure to the loaded pallet for a preset period, then retracting the platform.

7. A process as claimed in any of claims 2 to 6 wherein at the cover sealing station, the process includes the steps of: raising the pallet, applying a vacuum to an interior of the cover for drawing the cover closely about the stacked bags on the pallet, passing a rectangular flame ring with inwardly directed flame downwardly encircling the pallet to a lower end of the pallet, heating and shrinking the cover onto the pallet, raising the flame ring vertically in a controlled manner for shrinking the cover about the bags on the pallet, and blowing a charge of air into an interior of the cover for separating the cover from sides of bags on the pallet.

8. A process as claimed in any of claims 2 to 7 including the step of perforating the bags at an outlet of the bag sealing station by engaging the bags with a perforating wheel rotatably mounted at the outlet and having a number of radial spikes spaced along a circumference of the wheel to engage and perforate bags guided pissed the wheel.

9. A process for producing fertiliser substantially as hereinbefore described with reference to the accompanying drawings.

10. Fertiliser whenever produced according to the process as claimed in any preceding claim.