GB1594216A

GB1594216A - Recovery of material from refuse

Info

Publication number: GB1594216A
Application number: GB15213/77A
Authority: GB
Original assignee: MATERIAL RECOVERY Ltd
Current assignee: MATERIAL RECOVERY Ltd
Priority date: 1978-02-27
Filing date: 1978-02-27
Publication date: 1981-07-30

Description

(54) IMPROVEMENTS RELATING TO THE RECOVERY OF MATERIAL FROM REFUSE (71) We, MATERIAL RECOVERY LIM ITED, a British Company, of Perrywood Walk, Worcester WR5 1 EQ, Worcestershire, Eng]and, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to methods of, and apparatus for, sorting heterogeneous refuse to separate therefrom iron-containing refuse; to methods of, and plant for, recovering ironcontaining refuse from heterogeneous refuse including sorting the heterogeneous refuse to separate therefrom iron-containing refuse; and to matter containing metallic iron recovered by such methods.

In this specification, including the claims thereof, the term "iron-containing refuse" means magnetisable items of refuse mainly those which contain metallic iron (and therefore including items made wholly or partly of steel): "heterogeneous refuse" means refuse which may contain items of any solid material, e.g. iron-containing refuse, other metals, non-magnetisable mineral matter, paper, plastics, glass, bones, vegetable matter; "raw refuse" means heterogeneous refuse as received by the apparatus and before being subject to sorting by the latter; and "residue" means refuse from which at least some ironcontaining refuse has been separated in the apparatus.

According to the invention in a first aspect, a method of sorting heterogeneous refuse to separate therefrom iron-containing refuse, includes the steps of: (i) conveying raw refuse, on a carrying member of a conveyor incorporating main magnet means, at a velocity such that the raw refuse is flighted by being thrown, by its own momentum, clear off an end of the conveyor in a direction having a horizontal major component, into the field of said main magnet means in free space beyond said end; (ii) reversing the direction of the major component of the movement of iron-containing refuse in the raw refuse so flighted whilst it is free in said space, by attraction towards said main magnet means, thereby drawing the iron-containing refuse back towards said end of the conveyor at a level lower than that from which it was thrown clear; and (iii) allowing non-magnetisable matter of the flighted refuse to fall clear of the end of the conveyor.

Preferably, the iron-containing refuse is drawn back on to the carrying member of the conveyor, the iron-containing refuse being then conveyed by the carrying member under magnetic attraction and subsequently released therefrom. The iron-containing refuse is preferably drawn back on to a portion of the carrying member facing otherwise than upwardly.

The method preferably includes the subsequent step of cleaning said iron-containing refuse of entrained, non-magnetisable matter, by drawing said iron-containing refuse through free space in directions not having a downward vertical component, so as to allow said entrained matter to fall free thereof.

According to the invention in a second aspect, a method of recovering iron-containing refuse (as hereinbefore defined) from heterogeneous refuse comprises sorting the latter by a method according to said first aspect of the invention, and then forming the iron-containing refuse, thereby recovered, into bales. In a third aspect, the invention comprises baled iron-containing refuse so recovered.

According to the invention in a fourth aspect, apparatus for sorting heterogeneous refuse, to separate therefrom iron-containing refuse (as hereinbefore defined), includes: a conveyor having a movable carrying member for flighting raw refuse by throwing it clear off an end of the conveyor by its own memontum into free space in a direction having a major horizontal component; main magnet means incorporated in the conveyor and so disposed as to create a magnetic field, in said free space adjacent said end of the conveyor, such as to regress the direction of the major component of the movement of iron-containing refuse in the raw refuse so flighted whilst it is still free in said space, whereby to draw the iron-containing refuse back towards said end of the conveyor at a level lower than that from which it was thrown clear; and residue removal means arranged for removal thereby of non-magnetisable residue of the flighted refuse in a direction substantially different from that in which the iron-containing refuse is drawn back.

According to a preferred feature of the invention, the said carrying member of the flighting conveyor is an endless elongate member defining a substantially horizontal top run and a bottom run thereof, and extending at said end of the conveyor, being the delivery end of said top run, around a rotatable rolling member, which is preferably a magnetic drum.

Preferably the apparatus includes cleaning means, and intermediate conveyor means arranged to receive the iron-containing refuse recovered by separation from said residue by the action of said main magnet means, means being provided for releasing said iron-containing refuse from the influence of the main magnet means and for transfer thereof to the intermediate conveyor means, the cleaning means being associated with the intermediate conveyor means for receiving said iron-containing refuse therefrom.

The cleaning means preferably comprise a further movable carrier member arranged to follow a path through a zone spaced from said intermediate conveyor means by a further free space which lies generally at or above the level at which the iron-containing refuse is carried by the intermediate conveyor means, and further magnet means associated with said further carrier member for drawing iron-containing refuse through said further free space to a portion of the said further carrier member facing generally downwardly.

According to the invention in a fifth aspect, a plant for recovering iron-containing refuse (as hereinbefore defined) from heterogeneous refuse comprises sorting apparatus according to said fourth aspect of the invention, means for supplying raw refuse to the sorting apparatus, means for removing said residue from the sorting apparatus, and means for removing the iron-containing refuse thereby sorted.

One embodiment of the invention will now be described, by way of example only, with reference to the accompanying draw ings. of which: Figure 1 is a simplified end elevation of a static plant for recovering iron-containing refuse (as hereinbefore defined) from heterogeneous refuse, the plant being suitable for use at a large centralised refuse-processing depot; Figure 2 is a simplified side elevation taken in the plane 11 it of Figures 1 and 3; Figure 3 is a simplified top plan view on Figure 2; Figure 4 is an enlarged scrap section taken from Figure 2, and illustrates the action of an accelerating or flighting conveyor and a magnetic drum thereof; and Figure 5 is an enlarged scrap section taken from Figure 2 and illustrates the operation of a cleaning unit.

Referring to Figures I to 3, the plant comprises a substantial fixed permanent structural frame which is not shown, but which carries the various components of the plant hereinafter to be described. Essentially the plant (which will be described more fully hereinafter) comprises sorting apparatus for sorting heterogeneous raw refuse, so as to separate therefrom matter containing metallic iron; means 10,13 for supplying the raw refuse to the sorting apparatus; means 24,25 for removing from the sorting apparatus residue from which iron-containing refuse has been removed by the latter; and means 37,39.41 for removing the iron-containing refuse from the sorting apparatus.The sorting apparatus comprises those parts of the plant which connect the means 13 with the means 24 and 37, including the various components for handling refuse between the means 13 and the means 24 and 37.

The plant has an upwardly-inclined, endless-belt, infeed conveyor 10 having a lower or loading end 11 and an upper or discharge end 12, below which is a raw-refuse feed chute 13. The feed chute 13 discharges out of its lower end on to the first operative element of the sorting apparatus, viz. a generallyhorizontal, vibratable feed conveyor 14 of the endless belt type, which is driven by a motor, not shown, for example through a jogging linkage of known kind, or other suitable means, for maintaining the conveyor 14 in continual vibration throughout its operation.

The downstream end 15 of the conveyor 14 discharges over the upstream end of a relatively short flighting conveyor 16. The latter has an endless, linear carrying member in the form of a belt 17 extending over a drive roller 18 at its upstream end, and at its downstream or delivery end, a rotatable rolling member in the form of a drum 19 of relatively large diameter. The drive roller 18 is driven by a motor, not shown, at a speed such that the linear velocity of the substantially horizontal top run 20 of the flighting belt 17 is substantially higher than that of the feed conveyor 14. The drum 19 is rotated with the belt 17, and incorporates internally a powerful main electro-magnet of the apparatus. The drum 19 will therefore be referred to hereinafter in this description as a "magnetic drum".

The feed and flighting conveyors 14,16 are mounted in a tunnel 21 of the sorting apparatus, which is open at the bottom at least in the region of the flighting conveyor 16 and extends beyond the downstream end of the latter to define a terminal free space 22 within the tunnel. The tunnel 21 is totally enclosed, except at the bottom and where the feed chute 13 enters through the roof of the tunnel. The free space 22, the purpose of which will become evident hereinafter, is continued downwards in a main residue removal chute 23, which is open at the bottom to an upwardly-inclined residue discharge conveyor 24, again of the endless-belt type.

The discharge conveyor 24 deposits residue from its top end in any convenient manner; in the present embodiment this consists of a hopper or chute 25 arranged to empty into a waiting lorry 26 below.

Spaced upstream of the main residue chute 23, and adjacent thereto, is a first chute 27 for iron-containing refuse. The latter is in the embodiment arranged immediately below the magnetic drum 19, and in particular is below the point 28 (Figure 4) at which the bottom run of the flighting belt 17 leaves the magnetic drum 19.

The open bottom end of the first chute 27 for iron-containing refuse discharges on to an endless-belt type intermediate secondary or transfer conveyor 29, which extends horizontally to an associated cleaning unit generally indicated at 30. The cleaning unit 30 comprises a further endless linear carrying member, viz. a cleaning belt 31 driven by a suitable motorised drive (not shown) at a relatively low linear speed on a pair of rollers 32, which are so arranged that the lower run 33 of the belt is inclined downwardly in its direction of movement (indicated in Figure 2), that is to say away from the transfer conveyor 29. The discharge end 34 of the latter lies approximately below the proximal or upper one of the rollers 32 of the cleaning unit 30.The lower run 33 of the belt follows a path through a zone (which may be defined conveniently by the plane of the belt surface in its lower run) which is spaced from the intermediate conveyor 29 by a free space 36 approximately bounded by planes indicated at 50 in Figure 5. This free space 36 lies generally at or above the top run of the conveyor 29.

Associated with the belt, and closely overlying a substantial part of the length of its lower run 33, is a stationary cleaning unit magnet means in the form of a flat electromagnet 35. Below the distal or lower end of the cleaning unit 30 there is a third collecting means in the form of a final discharge chute 37 for removal of the cleaned iron-containing refuse from the sorting apparatus, whilst there is disposed, between this chute 37 and the transfer conveyor 29, a second residue chute 38. The electromagnet 35 overlies both of the chutes 37 and 38, but only overlies a relatively small part of the chute 37. The transfer conveyor 29 is arranged, as can be seen from Figure 5, to discharge residue directly into the residue chute 38.

The discharge chute 37 for cleaned ironcontaining refuse discharges to a mechanical baler 39, which may be of any known kind, for compressing the iron-containing refuse into bales 40, the latter being discharged along a conveyor or runway 41, for subsequent storage and removal by any convenient means.

The residue chute 38 may discharge to a conveyor, not shown, for recycling the residue therefrom back to the infeed chute 13 or the infeed conveyor 10, or to transport it to the residue discharge conveyor 24 or hopper 25. Alternatively it may be more convenient to provide a skip or other receptacle below the chute 38, as shown at 42 in Figure 2.

In operation, raw refuse is loaded on to the infeed conveyor 10 at its lower end 11, and is fed to the feed conveyor 14 by the conveyor 10 via the feed chute 13. The conveyor 14 shakes the refuse to loosen it as it carries the refuse towards the flighting conveyor 16, the finally deposits the loosened refuse upon the latter. The high horizontal linear velocity imparted to the refuse by the flighting conveyor 16 is sufficient to throw it clear of the conveyor 16, as shown in Figure 4, i.e. to "flight" the refuse, into the free space 22 beyond the downstream end of the conveyor, in a direction which is initially horizontal. It may here be observed that the flighting conveyor need not be horizontal; it may for example be inclined upwardly at a small angle to the horizontal (in which case, however, the direction of flighting will still have a major horizontal component).Substantially all of the raw refuse is thrown off in this manner including substantially all that part thereof which consists of iron-containing refuse (despite the presence of the magnetic drum 19).

Referring to Figure 4, it will be seen that non-magnetisable refuse 44, thus thrown clear, will tend to follow a natural trajectory so as to fall freely through the space 22 and down through the residue chute 23 on to the discharge conveyor 24, for removal thereby as residue. Magnetisable refuse, on the other hand, consisting of iron-containing refuse (as hereinbefore defined) with some non-magnetisable matter entrained therewith, tends to be attracted magnetically by the electromagnet in the drum 19. Thus, as soon as the horizontal component of the velocity of this refuse (indicated at 43 in Figure 4) has decreased sufficiently to be overcome by the magnetic force, it is drawn back on to the belt 17 in the general region indicated at 45, where the belt does not face upwards, and which is at a lower level than the top run 20 of the flighting belt 17.

It will be seen that where, as in this example, the magnet is on the same side of the free space 22 as is the flighting conveyor, the direction in which the magnetisable refuse is drawn magnetically out of the path followed by the non-magnetisable path (this direction having in any case a major horizontal component) has its horizontal component in the opposite direction from that of the direction of flighting movement. This reversal enables a particularly compact arranged ment of the apparatus to be adopted.

As the portion of the belt 17 carrying any particular piecce of magnetisable refuse continues to move downwards around the drum 19 at speed, that piece is conveyed by the belt, under magnetic attraction, positively away from the path of the non-magnetisable refuse; but it will increasingly tend to be thrown off again, to fall eventually by gravity into the first chute 27. Any iron-containing refuse not so dislodged will fall when it leaves the magnetic influence of the drum 19, or if knocked off by means such as the rear wall 46 of the chute 27 shown in Figure 4, as the refuse reaches an appropriate position.

The matter falling into the chute 27 typically consists of about 70% iron-containing refuse by weight, the remainder being paper or other residual matter that has been entrained with the iron-containing refuse.

Most of this residual matter is removed by the cleaning unit 30, so that what is discharged by the latter into the final discharge chute 37 (Figure 5) consists of at least 90% iron-containing refuse.

The operation of the cleaning unit 30 is as follows. Refuse 47 collected by the intermediate or transfer conveyor 29 from the chute 27 (Figure 2) enters the influence of the cleaning unit magnet 35 as it reaches the discharge end 34 of the conveyor 29. Ironcontaining refuse 48 thus tends to be drawn forward through the space 36, in directions not having a downward vertical component, towards the cleaning unit belt 31, to be carried by the latter towards the distal end 49 of the magnet 35, where it is released to fall by gravity into the chute 37, and so to the baler 39. Most residual matter entrained with the iron-containing refuse 47 in the flight of the latter from the transfer conveyor 29 to the cleaning unit belt 31, will tend to fall into the chute 38.

Many modifications to the arrangement described, besides those already mentioned hereinabove, are possible within the scope of the invention. For example the transfer conveyor 29 may be arranged to be vibrated to loosen the refuse thereon, so as to reduce the amount of non-magnetisable matter entrained with iron-containing refuse when the latter is flighted towards the cleaning belt 31.

A plurality of cleaning units may be arranged in series relationship, to improve the proportion of iron-containing refuse in the final product before the latter is introduced to the baler 39.

WHAT WE CLAIM IS: 1. A method of sorting heterogeneous refuse to separate therefrom iron-containing refuse (as hereinbefore defined), said method including the steps of: (i) conveying raw refuse, on a carrying member of a conveyor incorporating main magnet means, at a velocity such that the raw refuse is flighted by being thrown, by its own momentum, clear off an end of the conveyor in a direction having a horizontal major component, into the field of said main magnet means in free space beyond said end;; (ii) reversing the direction of the major component of the movement of iron-containing refuse in the raw refuse so flighted whilst it is free in said space, by attraction towards said main magnet means, thereby drawing the iron-containing refuse back towards said end of the conveyor at a level lower than that from which it was thrown clear; and (iii) allowing non-magnetisable matter of the flighted refuse to fall clear of the end of the conveyor.

2. A method according to Claim 1, wherein the iron-containing refuse is drawn back on to the carrying member of the conveyor, the iron-containing refuse being then conveyed by the carrying member under magnetic attraction and subsequently released therefrom.

3. A method according to Claim 2, wherein the iron-containing refuse is drawn back on to a portion of the carrying member facing otherwise than upwardly.

4. A method according to any one of the preceding claims, including the subsequent step of cleaning said iron-containing refuse of entrained, non-magnetisable matter, by drawing said iron-containing refuse through free space in directions not having a downward vertical component, so as to allow said entrained matter to fall free thereof.

5. A method of sorting heterogeneous refuse, performed substantially as hereinbefore described with reference to, and as illustrated in, Figure 4 of the accompanying drawings.

6. A method of sorting heterogeneous refuse according to Claim 1, including the steps of separating residue from iron-containing refuse and subsequently cleaning the latter, said steps being performed in a manner substantially as hereinbefore described with reference to, and as illustrated in, Figure 4 or Figure 5 of the accompanying drawings.

7. A method of recovering iron-containing refuse (as hereinbefore defined) from heterogeneous refuse, comprising sorting the latter by a method according to any one of

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. It will be seen that where, as in this example, the magnet is on the same side of the free space 22 as is the flighting conveyor, the direction in which the magnetisable refuse is drawn magnetically out of the path followed by the non-magnetisable path (this direction having in any case a major horizontal component) has its horizontal component in the opposite direction from that of the direction of flighting movement. This reversal enables a particularly compact arranged ment of the apparatus to be adopted. As the portion of the belt 17 carrying any particular piecce of magnetisable refuse continues to move downwards around the drum 19 at speed, that piece is conveyed by the belt, under magnetic attraction, positively away from the path of the non-magnetisable refuse; but it will increasingly tend to be thrown off again, to fall eventually by gravity into the first chute 27. Any iron-containing refuse not so dislodged will fall when it leaves the magnetic influence of the drum 19, or if knocked off by means such as the rear wall 46 of the chute 27 shown in Figure 4, as the refuse reaches an appropriate position. The matter falling into the chute 27 typically consists of about 70% iron-containing refuse by weight, the remainder being paper or other residual matter that has been entrained with the iron-containing refuse. Most of this residual matter is removed by the cleaning unit 30, so that what is discharged by the latter into the final discharge chute 37 (Figure 5) consists of at least 90% iron-containing refuse. The operation of the cleaning unit 30 is as follows. Refuse 47 collected by the intermediate or transfer conveyor 29 from the chute 27 (Figure 2) enters the influence of the cleaning unit magnet 35 as it reaches the discharge end 34 of the conveyor 29. Ironcontaining refuse 48 thus tends to be drawn forward through the space 36, in directions not having a downward vertical component, towards the cleaning unit belt 31, to be carried by the latter towards the distal end 49 of the magnet 35, where it is released to fall by gravity into the chute 37, and so to the baler 39. Most residual matter entrained with the iron-containing refuse 47 in the flight of the latter from the transfer conveyor 29 to the cleaning unit belt 31, will tend to fall into the chute 38. Many modifications to the arrangement described, besides those already mentioned hereinabove, are possible within the scope of the invention. For example the transfer conveyor 29 may be arranged to be vibrated to loosen the refuse thereon, so as to reduce the amount of non-magnetisable matter entrained with iron-containing refuse when the latter is flighted towards the cleaning belt 31. A plurality of cleaning units may be arranged in series relationship, to improve the proportion of iron-containing refuse in the final product before the latter is introduced to the baler 39. WHAT WE CLAIM IS:

1. A method of sorting heterogeneous refuse to separate therefrom iron-containing refuse (as hereinbefore defined), said method including the steps of: (i) conveying raw refuse, on a carrying member of a conveyor incorporating main magnet means, at a velocity such that the raw refuse is flighted by being thrown, by its own momentum, clear off an end of the conveyor in a direction having a horizontal major component, into the field of said main magnet means in free space beyond said end;; (ii) reversing the direction of the major component of the movement of iron-containing refuse in the raw refuse so flighted whilst it is free in said space, by attraction towards said main magnet means, thereby drawing the iron-containing refuse back towards said end of the conveyor at a level lower than that from which it was thrown clear; and (iii) allowing non-magnetisable matter of the flighted refuse to fall clear of the end of the conveyor.

the preceding claims, and then forming the iron-containing refuse thereby recovered into bales.

8. Baled iron-containing refuse recovered by a method according to Claim 7.

9. Apparatus for sorting heterogeneous refuse to separate therefrom iron-containing refuse (as hereinbefore defined), said apparatus including: a conveyor having a movable carrying member for flighting raw refuse by throwing it clear off an end of the conveyor by its own momentum into free space in a direction having a major horizontal component; main magnet means incorporated in the conveyor and so disposed as to create a magnetic field, in said free space adjacent said end of the conveyor, such as to reverse the direction of the major component of the movement of iron-containing refuse in the raw refuse so flighted whilst it is still free in said space, whereby to draw the ironcontaining refuse back towards said end of the conveyor at a level lower than that from which it was thrown clear; and residue removal means arranged for removal thereby of non-magnetisable residue of the flighted refuse in a direction substantially different from that in which the iron-containing refuse is drawn back.

10. Apparatus according to Claim 9, wherein said carrying member is an endless elongate member defining a top run and a bottom run thereof and extending at said end of the conveyor, being the delivery end of said top run, around a rotatable rolling member.

11. Apparatus according to Claim 10, wherein said top run is substantially horizontal.

12. Apparatus according to Claim 10 or Claim 11, wherein said rolling member incorporates said main magnet means.

13. Apparatus according to Claim 12, wherein the said rolling member is a magnetic drum.

14. Apparatus according to any one of Claims 9 to 13, wherein the residue removal means includes a chute extending downwardly from said free space, for receiving said residue for free fall down the chute.

15. Apparatus according to any one of Claims 9 to 14, including a vibratable conveyor upstream of the flighting conveyor, said vibratable conveyor being arranged to feed raw refuse to the flighting conveyor at a velocity substantially lower than that of the flighting conveyor.

16. Apparatus according to any one of Claims 9 to 15, including cleaning means, and intermediate conveyor means arranged to receive the iron-containing refuse recovered by separation from said residue by the action of said main magnet means, means being provided for releasing said iron-containing refuse from the influence of the main magnet means and for transfer thereof to the intermediate conveyor means, the cleaning means being associated with the intermediate conveyor means for receiving said ironcontaining refuse therefrom.

17. Apparatus according to Claim 16, wherein the cleaning means comprise a further movable carrier member arranged to follow a path through a zone spaced from said intermediate conveyor means by a further free space which lies generally at or above the level at which the iron-containing refuse is carried by the intermediate conveyor means, and further magnet means associated with said further carrier member for drawing iron-containing refuse through said further free space to a portion of the said further carrier member facing generally downwardly.

18. Apparatus according to Claim 9, for sorting heterogeneous refuse and being constructed, arranged and adapted to operate substantially as hereinbefore described with reference to, and as illustrated in, Figure 4 of the accompanying drawings.

19. Apparatus according to Claim 17 or 18, being further constructed, arranged and adapted to operate substantially as hereinbefore described with reference to, and as illustrated in, Figure 5 of the accompanying drawings.

20. A plant for recovering iron-containing refuse (as hereinbefore defined) from heterogeneous refuse, said plant comprising sorting apparatus according to any one of Claims 9 to 19, means for supplying raw refuse to the sorting apparatus, means for removing said residue from the sorting apparatus, and means for removing the ironcontaining refuse thereby sorted.

21. A plant according to Claim 20, including baling means for receiving ironcontaining refuse from the sorting means and for forming it into bales.

22. A plant for recovering iron-containing refuse (as hereinbefore defined) from heterogeneous refuse, said plant being constructed, arranged and adapted to operate substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.