GB1597443A

GB1597443A - Utilisation of waste materials

Info

Publication number: GB1597443A
Application number: GB1580278A
Authority: GB
Original assignee: PLM AB
Current assignee: Rexam AB
Priority date: 1977-04-22
Filing date: 1978-04-21
Publication date: 1981-09-09
Also published as: SE7704651L; DE2817304A1; SE430513B; DE2817304C2

Description

(54) IMPROVEMENTS RELATING TO THE UTILISATION OF WASTE MATERIALS (71) We, PLM AB a Swedish company of Djäknegatan 16, 201 10 Malt6 1, Sweden 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: The present invention relates to an arrangement which receives waste materials of various types, such as domestic refuse and which sorts out from this refuse materials which can be used again, as for example, paper, glass, metal and materials comparable therewith.

The fractions (materials) which are obtained are thereafter supplied for being further used in various ways. So as to reduce the expense for the handling of the waste or refuse which is sorted out, it is desirable for this waste to be able to be improved to a certain extent at the place where the said waste is supplied.

The present invention is concerned with an arrangement for the utilisation of waste or refuse as previously described, the arrangement being provided with an improving or finishing section for the production of a product in order to satisfy the requirements as previously discussed, it being possible for the said product to be directly used as a fuel. The fuel which is produced consists mainly of paper, synthetic plastics, textiles and wood. In order to reclaim the material which is contained in the fuel, the waste material which is supplied must first of all be comminuted with a suitable comminuting arrangement. It may be expedient in certain cases for a screening plant (sorting unit), through which the waste or refuse travels, to be arranged before the comminuting arrangement, as a result of which undesired constituents in the refuse - mainly wet material- are separated out.After the comminution, the comminuted material has to be supplied to a separating arrangement, which separates out the material which is used in the fuel, such material being in fact paper, synthetic plastics, textiles and wood. This material is preferably given the collective term of "light fraction".

According to the invention, in a first aspect thereof, apparatus for utilising combustible waste material comprised, inter alia, of domestic refuse, comprises: supply means for said waste materials, said supply means being linked to a comminuting plant; ballistic sorting means connected to the comminuting plant and adapted to sort out light, combustible materials, such as paper, synthetic plastics, textiles and wood; forming or shaping means which form the light, combustible materials into mainly solid bodies or pellets; and conveying means for conveying said materials respectively from said comminuting plant to said sorting means and from said sorting means to said forming or shaping means.

According to the invention, in a second aspect thereof, in a method of producing utilisable combustible products from combustible waste materials, using apparatus according to said first aspect, the said bodies have a length of between 15 and 80 mm, a thickness of between 5 and 30 mm and a density of between 0.7 and 1.1 g/cm3.

For separating out the light fraction, it is advisable in accordance with the invention to use a ballistic or aerodynamic separating arrangement. The ballistic separating arrangement receives the comminuted waste materials in such a form that each material drops on to the arrangement, solid, stiff particles rebounding and small particles passing through a screen or sieve. However, the light fraction is taken up by a conveyor surface, such as for example a conveyor table, which carries out a rotational movement with a retained directional orientation, the speed of rotation of the surface in the vertical direction being greater than the speed of descent of the light combustible particles.

The light fraction as thus obtained may be introduced into a drying arrangement, which preferably imparts to the fraction a dry substance content of about 70-80%.

If the fraction which is separated out before the drying stage has a too high dry substance content, then the drying plant may be replaced by a moistening or wetting arrangement, so as to lower the dry substance content to about 70 - 80%. If the fraction has the said dry content from the outset, then it is unnecessary for it to pass through either the moistening or drying arrangement.

If the light fraction, after having been dried, has a particle size which is too large, then the invention includes an additional grinding arrangement for reducing the size of the particles.

The arrangement according to the invention is equipped with a forming or shaping arrangement or a so-called pelleting unit, which receives the said light fraction, either from the moistening arrangement as previously referred to, or from the aforesaid drying arrangement. The forming, arrangement or pelleting unit takes up the light fraction and forms therefrom a continuous length of substance which is obtained under a pressure of about 3000 kp at a temperature which is between 70 and 1600C (343 and 433 K). In the higher portion of this temperature range, the included binders, polyethylene and lignin, become free, flow into the light fraction and can be used as bonding components and possibly surface-coating components.

The forming or shaping arrangement likewise contains a dividing apparatus, which divides the continuous length into cylindrical or parallelepipedic bodies. The bodies as thus obtained are normally referred to as pellets (balls).

The invention also includes a cooling arrangement for cooling and drying the bodies just referred to.

After having been cooled, the said bodies can be brought to a storage position or directly into a storage arrangement for a boiler. In certain cases, it may be more expedient for the units which are obtained to be burnt in a gas-recovery plant (generator gas) and for the gas to be introduced into the boiler.

Other specific properties which are associated with the present invention are to be seen from the accompanying claims.

The present invention is described in greater detail by reference to a constructional form which is illustrated as a block diagram in the accompanying drawing.

Represented at 1 in the drawing is a collecting storage unit or a unit comparable therewith, into which a garbage vehicle or a vehicle for removal of garbage empties (tips) its refuse. The said storage unit is connected to two different comminuting assemblies 2A and 2B. The connection may be achieved by conveyor screws or conveyor belts, these conveying arrangements being so linked that the storage unit 1 is either connected to the first comminuting arrangement 2A or to the other comminuting arrangement 2B. If the refuse mainly consists of wood particles, then it is desirable for the pieces of wood to be comminuted by a chipping machine 2B. The comminuting arrangement 2A may consist of a hammer mill of a horizontal or vertical type. The said horizontal type may be type 460K manufactured by the firm Williams, St. Louis, USA, (product specification 863).The vertical type may be type 42F made by Tollemache Environmental Engineers, Limited, Great Britain. It is obviously understood that any other suitable comminuting plants may be used instead of the hammer mill and chipping machine.

Although not represented in the drawing, it may be desirable for a screening plant bearing the name "rotary screen", manufactured by TrippellS Dynamics, Dallas, Texas, to be installed before the comminuting arrangement 2A. In this way, it is possible to operate as with a similar installation, which is manufactured by Gruendler in St. Louis. The plant which is constructed by this firm has the name "Revolving Drum Screen". The screening plant (sorting unit) has a connection to the comminuting arrangement 2A for waste or refuse which is not sorted out.

Both the comminuting arrangement 2A and the chipping machine 2B are linked by means of suitable conveyor arrangements such as conveyor screws or conveyor belts to a separating arrangement 3 for separating out pieces of iron. It is recommended in this connection to operate with an overhead magnet, for example that manufactured by Boxmag Rapid Limited, England, and described in their publication No. 037. or with an arrangement operating with revolving magnetic drums.

If the refuse from the units 2A and 2B does not contain any metal particles, the unit 3 may be omitted.

The waste or refuse from the unit 3 is supplied to a separating arrangement 4.

According to the present invention preference is to be given to the use of a ballistic separating arrangement described in British patent applicaton 3620/78 (Serial No.

1597442).

The light fraction from the separating arrangement 4 should have a dry substance content of 70 - 80%. If the dry content is substantially higher, then the light fraction from the separating arrangement should be conducted into a moistening or wetting plant 5, so that the refuse can be brought to a dry content of about 70 - 80%. The wetting plant can be by-passed or cut out by an appropriate conveyor arrangement if the refuse has the required dry content.

It may be necessary to have a drying plant instead of a wetting plant. This arrangement can be that manufactured by Fabrikat Atlas, of Ballerup, Copenhagen. Another drying plant which can also be used is sold by A. Ahlstr6m, Varkaus, Finland. The purpose of the drying plant 6 is to maintain a dry content of 70 - 80%. If the product from the separating arrangement has a correct dry content, then the drying plant may either be by-passed or cut out.

If the light fraction coming from the drying plant 6 has the required size, it is brought by means of suitable conveying arrangements into a forming machine or a pelleting machine 7, which may be that sold by EMM Aktieselskab, Esbjerg, Denmark, under the product specification 1002-72, or that sold by Papacube Co., San Diego, USA. This latter pelleting machine is given the name "Matador", or is also designated as "Kubaren". If the size of the produced parts of the fraction is too large, the light fraction is delivered into an additional comminuting arrangement, for example, a mill 9.The light fraction coming from the drying plant 6 is thereafter introduced into the pelleting machine or arrangement 7, in which the light fraction is shaped or formed under the action of pressure and temperature - this has already been discussed - into a continuous length of material, which is then divided, either into cylindrical units or parallelepipedic units. The units which are obtained and which are also referred to as "pellets" have a dry content of about 90%. They are conducted from the pelleting machine into a cooling arrangement and the drying plant 8 is a collecting container for prepared pellets.

Depending on the nature or type of the waste material emptied into the collecting unit 1, it is either the comminuting arrangement 2A or the comminuting arrangement 2B which is used. Furthermore, depending on the nature or type of the refuse which is supplied, it is possible to by-pass the various units 3, 4, 5 and 6 and also 9. If the material has the correct dry content from the outset, then it is unnecessary to use either the drying plant or the wetting plant. If the light fraction also has the correct particle size, it is even possible to avoid the comminuting arrangement 9. If it happens, for example, that only material of the light fraction is delivered into the collecting container, then it is obvious that the separating arrangement 4 is by-passed, i.e. is not utilised.

It has been established according to the invention, in connection with the production of pellets from domestic refuse, that the percentage of paper in the pellets is about 70%. The percentage of synthetic plastics materials is in the region of 10% and the remainder is composed of textiles and other materials.

Following the separator 4 and in front of either the moistening plant 5 or the drying plant 6, it is possible to arrange a fine screening or sifting unit for separating out other undesirable extremely small elements, so as to be able in this way to reduce the ash content in the final fuel. The drying plant 6 may also be so designed that it operates as a fine screening unit. The fine screening unit may also be the "Rotary Screen" as already described, with an apertured plate with an aperture diameter from about 6 to 16 mm.

It is scarcely necessary to refer to the fact that, in the arrangement as described herein, the magnetic separation unit 3 can be mounted at any desired position in the plant. One such expedient position is for it to be linked in association with the sorting stage 4.

The percentage composition of four different types of pellets is hereinafter set out in a table, the said pellets having been produced in accordance with the present invention. The table also contains the heat value (calorific value) and the ash content. Furthermore, it is possible to see from the table the dimensions which can be given to the pellets which are produced and the table also shows the density of the produced pellets.

TABLE SPECIFICATION FOR EUEL PELLETS Composition Type I II III IV Paper (percent by wt) 75 - 90 80 - 100 - 75 - 90 Synthetic plastics 5 - 10 0 - 20 - 5 - 10 Wood 0 - 5 - 99 - 100 0 - 5 Others 5 - 20 0 - 1 0 - 1 5 - 20 Dry substance content 85 - 90 85 - 95 85 - 90 35 - 90 Calorific value (Kcaly/ 3400 - 4000 4300 - 4900 4600 - 5200 3500 - 4100 kg) Ash content (percent by weight of the 10 - 15 4 - 8 0.1 - 2 8 - 12 dry specimen Size (mm) Cylindrical form diameter 8 - 15 8 - 15 5 - 12 8 - 15 length 15 - 30 15 - 30 10 - 30 15 - 30 Rod form width 15 - 30 15 - 30 15 - 30 15 - 30 thichness 15 - 30 15 - 30 15 - 30 15 - 30 lenght 50 - 80 50 - 80 50 - 80 50 - 80 Density (g/cm3) 0.7 - 1.1 0.7 - 1.1 0.7 - 1.1 0.7 - 1.1 In the table, I represents pellets which have been obtained from comminuted, separated and pelleted domestic refuse.Pellets according to II are produced from paper waste, which consists mainly of waste material from offices. Pellets produced from pure wood waste have the properties which are set out under III in the table. It has also been described in the foregoing that the domestic waste or refuse, prior to the comminution, passes through a screening unit. The properties of the pellets prepared from this refuse can also be seen under IV in the table.

When the pellets as produced are considered from chemical points of view, it is established that the chemical composition has the following form: C about 50% H about 6% 0 about 6% N about 8% Ash about 12% The ash, as such, contains about 0.3 - 0.5% chlorine and about 0.2% sulphur.

In accordance with the present invention the forming means are such that the moisture content, frictional heat and durability are adjustable in such a way that pathogenous microorganisms present may be killed on the surface of the fuel bodies.

The light fraction which is caught on the conveying area in accordance with the third paragraph hereof, may consist of part of a sheet of paper, of a complete sheet of paper, of part of a newspaper page and of an empty cigarette box or the like.

From the foregoing it follows clearly and unequivocally that the light fraction may consist of bodies of different sizes and different bodily configurations. The light fraction moreover has the property that bodies may form the subject of a compacted unit or of pellets. During compaction what may occur is that only one part of a body of the light fraction forms the complete unit or that the unit is formed by several bodies of the light fraction. If, for example, a body is present in the light fraction which more or less consists of an entire newspaper page, it is clear that this newspaper page can be used to produce several unit bodies or pellets.

WHAT WE CLAIM IS: 1. Apparatus for utilising combustible waste materials comprised, inter alia, of domestic refuse, the apparatus comprising: supply means for said waste materials, said supply means being linked to a comminuting plant; ballistic sorting means connected to the comminuting plant and adapted to sort out light, combustible materials, such as paper, synthetic plastics, textiles and wood; forming or shaping means which form the light, combustible materials into mainly solid bodies or pellets; and conveying means for conveying said materials respectively from said comminuting plant to said sorting means and from said sorting means to said forming or shaping means.

2. Apparatus according to Claim 1, wherein said comminuting plant is in the form of a hammer mill or a chipping machine.

3. Apparatus according to Claim 1 or Claim 2, wherein moistening or wetting means are linked to the sorting means.

4. Apparatus according to any one of the preceding claims, including a drying plant for receiving said light combustible materials from the sorting means.

5. Apparatus according to any one of the preceding claims, wherein said forming or shaping means comprise a pelleting device.

6. Apparatus according to any one of the preceding claims, comprising screening means which precede the comminuting plant, the materials passing through the screening apparangement being, in use of the apparatus, supplied to the comminuting plant.

7. Apparatus according to any one of the preceding claims, wherein the ballistic sorting means, in use of the apparatus, stiff solid particles are ejected by impact, extremely small fractions passing through a screen or sieve and light, combustible materials are caught by a conveyor surface which is arranged to execute a rotational movement while maintaining directional orientation, the speed of rotation of the surface in a vertical direction being greater than the speed of descent of the light, combustible particles.

8. Apparatus according to Claim 7, wherein said conveyor surface comprises an inclined plane.

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

Claims

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

In the table, I represents pellets which have been obtained from comminuted, separated and pelleted domestic refuse. Pellets according to II are produced from paper waste, which consists mainly of waste material from offices. Pellets produced from pure wood waste have the properties which are set out under III in the table. It has also been described in the foregoing that the domestic waste or refuse, prior to the comminution, passes through a screening unit. The properties of the pellets prepared from this refuse can also be seen under IV in the table.

When the pellets as produced are considered from chemical points of view, it is established that the chemical composition has the following form: C about 50% H about 6% 0 about 6% N about 8% Ash about 12% The ash, as such, contains about 0.3 - 0.5% chlorine and about 0.2% sulphur.

In accordance with the present invention the forming means are such that the moisture content, frictional heat and durability are adjustable in such a way that pathogenous microorganisms present may be killed on the surface of the fuel bodies.

The light fraction which is caught on the conveying area in accordance with the third paragraph hereof, may consist of part of a sheet of paper, of a complete sheet of paper, of part of a newspaper page and of an empty cigarette box or the like.

From the foregoing it follows clearly and unequivocally that the light fraction may consist of bodies of different sizes and different bodily configurations. The light fraction moreover has the property that bodies may form the subject of a compacted unit or of pellets. During compaction what may occur is that only one part of a body of the light fraction forms the complete unit or that the unit is formed by several bodies of the light fraction. If, for example, a body is present in the light fraction which more or less consists of an entire newspaper page, it is clear that this newspaper page can be used to produce several unit bodies or pellets.

WHAT WE CLAIM IS: 1. Apparatus for utilising combustible waste materials comprised, inter alia, of domestic refuse, the apparatus comprising: supply means for said waste materials, said supply means being linked to a comminuting plant; ballistic sorting means connected to the comminuting plant and adapted to sort out light, combustible materials, such as paper, synthetic plastics, textiles and wood; forming or shaping means which form the light, combustible materials into mainly solid bodies or pellets; and conveying means for conveying said materials respectively from said comminuting plant to said sorting means and from said sorting means to said forming or shaping means.
2. Apparatus according to Claim 1, wherein said comminuting plant is in the form of a hammer mill or a chipping machine.
3. Apparatus according to Claim 1 or Claim 2, wherein moistening or wetting means are linked to the sorting means.
4. Apparatus according to any one of the preceding claims, including a drying plant for receiving said light combustible materials from the sorting means.
5. Apparatus according to any one of the preceding claims, wherein said forming or shaping means comprise a pelleting device.
6. Apparatus according to any one of the preceding claims, comprising screening means which precede the comminuting plant, the materials passing through the screening apparangement being, in use of the apparatus, supplied to the comminuting plant.
7. Apparatus according to any one of the preceding claims, wherein the ballistic sorting means, in use of the apparatus, stiff solid particles are ejected by impact, extremely small fractions passing through a screen or sieve and light, combustible materials are caught by a conveyor surface which is arranged to execute a rotational movement while maintaining directional orientation, the speed of rotation of the surface in a vertical direction being greater than the speed of descent of the light, combustible particles.
8. Apparatus according to Claim 7, wherein said conveyor surface comprises an inclined plane.
9. Apparatus according to any one of the preceding claims, wherein the forming or

shaping means are so constructed that binders, such as polyethylene and lignin, which are contained in the waste materials, are released and utilised as jointing components or as surface-coating components of said bodies or pellets.
10. Apparatus according to any one of the preceding claims, wherein the shaping arrangement is such that moisture content, frictional heat and durability can be so regulated that it is possible to ensure that pathogenic microorganisms which are present on the surface of the fuel bodies are killed.
11. Apparatus according to any one of the preceding claims, wherein the comminuting means and the sorting means are so arranged that, in use of the apparatus, the readily combustible light materials obtained have different bodily forms and sizes, and wherein the forming means form solid units or pellets from part of the body of a light combustible material or from several bodies of light combustible materials.
12. Apparatus for utilising combustible waste materials, the apparatus being constructed, arranged and adapted to operate substantially as hereinbefore described with reference to, and as illustrated in, the accompanying diagrammatic drawing.
13. A method of producing utilisable combustible products from combustible waste materials, using apparatus according to any one of the preceding claims and wherein the said bodies have a length of between 10 and 80 mm, a thickness of between 5 and 30 mm and a density of between 0.7 and 1.1 g/cm3.
14. A method of producing utilisable combustible products from combustible waste materials according to Claim 13 and substantially as hereinbefore described with reference to the accompanying diagrammatic drawing.
15. A utilisable combustible product when produced by means of apparatus according to any one of Claims 1 to 12 or by a method according to Claim 13 or Claim 14.