GB2084534A

GB2084534A - Apparatus for receiving and discharging a mixture

Info

Publication number: GB2084534A
Application number: GB8129119A
Authority: GB
Original assignee: PLM AB
Current assignee: Rexam AB
Priority date: 1980-09-26
Filing date: 1981-09-25
Publication date: 1982-04-15
Also published as: DE3137869A1; ES8305652A1; SE8006731L; GB2084534B; ES506392A0; SE427646B; DE3137869C2; DE3153697C2

Abstract

Apparatus for receiving and discharging a flow of mixture, where the mixture comprises pieces of material and/or fragments of different materials and/or of different sizes, comprises a vibrating trough (10) having a support surface (15). A protuberance (20) is located at the receiving end of the trough (10) centrally thereof. The mixture from a feed unit (22) is spread over the support surface (15) by the protuberance (20) during the formation of a uniformly thick layer of mixture which is carried along the support surface to the discharge end of the vibrating trough. As shown a protrusion (30), not more than 1/5 of the height of the protuberance (20), is provided and extends between the two walls (13), (14) of the trough (10). <IMAGE>

Description

SPECIFICATION Apparatus for receiving and discharging a mixture The present invention relates to apparatus for receiving and discharging a mixture of pieces of material and/or fragments of different materials and/or of different sizes.

When handling products consisting of a mixture of pieces of material or fragments of different materials there exists a need to subdivide the mixture into a number of fractions, each containing only certain definite types of materials.

Examples of mixtures which require subdividing are fresh-cut peat (mixed with soil, stones sticks and twigs) and refuse (usually household refuse).

There are of course many other mixtures where a corresponding need exists.

When handling refuse it is known to grind the refuse down in mills and then sort the refuse into a number of fractions in mechanical separation plants. Separation plants are also used to separate peat from irrelevant materials such as soil, stones, sticks and twigs.

For reliable operation of the separation plant it is necessary for the mixture to be supplied to them in a uniformly thick layer having a predetermined maximum thickness and having a relatively large width.

In addition, the thickness of the layer and its flow rate should be relatively independent of time.

Achieving a layer with such properties has so far been fraught with problems.

The difficulties arise because mixtures of the type mentioned above consist of articles having different densities, different elasticities, irregular shapes, a certain degree of adhesion, and having varying moisture contents. When carrying refuse, for example, on conveyors or in conveying troughs the refuse has a tendency to form a stringy substance which has an adverse effect on the separation plant used. Further, it is not economically feasible to design the transport devices so that the refuse, when conveyed by them, is already in the thin layers required by the subsequent separation plant. There is consequently a need for equipment which spreads the stringy substance on the transport devices in a wide and uniformly thick layer which is supplied to the separation plant along its entire width.

Another problem associated with equipment used at present is that the flow rate of the mixtures varies. In the case of refuse, for example, this is due to uneven discharge from the mill. Such variations in the flow reduce the capacity of the subsequent separation plant. There is accordingly also a need for devices which equalize such variations.

For optimum operation of the separation plant it is generally necessary for the distribution of the different types of materials to be subsequently the same throughout the mixture supplied to the plant.

Some of the problems identified above can be solved by the use of vibrating troughs. The known vibrating troughs are provided with a number of relatively low plough-like protrusions situated one after the other with their ends facing the direction of transportation. The protrusions act to spread the material out towards the sides of the vibrating trough and thus a relatively uniform wide layer of material is discharged. However, the known vibrating trough has the serious disadvantage that the protrusions act as obstructions whereby the transport capacity of the vibrating trough is reduced at the same time as an undesirable division of the material occurs.

According to the present invention there is provided apparatus for receiving and discharging a flow of mixture, the mixture comprising pieces of material, and/or fragments of different materials and/or of different sizes, the apparatus comprising at least one vibrating trough having a support surface, and a protuberance arranged at the receiving end of the vibrating trough on the support surface, the protuberance being arranged to spread mixture received at the receiving end over the support surface as it is carried from the receiving end to the discharge end of the vibrating trough such that a substantially uniformly thick layer of the mixture is presented to said discharge end.

Apparatus of the invention is able to distribute the mixture relatively uniformly such that it forms a layer of the necessary width and correct thickness. In addition, the requirement of high transport capacity with unaltered distribution of material in the layer can also be satisfied. Practical tests have shown a twofold increase of transport capacity as compared'with the known vibrating troughs.

With apparatus of the invention an "artificial" pile of material is arranged in the feed section of the trough because the feed section is provided with a protuberance to which the material is fed.

This protuberance forms the core of a pile of material down the sides of which the material slides and is thereby spread over the surface of the vibrating trough right out to its sides. The boundaries of the protuberance thereby constitute supporting surfaces for a layer of material the top stratum of which slides against the underlying strata. A certain degree of material transfer naturally also takes place in the lowest strata but the main flow of material takes place in the upper strata. The "artificial" pile of material has less mass than a "homogeneous" pile of material would have while at the same time it can be given a shape which permits the simplest mechanical construction together with the best spreading effect.The small mass of the pile also simplifies the design of drive units and linkage systems for the vibrating trough since the smaller mass forces involved allow scope for the construction of less massive structures. By adapting the amplitude and frequency of the motion of the vibrating trough to the properties of the material, good spreading of the material over the surface of the vibrating trough is obtained.

The protuberance is a preferably located centrally at the feed end of the trough. The protuberance is of ridge-like shape and extends substantially from the edge of the feed end partway along the vibrating trough in the direction of movement of the material. The boundary surface of the protuberance joins the substantially planar support surface of the vibrating trough.

Preferably, the cross-section of the protuberance has a curved periphery which may be part of the circumference of a circle. The periphery of the protuberance is thus similar to the cross-section of a pile of material. In a preferred version, the protuberance is terminated in the direction of movement of the material by a substantially vertically extending surface. Adjacent to or slightly after, in the direction of movement of the material, the vertical surface, the support surface of the vibrating trough, is provided with one or more relatively low protrusions extending substantially at right angles to the direction of movement of the material. In a preferred embodiment two protrusions are provided, each extending from a respective side of the protuberance to one of the two longitudinal sides of the vibrating trough.In a further embodiment a single protrusion spaced from the protuberance extends between the two sides of the vibrating trough. The height of the protrusion is preferably at a maximum of about 1/5 of the height of the protuberance.

In an embodiment, an inclined surface, preferably a curved surface which is concave as viewed from above, is arranged at the feed end of the vibrating trough to prevent the material from accumulating at the feed edge of the trough. This inclined surface helps to reduce the mass forces occurring as a result of the motion of the vibrating trough.

For certain applications it is required to divide the mixture into a number of separate flows so that the respective layer of material will be of the thickness and the width to ensure reliable operation of the subsequent equipment, such as a separation plant. In an embodiment the vibrating trough is fitted with a wedge-shaped distribution member which comprises a continuation of the protuberance in the direction of feed. The upper edge of the wedge-shaped member is joined to the highest portion of the protuberance. The cross-sectional area and height of the wedgeshaped part preferably increases in the direction of movement of the mixture. The wedge-shaped member may have a triangular cross-section with one of the angles of the triangle facing upwardly and may extend a shorter or longer distance towards the discharge edge of the vibrating trough.If required the distribution member may extend right up to this discharge edge. Where the layer of material from the vibrating trough is to be divided into more than two flows, the discharge edge of the vibrating trough may be provided with a number of secondary edges, each of which is separated from the other and bounded by vertically arranged limiting walls. These walls may consist of wedge-shaped members similar to the distribution member described above.

In an embodiment, in which the mixture is divided into three layers of material, the vibrating trough is provided at its front discharge edge with a centrally situated opening comprising a part of the front edge of the vibrating trough.

The two sides of the opening, which extend in the direction of movement of the mixture, are joined to oblique edges comprising the remaining portion of the front edge of the vibrating trough.

Through this design the width of the layer of material which is divided between the centrally situated opening and the two oblique edges is reduced as compared with the total width of the vibrating trough. In cases where a larger width is necessary, each of the three layers of material is allowed to pass to a subsequent vibrating trough, each such trough being provided with a protuberance as described above. In the subsequent vibrating troughs the layers of material are thereby further reduced so that the required spreading of material over the entire width of the vibrating troughs is achieved and the width and thickness requirements of the layers of material are satisfied when they are supplied, for example, to the separation plants.

Where the layers of material pass over oblique edges a reduction of the layer thickness takes place with a corresponding increase in the spreading width which in certain applications may constitute a means of achieving the required spreading width and layer thickness in a layer of material supplied to a separation plant.

Embodiments of the present invention will hereinafter be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 a shows an embodiment of a vibrating trough viewed from above, Fig. 1 b shows a section on the line Il-Il of the trough of Fig. 1 a, Fig. 1 c shows a section on the line Ill-Ill of the trough of Fig. 1 a, Fig. 2a shows a second embodiment of a vibrating trough having a distribution wedge viewed from above, Fig. 2b shows a section on the line lV-IV of the trough of Fig. 2a, Fig. 2c shows a section on the line V-V of the trough of Fig. 2a, Fig. 3 shows the spread pattern of material in the vibrating trough of Fig. 1 a, Fig. 4 shows a view from above of apparatus comprising a vibrating trough having a distribution wedge, two additional vibrating troughs, and two separation plants, Fig. 5 shows a view from above of apparatus comprising a vibrating trough, and three additional vibrating troughs, Fig. 6a shows a further embodiment of a vibrating trough viewed from above, Fig. 6b shows a section on the line VI--VI of the trough of Fig. 6a, and Fig. Sc shows a section on the line VIl-VIl of the trough of Fig. 6a.

Figures 1 a to 1 c show a vibrating trough 10 having a rear wall 11 and a front edge 12. In the embodiment illustrated, the front edge 1 2 forms an angle of about 450 to the longitudinal direction of the vibrating trough. The vibrating trough is further bounded by two side walls 13 and 14 which extend upwardly from a support surface 1 5 of the trough and comprise the remaining outer boundaries of the trough. A protuberance 20 is arranged at the rear portion of the vibrating trough centrally on the support surface 1 5. The protuberance 20 extends from the rear wall 11 towards the front edge 12. However, the protuberance terminates short of the front edge 12.

The protuberance 20 has a ridge-like shape the bounding surface of which joins the planar support surface 1 5 of the trough, and the cross-section of the protuberance has a curved profile, preferably part of the circumference of a circle (cf. Fig. 1 b) The protuberance 20 has a front surface 21 which extends substantially vertically. In front of the front surface 21 in the direction of movement of the material the support surface 1 5 of the vibrating trough is provided with a relatively low protrusion 30 which extends between the the two walls 13 and 14 of the vibrating trough. The height of the protrusion 30 is a maximum of 1/5 of the height of the protuberance 20. A feed unit 22 is arranged at the rear end of the vibrating trough for feeding a mixture thereto.Figures 1 b and 1 c also show cross-sections through layers 60 and 61 of the mixture which arise in the sections Il-Il and Ill-Ill of the trough respectively during the movement of the mixture towards the front edge of the vibrating trough.

In operation, the mixture is fed to the rear portion of the vibrating trough by the feed unit 22 such that it drops onto the protuberance 20. A layer of material is thus formed around the protuberance, and the constituents of the material slide down from the centreline of the protuberance and hence of the vibrating trough and are in addition successively carried towards the two side walls 13 and 14 by the motion of the vibrating trough at the same time as the material is moved towards the front edge 12. The sequence of movement of the material has been described in detail hereinbefore. The resultant spread pattern of the material is shown in Fig. 3, In Fig. 3 level lines 32 are shown which indicate the thickness of the layer of material at different points on the vibrating trough.It has been found that near the protrusion 30 and the substantially vertically extending front surface 21 the mixture forms a substantially uniform thick layer 60 (cf. also Fig.

1 b) which is carried along by the motion of the vibrating trough towards the front edge 12 of the trough. The mixture is discharged from the front edge 12, for example, to a separation plant (not shown).

In certain applications a number of protrusions as 30 are arranged one after the other, particularly when equalization of a varying flow rate is especially pronounced.

In Figs. 2a to 2c protrusions 30a and 30b are arranged immediately adjacent to the front surface 21 on each side thereof. Furthermore, the vibrating trough 10' is provided with a wedgeshaped distribution member 40 the upper edge 41 of which is connected to the highest portion of the protuberance 20. The cross-sectional area of the wedge-shaped member 40 increases with its proximity to the front edge 1 2 of the vibrating trough, i.e. in the direction of movement of the mixture. In the embodiment illustrated the wedgeshaped member 40 has a triangular cross-section with the apex of the triangle defining the upper edge 41.

In Figs. 2a to 2c the wedge-shaped member 40 extends from the front edge 21 of protuberance 20 to the front edge 12 of the vibrating trough.

However, if required a wedge-shaped member having a more restricted length may be provided.

For reliable operation the upper edge 41 of the wedge-shaped member should rise comparatively steeply in the direction of movement of the material. For example, the upper edge 41 may be at an angle of about 300 relative to the support surface.

The wedge-shaped member 40 divides the mixture into two substantially equal flows of material as the mixture is carried towards the front edge 1 2 of the vibrating trough.

It may appear that the wedge-shaped member 40 counteracts the purpose of the invention which is to achieve a uniform thick layer of the mixture discharged at the front edge of the vibrating trough. In practice, however, a vibrating trough having a wedge-shaped member 40 is normally used only when the vibrating trough is followed in the direction of movement of the material by a number of vibrating troughs designed substantially as shown in Figs 1 a to 1 c. The wedge-shaped member comprises a means of dividing the flow of material into two sub-flows of substantially equal size. The need to bring about such a division arises when the flow of material in the vibrating trough is so great that is exceeds the capacity of the subsequent equipment, such as a separation plant.

Fig. 4 shows apparatus consisting of three vibrating troughs 10', 1 Oa, and 1 Ob followed by two plants 23 and 24. The first vibrating trough 10' is provided with a protuberance 20 and a wedge-shaped member 40. The two subsequent vibrating troughs 1 0a and 1 Ob are each provided with a respective protuberance 20a, 20b but no wedge-shaped member. The two vibrating troughs 1 0a, 1 Ob are arranged to feed material to a respective plant 23, 24 which may each comprise, for example, a separating table for sorting the material into a number of different fractions.From the figure it can be seen how at each transition between a vibrating trough and either a subsequent vibrating trough or a respective plant 23 or 24, the front edge of the respective vibrating trough forms an angle of about 450 to the direction of movement of the mixture.

Accordingly, each of plants 23, 24 is supplied with a proportion of the mixture over a greater width.

The front edge of the first vibrating trough 10' consists of two oblique edges 44 and 45 which are at an angle of about 900 to each other such that the support surface 1 5' at the front part of the vibrating trough has a pointed shape. Also shown in the figure is a feed unit 22 for supplying material to the first vibrating trough 10'.

The feed unit 22 supplies material to the rear of the vibrating trough 10' in the area where the protuberance 20 is situated. The movement of the vibrating trough carries the material towards the front edge thereof. On passing the area beside the end of the protuberance the mixture is spread into a comparatively uniform thick layer. The wedgeshaped member 40 divides the mixture into two sub-flows, one for the vibrating trough 1 Oa and the other for the vibrating trough 1 Ob. The subflows are supplied to the two subsequent vibrating troughs at the protuberance of the respective vibrating trough.The mixture is then carried towards the front edges of these latter two vibrating troughs and is simultaneously spread out over the support surfaces of the two vibrating troughs so that when the mixtures are supplied to the subsequent plants 23 and 24 they form a uniformly thick layer.

Fig. 5 shows apparatus consisting of four vibrating troughs, that is, trough 1 0", and three additional troughs 1 Oc to 1 Oe for dividing the incoming mixture into three equally large subflows, each sub-flow consisting of a substantially uniformly thick layer. In this apparatus the first vibrating trough 10" is somewhat modified at its front edge, i.e. at its discharge end. It is provided with a centrally situated opening 33 which has two of its edges extending mainly in the direction of movement of the mixture. Arranged at these edges are distribution units 43 which are preferably wedge-shaped. The remaining portions 34, 35 of the front edge of the vibrating trough 10" preferably form an angle of 450 to the direction of movement of the mixture.At the front edge of the vibrating trough 10" are arranged three vibrating troughs 1 Oc to 1 Oe. Two of the vibrating troughs 1 Oc and 1 Oe form an angle of about 45" to the vibrating trough 10" whilst the vibrating trough 1 Od extends in the same direction as the vibrating trough 10". All the vibrating troughs 10", and 1 Oc to 1 Oe have a respective protuberance 20, and 20c to 20e arranged as shown in Figs. 1 a to 1 c. Subsequent equipment, not shown in the figure, is arranged at the front edges 1 2c to 1 2e of the respective vibrating troughs 1 Oc to 1 Oe for further processing of the mixtures. A feed unit 22 is arranged close to the rear wall of the vibrating trough 10".

Mixture is supplied to the vibrating trough 10" by the feed unit 22 and is evenly spread over the support surface of the vibrating trough as described earlier so that the mixture forms a uniformly thick layer when it reaches the front edge of the vibrating trough. The layer is divided at the front edge into three sub-flows, each of which is supplied to a respective one of the troughs 1 Oc to 1 Oe at the rear wall of the respective vibrating trough. The mixture of each sub-flow is thereby concentrated within a comparatively small area at the rear wall of the respective vibrating trough where the protuberance of the respective vibrating trough is situated.From here each sub-mixture is spread out in the manner described earlier over the entire support surface of the respective vibrating trough as it is simultaneously carried towards the front edge of the respective vibrating trough where the respective sub-layer is transferred to a uniformly thick layer to the subsequent equipment.

Figs. 6a to 6c show an alternative embodiment of a vibrating trough 10"'. In this embodiment the rear portion of the vibrating trough, i.e. its feed portion, is provided with a sloping, preferably curved and, when viewed from above, concave surface 26 which joins the protuberance 20 and also the support surface 1 5 of the vibrating trough. At the transition between the protuberance 20 and the support surface 1 5 equalization surfaces 25a and 25b are provided.

The figures also show that the protrusion 30c has a substantially triangular cross-section. Other reference numbers in the figures correspond directly to the earlier description.

The curved surface 26 prevents material from accumulating at the rear wall 11 of the vibrating trough since the material slides along the surface 26 towards the front edge of the vibrating trough.

The equalization surfaces 25 fulfill a corresponding function at the transition between the protuberance 20 and the support surface 1 5.

The design of the protrusion 30c shown also prevents the accumulation of material. The features which are illustrated in Figs. 6a to 6c accordingly constitute practical improvements to the invention. The features help to further reduce the mass of the mixture which is carried along in the vibrating trough and thereby help to reduce the mass forces which occur as a result of the motion of the vibrating trough.

Claims

1. Apparatus for receiving and discharging a flow of mixture, the mixture comprising pieces of material, and/or fragments of different materials and/or of different sizes, the apparatus comprising at least one vibrating trough having a support surface, and a protuberance arranged at the receiving end of the vibrating trough on the support surface, the protuberance being arranged to spread mixture received at the receiving end over the support surface as it is carried from the receiving end to the discharge end of the vibrating trough such that a substantially uniformly thick layer of the mixture is presented to said discharge end.

2. Apparatus as claimed in Claim 1, wherein the protuberance is situated centrally in the receiving end of the vibrating trough.

3. Apparatus as claimed in Claim 1 or Claim 2, wherein the protuberance has a ridge-like shape the boundary of which joins the support surface of the vibrating trough, and the cross-section of the protuberance has a curved profile.

4. Apparatus as claimed in Claim 3, wherein the cross-section of the protuberance has a profile which is part of the circumference of a circle.

5. Apparatus as claimed in any preceding claim, wherein the protuberance is bounded in the direction of the flow of the material by a substantially vertically extending surface.

6. Apparatus as claimed in any preceding claim, wherein at least one protrusion extends across the support surface substantially at right angles to the direction of flow of the mixture, the or each protrusion being arranged adjacent to or after, in the direction of flow of the mixture, the substantially vertically extending boundary surface of the protuberance.

7. Apparatus as claimed in Claim 6, where the maximum height of the or each protrusion is approximately 1/5 of the height of the protuberance.

8. Apparatus as claimed in any preceding claim, wherein an inclined, preferably curved surface is provided at the receiving end of the trough to prevent the accumulation of mixture at the limits of the vibrating trough in the opposite direction to the direction of flow of the mixture.

9. Apparatus as claimed in any preceding claim, wherein the protuberance is extended in the direction of flow of the mixture by a distribution member arranged to divide the mixture into two separate flows of substantially equal size.

10. Apparatus as claimed in Claim 9, wherein the distribution member is substantially wedgeshaped and its upper edge joins the highest point of the protuberance, and wherein the height and cross-sectional area of said member increases in the direction of flow of the mixture.

11. Apparatus as claimed in Claim 9 or Claim 10, wherein the distribution member has a triangular cross-section with one of the angle of the triangle pointing upwardly.

12. Apparatus as claimed in any preceding claim, comprising three vibrating troughs, a first one of the vibrating troughs being arranged to transfer substantially equally large flows of mixture to the two other vibrating troughs, wherein the first vibrating trough is provided at its discharge end with two oblique front edges extending at an angle to each other such that the support surface at the front edge of the first vibrating trough has a pointed shape, whereby largely equal portions of the flow of mixture pass over the respective front edges to the receiving ends of the two other vibrating troughs, the respective portion of the flow of mixture being spread out over the support surface of the respective other vibrating trough during the formation of a substantially uniformly thick layer of mixture which is carried along the support surface to the discharge end of the respective other vibrating trough.

13. Apparatus as claimed in any of Claims 1 to 11, comprising four vibrating troughs, a first one of the vibrating troughs being arranged to transfer substantially equally large flows of mixture to the three other vibrating troughs, wherein the first vibrating trough is provided at its discharge end with a centrally situated opening comprising part of the front edge of the first vibrating trough, the two edges of the opening, which extend in the direction of movement of the mixture, being joined to oblique edges comprising the remaining portion of the front edge of the vibrating trough, whereby substantially equal portions of the flow of mixture pass through the opening and over the respective oblique edges to the receiving ends of said other vibrating troughs, the respective portion of the flow of mixture being spread over the support surface of the respective other vibrating trough during the formation of a substantially uniformly thick layer of mixture which is carried along the support surface to the discharge end of the respective other vibrating trough.

1 4. Apparatus for receiving and discharging a flow of mixture substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.