Separation-apparatus

Abstract

The invention relates to a separation-apparatus for separating from a particle-stream at least a first fraction with particles of a first group of dimensions, and a second fraction with particles of a second group of dimensions, comprising an infeed-device for the particle-stream, a rotatable drum having at its circumference plates, each plate having a radially extending hitting surface for the particles, at least a first receiving area proximal to the drum for receipt therein of particles of the first fraction, and at least a second receiving area distant from the drum for receipt therein of particles of the second fraction, wherein the apparatus has a housing so as to protect the particles from outside weather-conditions, allowing that the particles of the particle-stream to be processed by said apparatus have dimensions in the range 0-15 mm.

Claims

1. A method of classifying a moist particle stream of particles of bottom-ash of waste incineration plants into a first particle fraction of a first group of dimensions and a second particle fraction of a second group of dimensions, the method comprising: providing a moist particle stream of bottom-ash of waste incineration plants including particles in the range of about 0-2 mm and larger than 15 mm; flowing the moist particle stream as a continuous flow of particles with a limited thickness of the flow, the flow being essentially vertical; impinging upon the continuous flow of particles to cause a stepwise change in direction from essentially vertical flow to an essentially horizontal displacement, wherein the first particle fraction travels horizontally a first distance from the essentially vertical flow to a first receiving area and the second particle fraction travels horizontally a second distance from the essentially vertical flow to a second receiving area, the first distance being less than the second distance.

2. The method of claim 1, further comprising the particles of the continuous flow of particles are impinged upon with a horizontal speed in the range 10-30 m/s.

3. The method according to claim 1, wherein metals are classified from said ashes into the first fraction and the second fraction.

4. The method according to claim 3, further comprising processing the second fraction in a dry-separation method to separate the metals into ferrous and non-ferrous metals.

5. The method of claim 1 further comprising providing a housing and performing the steps of flowing and impinging within the housing to protect the particles form outside weather-conditions.

6. The method of claim 1 wherein the impinging step is performed by providing a rotatable drum rotating about a drum axis having plates with a substantially radially extending hitting surface which impinges on the continuous flow of particles in a vertically or near-vertically upwards oriented position to provide the essentially horizontal displacement.

7. The method of claim 1 wherein prior to the flowing step the moist particle stream is sieved to provide particles in a size range of about 0-15 mm.

8. The method according to claim 1 wherein the first fraction has particles having dimensions in the range of about 0-2 mm, and the second fraction has particles having dimensions in the range of about 2-15 mm.

9. The method according to claim 1, wherein the moist particle stream has a moisture-content of about 15-20 weight %.

10. The method according to claim 1 further comprising flowing a gas flow in a flow-direction that is pointed from the second receiving area towards the essentially vertical flow.

11. The method according to claim 1 further comprising providing at the second receiving area a conveyor for discharging at a conveyor outlet the particles of the second fraction received in the second receiving area and providing at the conveyor's outlet a downwardly directed airflow for removal of particles of the first fraction that stick to particles of the second fraction.

12. The method according to claim 1 wherein the continuous flow of particles resembles a monolayer flow.

Description

(1) The invention will hereinafter be further elucidated with reference to an exemplary schematic embodiment of the separation-apparatus of the invention and with reference to the drawing.

(2) In the drawing:

(3) FIG. 1 shows schematically the separation-apparatus of the invention;

(4) FIG. 2 and FIG. 3 show the drum of the separation-apparatus of the invention in a side and a frontal view, respectively, and

(5) FIG. 4 shows a conveyor for discharging particles being processed in the separation-apparatus of the invention.

(6) Wherever in the figures the same reference numerals are applied these numerals refer to the same parts.

(7) With reference first to FIG. 1 the separation-apparatus of the invention is generally denoted with reference numeral 1. This separation-apparatus 1 is used for separating particles 3 of a first fraction and of a second fraction wherein the respective fractions pertain to particles having different dimensions.

(8) The particles 3 are collectively supported by an infeed-device 2. The infeed-device 2 is a plate which is arranged to be vibrated causing then that the particles 3 leave the vibrating plate over the edge 2 in a particle stream as symbolised by the arrow 4. The particle stream 4 is over the edge 2 further supported by a downwardly sloping slide-plate 2 that supports the development of a monolayer-type flow of said particle stream 4.

(9) The edge 2 of the vibrating plate 2 is positioned above a drum 5, which can rotate around its axis 8 of rotation and which drum 5 has at its circumference 13, plates 6, 6. Each plate 6, 6 has a radially extending hitting surface 6, 6 for impinging on the particles 3 that arrive in the vicinity of the drum 5.

(10) In order to secure that a proper particle stream 4 resembling a monolayer stream arrives near the drum 5, it is further preferable that the vibrating plate 2 vibrates at a frequency of more than 10 Hertz, preferably 20 Hz and an amplitude of less than 5 mm, preferably one or two mm. As already mentioned it is preferred to apply a slide-plate 2 that slightly tilts downwards as seen from the edge 2. This tilting downwards can be in the range of 70-90 degrees as compared to the horizon.

(11) As FIG. 1 clearly shows the edge 2 of the vibrating plate 2 is positioned vertically or near vertically above the axis 8 of rotation of the drum 5 so as to cause that in use the particles 3 of the particle stream 4 fall towards the drum 5 in a direction aimed towards said axis 8 of rotation or to its immediate vicinity. This construction further arranges that the plates 6, 6 of the drum 5 impinge on said falling particles 3 at a moment that said plates 6, 6 are in a vertically or near vertically upwards oriented position extending from the drum 5. This is shown in FIG. 1 with respect to plate 6.

(12) As shown more clearly in FIG. 2, the plates 6, 6 are provided with a backing 14 that slopes from the free extremities 15, 15 of said plates 6, 6 towards the drum's circumference 13. This way turbulence behind the plates 6, 6 is effectively avoided during rotation of the drum 5.

(13) In use the drum 5 is caused to rotate at a speed such that the plates 6, 6 impinge on the particles 3 in the particle stream 4 with a horizontal speed (see arrow A in FIG. 2) in the range 10-30 m/s. Due to this action FIG. 1 shows that a cloud of particles moves in the direction of arrow B to be collected in at least a first receiving area 11, 11 proximal to the drum 5 for receipt therein of the smaller particles of the first fraction, and at least a second receiving area 12, 12 for receipt therein of the larger particles of the second fraction.

(14) With a proper tuning of the vibrating plate 2 in terms of vibrating frequency and vibrating amplitude and by a proper selection of the rotational speed of the drum 5 it is possible to realise an effective separation of the particles into a first and into a second fraction, wherein the first fraction pertains to particles having dimensions in the range 0-2 mm and the second fraction pertains to particles having dimensions in the range 2-15 mm. A proper operation of the apparatus of the invention can be identified when the particles leave the drum 5 in a manner that their angle of departure does not surpass 12 degrees as compared to the horizon (see FIG. 1).

(15) FIG. 1 further shows that the separation apparatus 1 is embodied with a housing 16 in order to protect the particles 3 from outside weather conditions, thus allowing that the particles 3 of the particle stream 4 having dimensions in the range 0-15 mm can at all be processed in the apparatus of the invention.

(16) Although not shown in FIG. 1 the apparatus 1 of the invention may in a preferred embodiment further be provided with means for providing a gas flow having a flow direction opposite to the arrow B, thus pointing from the second receiving area 12, 12 towards the drum 5.

(17) Any of the first receiving areas 11, 11 and the second receiving areas 12, 12 is in practice provided with conveyor belts for removing the collected particles from said areas. An example of a conveyor belt that is applied with anyone of the second receiving areas 12, 12 is shown in FIG. 4 and provided with reference numeral 17. Particles 3 are discharged from any such second area 12, 12 and transported by the conveyor 17 operating at a conveying speed that is high enough to cause that the particles 3 leave the conveyor belt 17 with a speed sufficient for the particles to travel through an essentially transversal air-flow 18. Due to the air-flow 18 particles of a first smaller fraction that attach or stick to larger particles 3 of the second fraction are released. The air-flow 18 can easily be arranged by application of a blower 19 providing preferably a downwardly directed air stream 18 immediately adjacent to the exit point or outlet 20 where the particles 3 leave the conveyor belt 17.

(18) The inventors expressly point out that the exemplary embodiment as discussed hereinabove relates to the operation and construction of the separation-apparatus of the invention without necessarily being restricted to the processing of waste-incineration ashes or bottom ashes. The separation apparatus of the invention is generally applicable to any type of particle that is required to be classified into fractions of particles having dimensions in the lower ranges such as 0-15 mm without being restricted to such particles as are derived from waste incineration plants.