EP3221057B1 - Method and device for separating materials according to their density - Google Patents

Description

Method and device for separating substances according to their density

Methods and apparatus for separating materials by density are known in the art. In such a method, for example, a mixture of substances of different specific gravity (density) is produced by comminution in a shredder or hammer mill and separated in a downstream screening plant to a preferably homogeneous grain size. But such mixtures can also be very inhomogeneous in size, density, surface finish, etc.

The mixture thus obtained is introduced via a conveyor into a liquid bath, for example a water bath, which is located in a container, the setting box. The water bath is subdivided into two bath sections by a sieve bottom extending horizontally across the container.

The sieved mixture of substances of different specific weight is fed to the part of the water bath located above the sieve tray. Specific lighter substances float in the water bath to its surface and are discharged via an overflow from the water bath. Specifically heavier proportions settle on the sieve bottom.

To facilitate the floating of the lightweight materials, a displacement body cyclically submerged in the water bath can produce pressure changes and currents in the water bath, which support the floating of lighter pieces of fabric.

The deposited on the sieve bottom fabric shares z. Be carried out by the fact that the sieve bottom performs a horizontal movement, which in the one Directed slowly and in the opposite direction accelerated and at the same time, before reaching the wall of the container, stops abruptly, so that settled on the bottom of the sieve sediment via a simultaneously opening gap between the bottom of the sieve and the wall of the container, due to the sediment by the acceleration inherent kinetic energy, is discharged across the gap.

Out DE 887 181 a piston setting machine is known, which causes a compensation of the suction action exerted on the material to be set by supplying additional liquid into the setting box when lifting the piston (suction stroke).

EP 040 519 A1 discloses a setting machine for separating materials and a method for separating coal from shale in which liquid is added according to a pressure drop in a compression chamber.

The known methods and equipment work quite time-consuming, since the light matter swims only slowly. Thus, these methods are also less efficient and do not allow to separate even inhomogeneous mixtures with high accuracy.

The object of the invention is to provide improved methods and apparatus for the separation of mixtures according to their density.

This object is solved by the invention which is defined in the independent patent claims; Embodiments of the invention are defined in the dependent claims.

In one aspect, depending on the duty cycle of the displacer, additional liquid is supplied to the liquid bath, controlled according to amount, pressure, and timing in the work cycle. The pressure in the liquid bath can be measured as a parameter for the control.

When lifting the displacement body from the liquid bath, creates a suction effect, the already flooded material sucks back to the sieve bottom. This suction controls the invention by one of the movement movement the displacement body corresponding additional amount of liquid is supplied.

Upon immersion of the displacement body in the liquid bath - depending on the composition of the mixture - a certain amount of additional liquid supplied to increase the generated by the submerged displacement body, upward movement of the liquid and thus specifically to allow heavier substances float up, which otherwise the sieve bottom would remain. The buoyancy on the sieve bottom can be controlled so accurately. This allows a fine separation between heavy and even heavier proportions of substance.

In the device for separating substances according to their density, at least one supply for liquid is provided in the region of the setting box below the sieve tray. The inflow of the liquid is regulated by a control device according to pressure and amount so that on the one hand improves the buoyancy of the light materials and on the other hand prevents a suction effect in the water when lifting the displacement body.

The supply of liquid in the lying below the sieve tray portion of the liquid container is synchronous with the movement of the cyclically submerged displacement body. The liquid feed control means operating in synchronism with the cyclical motion of the displacer operates to add an amount of liquid settable to the feed mixture upon immersion of the displacer and to control the supply of additional liquid as the displacer is lifted in the liquid bath, that there is no suction in the liquid bath.

The liquid to be supplied (eg water) must be dimensioned in both movements of the displacement body in such a way that on the one hand the buoyancy of the lighter substances is supported, but on the other hand it does not hinder the sinking of the heavy materials becomes. Likewise, the timing of the supply of liquid in the process cycle is tuned such that it takes place synchronously with the movement of the displacement body.

During lifting, liquid is supplied in such a way that its quantity corresponds to the respective volume fraction of the displacement body moving out of the liquid bath, so that no suction effect arises in the liquid bath, which would cause already floated material to be sucked again in the direction of the sieve bottom.

The upward flow in the liquid created by the immersion of the displacer is assisted by the simultaneous controlled delivery of additional liquid, the amount of which is matched to the substances to be separated. With the higher buoyancy forces thus achieved, even heavier materials can be made to float and be discharged over the weir, especially those parts which oppose the buoyant flow with a large attack surface and which would otherwise settle on the sieve tray (e.g., larger or larger plastic pieces).

The control can take place via pressure sensors in the liquid bath or via measuring devices on the drive of the displacement body. This control acts on one or more valves according to the number of supply lines for the liquid to be supplied. A pressure sensor in the liquid bath can interact with a liquid feed pump to control their speed and their delivery pressure and thus the flow rate. For adjustment can be provided in the supply line for the liquid still a manually operated valve.

figure description

The liquid container (setting box) 1 contains a liquid bath 2 (preferably water) and is filled to an overflow 6, are discharged through the floated substances. At about half the liquid level, at least one horizontally movable sieve bottom 4 is arranged in the setting box 1.

In the liquid bath, a mixture of different materials (with different density) is introduced. Lower density material floats in the liquid bath to its surface and is discharged via the overflow 6. Heavier material sinks to the sieve bottom 4 and forms there a sediment layer which is periodically discharged by means of a horizontal, jerky movement of the sieve bottom 4 via an opening 5, which can be formed as a gap to the wall of the liquid container 1. This results in a systematic separation of substances of different densities.

To accelerate the separation, a displacement body 3 can be provided in the liquid bath 2, which cyclically dips into the liquid bath 2 and generates a precisely defined pressure change which is determined empirically as a function of the material to be separated and increases the buoyancy of the lighter substances.

A pressure sensor 11 in the region below the sieve bottom 4 measures the pressure in the liquid bath and delivers it to controls 8 of a control and regulating device 9 for the supply of additional liquid.

When lifting the displacement body 3 in the liquid bath 2, a suction (and thus a pressure drop) would arise, which must be avoided so that not already floated material is sucked back to the sieve plate 4. In order to avoid such a suction in the liquid bath 2 is connected to the setting box, a controlled liquid supply 7 below the sieve plate 4.

The control of the liquid supply takes place synchronously with the movement of the displacement body. 3

When immersing the displacement body 3 in the liquid bath 2, the amount of additional liquid is controlled depending on the substance mixture to be separated so that not only light materials can be separated, which float from the outset, but also heavy materials are separated from even heavier materials, without controlled Feeding additional Flüssigkeit.beide deposited on the sieve bottom.

The controlled supply of liquid during immersion of the displacement body - which leads to stronger flows (or larger pressure changes) in the liquid bath than by immersing the displacement body alone - allows the invention a flexible and rapid adaptation of the separation performance of the present inhomogeneous mixture of light, heavier and heavier materials.

When lifting the displacement body 3 from the liquid bath 2 additional liquid is introduced into the liquid bath 2 under pressure, so that no suction (pressure drop) is formed in the liquid bath 2; For this purpose, the amount of additional liquid is adjusted according to the liquid volume released during lifting.

Between the displacement body 3 and the drive there may be a connection to the control device 9, which controls the additional amount of liquid according to time, pressure and quantity, alone or in cooperation with the pressure sensors.

In the area above the sieve bottom 4, sensors 10 can also be arranged, which supply control signals for the supply of additional liquid.

The substances discharged via the overflow 6 and the substances discharged from the sieve bottom via the opening 5 can each be picked up by a video camera and displayed via a display device (monitor). The operator can thus perform a manual fine control of the supply of additional liquid and thus specifically affect the separation performance of the device depending on the observed actual separation result.

In the described method and apparatus, additional liquid is supplied continuously and in a controlled manner to the liquid bath, both during the immersion of the displacement body and during its lifting. As a result, a movement is generated in the liquid bath, which can be set exactly to the substance mixture to be separated and allows a targeted and tunable separation between light, heavy and heavy substance components. In particular, floatable material parts are no longer guided in the direction of the sieve tray.

reference numeral

1. 1 fluid container
2. 2 liquid bath
3. 3 displacement body
4. 4 sieve bottom
5. 5 opening for the discharge of heavy material
6. 6 overflow for light material discharge
7. 7 Supply line for additional liquid
8. 8 controls for adding additional fluid
9. 9 Control device for pressure, quantity and timing of the supply of additional liquid
10. 10 sensors
11. 11 sensors below the sieve bottom to determine the pressure in the liquid container 1

Claims (5)

1. Method for separating mixtures of comminuted substances according to their density in a liquid bath (2) having at least one sieve bottom on which heavier parts of the fed mixture settle, and an apparatus for generating a cyclic change in pressure in the liquid bath, characterised in that, during an increase in the pressure, additional liquid is fed to the liquid bath, the quantity of which is determined according to the composition of the mixture to be separated.
2. Apparatus for separating mixtures of comminuted substances according to their density in a liquid bath (2) having at least one sieve bottom on which heavier parts of the fed mixture settle and having a displacement body (3) which is cyclically immersed in the liquid bath, characterised in that a control device (9) is provided which, when the displacement body is immersed, introduces additional liquid into the liquid bath via a feed (7), wherein the quantity of additional liquid is determined in accordance with the composition of the mixture to be separated.
3. Apparatus according to claim 2, wherein a feed for liquid and pressure sensors (11), which supply control signals to the control device, is provided in the liquid bath below the sieve bottom.
4. Apparatus according to one of claims 2 to 3, wherein an imaging device respectively indicates the separate substance fractions for manual fine control of the additional liquid.
5. Apparatus according to any one of claims 2 to 4, wherein the control means, when raising the displacement body, feeds liquid in an amount corresponding to the volume of liquid displaced by the displacement body.

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