WO2000021634A1

WO2000021634A1 - Method and device for sedimentation and washing

Info

Publication number: WO2000021634A1
Application number: PCT/EP1999/007521
Authority: WO
Inventors: Michael Haubs; Reinhard Wagener; Eberhard Fischer
Original assignee: Ticona Gmbh
Priority date: 1998-10-15
Filing date: 1999-10-07
Publication date: 2000-04-20
Also published as: EP1121186A1; AU6201599A

Abstract

The invention relates to a method and device for sedimentation and washing. The device of the inventive method contains at least one sedimentation part, whereby a sedimentation part contains n sedimentation bases and n represents a whole number > 1. The device comprises at least one head part (KT), at least one base part (BT) and n sedimentation bases arranged therebetween. A sedimentation base contains at least one sedimentation hopper, at least one mixing chamber, at least one washing liquid feed and at least one overflow return.

Description

description

Method and device for sedimentation and washing

The present invention relates to a method and a device for separation by sedimentation and washing.

The technology for separating solids suspended in liquids is known from US-A-5, 658,461.

In the existing apparatuses and processes for separating solids suspended in liquids, there is the disadvantage that components. which are dissolved in the liquid phase are discharged with the solid. In industry, there is often the task of discharging the solid so that it is completely separated from dissolved parts. It may be the case that a solid by-product has to be separated from a valuable substance dissolved in the liquid. that as little valuable material as possible is discharged with the solid. However, it may also be the case that the liquid phase contains an impurity which is to be separated from the solid. This problem exists particularly when recrystallizing. Here, too, there is interest in discharging the discharged solid as free of dissolved parts as possible.

According to the prior art, a separation can be carried out by filtration and subsequent washing of the filter cake. Considerable volumes of the washing liquid are often required for a good washing result with minimal losses of the dissolved valuable substance. As a result, a highly diluted solution of the valuable substance or, in addition to the concentrated main filtrate, a large amount of diluted washing filtrate is obtained, which is generally not desirable. There is therefore interest in discharging the dissolved valuable substance in as high a concentration as possible. From an economic point of view, there is still an interest in solving the separation task mentioned in a continuously operating separation apparatus.

The object of the present invention is to provide a method and a device for the separation of solids suspended in liquids, the amount of the dissolved fractions contained in the liquid discharged with the solid being minimized.

The object of the present invention is achieved by a method and a device for sedimentation and washing, the device of the method according to the invention containing at least one sedimentator and one sedimentator n sedimentation soils and n being an integer> 1.

According to the invention, the solid is sedimented and washed on each floor, so that this process is repeated sequentially in n steps in a sedimentator.

The object is further achieved by a method, the device of the method according to the invention containing at least one head part, at least one base part and in between π sedimentation floors.

A preferred embodiment of the invention is a method with a device which contains at least one sedimentation base, at least one sedimentation funnel, at least one mixing chamber, at least one washing liquid supply and at least one supernatant return.

The bottom part is funnel-shaped and opens into a drain that also represents the solids discharge from the bottom sedimentation floor. The head section contains an inlet for the FesW liquid mixture, which is connected to a mixing chamber. The head section also contains an exit for the supernatant of the highest sedimentation soil. The individual sedimentator is also referred to as a sedimentation column. The device of the method according to the invention makes it possible to separate the solid from the mixture in such a way that the proportion of the dissolved components in the liquid phase which is discharged with solid can be adjusted by the number of sedimentation trays. By means of the device of the method according to the invention the losses of dissolved substances can be minimized. The device of the method according to the invention has a high area-related throughput (DL).

The sedimentation soils are arranged one above the other. The washing liquid supply of a floor is connected to the excess return of the following floor below. In this way, the supernatant of a sedimentation soil is used as a washing liquid for the sedimentation soil lying above it. Fresh washing liquid is fed to the mixing chamber of the bottom sedimentation floor. While the solid passes through the device of the method according to the invention from top to bottom, the washing liquid flows from bottom to top. This counter current principle results in an extraordinarily effective washing.

The solid does not sediment in the individual sedimentation trays directly against the inflowing washing liquid, since the washing liquid is led to the next sedimentation tray above in separate washing liquid feeds. This is a largely undisturbed

Sedimentation and washing guaranteed, whereby solids with low sedimentation speed can be separated.

The separation effect of the device of the method according to the invention depends on the number of sedimentation soils. The separation effect can be adapted to the respective separation tasks by the number of sedimentation soils. The separating effect increases exponentially with the number of sedimentation soils. With an increasing number of sedimentation soils, the equipment expenditure increases at the same time.

A preferred embodiment of the invention is a method with a device, where n is an integer from 2 to 100. A particularly preferred embodiment of the invention is a method with a device, where n is an integer from 3 to 20.

A very particularly preferred embodiment of the invention is a method with a device, where n is an integer from 4 to 10.

The device of the method according to the invention can additionally be equipped with a stirrer. A stirrer can advantageously be used in the device. The stirrer can be designed in such a way that the stirrer shaft runs centrally through the mixing chambers and sedimentation funnels of the individual stages and contains stirring blades which convey the sedimentation of the individual sedimentation funnels to the center. This has the advantage that the steepness of the sedimentation funnel can be reduced, which enables a compact design of the device. The stirrer also prevents the solid from baking on parts of the apparatus.

It is often advantageous if the uppermost sedimentation bottom or the head part of the device has a larger diameter than the sedimentation bottoms below. This measure reduces the solids content in the overflow. The throughput through the device of the method according to the invention can also be increased. This is particularly the case when the solids content of the suspension in the inlet is smaller than the solids content in the sediment discharge.

The same effect can be achieved if the device is preceded by a presedimeter. The pre-sedimentator divides the suspension to be separated into a high-solids fraction and a low-solids fraction.

Mixtures in which the solid is sedimented under gravity are suitable as solid / liquid mixtures. The upper limit of the solids content is given by the flowability of the mixture. The sedimentator can also separate very small solids. The density of the solid is therefore greater than the density of the liquid. The sedimentation rate of the solid in the liquid should be greater than 1 mm / min. The rate of sinking of a solid depends on the density difference to the liquid, the average particle size, the particle size distribution and the viscosity of the liquid phase. With the device of the method according to the invention, solids with grain sizes> 1 μm can be separated. The separation is improved by increasing grain size and an increasing density difference.

The separation performance of the device of the method according to the invention can be adapted within wide limits to the respective separation task by changing the design and setting the operating conditions. The design can be changed by the number of floors. Inclination of the sedimentation funnel, size of the mixing chamber and diameter of the sediment outflow and the feed and return lines.

Favorable operating conditions are obtained by adjusting the inflow and outflow speed or the dilution of the suspension used.

By changing the design of the device and / or setting the operating conditions, the loss of solids discharged with the overflow is minimized. The portion of the dissolved portions discharged with the sediment is also minimized. The throughput of the device is maximized.

The device of the method according to the invention can contain exactly one sedimentator. In this case the device is the sedimentator or the sedimentation column.

The device of the method according to the invention can contain two or more sedimentators connected in parallel. This arrangement increases the throughput of solid / liquid mixture. The corresponding inputs and outputs are connected to each other The device of the method according to the invention can contain two or more sedimentators connected in series. This arrangement improves the separating effect with the same throughput.

The device of the method according to the invention can be used to separate solids suspended in liquids.

The device of the method according to the invention can be used to separate at least two liquids.

The invention is explained in more detail with reference to a drawing and examples.

drawing

The drawing consists of Fig. 1 to Fig. 4.

Fig. 1: shows an example of a preferred embodiment of the device of the method according to the invention as a sedimentator.

Fig. 2: shows an example of a preferred embodiment of a

Sedimentation floor.

Fig. 3: shows an example of the device with parallel connection

Sedimentators.

Fig. 4: shows an example of the device with series connected

Sedimentators.

The Bodeπteil (BT) of the sedimentator (S) according to Fig. 1 is funnel-shaped and opens into a drain that also represents the solids outlet (4) of the sedimentator (S). The head part (KT) contains an input for the solid / liquid mixture (1), which is connected to a mixing chamber (C). The head part (KT) also contains an outlet (2) for the supernatant of the sedimentator (S). The sedimentator (S) contains four (n = 4) sedimentation soils (SB-i, SB ₂ , SB ₃ and SB ₄ from top to bottom). A sedimentation tray (SB) according to Fig. 2 contains a sedimentation funnel (B), a mixing chamber (C) and a supernatant return (D). The washing liquid from the washing liquid supply (A) and the sediment outlet of the sedimentation funnel (B) are combined and mixed in the mixing chamber (C). The

Washer fluid supply (A) and supernatant return (D) are interconnected. The excess return (D) of a sedimentation tray (SB _n ) is connected to the washing liquid supply (A) of the sedimentation tray above it (SB ".ι). The line (3) for the washing liquid supply (A) of the bottom sedimentation block (SB4) is led to the outside. The washing liquid supply for the sedimentator (S) takes place through this line. The supernatant return (D1) of the uppermost sedimentation soil (SBi) is connected to the mixing chamber (C) of the head part.

The device can contain two or more sedimentators (S) connected in parallel. This parallel arrangement of the sedimentators (S) according to Fig. 3 increases the throughput of solid / liquid mixture. The corresponding inputs and outputs are interconnected.

The device can contain two or more sedimentators (S) connected in series. Due to the seπelle arrangement of the sedimentators (S) according to Fig. 4 the separation effect is improved with the same throughput.

example

example 1

Preparation for the experiment:

A 6 l mixture of 1.5 kg of Sircon 200 quartz powder (Quarzwerke GmbH Cologne, d50 = 32 μm) and 5 kg of distilled water was prepared in a first beaker. Quartz flour was kept in suspension by vigorous stirring. NaCl was added to the stirred suspension and dissolved until solid-free supernatant had set a conductivity of 20 mS / cm. With a peristaltic pump, a starting sample of 250 ml was pumped into a tared 250 ml measuring cylinder.

The sedimentator according to Figure 1 with an inner diameter of 60 mm. an inner diameter of the head part of 100 mm and a volume of 260 ml per tray was filled with distilled water. With a hose pump with a connected pulsation damper, 50 ml of water per minute were fed in via inlet (3) for the entire duration of the test.

Test execution

With a second peristaltic pump, 100 ml / min of the suspension was conveyed into the sedimentator via inlet (1). The throughput (DL) is 2100 l / m ² h. From the outlet (4) 20 ml / min discharge was conveyed into a second beaker with a third peristaltic pump. Overflow from outlet (2) was passed into a third beaker. The volume flows were controlled by increasing or decreasing the volume in the collecting vessels.

sampling

After 50 minutes, samples were taken at the outputs (2) and (4) and analyzed.

Example 2

Example 2 was carried out as in Example 1, with the difference that 70 ml / min instead of 50 ml / min were fed into inlet 3 during the test.

Example 3

Example 3 was carried out as in Example 1, with the difference that 150 ml / min instead of 100 ml / min were fed into inlet 1 during the test.

Example 4

Example 4 was carried out as in Example 1, with the difference that 120 ml / min instead of 100 ml / min were fed into inlet 1 during the test.

The results from Examples 1 to 4 are summarized in the table.

Table experiments from Examples 1 to 4

Claims

claims

1. Method for sedimentation and washing in n stages by at least one sedimentator with n sedimentation soils, where n is an integer> 1.

2. The method according to claim 1, wherein washing is carried out in countercurrent.

3. The method according to claim 1 or 2, wherein the solid does not sediment in the individual sedimentation trays directly against the inflowing washing liquid.

4. The method according to one or more of claims 1 to 3, wherein the sedimentator contains at least one head part (KT), at least one bottom part (BT) and in between n Sedimeπtationsbödeπ.

5. The method according to one or more of claims 1 to 4, wherein a sedimentation tray contains at least one sedimentation funnel, at least one mixing chamber, at least one washing liquid supply and at least one supernatant return.

6. The method according to one or more of claims 1 to 5, wherein n is an integer from 2 to 100.

7. The method according to one or more of claims 1 to 6, wherein n is an integer from 3 to 20.

8. The method according to one or more of claims 1 to 7, wherein and n is an integer from 4 to 10.

9. The method according to one or more of claims 1 to 8, wherein the sedimentator has a stirrer.

10. The method according to one or more of claims 1 to 9, wherein a plurality of sedimentators are connected in parallel.

11. The method according to one or more of claims 1 to 10, wherein a plurality of sedimentators are connected in series.

12. Device for sedimentation and washing containing at least one sedimentator, wherein a sedimentator contains n sedimentation soils and n is an integer> 1.

13. The apparatus of claim 12 for sedimentation and washing in countercurrent.

14. The apparatus of claim 12 or 13, wherein the solid does not sediment in the individual sedimentation trays directly against the inflowing washing liquid.

15. The device according to one or more of claims 12 to 14, wherein the sedimentator contains at least one head part (KT), at least one bottom part (BT) and n Sedimeπtatioπsbboden between them.

16. The device according to one or more of claims 12 to 15, wherein a sedimentation tray contains at least one sedimentation funnel, at least one mixing chamber, at least one washing liquid supply and at least one supernatant return.

17. The device according to one or more of claims 12 to 16, wherein n is an integer from 2 to 100.

18. The device according to one or more of claims 12 to 17, wherein n is an integer from 3 to 20.

19. The device according to one or more of claims 12 to 18, wherein and n is an integer from 4 to 10.

20. The device according to one or more of claims 12 to 19, wherein the sedimentator has a stirrer.

21. The device according to one or more of claims 12 to 20, wherein a plurality of sedimentators are connected in parallel.

22. The device according to a cαer several of claims 12 to 21, wherein a plurality of sedimentators are connected in series.

23. Use of a device according to one or more of claims 12 to 22 for the separation of solids suspended in liquids.

24. Use of a device according to one or more of claims 12 to 22 for the separation of at least two liquids.