SK88593A3 - Process and device for removing metal from flue dust - Google Patents

Abstract

Process and device for removing metal (m) from flue dust (f). The flue dust (f) is introduced into a solution (L) containing a chelating agent (c) and the metal chelate ions formed from the metal in the solution (L) are removed from the solution. This is achieved using an electrolytic cell on whose cathode the elemental metal (m) is deposited. The flue dust (f) can be flue dust (f) from the flue gas (r) of a low-temperature combustor (40).

Description

Obi. and s t t e c h i s

The invention relates to a method of separating a metal from a drift, which preferably comprises at least one metal compound, by means of a solution comprising at least one ehe and a forming agent.

The invention also relates to a device for separating a drift metal 2 having in particular at least one metal compound, with an extraction tank having a drift inlet and a solution containing at least one thermoforming agent.

The term metal ”is intended here to include in its own sense and meaning that exceeds metal compounds but also metal-like elements such as arsenic, selenium and tellurium and their compounds

Protect the cheesecloths

In the combustion of flammable liquids containing solid ethoxy, in particular in the combustion of garbage, a drift is produced which contains metal compounds, for example salts. A number of metals form volatile compounds in the combustion chamber which leave the combustion chamber together with the flue gas. Upon cooling of the flue gas, these compounds. they precipitate and form portions of the dust contained in the flue gas. This dust, which is called drift, is generally removed from the flue gas. For this purpose, for example, a filter device is used or the drift is separated in the boiler. The metal contained in the separate waste requires special separation.

**

If the drift is led back to the combustion chamber, f

metals bind partially to slag. The rest of the flue gas and hence the drift.

Da 1 with drift 2bav

For i and the possibility of metals.

the purpose of removing the drift was suggested.

The drift vaporized at high temperature gets back to maybe to be special and 1 is in it. by separating the metal compounds in the furnace and the field by condensation. The disadvantage of this method is the very high consumption?

energ i e.

Another possibility can be seen in the fact that the drift is extracted with mineral acid1, and the effect of the metal precipitates from the solution

Disadvantage of this method

It is understood that the board exhibits solubility in the miner.

č 1ánek

Rúckcjew i nnung aus Stahlwerkfl

Laben from Ekke-rhard Greinacher in Erzmetal

42 (1939).

7-8, pages Ο to 311. is known.

If the metals of the drift are:

The steels can be dissolved into the solution using a single dump of exo forming agent and in the form of a dump of exemplified metal compound.

Than

The complexing agent is used for this purpose, e.g.

A very high concentration is required in the known process

In addition, complex formation is difficult to control. In addition, in the later treatment of a solution containing metals in the co-expressed compound, it is scarcely possible to carry out a stepwise dissolution of the complex compound

Haturvissenschaf t to b63. disclosed are the complexes. The chelating agent is multi-toothed compared to conventional complexing agents. It can therefore form more links.

The drift is also dispensed with in the low-temperature carbonization process known from EP 0 302 310. This drift may also contain metal compounds as it is derived from high-temperature combustion.

DE 37 07 261 A1 discloses a method for leaching heavy metals from filter dusts, using aqueous solutions of metal-adsorbed metal-forming agents which are

Even then they are present in the solution, they are carried out by deprotonation, in which case, for example, calcium hydroxide is mixed into the solution. In doing so, the metal originally contained in the drift remains in solution.

JP-A-60 209 297 discloses a process for removing calcium salt from water, in which ethylenediamine ametetraacetic acid or trilotriacetic acid is used as the thermoforming agent. Using this method, the drift can not remove ¹ no metal. Also, no metal in elemental form can be obtained.

An apparatus for treating flue gas debris from combustion plants containing heavy metals is described in DE 39 18 292 A1. The device has an extraction tank which comprises at least one drift and solution inlet port. A solid-liquid separator can be connected downstream of the extraction tank. The liquid and solid components can then be further processed separately.

The invention si k 1 ad i e as a basic task, to give way to metal separation from drift, k t c> r s s porovnáLeľne small charge chemicals ma 1 ou consumption energy for it is high department reliability. L Besides that herself allow to make metal could get in

elementary form and thus could be reused as raw material.

and

Furthermore, it is an object of the present invention to provide a device for separating metal from drift, which would guarantee high reliability when using a comparatively small amount of chemicals and low energy consumption. In addition, the device should be controllable.

It should be possible for the metal from the drift to be separated in elemental form and recovered.

»I

Ppdstata_vyná1 esu

According to the invention, the first object is achieved by introducing the drift into the solution by removing the metal chelate ions formed in the metal solution from the solution by bringing the metal chelate-containing solution into an electrolyzer to which an electrolytic voltage is applied, and that metal chelate ions are removed from the solution there by precipitating the metal in elemental form on the electrolysis ™ cathode.

The solution may be an aqueous solution of one or more of the chemical agents to which the drift has been introduced.

By this method, a metal chelate complex is formed in the solution. Therefore, there are no free metal ions in solution. The metal is masked in a chelate complex. This masking gives the advantage that the solution appears to be still free of metal ions, so that metal from the drift can still be retained to the solution to an undiminished extent. Consequently, sparingly soluble metal compounds can be trapped at a constant rate. The drift is therefore free of metal.

After collecting the metal chelate metal ions into solution, the solution is purified by removing the metal chelate ions.

For this purpose, the solution is fed to the electrolyzer, where the metal is deposited on the cathode of the electrolyzer in elemental form.

The use of the chelating agent according to the invention provides the advantage that it is sufficient to use a small amount of chemicals. Given that the chelating agent is multi-toothed, multiple bonds with a central atom can be formed with a single chelating agent molecule. Consequently, few chelating agent molecules are consequently required for one central metal bond. Even may be enough! only one chelating agent molecule. This results in low energy consumption and high reliability.

The use of the electro-appearance according to the invention has the advantage that the metal originally present in the drift can be recovered in elemental form and can thus be reused as raw material.

If it is not intended, it can be removed because it is present in a small volume. In addition, an electrolytic metal free of polychlorinated aromatics, in particular PCDD / F, is eliminated.

Further, the recovered metal can be used, since it is free of chlorinated aromatics.

Instead of a single eheforming agent, a mixture of eheforming agents may also be used. Suitable thermoforming agents are nitric acetic acid or ethyleneaminetetraacetic acid or a mixture of these acids.

The stability of the chelate complex in aqueous solution depends largely on the pH of the solution. The use of the chelating agent according to the invention therefore provides the advantage that the addition of ligands to the central metal atom can be controlled by varying the pH of the solution.

Advantageously, a controlled, staged breakdown of the unnecessary chelate complex can be performed by changing the pH value.

The pH of the solution with the solution. Only because of the acid-forming or alkaline-forming agent used in the present invention, the formation or disruption of the chelate complex can be controlled by the addition of an acidic or alkaline solution. As a result, preferably >

the process of separating the metal from the drift can be controlled.

With such process control, the advantage is achieved that it is not necessary to use chemicals in excess.

After the fracture of the metal substance, insoluble dust is separated from the solution. This dust is then freed of the most perfect metals and, at the same time, of the soluble salts which have dissolved and can be further processed without problems. The separation can be carried out, for example, by filtration or decantation.

For example, different metals can be separated separately due to their different elimination stresses. For example, different electrolytic voltages need to be used for this purpose. This has the additional advantage that the metals are separately present for re-use.

The pH of the electrolyser is adjusted with an acidic or alkaline solution.

This ensures optimal exclusion.

Acidify a certain pH value. It is also possible to use them in reverse order.

The acidic and alkaline solution for adjusting the pH in the electrolyzer, but also in the solution which absorbs the drift, can be removed, for example, from the flue gas system present. The acidic and alkaline solution is further stored in stock.

Remaining solution. which is completely free of metal complex tons and possibly insoluble dust can again be used to trap the drift. Before re-use, a fresh solution of the extender can be added if necessary. By means of such re-use of the solution, the necessary amount of ee-forming is preferably maintained

The reagents have 1.

If this step of the method is used, the drift is introduced into a solution to which the drift has already been trapped and then cleaned.

For example, salts can be removed from the solution which has been de-ionized. This can be done, for example, by blowing off salts.

For example, the solution 2 containing the metal chelate ions is divided into two partial streams. The first partial stream is recycled to the separation process described and is then reused. The second substream is removed. The amount of liquid removed, as well as the removed fraction of the curing agent, is replaced by supplying water and the curing agent to the extraction tank next to the first partial stream. thereby, the liquids of the first partial stream are diluted with respect to the salt content. This prevents the solution from being concentrated with salts when reused, which could lead to crystallization with salt.

For example, the chelating agent may be recovered from the second sub stream. This makes sense because it saves the chelating agent.

The flue to be separated from the metal may be, for example, a flue gas flue, for example from the known low-temperature carbonization device. It is then achieved that the waste 2, which is fed to the low-temperature carbonization plant, is separated by metals, even if they are finely divided. The remains of the low-temperature carbonization process not only get rid of the metals and waste gases perfectly, but also recover metals separately according to their type as raw materials.

I

In particular, the method according to the invention achieves the advantage that the dust is free of metals and that the metals as such can be recovered in separate form as raw materials.

Only a small amount of chemicals is required to separate metals from the drift, since the molecule can form multiple bonds with the central metal atom in the eh-forming agent of the invention, and moreover, the e-chelating agent can be easily controlled by changing the pH.

According to the invention, a second object is achieved by providing a metal separator, which is an electrolyser, downstream of the extraction tank, and that the extraction tank inlet is connected to a system containing a thermoleptic agent and the extraction basin is designed to capture a solution of the thermolytic agent.

and

Therefore it is. it is possible for the solution in the extraction tank to contain at least one thermoforming agent.

The metal in the chelate complex is masked by the use of a chelating agent. Plus it seems. This means that a solution that is free of metal ions is always present in the extraction tank. Thereafter, the metal in solution is constantly absorbed from the drift. In the metal separator, the metal is separated from the solution. Due to the use of a metal separator, the advantage is achieved that the metal-free solution can be reused. In addition, it may be advantageous to recover the precipitated metal as a raw material and reuse it.

Since the metal separator is an electrolyzer, the metal originally contained in the drift is recovered in elemental form. Can be used as raw material.

The extraction tank is connected, for example, via acid and / or alkaline solution pipes to a flue gas scrubbing system. It uses the fact that in the washing system »

however, an acidic or alkaline solution is omitted. This solution is used to adjust the pH in the extraction tank. The pH of the chelate complex in aqueous solution can be controlled.

Also, the metal separator may be connected to the flue gas scrubbing system via the acid and / or alkaline solution lines. Here too, the pH can be varied to control the stability of the chelate complex. The device according to the invention can advantageously be controlled.

s

For example, the metal-free solution outlet in the metal separator is connected to the extraction tank via a return line. Through this line, the solution completely free of the metal complex ions can be recycled.

Said metal separator outlet may also be coupled to a separator for a thermoforming agent. There, it is advantageously possible to recover the re-forming agent. The separator for the chelating agent may be arranged in a branch which extends from the metal separator.

Downstream of the extraction tank, a solid / liquid separation device can be installed upstream of the metal separator. Insoluble dust can be separated there.

For example, the extraction tank inlet is connected to a low-temperature carbonization device. In this case, the waste which is lost during the recovery of the waste is advantageously freed of heavy metals and, moreover, the heavy metal is recovered as a raw material.

The device according to the invention can be easily controlled by varying the pH value.

EXAMPLES OF EXAMPLES

An exemplary embodiment of a method and a device for separating metal from drift is explained in more detail by means of the drawings.

Extraction tank 1 has a fifth inlet 2 or a first inlet throat for the drift inlet 6, a second inlet 3 or a second inlet throat for the curing agent c and a third inlet 32 or a water inlet. In the waters a32 there are controllable fittings 3a and

32a. The drift f can be supplied from the low-temperature carbonization plant 40.

The inlet 3 is connected to a system 30 comprising a thermoforming agent c. When the drift f is introduced for the first time into the extraction tank 1, there is already a solution L which contains a thermoforming agent. In this case, it is generally an aqueous solution L. The water is supplied by the inlet 3 for the thermoforming agent

J, or through an inlet 32 from a system 31 that contains water to an extraction tank 1.

The branch 4 or branch branch of the extraction tank 7 is connected to the solid and liquid separation device 5. There the dust is separated and is removed by a branch 6. The liquid phase branch 7 is connected to a metal separator 8, which is an electrolyser, to which a voltage U is applied. In the metal separator 8 the metal chelate complexes formed in the extraction tank 1 The remaining metal-free solution 1 can be returned via the return line 10 from the metal separator 8 to the extraction tank. The returned solution 11 can serve in the extraction tank 1 for new absorption of the substance. If desired, the chelating agent may be re-fed with water and / or water.

solution of

A drip-absorbing solution L is formed f. The addition of the chelating agent c and water w is particularly necessary when the solution 11 or part 12 of the solution 1 is discharged from the metal separator 8 via a branch 11. The solution which enters the extraction tank 1 is relatively salt-free, since

containing salt, discharged through branch 11, the volume fraction is replaced by the salt fraction, the chelating agent c and the water w. The discharged portion of solution 12 passes through the branch

1 into the separator 12 for the chelating agent c. The chelating agent from the separator 12 discharged via the branch 13 can be used in the extraction tank 1, with the conduit 14 for the precipitating agent fm.

12 is connected therewith showing a turn 15 for

In addition to the remaining solution ^1x , which leads to a neutralization unit

16. Its output is marked

15A. For control, valves or fittings 10a are provided in the return line 10 and in the branch 11, as well as in the lines 3 and 32 of the extraction tank 7, and

Ha. optionally 3a and 32a. With the extraction tank and also connected to the metal separator 8, there is a line 17 for supplying the acid solution p and a line 18 for supplying the alkaline solution q via valves or fittings 17a for controlling the pH value.

17b, 18a, 18b. The solutions p, q contribute only insignificantly to the dilution of solution L. Both the pipes 17 and 18 are fed by a flue gas scrubbing system, the pipes 17 being connected to the acid scrubber 19 and the pipes tg to the alkaline scrubber 20. Both devices

19 and 20, the flue gas line 21 extends.

flue gas, which may come from a low-temperature labeled 2.1A.

The acid scrubber 19 and the alkaline scrubber 19 can be connected via pipes 22 or 23 to the neutralization unit 16.

With the device described, the metal m can be removed quickly and perfectly from the drift f. In addition, the metal may be returned; gain.

Claims (9)

A method of separating metal (m) 1 of a flight which comprises, in particular, at least one metal compound. by means of solution ¹ (L) containing at least one epoxy-forming agent, by introducing the drift (f) into solution (L), the metal chelate ions formed in the metal solution are removed from the solution by removing the solution containing ions The metal is directly passed through the electro look (8) when the electro Here, too, the metal ethers of the metal (U) are removed from the solution. in that the metal (in) is deposited on the cathode of the electrolyzer in the elementary form. ‘1 The method of claim 1, in J. The solvent (c) nitrile acetic acid. Method according to one of Claims 1 and 2, characterized in that the pH of solution (L) is adjusted with an acidic and / or alkaline solution (p, q). Method according to one of claims 1 to 4 3, i by being in solution L) of this Section Method according to one of claims d, characterized in that different metals are eliminated by rubbing with a different electrolytic voltage (U). Method y according to one of Claims 1 to 15, characterized in that the pH value of the electrolyser (3) is adjusted with an acidic and / or alkaline solution (p, q). Process according to one of claims 3 to 6, characterized in that the acidic and / or alkaline solution (P, (q) draws from the system present (19); 20) for flue gas scrubbing. Method according to one of claims 1 to 7, characterized in that the solution (1), devoid of metal chelate ions, is used again to absorb the drift (f). 9. Method i according to one of Claims 1 to 3, characterized in that it is a chelate-free solution (1) Even the metal will remove salts. Method according to claim 9, characterized in that the solution (1) devoid of metal chelate ions is divided into two partial streams (11i, 12), wherein the first partial stream (11i) together with the ehe forming agent is formed. (c) and water (w) (L) to absorb the drift (f), and the second sub-stream discharges e. The method of claim 10, characterized in that the evacuating agent is recovered from the discharged second sub-stream (12). Method according to one of the claims 1 to 11, characterized in that the flue gas (£ 4) comes from the flue gas (r) from the low-temperature carbon plant (40) 13th Apparatus for separating metal (m) from a drift (f) having in particular at least one metal compound, with an extraction tank (1) having an inlet (2) for the drift (f) and for a solution containing at least one ehe forming agent (1) a metal separator (8), which is an extraction vessel (3) and an inlet (3) of an extraction tank containing ehe 1 and forming (1) is with reagent (c), µ / 0 & 5- extraction reservoir (1) is intended and for capture solution of che1 atptv arable action i dl a. 14 Equipment i e according to claim 13, s n a č u j ú c e clothes m, the extraction tank (1) T is connected naj mene j one pipeline m (17. 18) for acidic and / or and alkali solution (p. q) so system * (19, 20) for scrubbing the flue gas. 15th Equipment e according to one of claims 13 and 1 ebo 14, - z n a c u D u c e is that odlučovuč (8) metal is connected at least j pipeline ( 17, la) for acidic and / or 1ebo and 1 liter solution (p, q) with sys summer (19, 20) ' for washing flue P1 ynu 16th Sorting e by one of the claims 13 to 15, in y- from us j ú c e is that output for solution (i) metal u is on Separator i (8) metal coupling with extraction tank (1). 17. Apparatus according to one of Claims 13 to 16, characterized in that the outlet for the metal-free solution 1) is connected to a separator for the chelating agent (c) on the metal separator (18). Device according to one of Claims 13 to 17, characterized in that it is behind the extraction tank ( 1), a control device (5) for separating the solid and volatile material is connected upstream of the metal separator (8). Device according to one of Claims 13 to 18, characterized in that the inlet (2) of the extraction tank () is connected to a low-temperature carbonization device (40).