DE2724706A1 - METHOD FOR CLEANING UP SOLUTIONS OF MERCURY - Google Patents

Description

CHIFF ν. FONER STREHL SCHOBEL-HOPP EB = MNGHAl ¹ ST ¹ NCK

272006 -4-

description

The invention relates to methods of cleaning various solutions of mercury like

a) Wastewater from the production of chlorine and alkalis by electrolysis using a c ^ back over cathode attack;

b) technological solutions from the extraction of chlorine and alkalis by electrolysis using a mercury cathode (e.g., anolyte et al.);

c) solutions containing mercury, for example aqueous solutions Sublimate solutions

It is a method of purifying solutions, for example of the anolyte, of mercury by sorption of mercury from the bu cleaning solutions on a highly basic Anion exchangers »whose matrix is a gel-like copolymer of styrene with divinylbentol is known (see

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USA PS 3 213 006).

According to the known method, the degree of purification does not exceed 0.01 mg / l. The low degree of cleaning leads to Pollution of the environment with mercury, which is particularly important when discharging insufficiently purified mercury Wastewater takes place.

The anion exchanger used in the known method has a dynamic capacity for mercury (Capacity to breakthrough) of about 10 percent by weight. Such a relatively low capacity necessitates a frequent one Regeneration of the anion exchanger, whereby the friction. nigungssenema as a whole becomes more complicated.

The purpose of the present invention is to avoid the disadvantages mentioned.

The invention is based on the task in the process for the purification of solutions of mercury, which occurs in the sorption of the mercury on a highly basic anion exchanger exists, an anion exchanger having a high dynamic capacity according to mercury and conditions to choose for carrying out the sorption process, which ensure a higher degree of purification of mercury.

This object is achieved in that a ^ experience for cleaning the solutions of mercury by sorption of the mercury from the solutions to be cleaned on a highly basic anion exchange ^ · is proposed, where

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according to the invention, a highly basic anion exchanger usesι whose matrix a porous copolymer of 2-methyl-5-vinylpyridine with divinylbenzene, and the sorption is carried out in the presence of active chlorine by previously süine Brings concentration in the solution to 20 to 40 mg / l.

Hler and in the following is understood by the active Chlorine elemental chlorine or its compounds, for example sodium hypochlorite, which add metallic mercury to able to oxidize.

To increase the dynamic capacity of the anion exchanger After mercury, it is expedient to carry out the sorptic process in the countercurrent process, which consists in that during the sorption the anion exchanger is in countercurrent to the direction of migration of the solution to be purified periodically or continuously by adding the consumed part of the anion exchanger which is saturated with mercury out of the process, equivalent amounts of fresh anion exchanger containing no mercury brings in at the same time

According to the method according to the invention, a purification can be carried out Solutions are subjected which as such do not contain any active chlorine at all (for example aqueous sublimate solution or those resulting from the production of chlorine and alkalis by electrolysis using a mercury cathode Wastewater), as well as solutions that convert active chlorine

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compared to the amount required for an effective implementation of the sorption process insufficient or excess amount contain (for example, the anolyte, which is a spent aqueous solution of sodium chloride or potassium chloride, contains an excess of active chlorine 5 to 5 g / l), therefore the concentration of the active Chlorine is either generated in the solutions mentioned or at a level necessary for carrying out the sorption process Size (20 'to 40 mg / 1) set

For example, when cleaning an aqueous solution of sublimate, which does not contain any active chlorine, is produced the sorption in the solution mentioned a concentration of active chlorine of 20 to 40 mg / 1 by treating the solution mentioned with active chlorine until said solution is achieved Concentration according to active chlorine

When cleaning an anolyte that consumed one represents an aqueous solution of sodium chloride or potassium chloride and contains 5 to 5 g / l active chlorine, is produced in a concentration of active chlorine of 20 to 40 mg / 1 for the anolyte mentioned before sorption by dechlorination of the anolyte mentioned until the active chlorine concentration mentioned is achieved.

When cleaning solutions, which are produced during the production of chlorine and alkalis by electrolysis using a mercury cathode and have a solid phase containing mercury and do not contain any active chlorine.

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represent holding wastewater, treated for the purpose of separation of all the mercury contained in the wastewater (due to sorption on the anion exchanger, it is useful before it is fed to the Sorption these solutions with active chlorine at a pH of 2.5 to 5.5 until a concentration of active is achieved Chlorine in the solution from 180 to 200 mg / 1, separates the solid phase from the solutions and then generates in the above Solutions have a concentration of active chlorine of 20 to 40 mg / 1 either by dechlorinating the solutions mentioned to the desired concentration according to active chlorine or by separating the solutions into two parts, taking one of these subjected to dechlorination until the complete absence of active chlorine in the solution and then with the other part the solution not subjected to dechlorination, mixed

One uses one in the process of the invention Anlonenaus t from rather, which has a high dynamic capacity after mercury (up to 44 percent by weight) that reaches is due to both the new chemical composition of the matrix of the anion exchanger and its porous structure as auoh due to the conditions of carrying out the sorption process (countercurrent), they have high dynamic capacity of the anion exchanger makes it possible to reduce the duration of the Enlarge sorption cycle, thereby reducing the process as a whole vtreimplified and more effective

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The method according to the invention makes it possible to achieve a high degree of purification of the solutions from (mercury (0.005 mg / 1 and less), which is particularly important in the case of the preparation of chlorine and Alkalis by electrolysis using a mercury »cathode accumulating waste water« The high degree of purification is brought about by the presence of the active chlorine during sorption in the abovementioned quantities and the possibility of to introduce the fresh, non-mercury-free anion exchanger into the process *

The highly basic anion exchanger used in the process according to the invention is obtained as follows «

First, the matrix of the anion exchanger, the porous copolymer, is obtained by bead polymerization of 2-methyl-5-vinylpyridine with divinylbenzene in the presence of a modifying solvent, for example isooctane, benzoyl peroxide as a polymerization initiator and an aqueous solution of potato starch as a dispersion medium The structure and the physicochemical properties of the copolymer depend on the amount of diviftylbenzene and the modifying solvent. The copolymerization is carried out in accordance with the following gradual temperature control. The temperature is increased to 80 ^° C. for 2 h, and the temperature is maintained for 3 h , then increases the temperature to 90 ⁰ C for 30 min and holds at this temperature for 1 h «

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The following are the physicochemical properties of the copolymer of 2-methyl-5-vinylpyridine with divinylbenzene listed in table 1 «

Table 1

Salary of Salary of Copolymers Wt% 0.55 Rubble specific Copolymers to 2-methyl-5-vinyl- 0.35 weight, Surface, of divinyl pyridine, g / ml o ² / g benzene, Wt% 8.0 78 to 84 up to 0.65 10 to 20 14.0 68 to 72 up to 0.50 40 to 45

The highly basic aluminum ion exchanger is obtained by alkylating the copolymer with an N-alkylating agent, for example wise with dimethyl sulfate, in 20% aqueous solution of Methanol

The physicochemical properties of the anion exchanger are listed in Table 2.

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Table 2

Properties Content of the copolymer

of divinylbenzene,% by weight

8.0 14.0

Specific volume of the anion exchanger swollen in water, ml / g 2 »2 to 2.7 3 _t 6 to 4.0

Complete exchange capacity for chlorine ion, meq / g 5.0 to 5.4 4.8 to 4.9

Exchange capacity of highly basic functional groups
according to Chlbrion, mval / g 4.2 to 4.5 3.8 to 4.0 Mechanical strength, % 97 to 99 90 to 95 Specific surface area, m / g 4 to 10 17 to 25.

The solutions to be cleaned of mercury contain salts of divalent mercury and can also be metallic (Contains mercury and / or salts of monovalent mercury «before being fed to sorption solutions containing metallic mercury and / or salts of monovalent mercury must be used metallic mercury and monovalent mercury oxidize to bivalent mercury, since only the bivalent mercury Mercury to the one used in the method according to the invention Anion exchanger can be sorbed "

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In addition, a solid phase containing mercury (suspended substances on which mercury is adsorbed) is contained, for example, in wastewater from the production of chlorine and alkalis

Purification of wastewater from mercury is carried out according to the following scheme. The wastewater is treated with active chlorine at a pH value of 2.5 to 3.5 until a concentration of active chlorine between 180 and 200 mg / 1 is achieved in the solution · The treatment with Active chlorine is created by mixing the waste water with gaseous chlorine, a hypochlorite solution or with chlorinated water (Water, which contains 5 to 7 g / l active chlorine) carried out * The treatment mentioned is carried out for the purpose of transferring all forms of the mercury contained in the waste water » Silver into its chlorides through · There is also an effective transition of the mercury from the solid phase to The liquid phase of the wastewater · The solid phase is separated from the chlorinated wastewater, which is practically none Quicksilver contains * The separation of the solid phase can by centrifugation, settling or filtration. Filtration on mechanical filters (sand filters) is preferred, which is carried out in a filtration cycle of 4 to 6 hours ensure a practically complete transition of the mercury from the solid to the liquid phase of the wastewater « The waste waters containing active chlorine and no solid phase.

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step towards dechlorination «Dechlorination is carried out on activated carbon by, or mixed, the wastewater with reagents (for example with hydroxylamine, sodium sulfide), the active Ability to reduce chlorine «The dechlorination is carried out in such a way that the concentration of active chlorine in the sorbent wastewater is 20 to 40 mg / 1 « This is necessary to ensure that the divalent mercury contained in the waste water is reduced to metallic which occurs in the stage of dechlorination and sorption. The phenomenon of reduction of mercury Too metallic leads to a breakthrough of the mercury through the anion exchanger, making it impossible to achieve a high degree of purification of the solutions «

To generate a concentration of active chlorine of 20 to 40 mg / 1 in the wastewater reaching the sorption the dechlorination of the whole stream of the solution until a residual concentration of active chlorine is achieved in the solution 20 to 40 mg / 1 are subjected to «

It is technologically more advantageous to use part of the total flow to subject the wastewater to dechlorination until the total absence of active chlorine in the solution "Then the dechlorinated part of the waste water stream is mixed with the other part of the stream that is not subjected to dechlorination" The ratio of the volumes of the above Parts of the stream are chosen in such a way that after they are mixed, a concentration of active chlorine in the waste water

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serix of 20 to 40 mg / 1 is guaranteed.

The pretreatment according to one of the above procedures th wastewater is fed to an ion exchange column. In In the column, the wastewater comes into contact with the highly basic Anion exchanger, the matrix of which is a porous copolymer of 2-methyl «-5-vinylpyridine with divinylbenzene. The said anion exchanger has functional N-alkylpyridinium groups, for example N-methylpyridinium groups, on »The sorption process is carried out by you either pass the wastewater through a stationary layer of the anion exchanger until it reaches a permissible one Excessive concentration of mercury in the treated wastewater with subsequent regeneration of the anions exchangers in a known manner or a C-ego electricity process realized. The latter consists in moving the anion exchanger in the column periodically or continuously in countercurrent to the direction of flow of the wastewater can migrate · This process makes it possible for regeneration only the part of the anion exchanger whose dynamic capacity after mercury is completely exhausted. At the same time the column becomes the fresh one, no Anion exchangers containing mercury are supplied · Performing the sorption according to the countercurrent method described stable ensures the achievement of a high degree of mercury purification of wastewater

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An advantage of Method E according to the invention it is _y that the entire concentrated mercury contained in the cleaning supplied sewage and is passed out from the process with the exhausted anion "The mercury concentration in the exhausted anion exchange reaches 44 percent by weight · As a result, the mercury easily and lossless recovered (for example by burning the anion exchanger or its chemical regeneration) and fed back into the production process *

When cleaning an anolyte (the used aqueous solution of sodium chloride or potassium chloride), which contains 2 to 5 g / l of active chlorine, subjects this can be dechlorinated by vacuum distilling the chlorine with the subsequent treatment of the anolyte combined with sodium sulphide «The dechlorination is carried out up to Achieving a residual concentration of active chlorine in the anolyte of 20 to 40 mg / l carried out the anolytes of the ion exchange column and carries out the sorption process analogous to that described above.

When cleaning solutions containing mercury which do not contain any active chlorine or metallic mercury (for example aqueous sublimate solutions), these are treated with active chlorine until a concentration of the same in the solution of 20 to 40 mg / 1 is achieved, after which the above-mentioned solutions are used to the ion exchanger column

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UBd performs the sorption process analogously to that described above performs.

For a better understanding of the present invention, ground the following examples, given for their implementation

Example 1 « Wastewater from the production of chlorine and alkalis containing 12 mg / l metallic mercury, 18 mg / l mercury salts, 20 g / l sodium chloride, 4.5 g / l caustic soda, 3 g / l suspended mercury-containing substances (sludge ) with a mercury concentration of 0.8 percent by weight, 10 g / l organic substances and 1 g / l heavy metal salts are acidified with hydrochloric acid until a pH value of 2.5 to 3.5 is achieved and treated with gaseous Chlorine, by creating a concentration of active chlorine in the waste water of 180 to 200 mg / 1 «Mach 1§ min chlorination time, the liquid phase of the waste water contains 30 mg / 1 mercury chlorides, whereby the mercury concentration in the solid phase is 0, 05 weight percent drops · The chlorinated wastewater is filtered through a layer of quartz sand until a transparency of 98% is achieved, based on distilled water · When the quartz sand is regenerated, the concentration of mercury is determined concentration in the sludge separated from the wastewaterThis is 0.005 percent by weight

The filtered waste water in an amount of 80%, based on on the total volume, it is subjected to dechlorination by adding

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nan passes them through a layer of activated carbon · After dechlorination there is no active chlorine in the wastewater mixing said the concentration of active chlorine in the waste water 35 to 40 mg / 1 "Then passing the waste water at a rate of $ 0 m / h through an ion exchange column, which is filled with high-base Anionenauatauscher whose matrix porous copolymer of 2-methyl -5-vinylpyridine is 8 percent by weight of divinylbenzene The anion exchanger contains functional N-methylpyridinium groups The sorption process is interrupted after the occurrence of mercury in the purified waste water in a concentration exceeding 0.005 mg / 1 * At the time of the mercury breakthrough, the dynamic capacity is thereby of the anion exchanger 18 wt ight percent *

Example 2 · Waste water of the composition given in Example 1 is acidified with hydrochloric acid to a pH of 2.5 to 3.5 and mixed with chlorine water (water containing 5 to 7 g / l of active chlorine) by adding a Active chlorine concentration in the wastewater of 180 to 200 mg / 1 generated.After 20 minutes of chlorination, the liquid phase of the wastewater contains JO mg / 1 mercury chlorides, while the silver concentration in the solid phase drops to 0.05 percent by weight * The chlorinated wastewater is filtered man analogous to example 1 *

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The filtered waste water is dechlorinated by mixing with 5SÜ-ger aqueous solution of hydroxylamine up to Achieving a residual concentration of active chlorine in the waste water of 20 to 25 mg / 1 · The waste water is then passed along with it a speed of 40 m / h through an ion exchange column which is filled with highly basic anion exchanger, the matrix of which is a porous copolymer of 2-methyl-5-vinylpyridine with 14 percent by weight diviny! benzene « The said anion exchanger contains functional N-methylpyridinium groups. The waste water is passed through the ion exchange column from bottom to top. Every 4 to 6 Hours, the exhausted, mercury-saturated part of the anion exchanger (in an amount of 50 to 70 g exhausted anion exchanger per 1 no treated wastewater) at the same time the same amount of fresh, no Anion exchanger containing mercury to · The mercury concentration in the cleaned wastewater is sern 0.003 to 0.005 mg / 1 »The dynamic capacity of the aus the column periodically discharged anion exchanger for mercury is 44 percent by weight.

Example 5. An anolyte, which is a used aqueous solution of sodium chloride resulting from the production of chlorine and alkalis by electrolysis using a mercury cathode, 12 mg / 1 mercury

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chlorides, containing 200 g / l sodium chloride, 3 g / l active chlorine and having a pH value of 4, are fed to a column for vacuum dechlorination, after which the concentration of active chlorine in the anolyte drops to 110 to 120 mg / l _The anolyte is then dechlorinated by mixing it with 10% aqueous sodium sulfide solution to achieve a residual concentration of active chlorine in the anolyte of 30 mg / l. Then the anolyte is passed through an ion exchange column at a speed of 35 m / h is filled with a highly basic anion exchanger, the matrix of which is a porous copolymer of 2-methyl-5-vinylpyridine with 8 percent by weight divinylbenzene · The said anion exchanger contains functional N-ethylpyridinium groups. The anolyte is passed through the ion exchange column from bottom to top. The exhausted, mercury-saturated part of the anion exchanger (in an amount of 70 to 80 g exhausted anion exchanger per 1 nr of the purified anolyte) is led out continuously in countercurrent to the direction of flow of the anolyte continuously the same amount of fresh anion exchanger containing no mercury. The mercury concentration in the purified anolyte is 0.004 to 0.005 mg / 1

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16.5 percent by weight,

Example 4 ·. An aqueous solution of sublimate ₂ which does not contain any active chlorine is mixed with 20% aqueous solution of sodium hypochlorite, creating a concentration of active chlorine in the solution of 20 rag / 1. The aqueous sublimate solution is then introduced to the ion exchange column, where the sorption is carried out analogously to Example 1. Dor ßorptiorxcprozess is interrupted after occurrence in the purified solution of mercury in a concentration exceeding 0.005 lg / l, At the time of the mercury breakdown, the dynamic capacity of the anion exchanger is 26 Gev / ichtsprozont,

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BATH ORIGINAL

Claims (5)

Pa.TE.> JTANV.Ä_TC SCHIFF ν. FÜNER STREHL SCHÜBEL-HOPF EBBINGH MARIAHILFPLATZ 2 * 3, MDNCHEN 9O POSTAL ADDRESS: POSTFACH 95 OI 6O, D-BOOO MUNICH 95 Leonid Efimovitsch Postolov Valentin Alexandrovitsch Skripnik Alexandr Sergeevitsch Romaschev Z ^ide DIPHA «1N Georgia PAVETER EDBE DIPHA ·« 1 -. β. _. .js. ι ι T J t-iJ DR. INQ. DIETER FINCK Moisej Iosifovitsch Levinsky Grigorij Alexeevitsch Skorochod phone (οββ) 4β! .ΟΒ «Boris Nikolaevitsch Laskorin telex Sa3S65 auro d Anatoli j Vladimirovich Lomonosov TELEaRAU« E auromarcpat munich, Galina DA-179ulskaja DA-179ulskaya Nikolaev June 1, 1977 Process for Re.i.ni <run £ of solutions of mercury PATENT CLAIMS (i) Procedures for purifying the solutions from mercury by sorption of the mercury from the solutions to be purified on a pitch-based anion exchanger, characterized in that a highly basic anion exchanger is used used, the matrix of which is a porous copolymer of 2-methyl-5-vinylpyridine with divinylbenzene, and the sorption is carried out in the presence of active chlorine by previously adjusting its concentration in the solution to 20 to 40 mg / l brings. 2. The method according to claim 1, characterized in that that one uses the anion exchanger in the process of sorption periodically or continuously in countercurrent to the direction of flow of the solution to be purified by the exhausted, mercury-saturated part of the anion output 709850/1041 ORIGINAL INSFECTED exchanger from the process with simultaneous addition of equivalent amounts of fresh anion exchanger containing no mercury leads out. 3. The method according to claim 1, characterized in that that one in the purification of an aqueous sublimate solution of mercury before sorption in the said Solution a concentration of active chlorine of 20 to 40 mg / 1 by treating the said solution with active chlorine up to to achieve the stated concentration based on active chlorine. 4. The method according to claim 1, characterized in e t that one in the purification of an anolyte, which is a consumed aqueous solution of sodium chloride or potassium chloride represents and contains 3 to 5 g / l of active chlorine, a concentration of before sorption in said anolyte active chlorine of 20 to 40 mg / 1 by dechlorinating the anolyte mentioned until the concentration mentioned is achieved active chlorine generated. 5. The method according to claim 1, characterized in e t that one can use in the purification of solutions which are used in the production of chlorine or alkalis by electrolysis a mercury cathode and waste water containing mercury-containing solid phase, before the supply for sorption these solutions with active chlorine at a. 709850/1041 pH from 2.5 to 3.5 until concentration is achieved treated of active chlorine in the solution of 180 to 200 mg / 1, then a concentration of active in the solutions mentioned Chlorine from 20 to 40 mg / 1 either by dechlorinating the solutions mentioned until the required concentration is achieved generated by active chlorine or by separating the solutions into two parts, one of these being descrubbed Subjected to the complete absence of the active chlorine in the solution and then with the other, no dechlorination subjected part of the solution mixed. 709850/1041