JP3243290B2 - Metal collecting agent and metal collecting method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a metal collecting agent and a metal collecting method.

[0002]

2. Description of the Related Art In recent years,
Rivers and seas are polluted by metals in wastewater from factories, etc., incineration ash generated during garbage incineration, sludge generated as industrial waste during neutralization coagulation sedimentation treatment during wastewater treatment and sedimentation treatment with coagulants, There is a problem that metal contained in slag discharged from a mine or polluted soil or the like flows out and contaminates groundwater, rivers, the sea, and the like.

[0003] In particular, pollution by heavy metals harmful to the human body, such as mercury, cadmium, lead, zinc, copper, and chromium, is a major social problem, and particularly strict regulations are set for these heavy metals to prevent pollution. .

As a method for removing metals contained in wastewater or the like, a method such as an ion flotation method, an ion exchange method, an electrolytic flotation method, an electrodialysis method, or a reverse osmotic pressure method, or an alkali neutralizing agent is added. After the metal is converted to a hydroxide, a method of removing the metal by coagulation and precipitation with a polymer coagulant has been known.However, a method using a metal collecting agent has various advantages as compared with these methods. In recent years, a method of treating using a metal collecting agent has become mainstream.

[0005] As a method of treating waste water or the like with a metal collecting agent, a metal collecting agent is added to the waste water, and the metal collecting agent precipitates flocs formed by collecting the metal and separates them from the waste water. The method of removing is adopted. As a metal collecting agent used in this type of treatment, a metal collecting agent that can efficiently collect a metal with a small amount of addition, has a fast sedimentation of flocs, and has a small volume of flocs is considered to be suitable.

[0006] Conventionally, various metal collectors mainly intended for use in wastewater treatment have been proposed, and various improvements have been made to improve the sedimentation speed of flocs and to reduce the volume of flocs. . However, in the conventional wastewater treatment using a metal collecting agent, it is necessary to use a polymer flocculant in order to efficiently settle the floc. There was a problem of increasing.

[0007] The applicant of the present invention has found that, in order to efficiently settle flocs without using a polymer flocculant as much as possible, it is preferable that the molecular weight of the metal collecting agent be as large as possible. A method was proposed in which a compound having one dithiocarboxy group as a substituent was used in combination with sodium sulfide, sodium polysulfide, sodium hydrosulfide, and the like to collect metals in wastewater (Japanese Patent Publication No. 64-3549). .

However, even in this method, a polymer coagulant must be used together with a small amount in practice, and a relatively large amount of the metal collecting agent is required to surely collect the metal. There was a problem.

On the other hand, when a waste solid substance such as incineration ash, sludge, slag, soil, etc. is treated using a metal collecting agent, generally, a metal collecting agent is added to trap metals contained in the waste solid substance. After being adsorbed on the collecting agent, a method of solidifying with concrete, landfilling, or dumping into the ocean is adopted. For this reason, the metal trapping agent used for this type of treatment is to efficiently and reliably trap metals in solid substances, and has a high bond strength with metals. It is considered preferable that the metal does not leak through the concrete wall when discarded.

As a metal trapping agent suitable for this type of application, the present applicant has disclosed a polyamine derivative having a dithiocarboxy group as a substituent on a polyamine having a molecular weight of 500 or less, and a dithiocarboxy group on a polyethyleneimine having an average molecular weight of 5,000 or more. A metal collecting agent comprising a mixture with a polyethyleneimine derivative introduced as a substituent has been previously proposed (JP-A-3-231921). Further, as an aliphatic polydithiocarbamic acid or a salt thereof, a polyalkylenepolyamine or a polydithiocarbamic acid derivative of polyethyleneimine is known (JP-A-49-9997).
8).

However, it is necessary to use a relatively large amount of this metal collecting agent in order to surely collect the metal. There is a risk that the metal may come off and leak through the concrete wall.

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, the above-mentioned problem is caused by the fact that a compound obtained by introducing a dithiocarboxy group by the action of carbon disulfide on polyethyleneimine causes steric hindrance due to a structure having many branches. It turned out to be largely due. It was also found that these problems become larger as the molecular weight becomes larger. Also, when introducing a dithiocarboxy group by acting carbon disulfide on polyethyleneimine, even if a large amount of carbon disulfide is used for polyethyleneimine, the number of dithiocarboxy groups that can be introduced into polyethyleneimine is not so large. (Molecular weight 10
In the case of 10,000 polyethyleneimines, experimentally at most 1
It is about 700 in the molecule. ), It was also found that the metal adsorption amount could not be increased and the problem of low bond strength to metal was caused by the steric hindrance caused by the structure having many branches.

As a result of further intensive studies to solve the above problems, the present inventors have found that a compound obtained by independently polymerizing an ethyleneimine carbon disulfide adduct or a copolymer obtained by copolymerizing an ethyleneimine carbon disulfide adduct and ethyleneimine are used. The compound obtained had a dithiocarboxy group bonded as a substituent to the nitrogen atom of the main chain (polyethyleneimine chain) where ethyleneimine was polymerized, similarly to the compound obtained by introducing dithiocarboxy group by acting carbon disulfide on polyethyleneimine. Although they are similar in structure, they have a high linearity ratio and can increase the number of dithiocarboxy groups to be introduced in one molecule. As a result, they have found that the above-mentioned conventional disadvantages can be solved, and the present invention has been completed. Reached.

[0014]

That is, the metal scavenger of the present invention comprises an ethyleneimine carbon disulfide adduct or a salt thereof .
Na from homopolymerization obtained by polymerizing in Germany is, average molecular weight 10,
And wherein the Rukoto that have a 000～1,000,000. The metal collector of the present invention is ethyleneimine carbon disulfide.
Do not copolymerize the adduct or its salt with ethyleneimine.
Having an average molecular weight of 10,000 to 1,0
Including those having 000,000.

Further, in the metal collecting method according to the present invention, the metal collecting agent may be used alone or in the form of sodium monosulfide, sodium polysulfide,
It is characterized in that it is added to waste water in combination with at least one of sodium hydrogen sulfide, and metals in the waste water are collected and removed.

Furthermore, the metal collecting method of the present invention is characterized in that the above metal collecting agent is used alone or in combination with at least one of sodium monosulfide, sodium polysulfide and sodium hydrogen sulfide.
It is characterized in that it is added to incineration ash, slag, soil, and sludge, and the metals contained in these are collected and fixed.

The ethyleneimine carbon disulfide adduct, which is a raw material of the metal-collecting agent of the present invention, is obtained by reacting carbon disulfide with ethyleneimine. By performing the reaction in the presence of an alkali, a salt of an ethyleneimine carbon disulfide adduct can be obtained. Examples of the salt of the ethyleneimine carbon disulfide adduct include a lithium salt, a sodium salt, a potassium salt, a calcium salt, and a magnesium salt.

In reacting ethyleneimine with carbon disulfide, 1 mole of carbon disulfide is added to a solvent, preferably water or alcohol, per mole of ethyleneimine.
1 to 10 hours at 20 to 100 ° C, especially 2 to 0 to 50 ° C
The reaction is preferably performed for 5 hours.

The metal scavenger of the present invention is either polymerized alone ethylenimine carbon disulfide adducts or salts, obtained by copolymerizing ethylene imine carbon disulfide adduct, or a salt thereof with ethylene imine, Its average molecular weight is 10,000
0 to 1,000,000. In the case of copolymerizing ethylene imine carbon disulfide adduct, or a salt thereof with ethylene imine, it is preferable to copolymerize to ethyleneimine carbon disulfide adducts or salts thereof include 5 wt% or more in the copolymer .

The polymerization conditions for homopolymerizing the ethyleneimine carbon disulfide adduct or a salt thereof are -80 to 200 ° C.
For 1 to 10 hours, preferably at -20 to 150 ° C for 2 to 6 hours.
Time. The polymerization conditions for copolymerizing ethyleneimine carbon disulfide adduct or a salt thereof with ethyleneimine are as follows: −80 to 200 ° C. for 1 to 10 hours, preferably −
30 to 150 ° C. for 2 to 6 hours.

When the metal-collecting agent of the present invention is used for wastewater treatment, metal ions can be favorably collected in the range of pH = 1 to 12 of the wastewater, but particularly in the range of pH = 4 to 9. Adjustment is preferred. The acid or alkali for adjusting the pH of the wastewater may be any one that does not inhibit the formation of floc. Usually, hydrochloric acid, sulfuric acid, nitric acid, etc. are used as the acid, and sodium hydroxide, hydroxide Potassium, calcium hydroxide and the like are used.

In order to immobilize incinerated ash, sludge, slag and heavy metals in soil using the metal collecting agent of the present invention, an aqueous solution containing the metal collecting agent is applied to the incinerated ash, sludge, slag and soil surface. Spraying may be sufficient, but a method of kneading by adding to these is preferred. When kneading, water may be further added to facilitate the kneading operation. In addition, since the pH is preferably in the range of 3 to 12 in order to collect the metal in the slag, the pH is adjusted so that the pH when the aqueous solution containing the metal collecting agent is added to the above range using the above-mentioned acid or alkali. Adjustment is preferred.

The incinerated ash includes fly ash and residual ash. Fly ash is a collection of powdery dust generated from incineration of garbage and industrial waste, etc. and dust generated from a melting furnace in residual ash processing, and is classified as follows according to the dust collection method. .

The most widely used electric dust collection method (EP
Also called law. The fly ash collected by the method is referred to as EP ash.
The second most common dust collection method is the centrifugal dust collection method (cyclone method), especially the multi-cyclone method (M
Also called the C method. The fly ash collected by the method is referred to as MC ash. Further, there are dust ash collected by a washing dust collection method (scrubber method), dust ash collected using a bag filter, and the like. These dust collection methods may be used alone, but two methods may be used in combination (for example, the MC method and the EP method). In the present invention, fly ash obtained in this manner may be used. it can. On the other hand, residual ash is ash that remains in incinerators after incineration and contains harmful metals in garbage incineration plants and industrial waste incineration plants.

The metal trapping agent of the present invention has a large floc formed by adsorbing a metal without using a polymer flocculant in the same manner as the conventional metal trapping agent, and the sedimentation speed of the floc is high. The metal in the wastewater can be efficiently collected and removed using the metal collecting agent of the present invention as it is, and incineration ash,
Because of its excellent binding to metals in sludge, slag, and soil, metals can be reliably collected and fixed. However, the use of a polymer flocculant in combination is not impaired as long as the object of the present invention is not impaired.

When the metal scavenger of the present invention is used in combination with at least one of sodium sulfides such as sodium monosulfide, sodium polysulfide and sodium hydrogen sulfide, the amount of the metal scavenger can be further reduced. Yes, and at the time of wastewater treatment, the sedimentation speed of floc can be further increased,
More efficient processing can be performed.

In the treatment of solid substances such as incineration ash, sludge, slag, soil, etc., when used in combination with at least one of sodium sulfides such as sodium monosulfide, sodium polysulfide and sodium hydrogen sulfide, a small amount of metal trapping agent In quantity,
Metals can be fixed more reliably, and when the treated material is exposed to seawater or rainwater (especially acid rain) when the treated material is solidified with cement and landfilled or dumped into the ocean, the metal is fixed. Can be further reduced from coming off the metal collecting agent and leaking through the cement wall.

As the above-mentioned sodium polysulfide, sodium disulfide, sodium trisulfide, sodium tetrasulfide and sodium pentasulfide are used. When using a mixture of the metal trapping agent of the present invention and the above-mentioned sodium monosulfide, sodium polysulfide, and sodium sulfides such as sodium hydrogen sulfide,
The mixing ratio of the two may be in the range of 1:99 to 99: 1 by weight, but is preferably 20:80 to 98: 2. When both are used in combination, the metal trapping agent of the present invention and sodium sulfide are mixed in advance, and wastewater or incinerated ash, sludge,
Although it may be added to slag, soil, etc., it may be added separately,
It is preferable to mix and add both in advance. In addition, when adding separately, the effect is substantially the same regardless of which one is added first.

The amount of the metal scavenger used in the present invention is, when the metal scavenger is used alone for wastewater treatment, 0.8 to 1.4 mole equivalent, particularly 0.9, of the amount of metal ions in the wastewater. When it is used for treating incinerated ash, sludge, slag, soil, etc., it is generally 1.2 equivalents of a metal-collecting agent equivalent required for collecting metals contained therein. It is preferable to use up to 3.0 times the amount of the metal collecting agent.

When used in combination with sodium sulfide, the total amount of both is 0.8 to 1.4 mole equivalents, particularly 0.9 to 1 mole equivalent of the amount of metal ions in the waste water in the case of waste water treatment. .2 mol equivalent is preferred, and in the case of treating incinerated ash, sludge, slag, soil, etc., it is generally 1.2 to 3 equivalents of the metal collecting agent equivalent required to collect the metal contained therein. It is preferable to use 0.0 times the amount of the metal collecting agent.

[0031]

The present invention will be described below in further detail with reference to examples and comparative examples. The metal trapping agents used in the examples and comparative examples are as follows.

Metal scavenger Homopolymer of ethyleneimine carbon disulfide adduct obtained by reacting 1 mol of carbon disulfide per 1 mol of ethyleneimine (average molecular weight: 300,000).

Metal scavenger A copolymer (average molecular weight: 140,000) copolymerized with 2 mol of ethyleneimine per 8 mol of sodium salt of ethyleneimine carbon disulfide adduct.

Metal collector 700 mol of carbon disulfide, 70 mol of sodium hydroxide per mol of polyethyleneimine (average molecular weight 100,000)
Sodium salt of polyethyleneimine carbon disulfide adduct obtained by reacting 0 mol.

Examples 1-4, Comparative Examples 1-2 Wastewater containing 20 ppm of copper (II), 5 ppm of cadmium (II), 6 ppm of chromium (III) and 5 ppm of mercury (II) (pH = 4.
9) To 1 liter, add the metal collecting agent shown in Table 1 or a mixture of the metal collecting agent and the sodium sulfides shown in the same table as needed so that the added amount of the metal collecting agent becomes 100 mg. After stirring for 10 minutes, the amount of floc generated 30 minutes after standing was measured. Next, after the formed floc was filtered, the concentration of residual metal ions in the filtrate was measured by atomic absorption spectrometry. The results are shown in Table 1.

[0036]

[Table 1]

Examples 5-8, Comparative Examples 3-4 13,400 mg / kg lead, 630 mg / kg cadmium, 7,7 mg zinc,
890 mg / kg, total chromium 530 mg / kg, mercury 10 mg / k
g, copper ash (20 mg / kg), fly ash (EP ash) containing 50 g, and an aqueous solution of a metal collecting agent aqueous solution shown in Table 2 or an aqueous solution of a mixture obtained by mixing the metal collecting agent and sodium sulfides in the ratio shown in the same table, The metal scavenger was added so that the addition amount to fly ash was 2 g, and kneaded sufficiently at 80 ° C. for 10 minutes. A dissolution test (notified by the Environment Agency No. 13) was performed on the fly ash after the treatment and the untreated fly ash. The results are shown in Table 2 (dissolution test results for untreated fly ash are shown in the table as reference examples).

[0038]

[Table 2]

Examples 9-12, Comparative Examples 5-6 Mercury 2 mg / kg, lead 21 mg / kg, cadmium 2 as metal
To 500 g of sludge (water content: 82%) obtained by wastewater treatment at a garbage incineration plant containing 500 mg / kg, zinc 15 mg / kg, and nickel 3 mg / kg, an aqueous solution of a metal collecting agent shown in Table 3 or metal collection An aqueous solution of a mixture obtained by mixing the agent and sodium sulfide in the proportions shown in the table is added so that the amount of the metal-collecting agent added to the sludge becomes 1 g, and the mixture is sufficiently kneaded at room temperature for 15 minutes, and then filtered and filtrated. The metal concentration in the sample was measured. Table 3 shows the results
(The results of the dissolution test on untreated sludge are shown in the table as a reference example.)

[0040]

[Table 3]

Examples 13-14, Comparative Example 7 Mercury 25 mg / kg, cadmium 32 mg / kg, lead 48 mg / k
g, 100 mg of slag containing 70 mg / kg of total chromium and 54 mg / kg of copper, an aqueous solution of a metal collecting agent shown in Table 4 was added so that the amount of the metal collecting agent added to the slag was 1 g.
The mixture was sufficiently kneaded at 0 ° C for 20 minutes. The dissolution test similar to the above was performed on the slag after the treatment, and the dissolution amount of the metal was measured.
The results are shown in Table 4 (dissolution test results for untreated slag are shown in the table as reference examples).

[0042]

[Table 4]

Examples 15 to 16, Comparative Example 8 590 mg / kg of zinc, 4,850 mg / kg of lead, 10 mg / k of mercury
g, 25 mg / kg of copper, and 100 g of fly ash (bag filter ash) containing 34 mg / kg of nickel, an aqueous solution of the metal collecting agent shown in Table 5 was added in an amount of 3 g to the fly ash of the metal collecting agent.
And kneaded well at 60 ° C. for 25 minutes.
For the treated fly ash and the untreated fly ash, a dissolution test similar to that described above was performed, and the amount of dissolved metal was measured. The results are shown in Table 5 (the results of the dissolution test on untreated bag filter ash are shown in the table as reference examples).

[0044]

[Table 5]

Examples 17 to 19, Comparative Examples 9 to 10 Mercury 20 mg / kg, cadmium 65 mg / kg, total chromium 41
mg / kg, zinc 5 mg / kg, lead 16 mg / kg, 200 g of soil obtained from the site of a research laboratory, and an aqueous solution of a metal collecting agent shown in Table 6 or a metal collecting agent and sodium sulfide in the proportions shown in the table. An aqueous solution of the mixed mixture was added so that the addition amount of the metal collecting agent to the soil was 2 g, and the mixture was sufficiently kneaded at room temperature for 15 minutes. An elution test similar to that described above was performed on the treated soil and the untreated soil, and the amount of eluted metal was measured. The results are shown in Table 6 (dissolution test results for untreated soil are shown in the table as reference examples).

[0046]

[Table 6]

[0047]

Effects of the Invention Metal scavenger of the present invention, ethyleneimine carbon disulfide adduct or whether polymerizing a salt thereof, obtained by copolymerizing ethylene imine carbon disulfide adduct, or a salt thereof with ethylene imine , Average molecular weight 10,000 to 1,
The Rukoto that having a 000,000, as compared with the metal scavenger was introduced dithiocarboxy group by adding carbon disulfide to polyethyleneimine high linear rate, yet the dithiocarboxy group is functional substituent The content in one molecule is
Since it is higher than a compound obtained by adding carbon disulfide to polyethyleneimine, it has excellent metal collecting ability even when used in a small amount.

As a result, when the metal trapping agent of the present invention is added to the wastewater to treat the metal in the wastewater, the sedimentation speed of the flocs formed by collecting the metal without using a polymer flocculant is reduced. The post processing of the flocs is easy because it is fast enough and the volume of flocs produced is small.

When treating incinerated ash, slag, sludge, and soil containing metals using the metal collecting agent of the present invention, the metal can be reliably and firmly collected even if the amount of the metal collecting agent used is small. Can be fixed. For this reason, even if the incinerated ash, slag, sludge, soil, etc. after treatment are solidified with concrete and landfilled, or exposed to rainwater (especially acid rain, etc.) or seawater when dumped into the ocean, the metal trapping agent will There is no danger that it will come off and leak through the concrete wall to cause recontamination.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Ariaki Oi 4-66-1, Horikiri, Katsushika-ku, Tokyo Inside Miyoshi Oil & Fats Co., Ltd. (56) References JP-A-3-231921 (JP, A) Akira Tokubo 64-3549 (JP, B2) (58) Field surveyed (Int. Cl. ⁷ , DB name) C02F 1/62 C08G 73/04 C09K 3/00

Claims (5)

(57) [Claims] 1. A Ri name from ethyleneimine carbon disulfide adducts or homopolymer obtained by polymerizing a salt thereof alone, average
Metal scavenger, characterized in Rukoto which have a molecular weight from 10,000 to 1,000,000. 2. An ethyleneimine carbon disulfide adduct or
A copolymer obtained by copolymerizing the salt with ethyleneimine
And an average molecular weight of 10,000 to 1,000,000
A metal collecting agent, comprising: 3. The method according to claim 1, wherein the metal collecting agent is discharged.
Addition to water to collect and remove metals in wastewater
Metal collection method. 4. The method according to claim 1, wherein the metal collecting agent is fired.
Add to waste solids selected from incineration ash, slag, soil, and sludge
To capture and fix metals in waste solid substances
Metal collection method. 5. The method for collecting metal according to claim 3 or 4,
Together with the metal scavenger, sodium monosulfide, polysulfur
At least one of sodium hydride and sodium hydrogen sulfide
A metal collecting method characterized by being added in combination.