JP2003129035A - Heavy metal immobilizing agent and method for improving stability of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a heavy metal immobilizing agent which can immobilize a heavy metal existing in the solid, powder or slurry state of incineration fly ashes, slag, soil and sludge, preventing elution of the heavy metal, and to provide a method for improving the stability of the same. SOLUTION: The one-pack liquid heavy metal immobilizing agent is characterized by improving its stability at storage, at transport and at use by adding a phosphate to an aqueous solution of dithiocarbamic acid and/or its salt, suppressing generation of such poisonous gas as hydrogen sulfide, carbon disulfide, and the like.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to incineration fly ash, slag,
The present invention relates to a heavy metal immobilizing agent capable of immobilizing heavy metals present in solid, powdery or slurry-like substances such as soil and sludge to prevent the elution of heavy metals, and a method for improving the stability thereof.

[0002]

2. Description of the Related Art Conventionally, a chemical agent added to immobilize heavy metals present in solid, powder or slurry substances such as incinerated fly ash, slag, soil and sludge to prevent the elution of heavy metals. As an aqueous solution of dithiocarbamic acid (salt) (JP-A-8-224560 and JP-A-11-116).
No. 938, etc.) are known. However, conventional dithiocarbamic acid (salt) aqueous solution may generate toxic gas such as hydrogen sulfide and carbon disulfide during storage, transportation and use of the solution. A method for stabilizing by stabilizing the pH of the aqueous solution of the agent at 13 or more (JP-A-10-1090).
81 gazette) and the immobilizing agent when diluted with water.
A method of using after adjusting H to 12 or more (JP-A-10-11
No. 8612) is known.

[0003]

However, it is hard to say that it is still sufficient for suppressing the generation of harmful gas. An object of the present invention is to provide a heavy metal immobilizing agent that suppresses the generation of these toxic gases without impairing the immobilizing effect of heavy metals, and a method for improving the stability thereof.

[0004]

The present inventors have arrived at the present invention as a result of extensive studies to solve these problems. That is, the present invention provides a liquefied heavy metal immobilizing agent obtained by incorporating a phosphate (B) into an aqueous solution of dithiocarbamic acid and / or its salt (A), and an aqueous solution of dithiocarbamic acid and / or its salt (A). A method for improving the stability of a heavy metal immobilizing agent, characterized by comprising a phosphate (B).

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, among dithiocarbamic acid and / or its salt (A), dithiocarbamic acid is (a) a chain, branched or cyclic alkyldithiocarbamic acid having 1 to 8 carbon atoms, (A) 1-5
Phenyldithiocarbamic acid in which one hydrogen atom may be substituted with a hydroxyl group or an alkyl ether group, (c)
C1-C32 chain, branched or cyclic alkylbisdithiocarbamic acid, (E) C1-C32 chain,
Branched and cyclic alkyl trisdithiocarbamic acid, (e) C1-C32 chain, branched and cyclic alkyltetrakisdithiocarbamic acid, (f) 1-4
Each hydrogen atom is a hydroxyl group or an alkyl (having 4 to 1 carbon atoms).
2) Phenylbisdithiocarbamic acid optionally substituted with an ether group, (ki) Phenyltrisdithiocarbamic acid optionally having 1 to 4 hydrogen atoms substituted with a hydroxyl group or an alkyl (C 4-12) ether group ,
(H) A reaction product of polyamine and carbon disulfide, (ke) a reaction product of polyethyleneimine having a weight average molecular weight (hereinafter abbreviated as Mw) of 4,000 or less and carbon disulfide, and (co) polyamine and epihalohydrin. Reaction product of condensed polycondensate polyamine having Mw of 4,500 or less and carbon disulfide,
(A) Reaction products of polyvinylamine and carbon disulfide, and mixtures thereof. Incidentally, the reaction product of polyamine of (H) and carbon disulfide and the reaction product of polyethyleneimine of (K) and carbon disulfide are disclosed in JP-A-3-23.
It is obtained by the method described in Japanese Patent No. 1921.

Examples of the polyamine in the above (h) and (co) include the following compounds having two or more imino groups or amino groups each having one or two active hydrogen atoms bonded to a nitrogen atom.

(I) Aliphatic polyamine diamine having 2 to 22 carbon atoms (ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, N,
N'-dimethylethylenediamine, etc.)-Triamine (diethylenetriamine, dipropylenetriamine, dibutylenetriamine, etc.)-Tetravalent or higher polyamine (triethylenetetramine, tripropylenetetramine, tributylenetetramine, tetraethylenepentamine, tetrapropylenepentamine) Min, tetrabutylenepentamine, pentaethylenehexamine, etc.)] (ii) alicyclic polyamine diamine having 4 to 22 carbon atoms [1,4-cyclohexanediamine, 1,
3-bis (aminomethyl) cyclohexane, bis (4-
Aminocyclohexyl) methane, bis (4-amino-3)
-Methylcyclohexyl) methane, etc.] (iii) Aromatic (aliphatic) polyamine diamine having 6 to 20 carbon atoms (phenylenediamine, tolylenediamine, xylenediamine, diphenylmethanediamine, diaminophenylether, etc.) (iv) 3 to carbon atoms 20 heterocyclic polyamines-diamines (piperazine, 1-aminoethylpiperazine, etc.)-Triamines (melamine, etc.)

Of these, preferred are the diamines in (i) and (iv), more preferred are the diamines in (iv), especially piperazine.

The salt of dithiocarbamic acid is (a)
~ (Sa) alkali metal (lithium, sodium, potassium, etc.) salts, ammonium salts, amines [C1-8
Monoalkylamine, dialkyl having 2 to 16 carbon atoms (alkyl group having 1 to 8 carbon atoms) amine, 3 to 24 carbon atoms
Of a trialkyl (alkyl group having 1 to 8 carbon atoms) amine] salt, a quaternary ammonium salt having 4 to 20 carbon atoms, and a mixture thereof.

Of the above (A), (C) is preferable.
~ (Sa), salts thereof and mixtures thereof, more preferred are alkali metal salts of (c) to (sa), particularly preferred are potassium salts of (h), and most preferred are potassium salts of piperazine. . In the present invention, (A) is usually used as an aqueous solution, and its concentration is usually 10 to 80% by weight, preferably 20 to 70% by weight.

Examples of the phosphate (B) in the present invention include alkali metal (sodium, potassium, etc.) salts of phosphoric acid, such as trisodium phosphate, tripotassium phosphate, and the like. It is tripotassium phosphate. The alkali metal salt of phosphoric acid may contain partially unreacted dihydrogen phosphate or monohydrogen phosphate in which the H atoms of phosphoric acid are contained, and the content of these partially unreacted salts is It is usually 10% or less, preferably 0 to 5%, based on the total weight of the alkali metal salt. In the present invention (B)
Is usually used as a powder or an aqueous solution, and in the case of an aqueous solution, its concentration is usually 1 to 70% by weight.

In the present invention, the weight ratio (A) / (B) of (A) and (B) is preferably 0.1 / 1 to 200 /, from the viewpoint of the effect of immobilizing heavy metals and the suppression of generation of harmful gas.
1, more preferably 0.2 / 1 to 100/1, particularly preferably 0.3 / 1 to 50/1. (A) /
When (B) is in the above range, the effect of suppressing harmful gas generation is extremely good. The following method may be mentioned as a method of incorporating (B) in the aqueous solution of (A). (B) is added to the aqueous solution of (A). The aqueous solution of (A) is added to (B). The mixture obtained by adding (B) to (A) is dissolved in water. Phosphoric acid is added to the aqueous solution of (A) to form (B). (A) is formed in the presence of (B). It may be added in water or after water. (B) is added to dithiocarbamic acid and then a salt is formed. The temperature condition for containing (B) in the aqueous solution of (A) is 0 to 90 ° C., and the stirring condition is not particularly limited as long as it is a condition for uniform mixing. The aqueous solution pH of the heavy metal immobilizing agent of the present invention is usually 12 or more, preferably 12.2 or more, more preferably 12.5 or more. Here, the aqueous solution pH is a value at 25 ° C. of a 30 wt% aqueous solution of the heavy metal immobilizing agent of the present invention.

The heavy metal immobilizing agent of the present invention is effective for immobilizing heavy metals in heavy metal-containing materials having various properties such as block-like solids, powders, liquids, slurries and pastes, but incinerator fly ash and slag. , It is more effective in immobilizing heavy metals in solid, powdery or slurry-like heavy metal-containing materials such as soil and sludge, and is particularly effective in immobilizing heavy metals in incineration fly ash.

The amount of the heavy metal fixing agent of the present invention added is based on the weight of the heavy metal-containing material (the total weight of solids, powders and pastes, and the total weight of solids in the case of liquids and slurries). The solid content is preferably 0.1 to 30%, more preferably 0.3 to 20% from the viewpoint of the effect of fixing heavy metals.

When the heavy metal fixing agent of the present invention is added to the heavy metal-containing material and used, other additives may be used in combination. Examples of other additives include a flocculant and a surfactant.

As the coagulant, inorganic type [aluminum sulfate, polyaluminum chloride, sodium aluminate, ferrous sulfate, ferric sulfate, ferric chloride, etc.], organic type [polyacrylic acid (salt), acrylamide] -Based polymers [polyacrylamide, partially hydrolyzed polyacrylamide, polycationized cationized polyacrylamide, quaternized acrylamide / dialkylaminoethyl methacrylate copolymer, acrylamide / dialkylaminoethyl methacrylate quaternized product, etc.], Examples thereof include quaternized dialkylaminoethyl methacrylate polymers, polyethyleneimine, and natural products [guar gum, alginate, chitosan, etc.]. The amount of the flocculant added is usually 5% or less based on the weight of the heavy metal-containing material,
It is preferably 0.01 to 3%.

Examples of the surfactant include nonionic surfactants, anionic surfactants, cationic surfactants and amphoteric surfactants. Examples of the nonionic surfactant include alkylene oxide (C2-4) addition type nonionic surfactants [higher alcohols (C8-C8).
18), higher fatty acids (having 12 to 24 carbon atoms) or higher alkylamines (having 8 to 24 carbon atoms), and the like are directly linked to alkylene oxides (having 2 to 4 carbon atoms, such as ethylene oxide, propylene oxide, butylene oxide, and two or more kinds of these). (Combined use) added (molecular weight 158-200)
000); polyalkylene glycols obtained by adding alkylene oxide to glycols (molecular weight 15
0 to 6000) with higher fatty acid or the like; polyhydric alcohol (dihydric to octavalent or higher polyhydric alcohol such as ethylene glycol, propylene glycol, glycerin, pentaerythritol, sorbitan) reacted with higher fatty acid A product obtained by adding an alkylene oxide to the obtained esterified product (molecular weight 250 to 300).
00), higher fatty acid amide to which alkylene oxide is added (molecular weight 200 to 30,000), polyvalent (divalent to octavalent or higher) alcohol alkyl (having 3 carbon atoms)
To 60) ether to which alkylene oxide is added (molecular weight 120 to 30000), etc., and polyhydric alcohol (C3 to C60) type nonionic surfactant (polyhydric alcohol fatty acid (C3 to C3). 60) ester, polyhydric alcohol alkyl (C3-60) ether, fatty acid (C3-60) alkanolamide, etc.) and the like.

Examples of anionic surfactants include:
Carboxylic acid (saturated or unsaturated fatty acid having 8 to 22 carbon atoms) or a salt thereof (sodium, potassium, ammonium, alkanolamine salt, etc.), carboxymethylated salt (aliphatic alcohol having 8 to 16 carbon atoms and / or
Or a salt of a carboxymethylated product such as an ethylene oxide (1 to 10 mol) adduct thereof, a sulfuric acid ester salt [a higher alcohol sulfuric acid ester salt (a sulfuric acid ester salt of a fatty acid alcohol having 8 to 18 carbon atoms)], a higher alkyl ether Sulfuric acid ester salt [sulfuric acid ester salt of ethylene oxide (1 to 10 mol) adduct of fatty acid alcohol having 8 to 18 carbon atoms], sulfated oil (natural unsaturated fat or oil or unsaturated wax as it is to be sulfated and neutralized) Sulfated fatty acid ester (saturated lower alcohol ester of unsaturated fatty acid is neutralized), sulfated olefin (sulfurized olefin having 12 to 18 carbon atoms is neutralized), sulfonate [ Alkylbenzene sulfonate, alkylnaphthalene sulfonate, sulfosuccinic acid diester type, α- Reffin (C12-18) sulfonate, Igepon T type and the like] and phosphate ester salt [higher alcohol (C8-60) phosphate ester salt, higher alcohol (C8-60) ethylene oxide adduct phosphorus Acid ester salt, alkyl (C4-6)
0) Phenol ethylene oxide adduct phosphoric acid ester salt and the like].

As the cationic surfactant, a quaternary ammonium salt type [tetraalkyl (4 to 100 carbon atoms) ammonium salt, such as lauryltrimethylammonium chloride, didecyldimethylammonium chloride, dioctyldimethylammonium bromide, stearyltrimethylammonium bromide, can be used. Etc .; trialkyl (C3 to C80) benzylammonium salt, such as lauryldimethylbenzylammonium chloride (benzalkonium chloride); alkyl (C2 to C6)
0) Pyridinium salts, such as cetylpyridinium chloride; Polyoxyalkylene (C2-4) trialkylammonium salts, such as polyoxyethylenetrimethylammonium chloride; Sapamine-type fourth
Primary ammonium salts, such as stearamidoethyldiethylmethylammonium methosulfate, and the like, amine salt type [aliphatic higher amines (having 12 to 60 carbon atoms, such as laurylamine, stearylamine, cetylamine, hardened tallow amine, and rosinamine)] Salts or organic acid salts; Lower amines (C1-11) higher fatty acid (stearic acid, oleic acid, etc.) salts; Aliphatic amine (C1-30) ethylene oxide adducts, etc. Acid salts; inorganic or organic acid salts of tertiary amines (triethanolamine monostearate, stearamidoethyldiethylmethylethanolamine, etc.) and the like.

As the amphoteric surfactant, an amino acid type amphoteric surfactant [higher alkylamine (having 12 to 18 carbon atoms)
Of sodium propionate], betaine-type amphoteric surfactant alkyl (carbon number 12-18) dimethyl betaine, sulfate ester-type amphoteric surfactant [sulfate ester sodium salt of higher alkyl (carbon number 8-18) amine, hydroxy Ethyl imidazoline sulfate sodium salt, etc.], sulfonate-type amphoteric surfactants (pentadecylsulfotaurine, imidazoline sulfonic acid, etc.), phosphate ester-type amphoteric surfactants [glycerin higher fatty acid (8 to 22 carbon atoms) And phosphoric acid ester amine salts of esterified products] and the like.

The amount of the surfactant added is usually 5% or less, preferably 0.01 to 3 based on the weight of the heavy metal-containing material.
%.

The method of adding the heavy metal fixing agent of the present invention to a heavy metal-containing material is usually an aqueous solution of 20 to 70% by weight, and if necessary to prevent scattering of the heavy metal-containing material, further 1 to 100 times with water. Examples of the method include adding as a diluted aqueous solution, but the heavy metal fixing agent and water may be added separately, and when added separately, either may be added first. When the heavy metal-containing material is in the form of a slurry, only the heavy metal fixing agent may be added directly to the slurry.

When the heavy metal immobilizing agent of the present invention is added to the heavy metal-containing material, it may be sprinkled on the surface of the heavy metal-containing material, but after the addition, it is preferable to knead using a kneader such as a kneader.

[0024]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited thereto. In the examples, "part" means "part by weight" and "%" means "% by weight".

Synthesis Example 1 Synthesis of Potassium Piperazine Bisdithiocarbamate Aqueous Solution 600 parts of water and 100 parts of piperazine are charged and dissolved in a reaction vessel capable of cooling and stirring, and capable of nitrogen substitution, and then 130 parts of potassium hydroxide are charged. , And stirred at 200 rpm. After confirming that the solid matter in the reaction vessel became a slurry, 177 parts of carbon disulfide was added dropwise at 35 ° C. under a nitrogen atmosphere. After completion of the dropping, aging was carried out at the same temperature for 3 hours to obtain a 36.3% aqueous solution of potassium piperazine bisdithiocarbamate (A1). PH of aqueous solution
Was 13.

Example 1 30 parts of a 44% aqueous solution of tripotassium phosphate (B1) (A)
1) 70 parts were mixed and stirred to obtain the heavy metal immobilizing agent (a) (38.6% aqueous solution) of the present invention. Aqueous solution p of (a)
H was 13. Example 2 5 parts of a 44% aqueous solution of (B1) and 95 parts of (A1) were mixed,
The mixture was stirred to obtain the heavy metal immobilizing agent (b) of the present invention (36.7% aqueous solution). The pH of the aqueous solution of (b) was 13. Example 3 65 parts of a 44% aqueous solution of (B1) and 35 parts of (A1) were mixed and stirred, and the heavy metal fixing agent (c) (41.3%) of the present invention was mixed.
Aqueous solution) was obtained. The pH of the aqueous solution of (c) was 13.

Test Examples 1 to 3 and Comparative Test Example 1 200 ml of 50 g of each aqueous solution of the heavy metal immobilizing agents (a) to (c) of the present invention and the comparative heavy metal immobilizing agent (A1).
Weigh in a glass container (diameter 5 cm x height 10.2 cm), replace the inside of the container with nitrogen, seal, and leave at rest at 30 ° C for 7 days, then detect the concentration of carbon disulfide and hydrogen sulfide in the container. A tube (carbon disulfide NO.13 detector tube manufactured by Gastec, hydrogen sulfide was measured by Gastec NO.4LL detector tube). The results are shown in Table 1.

[0028]

[Table 1]

Test Examples 4 to 6 and Comparative Test Example 2 50 parts of fly ash produced by incineration of dust was added to the heavy metal fixing agents (a) to (c) of the present invention and the comparative heavy metal fixing agent (A).
0.17 parts of the aqueous solution of 1) as a heavy metal fixing agent, water 1
0 part was added, and the mixture was kneaded using a spatula at 80 ° C. for 10 minutes. After the kneading, the treated ash and the untreated ash were subjected to a dissolution test (Environmental Agency Bulletin No. 13) to measure the eluted lead ion concentration. The results are shown in Table 2.

[0030]

[Table 2]

[0031]

INDUSTRIAL APPLICABILITY The heavy metal immobilizing agent and the method for improving the stability thereof according to the present invention can be used without impairing the heavy metal immobilizing effect.
Further, it is extremely useful because it has an effect of suppressing generation of toxic gas such as hydrogen sulfide and carbon disulfide during storage, transportation and use of the heavy metal fixing agent.

Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C02F 11/00 ZAB B09B 3/00 304G C09K 15/02 304K 304Z (72) Inventor Ichimitsu Suzuki Hitotsubashi, Higashiyama-ku, Kyoto No. 1 No. 1 Sanyo Kasei Kogyo Co., Ltd. (72) Inventor Shinobu Kawaguchi No. 1 No. 11 Hitotsubashi Honcho, Higashiyama-ku, Kyoto City No. 1 Sanyo Kasei Kogyo Co., Ltd. F-term (reference) 4D004 AA02 AA37 AA41 AA43 AB03 CA15 CA22 CA34 CC03 CC06 CC11 CC15 DA03 DA10 DA20 4D059 AA00 BE55 BE56 BH04 BJ01 BK30 DA01 DA16 DA17 DA18 DA23 DA24 DA34 DA39 DB02 DB03 DB05 DB08 DB09 DB12 DB15 DB16 DB18 DB22 DB23 DB24 DB25 DB26 DB29 4H025 AA01 AB01 AC06 AC07

Claims (6)

[Claims] 1. A liquefied heavy metal immobilizing agent comprising a phosphate (B) in an aqueous solution of dithiocarbamic acid and / or its salt (A). 2. A weight ratio of (A) and (B) (A) / (B)
Is 0.1 / 1 to 200/1, The heavy metal fixing agent according to claim 1. 3. The heavy metal immobilizing agent according to claim 1, wherein (B) is an alkali metal salt of phosphoric acid. 4. The heavy metal immobilizing agent according to claim 1, wherein the heavy metal immobilizing agent has an aqueous solution pH of 12 or more. 5. The heavy metal fixing agent according to claim 1, which is for incineration fly ash. 6. A method for improving the stability of a heavy metal immobilizing agent, which comprises incorporating a phosphate (B) into an aqueous solution of dithiocarbamic acid and / or its salt (A).