JP3516278B2 - Solid waste treatment method - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to incineration ash, soot dust, slag,
The present invention relates to a solid waste treatment method capable of immobilizing a metal present in a solid waste such as sludge or soil and preventing metal elution from the solid substance.

[0002]

2. Description of the Related Art Various metals are present in solid wastes such as incinerated ash and dust produced in garbage incinerators, slag discharged from mines, activated sludge used in wastewater treatment, and contaminated soil. Contains, mercury, cadmium, lead, zinc,
It also contains many heavy metals that are harmful to the human body, such as copper and chromium. If the metal contained in these solid wastes flows out, there is a risk of contaminating groundwater, rivers, seawater and the like.

For this reason, conventionally, a method of solidifying solid waste with cement, followed by landfilling or dumping in the ocean has been adopted, but there is a possibility that metal may flow out through the cement wall, and this method is not always required. It was not a safe disposal method. In order to solve such a problem, a metal collector that has been conventionally used for treating wastewater containing heavy metals is added to these solid wastes to collect metals in the solid wastes. A method of immobilizing with a drug has been proposed.
As the metal scavenger, for example, as previously proposed by the present applicant, a dithio acid group or a dithio acid group is bonded to the nitrogen atom of a polyalkylene polyamine such as ethylenediamine or triethylenetetramine or a polyamine such as polyethyleneimine. Structured metal scavengers (Japanese Patent Publication No. 5-7079, Japanese Patent Publication No. 5-8080, etc.) are known.

[0004]

The presence of water is essential for the metal scavenger to react with the metal in the solid waste,
Further, in order for the reaction between the metal scavenger and the metal to proceed efficiently, it is necessary to have a large amount of water capable of rapidly and uniformly kneading the both.

However, the presence of water is indispensable in the step of kneading the metal scavenger and the solid waste to react the metal with the metal scavenger, but the metal was immobilized by the metal scavenger. It is not necessary that water be present afterwards, and if a large amount of water is contained in the solid waste treated with the metal scavenger, the weight becomes large, and the treated waste is treated in the next treatment step (for example, Problems such as high transportation costs for cementing, landfilling, and transfer to the ocean will occur.

As described above, it is preferable that the solid waste treated with the metal scavenger has a low water content, but the amount of water contained in the solid waste treated with the metal scavenger is small. The work of reducing the amount of noise is complicated and takes a lot of cost. On the other hand, in the step of kneading the metal scavenger and the solid waste, if the amount of water present in the treatment system is reduced,
There is a problem that the metal scavenger is not uniformly kneaded with the solid waste, and the metal scavenger cannot immobilize the metal efficiently.

As a result of intensive studies to solve the above problems, the present inventors knead a compound having a complex-forming ability with respect to a metal such as a metal scavenger with a solid waste in the presence of water to obtain a solid. By using an admixture together with the metal in the solid waste, the metal in the solid waste can be efficiently fixed even if the amount of water is reduced. It has been found that it becomes easy to reduce the water content in the solid waste, and the present invention has been completed.

[0008]

That is, the method for treating solid waste according to the present invention comprises a dithio compound having a metal complexing ability.
A solid waste 100 containing a compound containing an acid group as a functional group
The present invention is characterized in that 10 g or less of water per g and an admixture are added to a solid waste and kneaded to immobilize the metal in the solid waste.

In the present invention, the compound capable of forming a complex with a metal (hereinafter, simply referred to as a complex forming compound) is an atom having a coordinating ability with respect to a metal such as an oxygen atom, a nitrogen atom, a phosphorus atom and a sulfur atom. a compound containing, for example <br/>, di methyl dithiocarbamate, diethyl dithiocarbamate, dialkyl dithiocarbamates such as dibutyl dithiocarbamate; piperazine dithiocarbamic acid,
Functionality introduced by substituting an active hydrogen atom bonded to a nitrogen atom of pyrrolidinedithiocarbamic acid, monoethanolamine dithiocarbamic acid, diethanolamine dithiocarbamic acid, or an amino compound having at least one primary amino group or secondary amino group Examples thereof include compounds having a group . These complexing compounds are particularly water-soluble, those having a water-dispersible preferred.

The compound having a functional group bonded to the nitrogen atom of the amino compound is mainly known as a metal scavenger and has a dithio acid group or a salt thereof as a functional group . The salt of government functional groups, and lithium salts, sodium salts, alkali metal salts such as potassium salts, beryllium salts, magnesium salts, calcium salts, strontium salts, alkaline earth such as barium salts metal salt, ammonium salt and the like However, sodium salts and potassium salts are usually used as the alkali metal salts, and magnesium salts and calcium salts are used as the alkaline earth metal salts. In the case of a compound having two or more functional groups in one molecule, even if a mixture of functional groups of different types (acid type, alkali metal salt type, alkaline earth metal salt type, ammonium salt type, etc.) is used Good .

In the above compounds, examples of the amino compound having at least one primary amino group or secondary amino group into which a functional group is introduced include amines, polycondensed amines obtained by polycondensing amines with epihalohydrin, Examples thereof include a copolymer of an amine and a compound represented by the following chemical formula 1, or a compound having at least one unit represented by the following chemical formula 2 or chemical formula 3 in one molecule.

[0012]

[Chemical 1]

[0013]

[Chemical 2]

[0014]

[Chemical 3]

Examples of the amines include ethylamine, propylamine, dimethylamine, diethylamine, dibutylamine, aminoethylethanolamine,
Monoethanolamine, diethanolamine, piperidyl <br/> down, methylation ethylamine, methyl butyl amine, ethyl butyl amine, diethylene amine, dipropylene amine, ethylenediamine, propylene diamine, butylene diamine, hexamethylene diamine, diethylene triamine, dipropylene diamine, dibutylene Triamine,
Triethylenetetramine, tripropylenetetramine,
Tributylenetetramine, tetraethylenepentamine,
Aliphatic amines such as tetrapropylenepentamine, tetrabutylenepentamine, pentaethylenehexamine, iminobispropylamine, monomethylaminopropylamine, methyliminobispropylamine; phenylenediamine, o-, m-, p-xylylenediamine , Aromatic amines such as 3,5-diaminochlorobenzene; cycloalkane amines such as 1,3-bis (aminomethyl) cyclohexane;
Piperazine compounds such as 1-aminoethylpiperazine and piperazine; polymers of cyclic imines such as polyethyleneimine, polypropyleneimine, poly-3-methylpropylimine and poly-2-ethylpropylimine; polyvinylamine,
Polymers of unsaturated amines such as polyallylamine; unsaturated amines such as vinylamine and allylamine, and dimethylacrylamide, styrene, methyl acrylate, methyl methacrylate, acrylic acid, methacrylic acid, styrene sulfonic acid, and salts thereof, Examples thereof include copolymers with other monomers having a copolymerizable unsaturated bond. In the case of a polymer of a cyclic imine, a polymer of an unsaturated amine and a copolymer thereof, those having an average molecular weight of 300 to 2,000,000 are preferable,
The thing of 1000-500,000 is more preferable.

Examples of polycondensed polyamines include polycondensates of the above amines with epihalohydrins such as epichlorohydrin, epibromohydrin, epiiodohydrin, bromomethyloxirane, chloromethyloxirane, and iodomethyloxirane. However, it is necessary for the polycondensed polyamine to have two or more primary amino groups and two or more secondary amino groups remaining in one molecule.

The compounds represented by the above chemical formula 1 include epoxy compounds, cyclic sulfide compounds, cyclic ethers,
Obtained by reacting a homopolymer or copolymer of a cyclic compound containing oxygen, sulfur, or nitrogen, such as cyclic formal, N-substituted alkyleneimines, and epihalohydrin, formaldehyde, with an epoxy group or It is a compound having an aldehyde group or a compound having an epoxy group and / or an aldehyde group at both ends. This compound preferably has an average molecular weight of about 500,000 or less, particularly 500 to 200,000. The subscript "m" in the general formula shown in Chemical Formula 1 is a positive integer in which the molecular weight of the compound of Chemical Formula 3 falls within the above range.

The epoxy compound constituting the compound represented by the above chemical formula 1 is a compound represented by the following chemical formula 4, and examples thereof include ethylene oxide, propylene oxide and 1,2-epoxyalkane.

[0019]

[Chemical 4]

Examples of the cyclic flufide compound constituting the compound represented by the above chemical formula 1 include compounds represented by the following chemical formula 5 having a structure in which oxygen and sulfur of the epoxy group of the above epoxy compound are substituted. For example, ethylene sulfide,
Propylene sulfide and the like are exemplified, and as cyclic ethers, oxetane, mono- or bisalkyl (alkyl group having 1 to 5 carbon atoms) oxetane, mono- or bischloromethyloxetane, tetrahydrofuran, mono- or bisalkyl (alkyl group having 1 carbon atom) ~ 5) Tetrahydrofuran and the like can be mentioned.

[0021]

[Chemical 5]

Further, examples of the cyclic formals constituting the compound of the above chemical formula 1 include compounds such as 1,3-dioxofuran represented by the following chemical formula 6 and trioxane. The N-substituted alkyleneimines are represented by the following chemical formulas. The compound shown by 7 is mentioned.

[0023]

[Chemical 6]

[0024]

[Chemical 7]

The compound having at least one unit represented by the above chemical formula 2 in one molecule can be produced by the following method. First, the first method is a method of reducing polyacrylonitrile or polyacrylamide. Polyacrylonitrile can be reduced by a method of adding hydrogen in the presence of a hydrogenation catalyst. Specifically, polyacrylonitrile is dissolved in a solvent such as DMF or DMSO, and Raney nickel is used as a catalyst under high pressure (3 0.5 kg /
A method of adding hydrogen at about cm ² ) can be mentioned.

For the reduction of polyacrylonitrile, a method of dissolving polyacrylamide in a solvent such as THF, DMF or DMSO and reducing it with a metal alcoholate such as lithium aluminum hydride or sodium methylate can be adopted.

The second manufacturing method is a method of polymerizing allylamine. As a method of polymerizing allylamine,
For example, after converting allylamine into a hydrochloride or the like, polymerization is performed using a redox type initiator or a radical polymerization initiator. At this time, even if allylamine is polymerized alone, it is possible to copolymerize with allylamine such as dimethylacrylamide, styrene, methyl methacrylate, methyl acrylate, acrylic acid, methacrylic acid, styrene sulfonic acid, etc. and their salts. It may be copolymerized with another monomer having a bond. When copolymerizing, it is preferable that the allylamine component is contained in an amount of 5 mol% or more, particularly 15 mol% or more.

The compound having at least one unit represented by the above chemical formula 3 in one molecule is polyacrylamide or acrylamide, methacrylamide, lower alkyl ester of acrylic acid, α, β of acrylic acid, methacrylic acid and the like.
It can be obtained by a method such as Hoffmann rearrangement of a copolymer with an unsaturated compound or a method of polymerizing N-vinylphthalimide, N-vinylformamide or N-vinylacetamide and then hydrolyzing it.

Further, the amino compound may have a hydroxyalkyl group, an acyl group, an alkyl group or the like as an N-substituent. The N-hydroxyalkyl substituent is
It can be introduced by reacting the amine with an epoxyalkane, the N-acyl substituent is introduced by reacting the amine with a fatty acid, and the N-alkyl substituent with the polyamine. It is introduced by reacting with an alkyl halide. The N-hydroxyalkyl substituent has 2 to 2 carbon atoms in the alkyl group.
8 is preferable, and the N-acyl substituent has 2 carbon atoms.
It is preferably -24. The N-alkyl substituent preferably has 2 to 18 carbon atoms. These N
-When a functional group is introduced after introducing a substituent into an amino compound, at least one primary amino group or at least one secondary amino group remains in one molecule of the amino compound after the introduction of the N-substituent. There is a need.

[0030]

A major feature of the method of the present invention is that an admixture is present when the complex-forming compound as described above is added to solid waste and kneaded. As the admixture, lignin sulfonic acid, salt of condensate of creosote oil sulfonic acid and formalin, salt of condensate of alkylnaphthalene sulfonic acid and formalin, gluconate, sulfonate of melamine formalin resin, anthracene sulfonic acid and Formalin condensate salt, petroleum sulfonate, fatty acid salt (soap), alkane sulfonic acid, alkylbenzene sulfonate, alkyl sulfate, polyoxyethylene alkyl ether sulfate, resin acid salt, polyalkyl allyl sulfonate, Examples thereof include polycarboxylic acid salts, alkylallyl sulfonate-based modified lignin cocondensates, polyether carboxylic acid salts, aromatic amino sulfonic acid-based polymer compounds, and oxycarboxylic acid salts. The admixture is preferably contained in the solid waste in a proportion of 0.001 to 5%.

Also in the method of the present invention as in the conventional method, the presence of water is indispensable when the complex forming compound is added to the solid waste and kneaded. However, in the method of the present invention, the amount of water required in the conventional method is required. Even with the presence of about 40% of water,
It is possible to immobilize metal in solid waste efficiently.

[0033]

EXAMPLES The present invention will be described in more detail with reference to examples. The complex forming compounds used in the following examples and comparative examples are as follows.

Complex forming compound a: sodium diethyldithiocarbamate

Complex forming compound b: N, N'-dimethylethylenediamine-sodium dithiocarbamate

Complex-forming compound c: polyethyleneimine (MW = 1800) -potassium dithiocarbamate (dithiocarbamate group substitution ratio to active hydrogen bonded to the nitrogen atom of polyethyleneimine 30%)

Complex forming compound d: Polyvinylamine (M
(W = 26000) sodium dithioate group introduced by substituting active hydrogen bonded to nitrogen atom (40 mol%)
And a sodium ethylenecarboxylate group (20 mol%).

Complex forming compound e: Polyethyleneimine and polyethyleneglycol diepoxide polycondensate (MW =
59000) A compound having a potassium dithioate group (60 mol%) and an oxime group (30 mol%) introduced by substituting the active hydrogen bonded to the nitrogen atom.

Complex forming compound f: a sodium dithioate group (30) introduced by substituting the active hydrogen bonded to the nitrogen atom of the polycondensate of 1,3-bisaminomethylcyclohexane and epichlorohydrin (MW = 5300). (Mole%) and a disodium methylenephosphate group (40 mole%)

Complex-forming compound g: potassium dithioate group (30 mol%) and methylenecarboxylic acid group introduced by substituting active hydrogen bonded to nitrogen atom of allylamine-diallylamine copolymer (MW = 13000) Compound having (30 mol%) and amidoxime group (10 mol%)

Complex-forming compound h: 1 mol of pentaethylenehexamine and 1 part of epoxyalkane having 12 to 14 carbon atoms
Compound with 4 mol of ammonium dithioate

Examples 1-4 , Comparative Examples 1-6 Mercury 31 mg / kg, Lead 7890 mg / kg, Zinc 16
50 mg / kg, cadmium 754 mg / kg, nickel 252 mg / kg, copper 74 mg / kg, chromium 689
To 100 g of slag containing 0 mg / kg, the admixture shown in Table 1 (no admixture was added in Comparative Example), water and the complex-forming compound (0.8 g) were added, and the mixture was kneaded for 20 minutes. 50 g of this treated product was shaken in 500 ml of water of pH = 6 at room temperature for 60 minutes, and the metal concentration eluted from the treated product into water was measured by atomic absorption spectrometry. The results are also shown in Table 1.

[0043]

[Table 1]

[0044] Examples 5-8, Comparative Examples 7-12 mercury 16 mg / kg, zinc 349 mg / kg, copper 54m
g / kg, cadmium 390mg / kg, iron 542mg
Fly ash (EP ash) obtained from a garbage incinerator, containing 10 kg / kg
The admixture shown in Table 2 (no admixture was added in Comparative Example), water and the complex-forming compound (1.2 g) were added per 0 g, and the mixture was kneaded for 15 minutes. 50 g of this treated product was
The sample was shaken in 500 ml of water of 4 at room temperature for 60 minutes, and the concentration of the metal eluted from the treated product into water was measured by atomic absorption spectrometry. The results are also shown in Table 2.

[0045]

[Table 2]

[0046]

[0047]

[0048] Examples 9-12, Comparative Examples 13-18 Mercury 89 mg / kg, cadmium 542 mg / kg, chromium 254 mg / kg, nickel 58 mg / kg, lead 5
To 100 g of soil containing 4 mg / kg, the admixture shown in Table 4 (no admixture was added in Comparative Example), water and the complex forming compound (1.0 g) were added and kneaded for 10 minutes.
50 g of this treated product was shaken in 500 ml of water of pH = 6 at room temperature for 60 minutes, and the metal concentration eluted from the treated product into water was measured by atomic absorption spectrometry. The results are also shown in Table 4.

[0049]

[Table 3]

[0050]

The present invention method as described in the foregoing, the compounds comprising a dithio group having a complexing ability as a functional group,
Admixture with less than 10g of water per 100g of solid waste
It was added to the solid waste matter kneaded in the presence of a, complexing ability
Due to so as to fix the metal solid waste by compounds having, in less than conventional during kneading water
It can be efficiently immobilized metal solid waste by a compound having a complex forming ability even in the presence. As a result,
It is possible to reduce the amount of water remaining in the treated solid waste, facilitate the transportation work of the treated solid waste, and reduce the transportation cost.

Continuation of the front page (56) Reference JP-A-6-166862 (JP, A) JP-A-53-11758 (JP, A) JP-A-52-62186 (JP, A) Patent 3415892 (JP, B2) Patent 3243261 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) B09B 3/00 B09C 1/02 B09C 1/08

Claims (2)

(57) [Claims] 1. A dithio acid capable of forming a complex with a metal.
100 g of solid waste containing a compound containing a group as a functional group
A method for treating solid waste, which comprises adding 10 g or less of water per unit to a solid waste in the presence of an admixture and kneading to fix the metal in the solid waste. 2. The method for treating solid waste according to claim 1, wherein the compound having a complex-forming ability is a hydrophilic compound.