JP2005238050A - Method for reproducing waste reclamation disposal plant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that there is the possibility of the inclusion of harmful organic halides, such as dioxins, and heavy metals into the flying ash discharged from a garbage incineration plant etc., and the possibility of the occurrence of of environmental pollution due to elution of the organic halides and heavy metals from a waste reclamation disposal plant where such flying ash is used for landfill and therefore the excavation and retreatment of the reclaimed waste of the waste reclamation disposal plant is studied but there is the possibility of the occurrence of the environmental pollution as a result of scattering of the dust of the waste including the hazardous materials at the time of excavation. <P>SOLUTION: The reproducing method for the waste reclamation disposal plant comprises supplying a poymeric compound liquid to the landfill waste of the waste reclamation disposal plant and excavating the landfill waste then supplying a metal scavenger to the excavated waste, thereby performing immobilization treatment of the metals in the waste. The method is capable of performing the decomposition treatment of the dioxins along with the immobilization treatment of the metals in the waste by supplying a dioxins decomposing agent together with the metal scavenger to the excavated waste. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is a waste that can be safely reprocessed as waste ash containing hazardous substances such as heavy metals and dioxins, which is reclaimed in a waste landfill treatment plant, and the waste landfill treatment plant can be regenerated. The present invention relates to a reclamation method for a landfill site.

  Wastes such as municipal waste, industrial waste, and ash (main ash, fly ash) generated by incineration contain various substances such as SOx, NOx, hydrogen chloride, metal, and dioxins. In some cases, it contains a lot of harmful organic halogen compounds and harmful heavy metals such as mercury and chromium. These wastes are finally landfilled at the waste landfill, but if waste containing organic halogen compounds or heavy metals that are not insolubilized is landfilled, organic halides and Heavy metals may elute into groundwater or soil and cause environmental pollution. For this reason, in recent years, it has become stipulated by law that detoxification is performed before landfilling so that no harmful substances are eluted from the waste to cause environmental pollution. Since 1994, the law has mandated that the amount of elution of heavy metals from fly ash and main ash to be landfilled is below a certain standard value. Further, since 2002, it has been obliged to set the concentration of residual dioxins in fly ash and main ash to 3 ng-TEQ / g or less. For this reason, various methods for safely treating waste by immobilizing heavy metals contained in waste such as fly ash and decomposing organic halides such as dioxin have been proposed (Patent Documents). 1, Patent Document 2, Patent Document 3, etc.).

JP 2001-145862 A JP 2001-149888 A JP 2002-143805 A

  However, there are many landfill sites where wastes such as fly ash and main ash are landfilled before the legislation that regulates the amount of heavy metals and residual dioxins eluted from the waste, Recently, it has been pointed out that heavy metals and organic halides may elute from such landfill sites and cause environmental pollution. For this reason, excavation of landfilled waste, and the safe disposal of heavy metals and organic halides that may be contained in the waste, are being considered to recycle the landfill site. At landfill sites, waste is excavated and reprocessed with heavy metal fixing agents.

  However, when excavating the waste, the dust of the waste is scattered around, so there may be a risk of pneumoconiosis due to the inhalation of dust by workers and residents, and there is a possibility that it is included in the dust of the waste. It has been pointed out that there may be serious environmental pollution problems caused by certain heavy metals and organic halides. In order to prevent scattering of dust during excavation, a method of excavating while spraying a large amount of water has been studied, but there is a possibility that the dust may be dried and scattered in a short time to pollute the environment.

  The present invention has been made to solve the above problem, and can recycle a waste landfill treatment site by safely reprocessing waste containing an organic halogen compound and non-insolubilized heavy metals. The purpose is to provide a method for reclaiming landfill sites.

That is, the present invention
(1) Supplying a polymer compound solution to landfill waste at a landfill disposal site, excavating the landfill waste, and then supplying a metal scavenger to the excavated waste to immobilize the metal in the waste A method for recycling a waste landfill treatment site, characterized by
(2) Supplying a dioxin decomposing agent together with a metal scavenger to the excavated waste, immobilizing the metal in the waste, and decomposing the dioxin as described in (1) above Playback method,
(3) The method for recycling a waste landfill treatment site according to the above (1) or (2), wherein the polymer compound is an acrylic acid polymer compound and / or a vinyl acetate polymer compound,
Is a summary.

Since the method of the present invention excavates the landfill waste after supplying the polymer compound solution to the landfill waste, the dust of the waste hardly scatters to the surroundings at the time of excavation and is not treated in the solid waste. Even if hazardous substances such as dioxins and heavy metals are included, the environment around the treatment plant is not contaminated with dust containing hazardous substances, and the landfilled waste is safely reprocessed and discarded. The landfill site can be regenerated.

In the present invention, examples of the polymer compound liquid include emulsions and aqueous solutions of acrylic polymer compounds, vinyl acetate polymer compounds, polyamides, polyurethanes, polyimines, etc., but acrylic polymer compounds and vinyl acetate polymer compounds. More preferred are emulsions and aqueous solutions.

  Examples of acrylic polymer compounds include acrylic acid ester monomers such as methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, and methacrylic acid-i-butyl. , Homopolymers and copolymers of methacrylic acid ester monomers such as methacrylic acid-n-butyl, methacrylic acid-t-butyl, methacrylic acid-2-ethylhexyl, lauryl methacrylate, etc. Examples thereof include a copolymer of an acid ester monomer and a vinyl monomer copolymerizable with these monomers. Examples of the vinyl acetate polymer include vinyl acetate homopolymers and copolymers of vinyl acetate and vinyl monomers copolymerizable therewith.

  Examples of other vinyl monomers that can be copolymerized with monomers such as acrylate monomers, methacrylate monomers, and vinyl acetate include unsaturated groups such as styrene, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, and dimethylacrylamide. Those having a bond are listed. An acrylic polymer compound or a vinyl acetate polymer compound is a copolymer of an acrylic acid ester monomer, a methacrylic acid ester monomer, a vinyl acetate monomer, or any other vinyl monomer copolymerizable with these monomers. In the case of a polymer, the content of other vinyl monomers in the copolymer is preferably less than 20 mol%.

  As the polymer compound solution, an emulsion or an aqueous solution adjusted so that the content of the polymer compound is 40 to 60% by weight is used. In the polymer compound solution, anionic surfactants such as sodium fatty acids and sodium sulfonates can be blended in order to provide stability of the emulsion or aqueous solution.

In reprocessing a waste landfill treatment site by the method of the present invention, first, a polymer compound solution is supplied to the landfill waste and the landfill waste is excavated. Examples of the method of supplying the polymer compound liquid include a method of spraying on the surface of landfill waste using a shower or a spray nozzle, a method of applying to waste using a roller or a brush, and the like. preferable. The supply amount of the polymer compound solution to waste is preferably 0.1 to 10 kg / m ³ . The polymer compound solution may be supplied to the waste before excavating the waste, and then the waste may be excavated. However, the excavation of the waste is performed while supplying the polymer compound to the waste. A method may be adopted. When supplying the polymer compound before excavating the waste, the excavation may be performed immediately after supplying the polymer compound. However, after the supplied polymer compound is naturally dried or forcedly dried, the waste is excavated. It is preferable to do. In order to naturally dry the polymer compound solution supplied to the waste, it may be left for 3 to 24 hours. For forced drying, cold air or hot air is supplied to the polymer compound liquid supply surface by a blower, a hot air blower or the like. After the polymer compound solution supplied to the landfill waste surface is dried, the waste can be excavated without dust scattering around. If necessary, an operation of supplying a polymer compound solution again during excavation, drying it, and excavating can be repeated.

  Next, a metal scavenger is supplied to the excavated waste to immobilize the metal contained in the waste. As the heavy metal scavenger, a compound having a functional group containing an atom having a coordination ability to a metal such as oxygen, nitrogen, or sulfur is used. Examples of the functional group include a phosphoric acid group, an aminophosphoric acid group, a carboxylic acid group, an aminocarboxylic acid group, a carbamic acid group, a dithiocarbamic acid group, a thiol group, and a xanthate group. The metal scavenger used in the present invention may have the same functional group or may have two or more different functional groups. Further, two or more kinds of metal scavengers having different functional groups can be mixed and used, but those having water solubility and water dispersibility are preferred. In the present invention, the metal scavenger is preferably a metal scavenger having chelate-forming ability, and is preferably a compound having a dithiocarbamic acid group or a salt thereof.

  As a metal scavenger having a dithiocarbamic acid group or a salt thereof (hereinafter sometimes simply referred to as “dithiocarbamic acid group”) as a functional group, carbon disulfide is reacted with amines such as monoamine and polyamine. And the resulting compound. Monoamines include monomethylamine, dimethylamine, monoethylamine, diethylamine, monopropylamine, dipropylamine, monobutylamine, dibutylamine, isopropylamine, diisopropylamine, piperidine, piperazine, morpholine, methylphenylamine, ethylphenylamine, etc. Can be mentioned. Examples of the polyamine include ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, diethylenetriamine, dipropylenetriamine, dibutylenetriamine, triethylenetetramine, tripropylenetetramine, tributylenetetramine, tetraethylenepentamine, tetrapropylenepentamine, tetra Aliphatic polyamines such as butylenepentamine, pentaethylenehexamine, iminobispropylamine, monomethylaminopropylamine, methyliminobispropylamine; cycloalkane polyamines such as 1,3-bis (aminomethyl) cyclohexane; 1-aminoethyl Piperazines such as piperazine and piperazine; polyethyleneimine, polypropyleneimine, poly-3-methylpropylimine Polymers of cyclic imines such as poly-2-ethyl-propyl imine, polyvinyl amine, polymers of unsaturated amines of the polyallylamine and the like. It is also possible to copolymerize unsaturated amines such as vinylamine and allylamine with unsaturated amines such as dimethylacrylamide, styrene, methyl acrylate, methyl methacrylate, acrylic acid, methacrylic acid, styrene sulfonic acid, and their salts. Copolymers with other monomers having a saturated bond are also included.

  The amines may have a hydroxyalkyl group, an acyl group, an alkyl group or the like as an N-substituent. The N-hydroxyalkyl substituent can be introduced by reacting the amines with an epoxy alkane, and the N-acyl substituent is introduced by reacting the amines with a fatty acid. N-alkyl substituents are introduced by the action of the above amines and alkyl halides. The N-hydroxyalkyl substituent preferably has 2 to 28 carbon atoms in the alkyl group, and the N-acyl substituent preferably has 2 to 26 carbon atoms. The N-alkyl substituent preferably has 2 to 22 carbon atoms.

  Further, polycondensed amines and polycondensed ethyleneimines obtained by polycondensation of the above amines with epihalohydrin can also be used. Examples of the epihalohydrin include epichlorohydrin, epibromohydrin, epiiodohydrin, and the like. The amines may be other than those described above as long as they have an active hydrogen atom bonded to a nitrogen atom and can react with carbon disulfide to introduce a dithiocarbamic acid group as a functional group. good.

  N-substituent introduction reaction such as hydroxyalkyl group, acyl group, alkyl group and the like, and polycondensation reaction of amines with epihalohydrin may be performed before the reaction between amines and carbon disulfide. However, when the reaction is performed before the reaction with carbon disulfide, the N-substituent is introduced into the amines or the polycondensation of the amines with epihalohydrin is performed. Active hydrogen atoms that can react with carbon to form dithiocarbamic acid groups must remain in the amines. In the case of amines containing two or more active hydrogen atoms, one having one dithiocarbamic acid group introduced therein or one having two or more dithiocarbamic acid groups introduced may be used.

  The reaction between amines and carbon disulfide can be performed by, for example, a method in which amines are dissolved in a solvent such as water or alcohol, and carbon disulfide is added thereto for reaction. After completion of the reaction, an alkali metal hydroxide or carbonate (eg, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, etc.), an alkaline earth metal hydroxide or carbonate (eg, calcium hydroxide, hydroxide) Magnesium, calcium carbonate, magnesium carbonate, etc.), or an alkali such as ammonia, or a reaction between amines and carbon disulfide in the presence of these alkalis to form an alkali metal salt form of dithiocarbamic acid, A metal scavenger having an alkali salt type functional group such as an alkaline earth metal salt type or an amine salt type can be obtained. Although the supply amount of the metal scavenger to the waste varies depending on the amount of metal to be immobilized contained in the waste, it is usually preferable to supply 0.01 to 30% by weight.

  When dioxins may be contained in the excavated waste, it is preferable to supply a dioxin decomposing agent together with the metal scavenger to the excavated waste. Examples of the dioxin decomposition agent include reducing agents such as phosphorous acid and hypophosphorous acid. The dioxin decomposition agent may be supplied before or after supplying the metal scavenger, or may be supplied simultaneously with the metal scavenger.

  Phosphorous acid used as a dioxin decomposition agent includes phosphorous acid, lithium phosphite, potassium phosphite, sodium phosphite, sodium hydrogen phosphite, calcium phosphite, magnesium phosphite, phosphorous acid Examples include ammonium hydrogen. Examples of hypophosphorous acid include hypophosphorous acid, lithium hypophosphite, potassium hypophosphite, sodium hypophosphite, calcium hypophosphite and the like. The supply amount of the dioxins decomposer is preferably 0.1 to 50% by weight, although it depends on the amount of dioxins contained.

  Wastes treated with metal scavengers (or metal scavengers and dioxins decomposers) as described above are sorted and used separately as recyclable resources such as construction materials. By reducing the volume, it is backfilled or transported to other landfills and used as cover soil or landfilled.

Hereinafter, the present invention will be described in more detail with reference to examples.
Example 1
Two lightweight concrete blocks were arranged in parallel in a room (1 m ³ ) sealed with an acrylic plate with the long side facing down. Next, a sample bat (length 323 × width 233 × depth 52 mm) was placed thereon, and 1 kg of soil containing 1318 mg / kg of lead was flattened and solidified therein. After spraying 30 g of an acrylic ester emulsion (3% aqueous solution) from the soil spread over the vat, it was left to dry for 5 hours. Next, about 0.6 kg of flat chisel (blade width 25 mm x total length 215 mm) from a height of 50 cm is naturally dropped on a bat covered with soil, and the indoor dust concentration is measured with a laser dust meter (manufactured by Shibata: LD-1 (L) type) and the results are shown in Table 1. Further, after dust measurement, 10 ml of a 10% by weight aqueous solution of a heavy metal collector potassium diethyldithiocarbamate was added and treated, and the test was conducted in accordance with the No. 13 test method for lead environmental agency notice. The results are shown in Table 1.

Example 2
The same procedure as in Example 1 was performed except that 10 g of vinyl acetate emulsion (10% aqueous solution) was used instead of the acrylic ester emulsion and sodium polyethyleneimine dithiocarbamate was used as the heavy metal scavenger. The results are shown in Table 1.

Comparative Example 1
The same procedure as in Example 1 was performed except that 20 g of water containing no polymer emulsion and heavy metal scavenger was sprayed. The results are shown in Table 1.

(Table 1)

Example 3
Two lightweight concrete blocks were arranged in parallel in a room (1 m ³ ) sealed with an acrylic plate with the long side facing down. Next, a sample bat (width 323 × depth 233 × depth 52 mm) was placed thereon, and 1 kg of soil containing 1250 mg / kg of lead and 1020 pg / g of dioxins was flattened and solidified therein. After spraying 30 g of an acrylic ester emulsion (3% aqueous solution) from the soil spread over the vat, it was left to dry for 5 hours. Subsequently, about 0.6 kg of flat chisel (blade width 25 mm × total length 215 mm) was naturally dropped from a height of 50 cm on a bat covered with soil, and the indoor dust concentration was measured in the same manner as in Example 1. The results are shown in Table 2. In addition, after dust measurement, sodium hypophosphite is used as a dioxin decomposing agent, treated at 350 ° C. for 1 hour in a rotary kiln, and then treated by adding 10 ml of a 10 wt% aqueous solution of potassium heavy metal collector diethyldithiocarbamate. The lead and dioxin concentrations were measured. The results are shown in Table 2.

Example 4
The same procedure as in Example 3 was carried out except that 10 g of a styrene / acrylic copolymer emulsion (30% aqueous solution) was used in place of the acrylic ester emulsion and sodium polyethyleneimine dithiocarbamate was used as the heavy metal scavenger. The results are shown in Table 2.

Comparative Example 2
The same procedure as in Example 3 was performed except that 20 g of water containing no polymer emulsion and no heavy metal scavenger was sprayed. The results are shown in Table 2.

(Table 2)

Example 5
Two lightweight concrete blocks were arranged in parallel in a room (1 m ³ ) sealed with an acrylic plate with the long side facing down. Next, a sample bat (length 323 × width 233 × depth 52 mm) was placed thereon, and 1 kg of soil containing 1318 mg / kg of lead was flattened and solidified therein. Immediately after spraying 30 g of acrylic acid ester emulsion (3% aqueous solution) from the top of the soil spread on the bat, a flat chisel of about 0.6 kg from a height of 50 cm (blade width 25 mm × full length) 215 mm) was allowed to fall naturally, and the dust concentration in the room was measured with a laser dust meter (manufactured by Shibata: LD-1 (L) type). The results are shown in Table 1. Further, after dust measurement, 10 ml of a 10% by weight aqueous solution of a heavy metal collector potassium diethyldithiocarbamate was added and treated, and the test was conducted in accordance with the No. 13 test method for lead environmental agency notice. The results are shown in Table 3.

Example 6
The same procedure as in Example 1 was performed except that 10 g of vinyl acetate emulsion (10% aqueous solution) was used instead of the acrylic ester emulsion and sodium polyethyleneimine dithiocarbamate was used as the heavy metal scavenger. The results are shown in Table 3.

Comparative Example 3
Two lightweight concrete blocks were arranged in parallel in a room (1 m ³ ) sealed with an acrylic plate with the long side facing down. Next, a sample bat (length 323 × width 233 × depth 52 mm) was placed thereon, and 1 kg of soil containing 1318 mg / kg of lead was flattened and solidified therein. After laying on the bat, about 0.6 kg of flat chisel (blade width 25 mm x total length 215 mm) is dropped naturally from the height of 50 cm on the bat, and the indoor dust concentration is measured with a laser dust meter (made by Shibata: LD-1 (L) type) and the results are shown in Table 1. Further, after dust measurement, 10 ml of a 10% by weight aqueous solution of a heavy metal collector potassium diethyldithiocarbamate was added and treated, and the test was conducted in accordance with the No. 13 test method for lead environmental agency notice. The results are shown in Table 3.

(Table 3)

Claims (3)

Supplying a polymer compound solution to landfill waste at a landfill disposal site, excavating the landfill waste, and then supplying a metal scavenger to the excavated waste to immobilize the metal in the waste Recycling method of waste landfill processing site characterized by this. The method for reclaiming a waste landfill treatment plant according to claim 1, wherein a dioxin decomposing agent is supplied to the excavated waste together with a metal scavenger, the metal in the waste is fixed, and the dioxins are decomposed. The method for recycling a waste landfill treatment site according to claim 1 or 2, wherein the polymer compound is an acrylic acid polymer compound and / or a vinyl acetate polymer compound.