JPH11221543A - Hazardous material immobilizing material and immobilization treatment thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hazardous material immobilizing material having a higher hazardous material fixing capability than ordinary cement by consisting the material of a hydraulic compsn. composed essentially of the calcined matter consisting of >=1 kind of municipal refuse incineration ash and sewer sludge incineration ash as a raw material and contg. >=1 kind of C11A. 7CaC12, C3A, etc., at specific weight % and >=1 kind of C2S, C3S, etc., and gypsum. SOLUTION: The eco-cement compsn. as the hazardous material fixing material is the hydraulic compsn. consisting of the calcined matter with consists of >=1 kind of the municipal refuse incineration ash and sewer sludge incineration ash as the raw material and contains 10 to 40 wt.% >=1 kind of C11a 7CaC12, C11A 7CaF2, C3A and >=1 kind of C2S, C3S and the gypsum. The raw material is the dry powder of sewer sludge formed by mixing ewer with shells and sewer sludge, and other general waste and industrial waste. Further, the raw material is subjected to component adjustment by mixing the same with quicklime, clay, silica stone, aluminum ash, bauxite, iron, etc., which are the ordinary cement raw materials. The eco-cement is produced by firing the material described above at 1200 to 1500 deg.C, pulverizing and then adding gypsum.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a harmful substance-immobilizing material for reducing the amount of harmful substances eluted from an object contaminated with the harmful substances, and to a method for immobilizing the same. More specifically, the present invention relates to a harmful substance fixing material using a hydraulic composition (hereinafter, referred to as ecocement) manufactured from waste such as municipal waste incineration ash and sewage sludge incineration ash, and a method for fixing the same. .

[0002]

2. Description of the Related Art It is necessary to detoxify waste containing harmful substances in landfills and marine disposals in order to satisfy criteria for the disposal. Conventionally, hardened ordinary cement has the ability to fix harmful substances such as heavy metals, and thus has been used for immobilizing harmful substances. However,
Since ordinary cement alone lacks the immobilization treatment capacity, a treatment method combining other substances is adopted.

[0003] Japanese Patent Application Laid-Open No. Hei 5-237466 discloses a method for solidifying dry battery waste in which an aqueous solution containing an alkali metal salt and an ammonium salt is made to contain divalent cobalt ions in an aqueous solution. A method of immersing, then kneading and molding with a cement-based material and curing is disclosed. High concentrations of mercury, lead, chromium, cadmium, arsenic, antimony, PCB, and the like are fixed, but there is a drawback that the treatment cost is high because an aqueous cobalt solution is used.

Japanese Patent Application Laid-Open No. Hei 7-246373 discloses a method of adding and kneading cement, phosphoric acid and / or phosphate to dust as a method of treating dust. Installed bag filters and electric precipitators. Dust collected is reclaimed and effectively used for ground improvement work.However, a relatively simple cement solidification method is used to prevent heavy metals in the dust from being eluted. . The Cement Nationalization Law is a simple method of simply mixing cement and water into dust, so it is widely adopted as a method for preventing heavy metal from eluting dust.However, lead, an amphoteric metal, does not elute in a high pH range. In the case of dust containing a large amount of lead, elution of lead cannot be suppressed due to an increase in the amount of added cement. For this reason, a method in which phosphoric acid and phosphate are combined is adopted, insolubilized in the form of lead phosphate, and can be sealed in cement hydrate. In this case, the amount of added cement also needs to be at least about 10%.

[0005] In the case of sewage sludge, even if the content of harmful substances such as heavy metals is small, ordinary cement needs to be used in an amount of about 10% by weight or more. However, there is a disadvantage that the bulk of the treated product is increased and the burden on the final disposal site is increased due to the necessity of the addition of the compound. Hexavalent chromium, cyanide, etc. are relatively difficult to fix even when solidified with ordinary cement.To detoxify waste containing them, a larger amount of cement is needed. Was.

[0006]

The problem to be solved by the present invention is as follows.
Conventional fixing materials, mainly cements, are relatively difficult to fix elements to be treated containing harmful substances. Thus, the cost is high.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a calcined product using at least one of municipal garbage incineration ash and sewage sludge incineration ash, comprising C11A7CaCl2, C11A7CaF2, C3A.
A harmful substance fixing material comprising a calcined material containing 10 to 40% by weight of at least one of the above and C2S and at least one of C3S and a hydraulic composition mainly composed of gypsum.

Further, as harmful substances, Cr, Cd, Pb, Z
Adding 3% by weight or more of the harmful substance fixing material according to claim 1 to 100 parts by weight of the object containing n, Se, Hg, As, Cu, Mn, Ni, and cyan, mixing and solidifying. Includes a method for immobilizing harmful substances.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The ecocement composition as a harmful substance fixing material used in the present invention is a calcined material obtained from at least one of municipal waste incineration ash and sewage sludge incineration ash.
A hydraulic composition comprising gypsum and a calcined product containing 10 to 40% by weight of at least one of 11A7CaCl2, C11A7CaF2, and C3A and at least one of C2S and C3S.

The raw materials used here include sewage sludge dry powder obtained by mixing quicklime with shells and sewage sludge, other general wastes and industrial wastes, and limestone, clay, silica stone and aluminum, which are ordinary cement raw materials. Raw materials whose components have been adjusted by mixing with ash, bauxite, iron or the like may be used. One such raw material
After crushing the clinker obtained by firing at 200 to 1500 ° C., gypsum is added to the fired product to produce ecocement.

Since the aluminum source in the fired product is mainly derived from incinerated ash, C11A7CaCl2, C11A7Ca
If the content of aluminum compounds such as F2 and C3A is less than 10% by weight, the amount of incinerated ash used is reduced, which is not preferable from the viewpoint of effective use of waste and recycling. Also,
If it exceeds 40% by weight, it may expand excessively due to the progress of hydration.

The gypsum used in the present invention can be any of anhydrous gypsum, gypsum dihydrate and hemihydrate gypsum.
Gypsum is preferably added in an amount of 1 to 30 parts by weight based on 100 parts by weight of the fired product.

In order to solidify the object to be treated, it is necessary to add the amount of the harmful substance fixing material to the dry weight of the object by 3% or more. Further, in order to prevent harmful substances from being eluted from the solidified product, it is necessary to appropriately adjust the ratio of ecocement added to the contained harmful substances. The same applies when a plurality of harmful substances are contained in the object to be treated. Further, the solidified material can be in any form of cement paste, mortar, and concrete. If the amount of the immobilizing material is less than 3%, kneading and molding are often inadequate, and the adsorbing and replacement sealing effects of ecocement cannot be exhibited. Also, Cr, Cd, Pb, Zn, Se, Hg, A
The effect is particularly remarkable for a processing target containing s, Cu, Mn, Ni, and cyan.

For the kneading and shaping, ordinary kneading and forming methods of ordinary cement can be applied. If necessary, organic and inorganic admixtures can be added. A commonly used admixture such as a water reducing material can also be used. When cement is added to waste containing harmful substances, a large amount of cement is required for fixing harmful substances in ordinary cement. The effect is large compared to the amount of ordinary cement. This is due to the characteristic product of hydration of ecocement. When ordinary cement hydrates, C-S-H, calcium hydroxide, ettringite, monosulfate hydrate, etc. are formed, and even if harmful substances are contained inside the hardened cement, each hydrate It has the ability to immobilize harmful substances by being taken in and adsorbed on the surface of the hydrate, or by containment by the dense tissue formed by the hydrate.

Furthermore, since the hardened cement is highly alkaline, it has an effect of precipitating the metal element as a hardly soluble hydroxide. Among these harmful substance fixing functions of ordinary cement, ettringite has a property of easily replacing heavy metals, and is considered to be a hydrate having a particularly high toxic substance fixing ability. While the amount of aluminate hydrate (etringite and monosulfate, etc.) generated when ordinary cement hydrates is about 10%, the amount of aluminate hydrate generated when ecocement hydrates is It is overwhelmingly over 20%.

As described above, due to the characteristic hydration product composition of producing aluminate hydrate in a large amount, a cement hardened body obtained by mixing an ecocement and a processing object containing a harmful substance can be used as a cement cement. It is considered that a smaller amount of cement used has a higher ability to fix harmful substances as compared with the case where is used.

[0017]

Embodiments of the present invention will be described below. Ecocement is manufactured as follows. 54.3% by weight of dried municipal incineration ash, 42.5% by weight of limestone powder, 1.1% by weight of aluminum ash, 1.1% by weight of clay, and 0.5% by weight of fluorite shown in Table 1 were used as raw materials. 1300 using a rotary kiln
The clinker was calcined at 1450 ° C. The resulting clinker was subjected to a vertical mill with a Blaine specific surface area of 4000 cm 2 /
g of the calcined product, and 12 parts by weight of anhydrous gypsum were added to 100 parts by weight of the calcined product to give a Blaine specific surface area of 470.
0 cm2 / g of ecocement was produced. Table 2 shows the mineral composition of the manufactured fired product.

[0018]

[Table 1]

[0019]

[Table 2]

Table 3 shows the chemical compositions of incinerated ash and sludge (two types) containing harmful substances. These incinerated ash or sludge and eco-cement or ordinary cement are respectively 92: 8
, And water was added in an amount of 20% by weight to prepare a hardened cement. Kneading was performed with a Hobart mixer to prepare a 4 × 4 × 16 cm specimen, and after demolding the next day,
Underwater curing was carried out until the age of 28 days. A dissolution test was performed on the cured cement after curing according to the notification of the Environment Agency No. 13. That is, 0.5 to 5.
The particle size was adjusted to 0 mm, the temperature was raised to 20 ° C. with 10 times the amount of water of the hardened cement, and immersed for 6 hours. The filtrate after soaking is
Analyzed by CP.

[0021]

[Table 3]

Table 4 shows the above results. With ordinary cement, when the amount added is 8% by weight, the elution amount exceeds the environmental standard value. On the other hand, in the case of ecocement, it was confirmed that when the added amount was 8% by weight, the value became about the environmental standard or lower. In order to fix each harmful substance in the solidified cement, it is necessary to add eco-cement sufficient to fix each heavy metal, but it can be fixed in a smaller amount than ordinary cement.

[0023]

[Table 4]

[0024]

As described above, the hardened cement according to the present invention has a characteristic hydration product composition that produces a large amount of aluminate hydrate, and thus is harder than the case where ordinary cement is used. It was confirmed that the same amount of cement used had a higher ability to fix harmful substances. In addition, the use of this eco-cement makes it possible to fix harmful substances that are difficult to fix.

Claims (2)

[Claims] 1. A fired product made from at least one of municipal waste incineration ash and sewage sludge incineration ash, wherein C11A7CaC
A harmful substance fixing material comprising a calcined material containing 10 to 40% by weight of at least one of l2, C11A7CaF2 and C3A, and at least one of C2S and C3S, and a hydraulic composition mainly composed of gypsum. 2. As harmful substances, Cr, Cd, Pb, Z
Adding 3% by weight or more of the harmful substance fixing material according to claim 1 to 100 parts by weight of the object containing n, Se, Hg, As, Cu, Mn, Ni, and cyan, mixing and solidifying. A method for immobilizing harmful substances.