JP2009226385A - Method for recycling waste solidified fuel, woody biomass fuel, incineration ashes such as sludge solidified fuel, and contaminated soil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for insolubilizing lead contained in waste solidified fuel, woody biomass fuel, and sludge solidified fuel that exhibit high alkalinity since alkaline chemicals are added in a production process of fuels or a combustion process thereof. <P>SOLUTION: The technology that complies with a soil environmental quality standard by selecting one kind or two kinds or more from ferrous chloride, ferric chloride, ferrous sulfate, and ferric sulfate out of iron salts and mixing them in an addition amount of 0.2 to 0.001%, wherein the produced materials may be utilized as the roadbed and landfill material of roads by using them together with binder materials such as cement of high alkalinity is provided. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

Detailed Description of the Invention

  In the present invention, heavy metals are insolubilized to an incineration ash such as waste solidified fuel, woody biomass fuel, sludge solidified fuel, etc., and waste or contaminated soil with an addition amount of iron salt of 0.2% or less. The present invention relates to a technical field that is recycled and used for roadbed materials.

  Regarding the use of waste solidified fuel, woody biomass fuel, and sludge solidified fuel, it is necessary to reduce the amount of waste when it is disposed of (because there is less room in the waste disposal site), industrial boilers, etc. The problem of soaring heavy oil used in Japan and the effect of suppressing methane gas generation, which has a high temperature rise effect due to decay and decomposition, and the purpose of reducing carbon dioxide generation from fossil fuels (the purpose of preventing global warming, so-called carbon neutral As a policy, it has been actively addressed by the national and local governments (waste disposal) or industrial industries (electrical, steel, paper, petroleum, automobiles, soft drinks, food, gas, forestry, etc.) Is in a situation.

The incinerated ash that burns these contains heavy metals such as lead in units of thousands of mg / kg, so soil environmental standards (for example, lead elution standards: 0.01 mg / L, environmental standards related to soil contamination) Value) and has been landfilled at the final disposal site as waste.

In terms of the disposal category at the final disposal site, lead elution amount of 0.3 mg / L or less can be treated as general industrial waste at the final disposal site, but solidified fuel, woody biomass fuel and sludge solidified fuel. Incineration ash such as [041]. 1 and [042]. As shown in Fig. 2, since those exceeding this standard are included, it is currently being landfilled as a specially managed waste in a block-type disposal site. Expenses related to landfill disposal, etc.) were increasing.

In addition, due to the increase in incineration ash due to new use of solidified garbage fuel, woody biomass fuel, sludge solidified fuel, etc., in the future, the amount of landfill in all facilities will decrease at limited final disposal sites in Japan. There are concerns that some local governments will be unable to secure landfill disposal sites, and there is an urgent need to develop technology to recycle these disposal targets.

Waste solidified fuel, woody biomass fuel, sludge solidified fuel, etc. contain heavy metals such as lead, but as a technology for insolubilizing heavy metals, generally insolubilization due to containment effect by cement, gypsum or asphalt resin, etc. In addition, classification, cleaning, chemical treatment, biological treatment, high temperature treatment, melting treatment, and the like have been developed. Among these, as a measure with relatively low cost, there are many cases that are mainly based on chemical treatment.

In this patent, it is a technical field related to chemical treatment of incinerated ash, waste or soil containing heavy metals, but as a conventional technology related to such chemical treatment, as a chemical excellent in insolubilizing effect regardless of pH change Currently, many treatments of chemically synthesized organic compounds with chelating agents are being carried out. In the actual treatment of the chelating agent, several treatment methods by the chelating agent alone or in combination with a plurality of inorganic compounds are shown. These techniques are described in Patent Document 1 to Patents below. It seems that it was shown in literature 6.
JP-A-9-57234 JP 2002-194328 A JP 2006-686 A JP 2006-136805 A JP 2006-316183 A JP 2007-216078 A

[007] Regarding the treatment method using the chelating agent described in [007], the chelating agent is generally expensive and expensive, and the chelating agent itself is an artificially synthesized chemical substance that does not exist in nature. From the viewpoint of biodegradability, easy and frequent use has been pointed out as a drug that may cause problems.

Against this background, many treatment techniques using chemicals using inorganic compounds have been proposed. Particularly, insolubilization techniques for heavy metals contained in conventional incineration ash etc. are difficult to elute using iron salts. The technology of compounding and the containment technology using the adsorption effect and solidifying agent are shown. In the following [010] description to [029] description, Patent Literature 7 to Patent Literature 22 and Non Patent Literature 1 to Non Patent Literature 2 are shown as conventional techniques. As apparent from these techniques, the most common inorganic chemicals are iron salts. From the description of the addition amount of iron salts (addition amount to incineration ash, waste or contaminated soil), among these materials, the technology with the smallest addition amount is 0.2% or more of iron (described in [021] ( In terms of ferrous chloride, it is 0.23% or more, and for ferric chloride, it is used at an addition amount of 0.29% or more as well. ing. Here, the present invention is characterized in that it can be processed in a state where the addition amount of the smallest iron salt is further reduced, and as a result of detoxification treatment, it is shown to be recycled for banking materials such as roads. The main feature is that it is also a processing technology. In this way, the major factor that has made the detoxification treatment possible by greatly reducing the amount of conventional iron chlorides added is that the waste solidified fuel to be treated is calcium hydroxide during the solidification and molding process. Incineration ash of woody biomass fuel or sludge solidified fuel, etc. are all highly alkaline sprays such as calcium hydroxide and ammonia during the combustion process, and all change to highly alkaline incineration ash. There was to be. Therefore, for such highly alkaline incineration ash, the addition of a small amount of acidic iron salts effectively promotes the agglomeration effect (agglomeration reaction), and thus the insolubilization effect is remarkably exhibited. This is due to the finding. The following shows each treatment technology for incineration ash, waste, and soil using inorganic compounds including iron salts.

Lead content: 6 by adding 50% 15% aqueous solution of ferrous chloride (FeCL ₂ ) to incineration ash and heating to 50-95 ° C. (referred to as ferrite treatment method) , 600 mg / kg of ash has the effect of improving to 0.05 mg / L, and the pH of incinerated ash is adjusted to be effective at pH 7.0 to 11.5.
JP-A-6-134436

A mixture of ferrous chloride solution, ferric chloride solution (FeCl ₃ ) and ferrous sulfate (FeSO ₄ ) for hazardous industrial waste containing heavy metals from municipal waste incineration ash and wastewater treatment plants The lead elution amount 120 mg / L is improved to 0.22 mg / L by adding 30 mL / 100 g ash of the mixed solution, and is improved to 0.1 mg / L or less by adding 40 mL / 100 g ash. It has been shown. In addition, in any claim of Patent Document 8, there is no description about the addition amount of iron chloride.
JP-A-8-99075

It is shown that lead elution 7.5mg / L was improved to 0.05mg / L or less by adding 20% by mixing ferrous sulfate with ferrous chloride solution to insolubilize heavy metals. Has been. Further, in claim 3 of [Patent Document 9], it is indicated by adding 1% to 90% (weight ratio with respect to waste) in terms of Fe for the concentration at which these iron salts are added. In terms of iron salt concentration, the concentration of ferrous chloride (iron molecular weight ratio: 56/128) is about 2.3% to 207% (weight ratio to waste).
JP 2004-209372 A

By adding 10% iron compound consisting of ferric chloride aqueous solution and ferric polysulfate and 10% slaked lime as pH adjuster, lead elution amount of incineration ash: 38mg / L is improved to 0.05mg / L The method is shown.
JP 2005-288378 A

The amount of lead dissolved in incineration ash can be improved from 25 mg / L to 0.05 mg / L or less by adding 7.5 to 10% mixed aqueous solution with ferrous chloride containing a small amount of ferric chloride. It is shown that the mixing ratio of ferric chloride aqueous solution and ferrous chloride was 0.2 to 1.0% (ferric chloride aqueous solution 1.5 to 10% concentration).
JP 2006-150339 A

Regarding the insolubilization technology of heavy metals mixed with sodium silicate (water glass) and sodium carbonate, sodium silicate 5-10%, sodium carbonate 10-20% addition, lead elution 4.1mg / L is 0.19mg / L It is shown that it was able to improve.
JP-A-9-187750

This is a technology that mixes sodium sulfate (Na ₂ S) and iron sulfate (FeSO ₄ ) to insolubilize them as synthetic iron sulfide minerals. These are mixed 0.5% and lead elution is 0.09 mg / L to 0.01 mg. It is shown that the improvement is less than / L.
JP 2001-121130 A

Add 10% acidic substance consisting of aluminum sulfate powder or ferrous sulfate powder, reduce the alkalinity from pH 12.4 to 7.78, and suppress lead elution, and heat-mold and solidify with resin The lead elution was improved from 0.247 mg / L to 0.001 mg / L.
JP 2001-46998 A

It is a technique of solidifying with a combination of iron oxide powder, iron hydroxide and gypsum, and it has been shown that addition of 70% or more is effective for insolubilizing heavy metals in mud-like materials.
JP 2006-205152 A

It is a technology that heats a magnesium ammonium phosphate compound to enhance the adsorption effect and adsorbs and insolubilizes heavy metals.
JP-A-2005-230657

As an insolubilization treatment of heavy metals contained in incineration ash, spraying of slaked lime water has been made to remove SOx from the combustion gas of incineration ash, and as a result, the original pH of the incineration ash was about 5.8 to 7.0 However, there is a problem that lead is easily eluted with pH 12 and high alkalinity. In order to suppress the elution of lead from such highly alkaline incineration ash, it is considered effective to reduce the alkalinity, and a sulfuric acid solution is added, and as a result, the pH is adjusted to about 10 ± 0.5. Thus, a technique that suppresses lead elution is shown.
JP 2000-288505 A

As a method for preventing heavy metal elution from incinerated fly ash, 15-30% cement is added, ferrous sulfate is added 11-15%, and 15-20% is added, and the lead elution amount is 1.4-2.8 mg / L. Is improved to 0.01 mg / L or less. Claim 1 of Patent Document 18 describes that 0.1% or more of iron salt (including ferric chloride) is added in terms of iron. This is 0.23% in terms of concentration of ferrous chloride (iron molecular weight ratio: 56/128) solution, and in terms of concentration of ferric chloride (iron molecular weight ratio: 56/162) solution, It becomes 0.29%.
JP 2002-86100 A

Technology is shown to add 5-30% cement to incineration ash, sludge, low quality, stone powder, regenerated powder, etc., stir using an agitation granulator, and cure and solidify this to contain harmful substances Yes.
JP 2004-8945 A

About the method for reducing heavy metal elution from incinerated fly ash, a technique that uses ferrous sulfate and an oxidizing substance (hydrogen peroxide or sodium hypochlorite) in combination. It shows that 2 mg / L is improved to 0.01 mg / L or less, and it is shown that the effect is obtained particularly when 10% of cement is mixed. Also, ferrous hydrochloride and ferrous nitrate are indicated in the claims by the same treatment.
JP-A-10-113637

In order to promote solidification in the soil solidifying agent, magnesium oxide and ferric chloride aqueous solution are used, but the ferric chloride aqueous solution has a remarkable agglomeration effect. This technique is characterized in that an aqueous ferric chloride solution is adsorbed in advance and both agents can be mixed at once. Although it has the effect of suppressing corrosion of equipment by ferric chloride aqueous solution, it does not mention the problem of insolubilization of heavy metals due to solidification of soil.
JP 2002-167582 A

In order to insolubilize heavy metals such as soil, there is a technology to neutralize by adding 10% or more of aluminum sulfate, polyaluminum chloride, ferrous sulfate, ferric chloride, etc. as magnesium oxide and acidic solidification aid It is shown.
JP 2002-206090 A

So far, incineration ash, mainly coal ash. Although it has been limited to cement raw materials, a technology to recycle resources by removing harmful substances with sulfuric acid cleaning and cleaning liquid centrifuges has been introduced.
"Succeeded in detoxifying coal ash" described in the Hebei Shinpo Newspaper (February 16, 2008, morning edition)

As for the purification method of contaminated soil, a technique is shown in which contaminants are separated by classification and washing, and these contaminants are separated by vibration, bubbles, etc. in a separation tank.
JP 2002-254063 A

A technology that uses magnesium oxide powder to solidify and insolubilize contaminated soil is shown.
JP 2003-334526 A

An example of insolubilization treatment using ferric chloride solution on soil contaminated with arsenic is shown.
Homepage (High-speed insolubilization treatment of low-concentration arsenic-contaminated soil, Konoike-gumi Civil Engineering Publication)

Problems to be solved by the invention

  Waste solidified fuel, woody biomass fuel, and sludge solidified fuel are energy sources almost comparable to the calories burned by lignite, so the recent problem of soaring crude oil, etc. and the problem of restraining carbon dioxide emissions from fossil fuels (Kyoto Protocol) From this background, there is a tendency to increase use as new thermal energy. However, as a result of the expansion of incineration of these newly manufactured fuels, a large amount of incineration ash is also discharged, and the treatment is landfilled at the final disposal site. The development of technology that makes them harmless and uses them effectively (recycles) is desired.

In particular, as for solidified fuel, the use of what has been disposed of before incineration has been promoted as a measure, and the generation of incinerated ash will increase. In addition to the use of construction waste, etc., woody biomass (because it has become difficult to secure construction waste due to the expansion of use), unused parts discharged from the sawmill (in the sawmill process) 60 to 70% of lumber and 30 to 40% of unused parts) are also being used, and effective use of all organic matter discharged from thinned wood, lumber mills and paper mills is promoted. Similarly, incineration ash will increase in the future.

Sludge solidified fuel uses sludge discharged from sewage treatment facilities and food factories that treat sewage and human waste, but the manufacturing process consists of dried or steamed and shaped into granules or pellets. Of these, steamed and carbonized (steamed at 850 ° C, there is a problem of dioxins formation in the absence of oxygen, and their decomposition; temperature setting considering 800 ° C), breathability, water retention, water permeability It has excellent properties and contains minerals and phosphoric acid, so it is used as a soil improvement material for horticulture, snow melting material, etc. Since it has a calorific value, many are incinerated as solid fuel. For this reason, it is thought that incineration ash of sludge solidified fuel will increase in the future, and it is necessary to develop effective utilization (recycling) technology instead of landfill disposal at the final disposal site as a treatment measure. .

Incineration of such waste solidified fuel, wood ash biomass fuel, sludge solidified fuel, etc. has a problem of generating highly toxic dioxins, but in order to prevent the generation of dioxins during combustion, as described in [032] As an effective technique for promoting the decomposition, it is in the process of incineration at a high temperature of about 850 ° C. (because dioxins are decomposed at 800 ° C. or more). Among the heavy metals originally contained in mercury, mercury (Hg) is also incinerated at a temperature higher than the boiling point (boiling point of mercury: 356.73 ° C.), and thus vaporization is promoted. Incineration ash contains almost no mercury. It is also a feature that is not a problem in terms of elution standards.

As for the characteristics of these incineration ash, incineration facilities that burn these are often large-scale, but in such incineration facilities, SOx (sulfide) and NOx (nitrate oxide) from exhaust gas in the combustion process. ) Emission control (which forms a compound and is removed by solidification / precipitation), a technology to spray calcium hydroxide (Ca (OH) ₂ ) and aqueous ammonia (NH ₄ OH) was introduced. ing. As a result, the incineration ash originally exhibits weak acidity (pH 5.8 to 7.0), but the incineration ash generated by the addition of these highly alkaline chemicals (particularly incineration fly ash) A major feature is that it exhibits a high alkalinity of pH 11 or higher.

In order to insolubilize heavy metals such as lead using iron salts (here, ferrous chloride) with the techniques of Patent Document 7 described in [010] and Patent Document 17 described in [020], slaked lime This shows a technique for promoting the reaction by adding acidic iron chloride after adding (calcium hydroxide) to make it alkaline. However, all of the incinerated ash, such as waste solidified fuel, woody biomass fuel, and sludge solidified fuel, which is the object of this patented technology, is now being sprayed with alkaline chemicals as shown in [034] in the combustion process. It is a great feature that it exhibits high alkalinity of pH 11 or higher, and there is no need for pH adjustment (adjustment for making incineration ash alkaline) when adding iron salts.

Of these, incineration ash of solidified fuel is the one that exhibits the highest alkalinity, but this is caused by the measures taken to prevent dehydration, decay, and odor generation in the process of solidification and processing into pellets when producing solidified solid fuel. For this purpose, about 5% slaked lime (calcium hydroxide, half of water molecules are removed when baked) or quick lime (calcium oxide, which reacts violently with water to form calcium hydroxide) is mixed. It is characterized by the fact that the mixing of these is aimed at removing moisture contained therein and raising the temperature to promote drying, as well as sterilization, anti-corruption and deodorizing effects. As a result, although the weight of the combustion ash of the solidified fuel is reduced to about one-tenth of that before combustion, a large amount of calcium hydroxide remains as an incombustible material, so that the pH is 12 as described in [041]. It is characterized by being a factor exhibiting the above high alkalinity.

In addition, as shown in the analysis results described in [041], such incinerated ash shows that elution of lead (Pb), which is the most contained of heavy metals, is a problem. From the viewpoint of the elution characteristics of lead, it is known that there is a characteristic that it is easy to elute in a highly alkaline region (pH 11 or more) and an acidic region (pH 6 or less), and difficult to elute in a neutral region.

Thus, because of the elution characteristics of lead, any incineration ash such as waste solidified fuel, woody biomass fuel, and sludge solidified fuel exhibits a high alkalinity of pH 11 or higher. It can be seen that insolubilization measures are a major problem.

As for the general waste and industrial waste according to claims 4 and 5, those that contain organic matter such as household waste and food waste are mostly treated at the incineration site, [034] By the combustion process similar to that described, the incinerated material exhibits high alkalinity. Currently, the surplus amount of final disposal sites for these wastes is decreasing in each local government, and it is difficult to construct new disposal sites, so it will be necessary to develop technologies to recycle these wastes. it is conceivable that.

The need for such a regeneration technique is the same for the treatment of contaminated soil, and there is a need for recycling as well, and the technique described in claim 6 is necessary. We think that it is desirable to use for materials.

table. Fig. 1 shows the analysis results of incinerated ash (in this example, incinerated fly ash) using solidified fuel prepared from collected household waste for boiler overheating. From the table, lead is contained in a large amount and is highly alkaline with a pH of 12.6. In the dissolution test results (analysis method: according to Notification No. 46 of the Ministry of the Environment, 1991), lead is 7 .5mg / L, which is much higher than the environmental standard, and it is 0.3mg / L or more from the waste acceptance standard. The final disposal of specially managed waste is obliged to be landfilled at a shut-off type final disposal site, and with such a disposal method, the disposal cost increases and the amount of surplus disposal site is drastically reduced. It is a big problem, and technology development to recycle these is necessary.

table. Fig. 2 shows the results of analysis of incineration ash (in this case, incineration fly ash) of woody biomass fuel. The raw material of the woody biomass here is mainly construction waste, which is made into chips and burned for boiler heating in a large paper mill. Also in the table, the lead content is high, indicating a high alkalinity of pH 12.1. Table. 2 is a table described in [041] in the lead dissolution test results. The value is smaller than 0.5 (0.52 mg / L), but this is caused by the final disposal or intermediate disposal acceptance standard of discharged incinerated ash (lead elution standard is 0.3 mg / L or less) For the purpose of clearing the acceptance criteria for intermediate disposal sites for disposal or recycling as normal industrial waste, a chelating agent has already been added to incineration ash to suppress lead elution. It is because it is.

table. 3, the table. In order to recycle the incinerated ash of the solidified fuel shown in Fig. 1, the lead containment effect by cement solidification was tested (container test with 1 kg of test sample, elution test conducted for 7 days). . As is apparent from this test result, since the cement itself is mainly composed of strong alkaline (about pH 13) calcium hydroxide, the increase in the mixing amount of cement makes it more alkaline and facilitates the elution of lead. It has been shown. Therefore, it can be understood that the containment method by cement solidification does not exhibit the effect of insolubilization of lead even if the amount of cement is increased, and it is difficult to perform the insolubilization treatment with cement alone (the amount of cement mixed is 10% or more for solidification).

Table 6 shows examples of test data for purification treatment of contaminated soil according to [Claim 6]. 4 (container test of 3 kg test sample). In the same table, it was carried out as a laboratory test for carrying out insolubilization treatment work in which cement was mixed with soil containing low levels of lead and contained. From the same table, the insolubilization effect of lead can be seen even when a small amount of cement is mixed, and the environmental standard is satisfied by mixing 1.5% and 2.5%. It is also shown that the elution suppression effect is not exhibited, and it is understood that the cause thereof exhibits high alkalinity due to an increase in cement. Therefore, in carrying out the method for insolubilizing lead with cement, an increase in the amount of highly alkaline cement has an adverse effect, and in order to carry out the containment method with cement, as described in [043] In combination with other insolubilizing agents, it is necessary.

Means for solving the problem

  In the recycling of incinerated ash from solid waste fuel, woody biomass fuel and sludge solidified fuel, it is necessary to suppress lead elution and satisfy the soil environment standard (lead elution amount 0.01 mg / L or less). However, since both are highly alkaline with a pH of about 11, measures for insolubilization of lead among heavy metals are the most important issue. Also, waste and contaminated soil that have already been disposed at the final disposal site can be used as recycled materials if insolubilization of heavy metals including lead is removed.

In the present invention, since such incineration ash exhibits high alkalinity, one or two kinds of ferrous chloride, ferric chloride, ferrous sulfate, and ferric sulfate are used from acidic iron salts. It is selected as described above, and it is characterized by being a technology that satisfies the soil environmental standards by adding 0.2% or less and insolubilizing lead, which is the most problematic in the use of incinerated ash.

Among these iron salts, strong acid chemicals such as ferric chloride have a concentration of 37% (31% ferrous chloride solution) when transported from the manufacturing plant. Originally, it is used for etching electronic parts or recently as a drug for eluting metal from shredder waste, and it is a chemical that has a remarkable corrosion effect on metals that corrode stainless steel. When such strongly acidic chemicals are actually used in intermediate processing facilities or mobile processing facilities, corrosion damage is a major obstacle to the equipment and plants used. Since the addition amount is 0.2% or less, it has become possible to minimize the influence from the corrosion failure by diluting with water in advance. That is, the incineration ash to be treated has a high alkalinity of pH 11 or higher as described above, and even if a strongly acidic chemical of 0.2% or less is added to this, it is mixed and quickly becomes highly alkaline (pH Therefore, the problem of corrosion of the equipment used is minimally reduced (contact with the bottom and side surfaces of the container or the splashed chemical adheres at the moment of addition). Rather, it was also confirmed that mechanical abrasion or chipping becomes a problem due to stirring when mixing incinerated ash. From this, it is possible to use a strong acid ferric chloride solution in a safe manner, and it can be said that this is a technique in which hesitation in use has been eliminated.

Of the iron salts, ferrous sulfate is neutral and is a food additive used for iron supplements. However, ferric sulfate and ferric chloride are strongly acidic drugs. Among them, ferric chloride had a total production of about 350,000 tons in Japan, but recently its production is low. It is a drug that has become. This is due to changes in the structure of the industry, and the most demanding area for ferric chloride was the production process of cathode ray tubes for electronic equipment. Is in a situation. In addition, a pharmaceutical manufacturer with the highest production volume in Japan (production of 200,000 tons per year) caused major environmental problems due to a leakage accident from a production plant in 2004 and a spill accident in a rear-end collision on a highway in 2006. It is also a drug that has been discontinued due to this.

Based on such circumstances, it is necessary to ensure the safety of storage facilities and additive facilities of this chemical for treatment methods using strong acidic chemicals such as ferric chloride. When storing (in the case of ferric chloride solution: 37% concentration), store it in a receiving container diluted to 10% concentration, and add it to a solution of 0.2% or less by adding water in the adding step. Therefore, safety in storage and use can be secured.

The incineration ash to be treated such as waste solidified fuel, woody biomass fuel, sludge solidified fuel, etc. is highly alkaline with a pH of 11 or higher, but when mixed with about 10-15% of highly alkaline cement. However, since the properties are the same (pH becomes higher by about 0.5), it can be used together with cement solidification. In mixing the cement, the pH transitions to a higher alkalinity and lead is more likely to be eluted. Therefore, it is necessary to increase the amount of iron salt added. However, even in this case, it has been confirmed that an insolubilizing effect can be obtained with an addition amount of 0.2% or less.

In addition, what mix | blended cement is also characterized by the technique which can be utilized as a reclaimed material for the embankment of a road, etc. by grind | pulverizing the lump-like processed material after solidification, or granulation with an agitator etc.

Embodiments of the Invention

  The composition analysis of the incineration ash of the solidified fuel and the incineration ash of the woody biomass fuel was carried out to confirm the components, content and pH of the heavy metals contained. Next, the incineration ash elution test was carried out, and the heavy metals in question were identified against the environmental standards. As a result, it was confirmed that the insolubilization treatment of lead was the most important because all the incineration ash exceeded the elution standard of lead. In addition, since all incineration ash is highly alkaline with a pH of 12 or higher, select ferric chloride solution and ferrous sulfate from iron salts with insolubilizing effect in order to achieve insolubilizing effect of lead. The insolubilization effect was confirmed. In the addition test of these agents, the addition test of the chelating agent was performed as a guideline for the insolubilizing effect because the chelating agent shows a certain insolubilizing effect.

In conducting the insolubilization effect test of chemical treatment with iron salts, in addition to confirming the insolubilization effect by addition of iron salts alone, the effect of commercially available chelating agents was confirmed, and in consideration of cost, chelating agents and iron A combination test with salts was also conducted. Among the iron salts, ferrous sulfate (powder) is commercially available, and ferric chloride (liquid) was obtained as a reagent in the container test, but in the kneading machine and actual machine test, the production factory ( Rasa Industrial Co., Ltd., Gunma Factory).

The insolubilization test was conducted by diluting iron salts and changing the amount added. The first scale of the test was an indoor container test (test with a sample of about 1 kg). ) The second is a test with a 50 L kneader (test with a 20 kg sample), and the third is a real machine (test with a 1 t sample with a 2.9 m ³ stirrer that is actually operating in an intermediate processing plant). The dissolution test was carried out after curing for 1 to 7 days to confirm the insolubilization effect.

In addition, the insolubilized material was subjected to a physical test (test according to JIS standards) of the roadbed material to confirm that it could be recycled.

  The insolubilization effect test of the chemical | medical agent about the refuse solidification fuel and woody biomass fuel of Claim 1 and Claim 2 was implemented. For the selection and use of chemicals and test procedures, (1) test with chelating agent (commercially available), (2) ferrous sulfate (powder, commercially available), and (3) chelating agent, ferrous sulfate used Tests such as a case of cement mixing by (4), a test by (4) ferric chloride, and (5) a case of cement mixing by ferric chloride were carried out. It should be noted that both the mixing machine and the actual machine test are cement mixing cases.

table. 4 shows the result of a chemical treatment test (using a chelating agent) of the incinerated ash (unit volume weight: 0.65 t / m ³ ) of the solidified fuel. From the table, it was confirmed that the amount of the chelating agent added was 3% and the environmental standard was satisfied with respect to the lead elution amount of 7.5 mg / L.

table. Fig. 5 shows the results of a chemical treatment test (using ferrous sulfate) of incinerated ash of solidified fuel. From the table, it is considered necessary to use an addition amount of 6% or more in order to satisfy the environmental standards due to the addition of ferrous sulfate. Here, ferrous sulfate is a neutral chemical and has little effect of reducing pH against highly alkaline incinerated ash, but heavy metal such as lead is adsorbed to the added ferrous sulfate powder and insolubilized. It is considered that an effect can be obtained.

table. 6 shows the results of a chemical treatment test (using a chelating agent) of incinerated ash of woody biomass fuel. From the table, it was confirmed that the amount of chelating agent added was 0.5% and the environmental standard was satisfied with respect to the lead elution amount of 0.52 mg / L.

table. 7 shows the results of a chemical treatment test (using ferrous sulfate) of wood biomass fuel incineration ash. From the table, it was confirmed that the environmental standard was satisfied with the addition amount of 0.5%. From the table, it is shown that it is difficult to add 0.2% or less shown in claim 1 of this patent in order to insolubilize lead by adding ferrous sulfate.

table. 8 shows the results of a chemical treatment test of incinerated ash of woody biomass fuel (when solidified by mixing 10% of cement, the addition of the chemical is by the combined use of a chelating agent and ferrous sulfate). It was confirmed that the environmental standard was satisfied by adding 2% of the chelating agent added 0.5% by mixing 10% of cement and 1% of ferrous sulfate added thereto. From the same table, the pH of [060] described by mixing 10% cement. 7 was confirmed to rise from 10.5 shown to 11.8, and the pH at which lead is more easily eluted is exhibited. As a result, it was confirmed that the amount of drug added increased as a result.

table. 9 shows the result of the chemical treatment test of the incinerated ash of the solidified fuel (in the case of 10% cement mixing, using ferric chloride solution). In this table, the ferric chloride solution stock (concentration 37%) was diluted to a concentration of 10%, and this was carried out as the basis of the amount added. By adding 3% of this to the weight of the incinerated ash, it has been confirmed that the environmental standard is satisfied. The amount of ferric chloride added at this time is 0.25% of the total weight of the incinerated ash considering water (20%). In the same table, the reason why the insolubilization effect of lead is not exhibited in proportion to the increase in the amount of ferric chloride used is that the formation of lead chloride was promoted by the addition of ferric chloride. As a result, it can be considered that lead chloride is the compound most easily dissolved in water among lead compounds.

table. 1 is an effect test using a 20 kg sample by a 50-liter kneader, in which the incineration ash of the solidified fuel and the incineration ash of the woody biomass fuel were mixed at a ratio of 1: 3, when the cement was mixed with 10%. This is a test in which ferrous sulfate was added. The amount of ferrous sulfate added is approximately 1%, which is considered to satisfy environmental standards. This kind of incineration ash mixing treatment is caused by the fact that the amount of incineration ash from the solidified fuel carried into the intermediate treatment facility is less than the incineration ash from the woody biomass fuel. Thus, the treatment method can be handled by the same treatment method at a time without changing the addition amount of the drug, and is considered to be an effective means in practice.

table. 11 shows the results of a demonstration test in which a ferric chloride solution was added to a test sample of 20 kg using a 50 L kneader. From the table, solidified fuel is set to this mixing ratio because the amount of arrival at the intermediate treatment facility is relatively small. At this time, it was confirmed that the insolubilization of lead satisfying the environmental standard could be achieved by adding 10% concentration of ferric chloride solution at 1% (the total amount of ferric chloride was 0.058%). It was done. After this test result, a demonstration test (test sample 1t, tested in 3 cases) using actual equipment (2.9m ³ agitator, 2 units) of the processing plant actually operating in the intermediate treatment facility As a result of carrying out (implementation), a similar insolubilization result could be obtained.

The invention's effect

  The present invention arranges the existing knowledge about the composition and elution characteristics of incinerated ash such as solidified solid fuel, woody biomass fuel, and sludge solidified fuel that is expected to increase. It is clear that all of these have high alkalinity and lead elution is a problem. In this detoxification treatment, insolubilization of lead is the most necessary, and the development of effective drugs for this purpose And the development of the addition method has been carried out using the sample and analysis room of the facility that actually performs the intermediate treatment. As a result, it was confirmed that it is effective to select one or more of ferrous chloride, ferric chloride, ferrous sulfate, and ferric sulfate among iron salts, and a series of treatments. The test has been conducted from a container test to a kneading machine test and a demonstration test using an actual machine (large stirrer) actually operated in an intermediate treatment facility. As a result, these incineration ash is characterized by high alkalinity having a pH of 11 or more due to the addition of alkaline chemicals (calcium hydroxide, ammonium, etc.) during the fuel production process or combustion process. For this reason, for example, it was confirmed that the insolubilizing effect of lead appears remarkably by mixing and stirring by adding a strong acidic solution such as ferric chloride solution. When the above-mentioned ferric chloride solution is used by confirming such a remarkable insolubilizing effect, the addition amount described in the claim of Patent Document 18 described in [021] (Claim 1:. As shown in [062] and [064], it was confirmed that environmental standards were satisfied with less than 2% to 100%). The knowledge of effective drug use was the first in the present invention.

Therefore, for such detoxification treatment of incinerated ash generated in large quantities, the addition amount of chemicals such as ferric chloride is effective at a small amount of 0.2% or less, which is the cost of using chemicals It is also very effective for reduction, and it can be said that it is the most advantageous treatment method at present compared with the conventional treatment costs with chelating agents and other inorganic compounds.

table. 12 shows the estimated construction cost from the amount of chemicals used to satisfy the environmental standards and the purchase price, which was clarified from the results of this treatment test in the detoxification treatment of incinerated ash of solidified solid waste fuel and woody biomass fuel. Is a comparison. As apparent from the table, when ferric chloride is added, it is possible to add the amount of 0.2% or less, which is the claim of the present invention, and from the viewpoint of cost, the conventional chemical treatment can be performed. It will drop to 4 to 5 times.

table. 13 shows a test result as a roadbed material by a sample after cement solidification generated in an actual machine test. This sample has already been subjected to a series of test results of environmental standards related to soil (first type: organic solvent type, second type: heavy metal type, dioxins, etc.). Of course.

[067] The test results as roadbed materials in the sample of detoxified mixture of waste solidified fuel and wood biomass fuel incinerated ash shown in [067] are materials that can be sold to construction companies, etc. , Processing costs when receiving treatment as an intermediate treatment facility (income: 20,000-30,000 yen / ash t) and treated recycled materials can be sold to construction companies etc. (income: 500-1,000 yen / ash) Therefore, a stable income source can be obtained. From the perspective of a construction company that purchases such recycled materials, the purchase cost of ordinary roadbed materials is around 3,000 yen / t. As a result, it is considered that recycling can be surely expanded by establishing mutual distribution routes.

As described in [004] and [005], the expansion of the use of waste solidified fuel, woody biomass fuel and sludge solidified fuel means that incineration ash generated from them will be landfilled at the final disposal site as before. However, there is a problem that causes a rapid decrease in the amount of the disposal site. However, if the recycling is expanded as described in [068], these problems can be solved. In addition, it can be said that good news will be given to the situation where it is difficult to develop a new disposal site if this recycling can be applied to incinerated waste and contaminated soil that have already been landfilled.

In addition, as a problem remaining in the future, it is widely used in construction materials such as roadbed materials as described in [068] by adding ferric chloride as shown in the present invention in the detoxification treatment of each incineration ash. When it is done, it is necessary to grasp and evaluate the durability of lead re-elution problems in detail. For this purpose, for example, it is necessary to carry out an availability test (elution test standard in pH 4 and alkaline region), and the test is currently being prepared. Therefore, in the present use for construction materials such as roadbed materials and banking, a certain degree of blending (about 5 to 30%) is used with general crushed stones.

Claims (6)

Among ferrous salts, select one or more from ferrous chloride, ferric chloride, ferrous sulfate and ferric sulfate, and add in the range of 0.2% to 0.001% , Recycling incineration ash from solidified fuel. Among ferrous salts, select one or more from ferrous chloride, ferric chloride, ferrous sulfate and ferric sulfate, and add in the range of 0.2% to 0.001% , Recycling incineration ash of woody biomass fuel. Among ferrous salts, select one or more from ferrous chloride, ferric chloride, ferrous sulfate and ferric sulfate, and add in the range of 0.2% to 0.001% , Recycling sludge solidified fuel incineration ash. Among iron salts, one or more selected from ferrous chloride, ferric chloride, ferrous sulfate and ferric sulfate, with an addition amount in the range of 0.2% to 0.001%, A method of recycling general waste. Among ferrous salts, select one or more from ferrous chloride, ferric chloride, ferrous sulfate and ferric sulfate, and add in the range of 0.2% to 0.001% , How to recycle industrial waste. Among ferrous salts, select one or more from ferrous chloride, ferric chloride, ferrous sulfate and ferric sulfate, and add in the range of 0.2% to 0.001% , How to recycle contaminated soil.