JP2006181535A - Combustion ash treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a processing method of incineration ash for suppressing the elution amounts of fluorine and boron contained in incineration ash to environmental quality standard values. <P>SOLUTION: The processing method of incineration ash involves mixing the incineration ash with calcium oxide and/or calcium hydroxide, blast furnace cement, and aluminum sulfate in the presence of water and is capable of suppressing elution of fluorine and/or boron contained in the incinerator ash to 0.8 mg/L or lower for the fluorine elution and 1.0 mg/L for boron elution in the case the elution is measured by an elution testing method according to No. 18 Notification of Ministry of Environment in 2003. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for treating combustion ash. In particular, the present invention relates to a treatment agent and a treatment method for combustion ash containing fluorine and boron. In addition, since the present invention conforms to the elution regulation values of fluorine and boron, which are substances regulated by the Soil Contamination Countermeasures Law enacted in February 2003 by the Ministry of the Environment, combustion ash containing them is converted into calcium oxides. And / or by mixing with calcium hydroxide, blast furnace cement and aluminum sulfate in the presence of water, the elution amount of fluorine contained in the combustion ash is 0.8 mg / L or less, and when boron is contained. The present invention relates to a method for treating combustion ash that makes an elution amount of boron 1.0 mg / L or less.

  Fluorine has been considered effective in preventing dental caries, but its overdose is not limited to patchy teeth, and bones and joints called fluorosis are deformed, causing osteosclerosis and affecting the nervous system. It is coming. Boron is a basic material that is widely used in the production of surface treatments such as plating, glass, disinfectants, resins, chemicals, and fertilizers. As for the health effects on rats, cases such as vomiting, diarrhea and nausea due to high concentration intake have been reported, and it is said that suppression of fetal weight gain was observed in teratogenicity tests in rats. In order to prevent these effects, insolubilization technology of fluorine and boron plays an important role.

  Fluorine and boron are also contained in combustion ash such as household waste incineration ash, coal combustion ash (coal ash) from thermal power plants, sewage sludge incineration ash, and various industrial wastes. Since the coal originally contains several to several hundred mg / kg of fluorine and boron, the content of fluorine and boron is high. In addition, since most of the combustion ash is used as a soil conditioner or backfill material, there is a concern that it will elute due to rain and cause groundwater contamination. In addition, since there is also a shortage of landfills where the combustion ash is reclaimed, it is desired to make effective use by making fluorine and boron in the combustion ash non-eluting.

  As methods for detoxifying harmful substances in combustion ash, melt solidification methods, cement solidification, addition of lime, etc., extraction treatment with acids or other solvents, and the like have been proposed. However, there are few means that can suppress elution of fluorine and boron at the same time, and there are still few practical ones.

  The melt-solidification method (Patent Document 1) decomposes organic matter by heating waste to a high temperature of 1400 to 1600 ° C., and encloses and fixes the waste in slag that generates toxic substances such as heavy metals. However, there is no description or suggestion that fluorine or boron is immobilized. In addition, this method is said to have the highest safety, but there are drawbacks such as the problem of fly ash treatment containing newly generated higher concentration of harmful substances, and the processing cost including equipment costs is low. The highest is also a problem.

  There is a method of suppressing elution by solidifying boron in coal ash with blast furnace cement (Patent Document 2), but since it takes about one week to cure before solidifying, it is subject to the restriction that an ash storage place after treatment is required In addition, even if solidified due to the properties of ash, the solidified product may not be durable. For example, cement is weathered and ash components are eluted, and contamination due to this may be considered. Further, elution can be suppressed by this method only with boron, and an effect on fluorine cannot be expected.

  In addition, there is a method (Patent Document 3) in which lime, coal combustion ash, and gypsum are kneaded in the presence of water to control sludge and elution of fluorine and boron. It takes about one week to cure, and is subject to restrictions such as the need for a post-treatment ash storage place as above. Furthermore, solidification proceeds after the treatment, and it becomes difficult to use it for soil improvement materials or banking.

  Furthermore, there are methods of adsorbing and removing fluorine and boron in wastewater by hydrous zirconium oxide composite hydrophilic polymer molding (Patent Document 4) and magnesium oxide baked at a temperature of 1400 ° C. or lower (Patent Document 5). It is technically difficult to apply this method to detoxification of combustion ash, and even if these expensive and time-consuming adsorbents are added to ash, the effect of insolubilizing fluorine and boron is unknown, The adsorbent cannot be recovered and is a very expensive technique, which is not realistic.

  Boron removal by extraction of acids such as acids (for example, Non-Patent Document 1) requires a large amount of water and time for the treatment, and also requires ancillary facilities such as treatment of wastewater containing boron. Necessitating a large amount of equipment and the equipment cost is enormous, which is not suitable for practical use. Also, this method has no clear effect on fluorine.

There are also a method in which fluorine or boron in soil or incinerated ash is solidified by adding calcium salt to cement (Patent Document 6) and a method in which magnesium oxide and gypsum are solidified and insolubilized (Patent Document 7). However, it takes 7 days to cure and is restricted due to its solidification. When burning ash is used as a soil conditioner used to improve snowmelt or acid soil, as a banking material for construction work, and as a backfill material, methods for simultaneously suppressing elution of fluorine and boron are limited. Also, it is not possible to use methods such as cementing with cement. Furthermore, there should be no restriction that the processing requires a lot of time and place, and furthermore, the suppression effect must be exhibited in response to fluctuations in the fluorine and boron contents in the combustion ash. As described above in detail, no satisfactory ash treatment method that can simultaneously suppress the elution of fluorine and boron has been proposed.
JP-A-9-271738 JP 2001-310175 A JP 2002-346595 A JP 2002-38038 A JP 2001-340872 A JP 2004-89816 A Japanese Patent Laid-Open No. 2004-298741 Obayashi Institute of Technology Report No. 65 2002 P95-100

  The present invention provides a method for suppressing elution of fluorine and boron from ash discharged from an incinerator such as combustion ash and paper sludge discharged from a boiler using coal or RPF as a fuel. Such as complicated, time-consuming and costly methods, and simple and inexpensive methods that replace time-consuming methods to achieve the effects. The purpose is to make effective use of combustion ash, which has no fear of causing, in various applications such as soil improvement material, grassland improvement material, backfilling material, and embankment.

  The present invention is a method for suppressing elution of fluorine and boron contained in combustion ash, and includes the following inventions that can solve the above-mentioned technical problems.

(1) Combustion ash is mixed with calcium oxides and / or calcium hydroxide, blast furnace cement and aluminum sulfate in the presence of water, and the above-mentioned is carried out according to the dissolution test method based on Notification No. 18 of the Ministry of the Environment in 2003. Combustion ash having a fluorine elution amount of 0.8 mg / L or less and a boron elution amount of 1.0 mg / L or less when fluorine contained in the combustion ash is eluted is prepared. , Combustion ash treatment method.

(2) The combustion ash is at least one selected from coal combustion ash, RPF (Refused Paper and Plastics Fuel) combustion ash, combustion ash discharged from a papermaking sludge incinerator, etc. Alternatively, the combustion ash treatment method according to (1), wherein the combustion ash contains boron.

(3) lime obtained by calcining a calcium source selected from limestone, dolomite, scallops, paper sludge, and waste paper cake, and the calcium oxides and / or calcium hydroxides used in the treatment of the combustion ash, and The method for treating combustion ash according to item (1) or (2), which is at least one kind of hydroxide.

(4) Any of (1) to (3), wherein the blast furnace cement is at least one selected from Class A, Class B, and Class C having quality defined in Japanese Industrial Standards of JIS R 5211 2. A method for treating combustion ash according to item 1.

(5) The mass ratio of the combustion ash and calcium oxides and / or calcium hydroxide, the mass ratio of combustion ash and blast furnace cement, and the mass ratio of the aqueous solution of combustion ash and aluminum sulfate are: Or calcium hydroxide is 100 / 0.5-10, combustion ash / blast furnace cement is 100 / 0.5-10, and the aqueous solution of combustion ash / aluminum sulfate is 100 as the ratio of combustion ash / aluminum sulfate. The method for treating combustion ash according to any one of (1) to (4), which is /0.5 to 10.

(6) The mass ratio of the combustion ash to calcium oxides and / or calcium hydroxides is 100/5 to 10 for combustion ash / calcium oxides and / or calcium hydroxides (1) to (5) The method for treating combustion ash according to any one of items 1).

  The present invention is a method for simultaneously suppressing the elution of fluorine and boron from ash discharged from an incinerator such as combustion ash from a boiler fueled with coal or RPF and paper sludge. It is possible to provide a simple and inexpensive method that replaces the complicated and time-consuming method described above and the method that takes time to achieve the effect. Soil contamination and water contamination by suppressing elution of fluorine and boron. It is possible to use the burned ash that does not cause the occurrence of snow as a snow melting material, soil improving material, grassland improving material, backfilling material, embankment, etc. without adversely affecting the environment.

The present invention will be specifically described below.
The insolubilization mechanism of fluorine and boron contained in combustion ash etc. is not clear at present, but various sulfate groups in the presence of calcium oxides and / or calcium hydroxides and blast furnace cement as treatment agents as in the present invention. When trying to add an aqueous solution containing (sulfuric acid, gypsum, sodium sulfate, aluminum sulfate, ferrous sulfate, etc.), surprisingly, by using an aqueous aluminum sulfate solution, fluorine and boron can be added in just a few hours after treatment. At the same time, it was found that there is an effect of suppressing elution. Therefore, the method of the present invention is most effective when applied to the treatment of combustion ash containing both fluorine and boron.

  The combustion ash to which the method of the present invention is applied is combustion ash generated when coal, RPF (Refused Paper & Plastics Fuel), papermaking sludge, and the like are burned. Specifically, the ash is discharged when these are burned. Fly ash (abbreviated as EP ash and bag ash, respectively) captured by an electric dust collector (EP) or a bag filter.

  For the calcium oxides and / or calcium hydroxides used in the present invention, it is necessary to incorporate fluorine, boron or their compounds in the combustion ash into the crystal structure, and as such, as calcium oxides and / or calcium hydroxides Fluorine, slaked lime or limestone, dolomite, scallops, paper sludge, lime calcined from calcium sources such as waste paper straw, and any one of these hydroxides, or any combination of fluorine And preferred for suppressing boron elution.

  The blast furnace cement used in the present invention is obtained by uniformly mixing blast furnace slag with Portland cement, and is classified into A type, B type, and C type depending on the mixing ratio, but is not limited thereto. In addition, commercially available products that are easily available are preferred for use, but are not limited thereto.

  Combustion ash and calcium oxides and / or calcium hydroxide, blast furnace cement, and mass ratio when treated with aqueous aluminum sulfate are 200/1 for combustion ash / calcium oxides and / or calcium hydroxide and combustion ash / blast furnace cement. To 100/10 is preferable, and 100/1 to 100/5 is more preferable. If the mass ratio is less than 200/1, fluorine and boron cannot be sufficiently fixed. Conversely, if the mass ratio exceeds 100/10, the absolute amount of ash after treatment increases, the usage is limited, and the cost is also low. It is not practical because it increases. On the other hand, the mass ratio of combustion ash / aluminum sulfate is preferably in the range of 200/1 to 100/10, and more preferably 100/1 to 100/10. The amount of water added is preferably 5 to 30% by mass with respect to the combustion ash.

  It is preferable to stir well after adding calcium oxides and / or calcium hydroxide, blast furnace cement and aluminum sulfate aqueous solution to the combustion ash. By stirring, the additives are more uniformly dispersed in the combustion ash, Immobilization of fluorine and boron is performed in a minimum amount. As the stirrer, a commercially available general one is used, but it is not particularly limited. It is an extremely safe technique because no odor is generated during processing.

  The combustion ash treated according to the present invention, after only 3 hours, the amount of fluorine and boron eluted based on the dissolution test method of the Ministry of the Environment Notification No. 18 of 2003 was 5.2 mg / L of fluorine when untreated. While it was 2.5 mg / L or more for boron, both fluorine and boron were less than half of the regulation values (fluorine: 0.8 mg / L, boron: 1.0 mg / L). In addition, elution of heavy metals other than fluorine and boron can be suppressed. The form after the treatment is not solidified and is easy to handle because it is in a wet state, and can be used for various applications such as a snow melting material, a soil improving material, a grassland improving material, a backfilling material, and embankment.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is of course not limited by these examples, and the implementation thereof is not departed from the spirit of the present invention. Aspects can be changed.

  In addition, the combustion ash used as an elution suppression sample of fluorine and boron in Examples and Comparative Examples below is EP ash captured by an electric dust collector (EP) of a stalker furnace using coal as fuel. The chemical composition, fluorine and boron contents, and elution amounts are as shown in Table 1 below.

1) Fluorine and boron elution method In each of the following examples and comparative examples, the boron elution test was conducted in accordance with 2003 Ministry of the Environment Notification No. 18. In other words, air-dried untreated or treated ash samples collected by the electric dust collector (EP) in the stalker's flue, air-dried, crushed the aggregates, removing medium pebbles, wood chips, etc. Pass through a non-metallic mesh 2 mm sieve and mix them well. 50 g of this sample is put into a 1000 ml polyethylene container with a lid, and 500 ml of pure water (pH 5.8 to 6.3) is added. This prepared sample solution was shaken continuously (shaking width: 4 to 5 cm, vibration frequency: 200 times / min) at room temperature and atmospheric pressure using an industrial waste elution shaker (manufactured by Taitec Corporation) for 6 hours. This solution was allowed to stand for 30 minutes and then centrifuged at about 3000 rpm for 20 minutes. The supernatant was filtered through a membrane filter having a pore size of 0.45 μm, the filtrate was taken, the amount required for quantification was accurately measured, and this was used as a test solution.

2) Fluorine measurement method The test solution was analyzed by ion chromatography (DX-120 / DIONEX), and the eluted fluorine was quantified.

3) Measuring method of boron The test solution was analyzed with ICP-OES (inductively coupled plasma emission spectrophotometer, Rigaku / Spectoro, CIROS-120 type), and the amount of boron eluted was quantified.

Example 1
The coal ash EP ash was weighed into a 500 g vinyl bag, and 25 g of kiln calcined quicklime and 15 g of blast furnace cement B were added and stirred well. 5 parts by mass of aluminum sulfate with respect to 100 parts by mass of ash (absolutely dry), The aluminum sulfate aqueous solution adjusted so that the amount of added water was 25 parts by mass was uniformly sprayed and then stirred well. The curing days were 3 hours, 1 day, 3 days, and 10 days, and analysis was performed for each curing day by the above elution method and measurement method, and the elution amounts of fluorine and boron were determined. The results are shown in Table 2.

Example 2
Weigh 500 g of coal boiler EP ash in a vinyl bag, add 25 g of kiln calcined lime and 15 g of blast furnace cement B, and then stir well. 3.5 mass of aluminum sulfate per 100 mass parts of ash (absolutely dry) The aqueous solution of aluminum sulfate adjusted to 10 parts by weight and 10 parts by weight of the added water was uniformly sprayed and then stirred well. The curing days were set to 3 hours, 1 day, 3 days, and 10 days, and the above elution method and measurement method were used for each curing day to determine the elution amounts of fluorine and boron. The results are shown in Table 2.

Example 3
Weigh 500g of coal boiler EP ash in a vinyl bag, add 25g of slaked lime and 15g of blast furnace cement B, and then stir well. The aluminum sulfate aqueous solution adjusted so that the amount of added water was 10 parts by mass was uniformly sprayed and then stirred well. The curing days were 3 hours, 1 day, 3 days, and 10 days, and analysis was carried out for each curing day by the above elution method and measurement method to determine the elution amounts of fluorine and boron. The results are shown in Table 2.

Example 4
Weigh 500 g of coal ash EP ash in a vinyl bag, add 15 g of slaked lime, and 15 g of blast furnace cement B, and then stir well. The aluminum sulfate aqueous solution adjusted so that the amount of added water was 10 parts by mass was uniformly sprayed and then stirred well. The curing days were set to 3 hours, 1 day, 3 days, and 10 days, and the above elution method and measurement method were used for each curing day to determine the elution amounts of fluorine and boron. The results are shown in Table 2.

Comparative Example 1
The coal boiler EP ash was analyzed by the above elution method and measurement method, and the elution amounts of fluorine and boron were determined. The results are shown in Table 2.

Comparative Example 2
500 g of EP ash of a coal boiler was weighed into a vinyl bag, and 125 ml of pure water was sprayed uniformly with a spray and then stirred well. The curing days were 3 hours, 1 day, 3 days, and 10 days, and each of the curing days was analyzed by the above elution method and measurement method to determine the elution amounts of fluorine and boron. The results are shown in Table 2.

Comparative Example 3
500 g of EP ash of a coal boiler was weighed into a vinyl bag, 15 g of blast furnace cement B was added, and the mixture was sufficiently stirred, and 125 ml of pure water was sprayed uniformly with a spray and then stirred well. The curing days were 3 hours, 1 day, 3 days, and 10 days, and each of the curing days was analyzed by the above elution method and measurement method to determine the elution amounts of fluorine and boron. The results are shown in Table 2.

Comparative Example 4
Weigh 500g of coal boiler EP ash in a vinyl bag, add 25g of kiln calcined lime and 15g of blast furnace cement B, and stir well. After spraying 125ml of pure water uniformly with ash (absolutely dry) Stir well. The curing days were 3 hours, 1 day, 3 days, and 10 days, and each of the curing days was analyzed by the above elution method and measurement method to determine the elution amounts of fluorine and boron. The results are shown in Table 2.

Comparative Example 5
500 g of EP ash of a coal boiler is weighed into a vinyl bag, 25 g of kiln calcined lime, 15 g of blast furnace cement B and 5 parts by mass of concentrated sulfuric acid with respect to 100 parts by mass of ash (absolutely dry) and 25 parts by mass of added water The aqueous sulfuric acid solution thus prepared was uniformly sprayed and then stirred well. The curing days were 3 hours, 1 day, 3 days, and 10 days, and each of the curing days was analyzed by the above elution method and measurement method to determine the elution amounts of fluorine and boron. The results are shown in Table 2.

Comparative Example 6
Weigh 500g of coal boiler EP ash into a vinyl bag, 25g of kiln calcined lime, 15g of blast furnace cement B and calcium sulfate as calcium sulfate so that it becomes 5 parts by mass with respect to 100 parts by mass of ash (absolutely dry). The pure water was sprayed uniformly with a spray so that the total amount of the added water and the crystal water of hemihydrate gypsum was 25 parts by mass with respect to 100 parts by mass of ash, and then stirred well. The curing days were 3 hours, 1 day, 3 days, and 10 days, and analysis was performed for each curing day by the above elution method and measurement method, and the elution amounts of fluorine and boron were determined. The results are shown in Table 2.

Comparative Example 7
Weigh 500g of coal boiler EP ash in a vinyl bag, add 25g of kiln calcined lime, 15g of blast furnace cement B and 25g of sodium sulfate, stir well, spray 125ml of pure water uniformly with a spray, and stir well did. The curing days were 3 hours, 1 day, 3 days, and 10 days, and each of the curing days was analyzed by the above elution method and measurement method to determine the elution amounts of fluorine and boron. The results are shown in Table 2.

Comparative Example 8
Weighed EP ash 500g of coal boiler vinyl bag, the kiln lime 25 g, blast furnace cement B 15 g, thoroughly stirred after addition (48 g in BASIS) 25 g of ferrous sulfate as FeSO _4, ashes 100 Pure water was sprayed uniformly with a spray so that the added water was 25 parts by mass including the crystal water of ferrous sulfate with respect to parts by mass, and then stirred well. The curing days were 3 hours, 1 day, 3 days, and 10 days, and each of the curing days was analyzed by the above elution method and measurement method to determine the elution amounts of fluorine and boron. The results are shown in Table 2.

  As can be seen from Table 2, in Examples 1 to 4, the calcium oxides or slaked lime, blast furnace cement and aluminum sulfate aqueous solution were added to the coal EP ash and stirred, and the reference value was greatly increased in only 3 hours after the treatment. Below, fluorine and boron non-eluting were simultaneously achieved.

  On the other hand, when the coal EP ash is humidified only with water as in Comparative Example 2, the elution amount of fluorine and boron can be slightly reduced as compared with the dry ash, but it exceeds the regulation value. Further, when only blast furnace cement and water were added in Comparative Example 3 and calcined lime, blast furnace cement and water were added in Comparative Example 4, the boron elution suppression effect was observed, but the fluorine elution suppression effect appeared slowly, and the regulation value It takes 10 days to cure. In Comparative Examples 5 to 8, when addition of an aqueous solution containing various sulfate radicals such as sulfuric acid, gypsum, sodium sulfate or ferrous sulfate in the presence of calcined lime / blast furnace cement, both fluorine and boron In order to be able to suppress elution to below the regulation value at the same time, curing for 10 days is required.

  As mentioned above, calcium oxides and / or calcium hydroxide, blast furnace cement and aluminum sulfate aqueous solution are added to the combustion ash and agitation treatment is performed, and elution of fluorine and boron in the combustion ash is simultaneously suppressed in only 3 hours. However, it can be seen that the present invention, which can be reduced to the regulation value of the Soil Contamination Countermeasures Law, is a quick, simple and extremely effective method.

  In the method of the present invention, the ash discharged from a coal boiler or an RPF boiler using RPF as fuel, the above-mentioned calcium oxides and / or calcium hydroxides, blast furnace cement and aluminum sulfates at a flue or outlet. It is possible to detoxify by simply adding water, and because the obtained ash is not solidified, the application destination is not limited, snow melting material, soil improvement material, grassland improvement material, It can be used effectively for backfilling and embankment.

Claims (6)

  Combustion ash is mixed with calcium oxides and / or calcium hydroxide, blast furnace cement and aluminum sulfate in the presence of water, and the combustion ash is mixed into the combustion ash by the dissolution test method based on Notification No. 18 of the Ministry of the Environment in 2003. A combustion ash having a fluorine elution amount of 0.8 mg / L or less and a boron elution amount of 1.0 mg / L or less is prepared. Processing method.   The combustion ash is at least one selected from coal ash, RPF (Refused Paper and Plastics Fuel) ash, and combustion ash discharged from a paper sludge incinerator, and fluorine and / or boron The method for treating combustion ash according to claim 1, wherein the combustion ash is contained.   Calcium oxides and / or calcium hydroxides used in the treatment of the combustion ash are lime obtained by firing a calcium source selected from limestone, dolomite, scallops, paper sludge, and waste paper cake, and hydroxides thereof The method for treating combustion ash according to claim 1 or 2, wherein the method is at least one of the following.   The combustion ash according to any one of claims 1 to 3, wherein the blast furnace cement is at least one selected from Class A, Class B and Class C having quality defined in Japanese Industrial Standards of JIS R 5211. Processing method.   The mass ratio of the combustion ash and calcium oxides and / or calcium hydroxide, the mass ratio of combustion ash and blast furnace cement, and the mass ratio of the aqueous solution of combustion ash and aluminum sulfate are combustion ash / calcium oxides and / or hydroxylation. The calcium is 100 / 0.5 to 10, the combustion ash / blast furnace cement is 100 / 0.5 to 10, and the combustion ash / aluminum sulfate aqueous solution has a combustion ash / aluminum sulfate ratio of 100/0. It is 5-10, The processing method of the combustion ash of any one of Claims 1-4. The mass ratio of the combustion ash to calcium oxides and / or calcium hydroxides is 100/5 to 10 for combustion ash / calcium oxides and / or calcium hydroxides. The processing method of combustion ash as described in 2.