JP2015081270A - Harmful substance treating agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide insolubilization treating agent for harmful substances capable of insolubilizing harmful substances in polluted sludge, burned ash or soil generated in a factory or the like and recycling them to a landfill material or the like.SOLUTION: There is provided a powder type harmful substance treating agent for insolubilization processing of harmful substances consisting of a mixture of 5 to 90 wt.% of water-soluble acidic metal salt selected from iron, manganese or aluminum, 2 to 80 wt.% of a slightly water-soluble basic compound of alkali metal or alkali earth metal and 1 to 30 wt.% of water and containing a reaction product from chemical reaction of at least a part of the water-soluble acidic metal salt and the slightly water-soluble basic compound in presence of water.

Description

  The present invention uses arsenic, lead, cadmium, hexavalent chromium, selenium, mercury, fluorine, boron, nickel, copper to safely use toxic substance-containing sludge, incinerated ash or contaminated soil generated in factories, etc. The present invention relates to a chemical for stabilizing harmful substances such as zinc, antimony and barium and insolubilizing them.

  In chemical factories, mines, smelters, steelworks, incineration disposal sites, etc., wastes containing various hazardous substances are generated from product manufacturing processes, smelting processes, surface treatment processes, plating processes, incineration processes, etc. Of these, those containing high-concentration components are recovered by the recycling process and returned to the raw material as resources, but those with low concentrations and those originally contained as impurities are treated as waste. Yes.

  For hazardous substances contained in wastewater, in general, in the wastewater treatment process, it is precipitated as floc in the water by adding an alkaline agent, oxidizing agent, etc., and after adding aggregating material, it is concentrated and precipitated using a thickener, etc. It is dehydrated by a press and disposed of as sludge in landfills.

  When disposing of sludge and incinerated ash by landfill, etc., it is necessary to fix and stabilize toxic substances so that they do not melt out in order to prevent surrounding contamination, and at the same time maintain workability during disposal. Therefore, it is necessary to have a certain degree of construction strength.

When disposing of toxic substance-containing waste or toxic substance-contaminated soil, it is necessary to stabilize the toxic substance so that it does not elute. It is known that chelating agents are effective for insolubilizing harmful substances, but since this is used in the acidic to neutral range, it is an inexpensive cement to maintain workability during disposal. When solidifying materials such as these are mixed, there arises a problem that the insolubilization performance is lowered. Therefore, increasing the addition amount of the chelating agent has a problem of increasing processing costs.

JP 2001-121131 A JP 2006-272144 A JP 2012-188544 JP JP 2012-210577

  Patent Document 1 discloses that, in order to detoxify harmful metals, iron (II) sulfate and water are added to and mixed with waste containing them, and then a calcium compound is added to adjust the pH. This method requires a large amount of water and is entirely muddy. Patent Document 2 discloses a heavy metal insolubilizing agent obtained by calcining calcium aluminate hydrate at a high temperature to form a hardly water-soluble calcium salt on the particle surface. This method requires high-temperature calcination and a surface treatment process. Patent Document 3 discloses a heavy metal insolubilizing agent containing phosphoric acid such as hypophosphorous acid or phosphates. Patent Document 4 discloses a method for insolubilizing arsenic in soil by mixing iron sulfate and calcined dolomite in soil after making arsenic into a pentavalent form by oxidizing bacteria in order to detoxify arsenic in soil. In these methods, the production of the treatment agent or the use of the treatment agent is complicated, and the effect is not sufficient for many kinds of heavy metals and non-metallic harmful substances.

  An object of this invention is to provide the chemical | medical agent insolubilization treatment of the harmful substance in sludge, incineration ash, or soil.

  The present invention comprises 5 to 90% by weight of a water-soluble acidic metal salt of at least one metal selected from iron, manganese and aluminum, and 2 to 80% by weight of a poorly water-soluble basic compound of an alkali metal and / or alkaline earth metal. And hydrated by reacting at least a part of a water-soluble acidic metal salt and a poorly water-soluble basic compound during the powder mixing. It is a powdery hazardous substance treating agent for insoluble substance insolubilization treatment characterized by containing a reaction product.

  Examples of the water-soluble acidic metal salt include at least one selected from iron chloride, iron nitrate, iron sulfate, manganese chloride, manganese sulfate, aluminum chloride, and aluminum sulfate, and these powders or a 15 to 35 wt% aqueous solution are used. Is done.

  Examples of the poorly water-soluble basic compound include at least one selected from calcium oxide, calcium hydroxide, calcium silicate, magnesium oxide, magnesium hydroxide, sodium silicate, potassium silicate, silicate glass, iron slag and cement, These powders are used.

  The hazardous substance treating agent is a sludge containing at least one ion selected from arsenic, lead, cadmium, hexavalent chromium, selenium, mercury, fluorine, boron, nickel, copper, zinc, antimony and barium as harmful substances, Excellent for insolubilization treatment of incinerated ash and / or harmful substances in soil.

  The above hazardous substance treatment chemicals include: a) a material containing 10 to 90% by weight of iron sulfate and / or aluminum sulfate, 3 to 80% by weight of magnesium oxide and / or calcium silicate, and 1 to 30% by weight of water, and b) iron sulfate. And / or 10 to 90% by weight of aluminum sulfate, 3 to 80% by weight of calcium hydroxide, 1 to 30% by weight of water, c) 10 to 90% by weight of iron sulfate and / or aluminum sulfate, and 3 to 3% of cement. A material containing 80% by weight, 1-30% by weight of water, or d) a material containing 10-90% by weight of iron sulfate and / or aluminum sulfate, 3-80% by weight of calcium hydroxide, and 1-30% by weight of water. Some are obtained by powder mixing.

  According to the present invention, it is possible to insolubilize sludge, incinerated ash, and harmful substances in soil by simple means. This insolubilized waste does not re-elute heavy metals or the like even if it becomes wet with rainwater or the like, or is greatly reduced, so that it can be safely disposed of in landfills.

It is a chart of the differential thermal analysis of the hazardous | toxic substance processing chemical | medical agent 5. FIG. It is a chart of the differential thermal analysis of the hazardous | toxic substance processing chemical | medical agent 7.

  Hazardous substance-containing substances to be treated in the present invention are mainly in chemical factories, mines, smelters, iron mills, plating plants, incineration plants, etc., in product manufacturing processes, smelting processes, surface treatment processes, plating processes Inorganic sludge, incinerated ash, fly ash, or contaminated soil generated by the operation of these factories, etc. discharged in the incineration process or the like.

  The hazardous substance treating agent according to the present invention comprises a mixture of at least one water-soluble acidic metal salt selected from iron, manganese and aluminum, and an alkali metal and / or alkaline earth metal poorly water-soluble basic compound. A part thereof contains a reaction product that is chemically reacted in the presence of water when powder is mixed.

  The water-soluble acidic metal salts of iron, manganese, and aluminum used as raw materials for hazardous substance treatment chemicals are required to have a high solubility in water and to have an acidic pH when added to water. Iron, iron sulfate, manganese chloride, manganese sulfate, aluminum chloride, and aluminum sulfate can be used, but iron chloride, iron sulfate, aluminum chloride, and aluminum sulfate, which are friendly to the natural environment and low in cost, are suitable. As the iron compound, either a divalent compound or a trivalent compound can be used. Moreover, the acidic metal salt to be used is used as a powder or 15-35 wt% aqueous solution.

  Alkaline metal and alkaline earth metal poorly water-soluble basic compounds used as raw materials for toxic substance treatment chemicals are required to have a low solubility in water and to exhibit pH alkaline when added to water. Calcium hydroxide, calcium silicate, magnesium oxide, magnesium hydroxide, sodium silicate, potassium silicate, silicate glass, iron slag, cement, etc. can be used, but are easily available and low cost calcium hydroxide, calcium silicate Magnesium oxide, steel slag, and cement are suitable. The poorly water-soluble basic salt of alkali metal or alkaline earth gold is preferably a powder.

  The hazardous substance treating agent according to the present invention is prepared by adding 1 to 30% by weight of water in a mixture of a water-soluble acidic metal salt and a poorly water-soluble basic compound, mixing the mixture, and at least a part thereof is chemically reacted in the presence of water. It is necessary to contain the reaction product. At this time, if the amount of water added is excessive, the mixture will be slurried and a powdery hazardous substance treating agent cannot be obtained. On the other hand, if the amount of water added is too small, the amount of hydration reaction product produced is reduced and the processing performance of harmful substances is lowered. As a method for adding water, water is added to the water-soluble acidic metal salt, water-soluble acidic metal salt and / or water-insoluble basic compound individually added with water, or water-soluble acidic metal salt , A poorly water-soluble basic compound, and water may be mixed at the same time.

  A material containing a water-soluble acidic metal salt, a poorly water-soluble basic compound and water is powder-mixed. At this time, a part of the water-soluble acidic metal salt and the hardly water-soluble basic compound reacts in the presence of water to generate a hydration reaction product. This product is composed of a compound such as MY and AX, a double salt thereof, a crystalline mineral containing MY and AX, or these minerals when the water-soluble acidic metal salt and the poorly water-soluble basic compound are represented by MX and AY, respectively. Presumed to be a hydrate (metal hydroxide). If the above material is a powder, these occur on the surface portion, the hydration reaction product is present on the powder surface, and the inside of the powder is presumed to remain a water-soluble acidic metal salt and a poorly water-soluble basic compound. Is done. Simply mixing a water-soluble acidic metal salt and a poorly water-soluble basic compound without water does not sufficiently improve the performance as a hazardous substance treatment chemical. It is desirable to fully contact the powder. The kneading time by the kneader is 2 minutes or more, preferably 5 minutes or more. The hazardous substance treating agent thus obtained is consumed as the hydrated reaction product is added, so that the surface becomes a dry powder with a relatively dry surface. Therefore, heat drying may be performed or granulation may be performed.

  The compounding quantity with respect to to-be-processed materials (referred to as waste etc.) of the sludge, incineration ash or soil of the hazardous substance treatment chemical according to the present invention is 0.5 to 50% by weight with respect to the waste etc. In addition, when waste etc. contain a lot of water | moisture contents, it is preferable to calculate in conversion to solid content, but if a moisture content is 20% or less, the weight as it is may be sufficient.

  The mixing of the waste or the like and the harmful substance treatment chemical may be performed by mixing or kneading for several minutes or more using a mixing device that makes the whole uniform. The insolubilized waste obtained in this way is a highly active hydroxylated product produced by a prior reaction of a water-soluble acidic metal salt and a poorly water-soluble basic compound contained in the hazardous substance treating agent of the present invention. It is insoluble in water due to the chemical reaction between the adsorption effect of metals and the wastes mixed with unreacted water-soluble acidic metal salts and alkali metals and alkaline earth metal compounds contained in chemicals for treating hazardous substances. It is considered that the insoluble material is achieved by adsorbing and coprecipitation of harmful substance ions contained in the sludge. In other words, the adsorption action by the metal hydroxide contained in the toxic substance treatment chemical and the adsorption / cooperation of toxic substance ions by the chemical reaction that occurs when unreacted water-soluble acidic metal salt and basic compound are mixed in the waste. Stabilized in two stages by sedimentation. Therefore, even if this insolubilized waste is piled up or used for landfill, harmful substances will not be re-eluted or greatly reduced.

Example 1
As a harmful substance treatment drug, water-soluble acidic metal salt, poorly water-soluble basic compound and water were reacted at a mixing ratio (% by weight) shown in Table 1 while mixing to prepare drugs 1 to 12 shown in Table 1.
The water-soluble acidic metal salts used are powdered industrial chemicals of ferrous sulfate (FS), ferrous chloride (FC), aluminum sulfate (AS) and aluminum chloride (AC), and are poorly water-soluble basic compounds. As calcium silicate powder (CS) mainly composed of powdered industrial chemicals of magnesium oxide (MO) and calcium hydroxide (CH) and synthetic tobermorite, and purified water was used as water. These materials were mixed and reacted at a blending ratio shown in Table 1 using a commercially available powder mixing device to prepare hazardous substance treating agents 1 to 12.

Comparative Example 1
The same water-soluble acidic metal salt (A) as used in the examples, poorly water-soluble basic compound (B), water and powder were mixed using a powder mixing apparatus to prepare Comparative Examples 1 to 18 shown in Table 2.
In the table, FS, FC, AS, AC, MO, CH, and CS are abbreviations attached to the above water-soluble acidic metal salts and poorly water-soluble basic compounds. % Of the amount is wt%.

Example 1
As the toxic substance-containing sludge, a dehydrated slime product (water content 45%) generated from the wastewater treatment process at the chemical factory was used (sludge 1). Any one of the chemicals 1 to 12 was added to the sludge in an amount (% by weight) shown in Table 3 and mixed for 10 minutes with a mixer. About the obtained insolubilized sludge, the result of having performed the elution test based on the official method on the curing 1st is shown in Table 3. For comparison, a dissolution test was performed in the same manner except that no drug was added.
The amount of Pb elution when no drug is added is 0.21 mg / L. In contrast, when 3 wt% of the drug is added, the elution amount is less than the detection limit or 0.004 mg / L or less. Reduced to 50 or less.

Example 2
As the toxic substance-containing sludge, a dehydrated slime product (water content 40%) generated from the surface treatment process of the metal processing factory was used (sludge 2). The chemicals were added to the sludge in the amounts (% by weight) shown in Table 4 and mixed for 10 minutes with a mixer. About the obtained insolubilized sludge, the result of having performed the elution test based on the official method on the curing 1st is shown in Table 4.
When no drug was added, the Ni elution amount was 5.0 mg / L and the Cr ⁶⁺ elution amount was 0.48 mg / L. In contrast, when 3 wt% of the drug was added, the elution amount was the detection limit. It decreased to the following 0.005 mg / l or less.

Example 3
As the sludge containing toxic substances, dehydrated slime (water content 49%) generated from the wastewater treatment process at the chemical factory was used (sludge 3). The chemical was added to the sludge in the amount (% by weight) shown in Table 5 and mixed for 10 minutes with a mixer. About the obtained insolubilized sludge, the result of having performed the elution test based on the official method on the curing 1st is shown in Table 5.
When the drug was not added, the As elution amount was 0.14 mg / L, and when the drug was added at 3 wt%, the elution amount decreased to 0.001 mg / l or less below the detection limit.

Example 4
As heavy metal-containing soil, contaminated soil (moisture content of 26%) generated from the site of the chemical factory was used (contaminated soil 1). The chemicals were added to the contaminated soil in the amounts (% by weight) shown in Table 6 and mixed with a mixer for 10 minutes. Table 6 shows the results of the dissolution test based on the official method for the obtained insolubilized and contaminated soil on the first day of curing.
When the drug is not added, the As elution amount is 0.060 mg / L, and when compared with the drug 1, 0.5, 1, 2, or 3 wt%, or drugs 2, 3, 5 are added 1 wt% In both cases, the elution amount decreased to 0.001 mg / l or less below the detection limit.

Example 5
As heavy metal-containing soil, contaminated soil (moisture content 28%) generated from the site of the chemical factory was used (contaminated soil 2). The chemical was added to the contaminated soil in the amount (% by weight) shown in Table 7 and mixed for 10 minutes with a mixer. Table 7 shows the results of the dissolution test based on the official method for the obtained insolubilized contaminated soil on the first day of curing.
When no drug is added, the Se elution amount is 0.18 mg / L. When 3% by weight of drug 7, 8 or 9 is added, the elution amount is 0.001 mg / L or less below the detection limit. Decreased.

Example 6
As the heavy metal-containing soil, contaminated soil (water content 25%) generated from the site of the chemical factory was used (contaminated soil 3). The chemical was added to the contaminated soil in the amount (% by weight) shown in Table 8 and mixed for 10 minutes with a mixer. Table 8 shows the results of the dissolution test based on the official method for the insolubilized and contaminated soil obtained on the first day of curing.
When no drug is added, the Cd elution amount is 32.3 mg / L, the Pb elution amount is 1.34 mg / L, and in comparison with the case where 3, 5 or 7 wt% of drug 1 is added, The amount of elution was greatly reduced.

Example 7
As heavy metal-containing soil, contaminated soil (water content 27%) generated from the former site of the chemical factory was used (contaminated soil 4). The chemicals were added to the contaminated soil in the amounts (% by weight) shown in Table 9 and mixed for 10 minutes with a mixer. Table 9 shows the results of an elution test based on the official method for the insolubilized and contaminated soil obtained on the first day of curing.
When no drug is added, the Cd elution amount is 6.7 mg / L, and the Pb elution amount is 7.5 mg / L. In contrast, when 3 wt% of the drug is added, the elution amount is below the detection limit. Of less than 0.001 mg / l.

Example 8
As the heavy metal-containing soil, contaminated soil (water content 25%) generated from the site of the chemical factory was used (contaminated soil 5). The chemicals were added to the contaminated soil in the amounts (% by weight) shown in Table 10, and mixed for 10 minutes with a mixer. Table 10 shows the results of an elution test based on the official method for the obtained insolubilized and contaminated soil on the first day of curing.
When no drug was added, the Hg elution amount was 5.3 mg / L, and when the drug was added in an amount of 3 wt%, the elution amount was significantly reduced in all cases.

Example 9
As the heavy metal-containing soil, contaminated soil (water content 23%) generated from the site of the chemical factory was used (contaminated soil 6). The chemicals were added to the contaminated soil in the amounts (% by weight) shown in Table 10, and mixed for 10 minutes with a mixer. Table 11 shows the results of an elution test based on the official method for the obtained insolubilized and contaminated soil on the first day of curing.
The F elution amount when no drug was added was 5.0 mg / L. Compared with this, when 2 wt% of the drug was added, the elution amount decreased to 1/10 or less.

Comparative Example 1
As the heavy metal-containing sludge, the same sludge 1 as used in Example 1 was used, and the comparative agents 1 to 12 shown in Table 2 were added to the sludge in the amounts (% by weight) shown in Table 12, and mixed with a mixer. Mix for 10 minutes. About the obtained insolubilized sludge, the result of having performed the elution test based on the official method on the curing 1st is shown in Table 12.
The amount of elution of Pb without the addition of the comparison agent was 0.21 mg / L. Compared with that, when 3 wt% of any of comparison agents 1 to 12 was added, the elution amount decreased in all cases, but to that extent Is low.

Comparative Example 2
The same sludge 2 as used in Example 2 was used as the heavy metal-containing sludge, and the comparison agent shown in Table 2 was added to the sludge in the amount (% by weight) shown in Table 12 and mixed for 10 minutes with a mixer. did. About the obtained insolubilized sludge, the result of having performed the elution test based on the official method on the curing 1st is shown in Table 13. When the comparison agent is not added, the Ni elution amount is 5.0 mg / L, and the Cr ⁶⁺ elution amount is 0.48 mg / L.

Comparative Example 3
The same sludge 3 as used in Example 3 was used as the heavy metal-containing sludge, and the comparison agent shown in Table 2 was added to the sludge in the amount (% by weight) shown in Table 13 and mixed for 10 minutes with a mixer. did. Table 14 shows the results of an elution test based on the official method for the insolubilized sludge obtained on the first day of curing. In addition, the As elution amount when a comparison agent is not added is 0.14 mg / L.

Comparative Example 4
The same contaminated soil 1 as used in Example 4 was used as the heavy metal-containing soil, and the comparison agent shown in Table 2 was added to the sludge in the amount (% by weight) shown in Table 14, and the mixture was mixed for 10 minutes. Mixed. About the obtained insolubilized sludge, the result of having performed the elution test based on the official method on the curing 1st is shown in Table 15. In addition, when a comparison agent is not added, the As elution amount is 0.060 mg / L,

Example 10
About the hazardous | toxic substance processing chemical | medical agents 5 and 7 created in Example 1, using the differential thermal analyzer (TG / DTA), it heated up sample temperature from 30 degreeC to 1000 degreeC with the temperature increase rate of 10 degreeC / min. The DTA and TG at that time were measured. The results for the drug 5 are shown in FIG. 1, and the results for the drug 7 are shown in FIG.

Claims (8)

  5 to 90% by weight of a water-soluble acidic metal salt of at least one metal selected from iron, manganese and aluminum, 2 to 80% by weight of a water-insoluble basic compound of an alkali metal and / or alkaline earth metal, and water 1 A hydration reaction product comprising a mixture obtained by powder-mixing a material containing ˜30% by weight, wherein a water-soluble acidic metal salt and at least a part of a poorly water-soluble basic compound are reacted during powder mixing. A powdery toxic substance treatment agent for insoluble treatment of toxic substances characterized by containing.   The harmful water according to claim 1, wherein the water-soluble acidic metal salt is at least one powder selected from iron chloride, iron nitrate, iron sulfate, manganese chloride, manganese sulfate, aluminum chloride, and aluminum sulfate, or a 15 to 35 wt% aqueous solution. Substance treatment chemicals.   The poorly water-soluble basic compound is at least one powder selected from calcium oxide, calcium hydroxide, calcium silicate, magnesium oxide, magnesium hydroxide, sodium silicate, potassium silicate, silicate glass, iron slag and cement. The harmful substance treatment agent according to 1 or 2.   The hazardous substance treatment chemical is a hazardous substance treatment chemical for sludge, incinerated ash and / or insolubilization treatment of harmful substances in soil, and the harmful substances are arsenic, lead, cadmium, hexavalent chromium, selenium, mercury, fluorine, The hazardous substance treating agent according to any one of claims 1 to 3, which is at least one ion selected from boron, nickel, copper, zinc, antimony and barium.   Harmful according to claim 1, obtained by powder mixing a material containing 10 to 90% by weight of iron sulfate and / or aluminum sulfate, 3 to 80% by weight of magnesium oxide and / or calcium silicate and 1 to 30% by weight of water. Substance treatment chemicals.   The hazardous substance treating agent according to claim 1, obtained by powder mixing a material containing 10 to 90% by weight of iron sulfate and / or aluminum sulfate, 3 to 80% by weight of calcium hydroxide, and 1 to 30% by weight of water. .   The hazardous substance treating agent according to claim 1, obtained by powder mixing a material containing 10 to 90% by weight of iron sulfate and / or aluminum sulfate, 3 to 80% by weight of cement, and 1 to 30% by weight of water.   The hazardous substance treating agent according to claim 1, obtained by powder mixing a material containing 10 to 90% by weight of iron sulfate and / or aluminum sulfate, 3 to 80% by weight of iron slag powder, and 1 to 30% by weight of water. .

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