JP6749126B2 - Hazardous substance treatment material and treatment method - Google Patents

Description

The present invention is a factory, a mine, a waste treatment facility, a hazardous substance-containing wastewater generated in a civil engineering site, etc., for safely processing and discharging sludge, incinerated ash or contaminated soil, or for use in landfill, etc. The present invention relates to a material for stabilizing and insolubilizing harmful compounds such as arsenic compounds, fluorine compounds and boron compounds, and a method for treating harmful compounds using this material.

At chemical plants, mines, smelters, steelworks, incineration sites, etc., wastes containing various harmful substances are generated from product manufacturing processes, smelting processes, surface treatment processes, plating processes, incineration processes, etc. However, of these, those containing high-concentration components are recovered by the recycling process and returned to the raw materials as resources, but those with low concentration or those originally contained as impurities are treated as waste. There is.

Regarding harmful substances contained in wastewater, generally in the wastewater treatment process, it is precipitated as floc in water by adding an alkaline chemical agent, an oxidizing agent, etc., and after adding a flocculant, it is concentrated and precipitated using a thickener, etc., and further filtered. It is dehydrated by a press or the like and discarded as sludge in landfills.

When disposing of sludge and incinerated ash by landfill, etc., it is necessary to stabilize and stabilize toxic substances to prevent contamination of the surroundings, and at the same time maintain workability at the time of disposal. Therefore, it is necessary to have a certain degree of construction strength. In addition, it is often desired to insolubilize harmful substances in excess soil generated at civil engineering work sites in order to discard or reuse it.

In particular, a large amount of surplus soil is generated in tunnel construction and road and rail construction work that involves soil excavation, but when using this soil for disposal or landfill, it is necessary to keep the amount of leaching harmful substances below a certain level. There is. In order to treat a huge amount of excess soil, not only a large amount of treatment material is required, but also the treatment device becomes large, but it is also possible to perform treatment with a movable treatment device that can treat excess soil on site. desired.

Regarding the soil generated by the shield tunnel construction on the Tokyo outer ring road, etc., the excavated material at the time of being discharged from the "integrated construction system" in the "Construction Waste Management Guideline (2010 version) Environmental Waste Management No. 11032904 Depending on the property of (soil), it will be judged whether it is sediment or sludge. Since the soil generated by the shield tunnel construction needs to have the strength required for effective use for embankment etc. at the recipient, a modifier is added before storage by the hopper, etc., and treated as earth and sand. It is required to exceed the cone index of 200 KN/m ² , which is a necessary condition for this. Excavated soil with a corn index of 200 KN/m ² or less needs to be handled as construction sludge (industrial waste), and appropriate measures must be taken based on relevant laws such as the Waste Disposal Law.

When disposing of wastewater containing hazardous substances, waste containing hazardous substances and soil contaminated with hazardous substances, it is necessary to separate the hazardous substances contained therein and to stabilize them so that the hazardous substances do not elute. It is known that a chelating agent is effective for insolubilizing harmful substances, but since it is used in the acidic to neutral range, it is an inexpensive cement to maintain workability at the time of disposal. When a solidifying material such as is mixed, the insolubilization performance is deteriorated. Therefore, increasing the amount of the chelating agent added causes a problem of increasing the processing cost.

JP 2015-81270 JP JP 2013-119068 JP

Patent Document 1 discloses a harmful substance treating agent obtained by powder-mixing a water-soluble acidic metal salt of iron, manganese, or aluminum, a poorly water-soluble basic compound of an alkali metal or an alkaline earth metal, and a material containing water. Disclose. Here, the water-soluble acidic metal salt may be aluminum sulfate, and the harmful substances include arsenic, lead, cadmium, hexavalent chromium, selenium, mercury, fluorine, boron, nickel, copper, zinc, antimony or barium. I'm trying to be ionic. The poorly water-soluble basic compound is said to be calcium oxide, calcium hydroxide, calcium silicate, magnesium oxide, magnesium hydroxide, sodium silicate, potassium silicate, silicate glass, iron slag, cement or the like, I won't tell you how to use cement. This technique requires a special chemical reaction to occur during powder mixing in the presence of water, and its adjustment is difficult.

Patent Document 2 relates to a wastewater treatment material for construction work containing amorphous calcium aluminate, aluminum sulfate, calcium oxide and polysaccharides, and an object thereof is to treat wastewater containing cement or mud generated in construction work. Aluminum sulfate and polysaccharides are said to cause precipitation of contaminants and accelerate clarification. Examples of amorphous calcium aluminate are only certain clinker examples, and examples of polysaccharides are only hemicellulose and alginates. It does not teach the removal of harmful compounds such as boron.

The present invention provides a treatment material for insolubilizing harmful compounds such as arsenic compounds, lead compounds, fluorine compounds and boron compounds in wastewater, sludge, incineration ash or soil, and of the harmful substances using this treatment material. The purpose is to provide a processing method.

The present invention comprises a mixture containing cements selected from clinker or cement, aluminum sulfate, and gluconic acids selected from gluconic acid or gluconate, wherein the total content of cements, aluminum sulfate and gluconic acids is 100 wt%. When the content of cement is 50-98 wt%, the content of aluminum sulfate is 1-10 wt%, and the content of gluconic acids is 0.5-5 wt%, boron, fluorine, It is a treatment material for harmful substances containing at least one harmful compound selected from lead and arsenic.

Then, the content of cements in the treated material of this harmful substance is 50 to 95 wt %, the content of aluminum sulfate is 1 to 10 wt %, and the content of gluconic acids is 0.5 to 5 wt %. Is good.

Suitable cements are clinker powder, Portland cement or blast furnace cement. Suitable gluconic acids are potassium gluconate or sodium gluconate.

In addition, the present invention is to add the above-mentioned harmful substance treatment material to waste water or sludge containing at least one harmful compound selected from boron, fluorine, lead and arsenic, or contaminated soil, and mix this harmful compound. Is a method for treating harmful substances, which comprises adsorbing, precipitating or solidifying.

Furthermore, the present invention is the above-mentioned insolubilization method, characterized in that a pH adjusting agent is added to and mixed with wastewater or sludge containing contaminated compounds, or contaminated soil, together with a treatment material for the contaminated substances.

According to the hazardous substance treating material and the treating method using the same of the present invention, it is possible to insolubilize the hazardous substance in wastewater, sludge, incinerated ash and soil by a simple means. This insolubilized waste does not re-elute or significantly reduces harmful compounds even when wet with rainwater or the like, and thus can be safely disposed of by landfill or the like. For soil discharged in large quantities during civil engineering work, it is possible to suppress the elution of harmful compounds as well as improve the strength of the soil, making it possible to raise the ground and improve the ground. It can also be effectively used as a etc.

The hazardous substances containing the harmful compounds to be treated with the hazardous substance treating material of the present invention include mainly chemical plants, mines, smelters, steel plants, plating plants, incinerators, etc. Waste water, sludge, incinerated ash discharged from processes, surface treatment processes, plating processes, incineration processes, disposal processes, etc., or contaminated soil generated during civil engineering work.

Hazardous substances suitable for treatment with the treatment material of the present invention include at least one harmful compound selected from boron compounds, fluorine compounds, lead compounds and arsenic compounds, and particularly for harmful substances containing boron compounds. And shows excellent effects. Therefore, a substance containing a boron compound is suitable as the harmful substance. However, since it is also effective for fluorine compounds, lead compounds or arsenic compounds, it can also be used for harmful substances containing no boron compounds.

There are many volcanoes, hot springs, and various mines in Japan, and the soil in the vicinity is often contaminated with one or more of the harmful substances listed above. Soil is often generated. The harmful substance treating material of the present invention enables these efficient treatments.

The treating material of the present invention is a mixture containing cements, aluminum sulfate and gluconic acids as essential components.

There are no particular restrictions on the cements used as the raw material for the treatment material, but common cements such as Portland cement and blast furnace cement are easily available. Clinker is the main component of Portland cement, and it can be expected to have an effect equal to or higher than that of cement. The clinker is preferably used as a ground powder like cement.
Since cements are basic materials, it is considered that the harmful substances to be treated are made basic and have the effect of fixing harmful compounds. Cement has the advantage that it is easier to handle and store than basic materials such as calcium hydroxide.

The aluminum sulfate is not particularly limited, but anhydrous (Al ₂ (SO ₄ ) ₃ ) or hydrate (Al ₂ (SO ₄ ) ₃ ·16H ₂ O) is suitable. Aluminum sulfate has an aggregating action, and is considered to have an action of aggregating or solidifying harmful substances that have been insolubilized or immobilized to prevent their elution. In addition to aluminum sulfate, aluminum chloride or the like can be used, and a part thereof may be aluminum chloride or the like. However, sulfate can bind to calcium in the cement and insolubilize it, but chlorine is difficult, so if there is a limit to the elution of other harmful compounds such as chlorine, it may be a small amount. Good.

The gluconic acid is not limited, but gluconic acid or an alkali metal salt of gluconic acid is suitable. Sodium gluconate for industrial use is suitable in terms of ease of entry and effect. Gluconic acid and gluconate can be blended as powders and are preferably water-soluble. Gluconic acids are water-soluble, and are considered to have not only the effect of removing harmful substances but also the effect of preventing (or delaying) the solidification of cement. The anti-solidification effect is presumed to be because gluconic acids chelate the calcium content in cements. Therefore, it can be said that calcium gluconate is not desirable as the gluconic acid.

It is also possible to use sucrose instead of or together with gluconic acids. It is considered that sucrose also has a function of preventing solidification of cement. Sucrose is slightly less effective than gluconic acids, but has the advantage that it can be obtained relatively easily as sugar, crude sugar, etc. When sucrose is used, its blending amount and the like are similar to those of gluconic acids.

Therefore, when a harmful substance is treated with a treatment material containing an appropriate amount of gluconic acid, it is possible to prevent the harmful substance from solidifying together with the treatment material, prevent clogging of the treatment equipment, and remove and process the treated material. Also, it is easy to carry. Regarding contaminated soil discharged from civil engineering work, etc., after mixing the treatment materials, only those that have passed the elution test of harmful substances will be transferred to the disposal site, etc. It takes a certain amount of time to transfer, and if the soil hardens during that time, it becomes difficult to transfer it. Furthermore, when solidification of cement occurs, ettringite is produced and aluminum is consumed at this time, but gluconic acids also prevent this.

The content of these in the treated material is 50 to 98 wt% for cements, 1 to 10 wt% for aluminum sulfate, and glucon, when the total amount of cements, aluminum sulfate and gluconic acids is 100 wt %. The content of acids is 0.5 to 5 wt %. Preferably, the cements are 70 to 95 wt%, the aluminum sulfate is 2 to 8 wt%, and the gluconic acids are 1 to 4 wt%.

From another viewpoint, it is preferable that the cement content in the treated material is 50 to 95 wt %, the aluminum sulfate content is 1 to 10 wt %, and the gluconic acid content is 0.5 to 5 wt %. If necessary, additives such as a pH adjusting agent, a filler and a specific gravity adjusting agent may be added. Here, inactive ingredients such as fillers are not included in the above calculation of the blending amount.

When the content of gluconic acids is low, the cement in the object to be treated mixed with the treatment material may proceed to solidify, resulting in strong solidification. When the content is high, the concentration of contaminants such as COD increases.

The treatment material for harmful substances of the present invention is prepared by mixing the above raw material components in a predetermined ratio. The mixing method is not limited, and the fineness is preferably in the range of 1 to 1000 μm as the average particle diameter (Md50). If the hazardous substance to be treated is solid such as soil, it should have a relatively large particle size from the viewpoint of workability, and if it is wastewater or sludge, it should be relatively small because of its solubility and dispersibility. The particle size is preferably. In addition, since the average particle size of commercially available cement is around 10 μm, when cement is used, the total average particle size may be set in the range of 5 to 100 μm in accordance with this.

In the treatment material of the present invention, the amount of the waste material, sludge, incineration ash, soil, etc. to be treated (referred to as waste, soil, etc.) is 0.1 to 50% by weight based on the waste, soil, etc. It is preferably 1 to 20% by weight. If the wastes are wastewater or sludge containing a large amount of water, a relatively small amount may be used. If the waste, soil, etc. do not contain water or moisture, gluconic acids and aluminum sulfate in the treated material should be dissolved, and more water than the amount necessary for the hydration reaction of the cements may be added. Good. For soils dug from the ground, the moisture normally contained is sufficient.

Mixing waste, soil, etc. with the treatment material is generally stirring mixing in the case of liquid such as wastewater and sludge, and uniform in the case of solid such as incineration ash or soil. A mixing device may be used to mix or knead for several minutes or longer.

Wastes after the insolubilization treatment thus obtained, soil, etc., the cements contained in the treatment material of the present invention, the above-mentioned chemical reaction and aggregation action due to aluminum sulfate, further cement with gluconic acids It is considered that a solidification-preventing action occurs to form a water-insoluble reaction substance, and at that time, harmful substance ions contained in waste, soil and the like are adsorbed and coprecipitated to achieve insolubilization. In other words, it is due to the adsorption action of metal hydroxide generated by basification with cement and the adsorption/coprecipitation action of harmful substance ions due to the chemical reaction that occurs when aluminum sulfate and cement are mixed in waste, soil, etc. Stabilized in stages. Furthermore, since gluconic acids prevent strong solidification by cements, the insolubilized waste can be easily taken out, piled up, and landfilled. Then, harmful substances from the insolubilized waste are prevented from being re-eluted or greatly reduced.

Example 1
Commercially available Portland cement (manufactured by Taiheiyo Cement Co., Hidaka Plant), aluminum sulfate (anhydrous powder; manufactured by Daimei Chemical Co., Ltd.), sodium gluconate (powder; manufactured by Fuso Chemical Co., Ltd.) in Table 1 (wt%) ) And processed materials 1 to 3 were prepared.

Comparative Example 1
Treatment materials 4 to 6 were prepared using one or two kinds of the same Portland cement, aluminum sulfate or sodium gluconate as used in Example 1.

Example 2
As the boron-containing wastewater, leachate (boron concentration 54 mg/L) of boron-containing rock (excavated soil) was used (wastewater A). To 1000 mL of this wastewater, 60 g of the treating material 1, 2 or 3 was added, and the mixture was stirred at 25°C for 15 minutes and allowed to stand. After 24 hours, the solution was filtered with 5 A filter paper, and the boron concentration in the filtrate was measured by the official method. The results are shown in Table 2.

Comparative example 2
Using the wastewater A used in Example 2, 60 g of the treating material 4, 5 or 6 was added to 1000 mL of this wastewater, and the boron concentration in the filtrate was measured in the same manner as in Example 2. The results are shown in Table 2.

Example 3
Using boron-containing soil (boron elution concentration 5.5 mg/L), in 100 g of this soil, 3 wt% of the treatment material 1, 2 or 3 was added in a dry weight ratio, and further 7 wt% was added in a dry weight ratio. Well mixed with a tabletop mixer and cured at room temperature for 1 day, the elution concentration of boron was measured by the official method. The results are shown in Table 3.

Comparative Example 3
Using the boron-containing soil used in Example 3, 100% of this soil was added with treatment material 4, 5 or 6 in a dry weight ratio of 3%, and further added in a dry weight ratio of 7% with a tabletop mixer. After thoroughly mixing and curing at room temperature for 1 day, the elution concentration of boron was measured by the official method. The results are shown in Table 3. In the table, none is an example in which the amount of the treatment material added was 0.

Example 4
Commercially available B-type blast furnace cement (manufactured by Nippon Steel & Sumikin Cement Co., Muroran Plant), aluminum sulfate (anhydrous; manufactured by Daimei Chemical Co., Ltd.), sodium gluconate (manufactured by Fuso Chemical Co., Ltd.) in a mixing ratio shown in Table 4 (wt%). ), and the processed material 7 was created.

Comparative Example 4
The same Type B blast furnace cement, aluminum sulfate, or sodium gluconate used in Example 4 were mixed or used alone at the compounding ratios shown in Table 4 to obtain treatment materials 8 to 9.

Example 5 and Comparative Example 5
To 1000 mL of the wastewater A (boron concentration 54 mg/L) used in Example 2, 60 g of the treatment material 7 or 8 or 9 was added, and the mixture was stirred at 25° C. for 15 minutes and allowed to stand. After 24 hours, the solution was filtered with 5 A filter paper, and the boron concentration in the filtrate was measured by the pack test. The results are shown in Table 5.

Example 6
As the fluorine-containing wastewater, leachate of fluorine-containing rock (fluorine concentration 212 mg/L) was used (wastewater B). To 1000 mL of this wastewater, 100 g of the treating material 1, 2, 3 or 7 was added, and the mixture was stirred at 25°C for 15 minutes and allowed to stand. After 24 hours, the solution was filtered with 5 A filter paper, and the fluorine concentration in the filtrate was measured by the pack test. The results are shown in Table 6.

Comparative Example 6
Using the same wastewater B as that used in Example 6, 100 g of the treating material 4, 5, 6, 8 or 9 was added to 1000 mL of this wastewater, and treated in the same manner as in Example 6 to obtain a fluorine concentration in the filtrate. Was measured. The results are shown in Table 6.

Example 7
Leachate from arsenic/lead-containing soil (arsenic concentration: 1.6 mg/L, lead concentration: 0.5 mg/L) was used as wastewater containing hazardous substances (wastewater C). To 1000 mL of this wastewater, 100 g of the treating material 1, 2, 3 or 7 was added, and the mixture was stirred at 25°C for 15 minutes and allowed to stand. After 24 hours, the solution was filtered with 5 A filter paper, and the arsenic concentration in the filtrate was measured by a digital pack test. Also, the lead concentration was measured by the pack test. The results are shown in Table 7.

Comparative Example 7
The same arsenic-containing wastewater C as that used in Example 7 was used, 100 g of the treating material 4, 5, 6, 8 or 9 was added to 1000 mL of this wastewater, and the same treatment as in Example 7 was carried out to obtain a filtrate. The arsenic concentration inside was measured. Also, the lead concentration was measured by the pack test. The results are shown in Table 7.

Example 8 and Comparative Example 8
To 1000 mL of the wastewater A used in Example 2, 100 g of each of the treating materials 1, 2, 3, 7, 4, 6, 8 or 9 was added, and the mixture was stirred at 25°C for 15 minutes and allowed to stand.
This was left standing for 3 days, and the property of the precipitate was investigated. The results are shown in Table 8.
The evaluation of the solidification state of the precipitate is as follows.
A: Solidified (very hard)
B: Solidified (somewhat hard)
C: Solidification (fragile, can be crushed with fingers)
D; Slightly solidified (very brittle, can be crushed with fingers)

Example 9 and Comparative Example 9
Tunnel excavated soil (water content ratio: 31%, arsenic elution concentration: 0.80 mg/L) was used as contaminated soil, and 1 kg of this soil was treated with 1, 2, 3, 7, 4, 6, 8, or 9 treatment materials. 5 wt% of each was added, and the mixture was kneaded with a soil mixer for 3 minutes to form a cylindrical specimen of φ50×100 mm. The specimen was sealed and cured at 20° C. until the age of 7 days. Aged samples were subjected to a dissolution test in accordance with the Environmental Agency Notification No. 46, and the arsenic concentration in the filtrate after shaking was measured. Further, the uniaxial compressive strength of this cylindrical specimen was measured with a universal testing machine. The results are shown in Table 9. In the table, the blanks are similar examples except that the amount of the treatment material added was 0.

Reference Example Commercially available Portland cement, aluminum sulfate (anhydrous), sucrose or commercially available magnesium oxide (light burned magnesia) were mixed at the compounding ratio (wt%) shown in Table 10 to prepare treatment materials 11 to 16. ..

As the boron-containing wastewater, leachate of boron-containing rock (boron concentration: 108 mg/L) was used. To 1000 mL of this wastewater, 60 g of the treating material 11, 12, 13, 14, 15 or 16 was added, and the mixture was stirred at 25° C. for 15 minutes and allowed to stand. After 24 hours, the solution was filtered with 5 A filter paper, and the boron concentration in the filtrate was measured by the official method. The results are shown in the upper part of Table 11.
As the fluorine-containing wastewater, leachate of fluorine-containing rock (fluorine concentration 212 mg/L) was used (wastewater C). To 1000 mL of this wastewater, 100 g of the treating material 11, 12, 13, 15 or 16 was added, and the mixture was stirred at 25° C. for 15 minutes and allowed to stand. After 24 hours, the solution was filtered with 5 A filter paper, and the fluorine concentration in the filtrate was measured by an official method. The results are shown in the lower part of Table 11.

Claims (7)

Cement selected from clinker or cement, aluminum sulfate, and gluconic acid or gluconic acid for chelating the calcium content in the cement, preventing the production of ettringite and preventing the consumption of aluminum, and preventing strong solidification. It is composed of a mixture containing gluconic acids selected from salts, and when the total content of cements, aluminum sulfate and gluconic acids is 100 wt %, the content of cements is 50 to 98 wt %, and the content of aluminum sulfate is 1 to 1. 10 wt%, and the content of gluconic acids is 0.5 to 5 wt%, a treatment material for a harmful substance containing a boron compound as a harmful compound . The treatment material for harmful substances according to claim 1, wherein the cements are clinker powder, Portland cement, or blast furnace cement. The material for treating harmful substances according to claim 1 or 2, wherein the gluconic acid is sodium gluconate or potassium gluconate. The content of cements in the treated material is 50 to 95 wt%, the content of aluminum sulfate is 1 to 10 wt%, and the content of gluconic acids is 0.5 to 5 wt%. Material for treating harmful substances described in. A method for adsorbing, precipitating or insolubilizing a harmful substance treatment material according to any one of claims 1 to 4 by adding and mixing sludge containing a boron compound as a harmful compound or contaminated soil, and mixing the harmful compound. Characteristic method for treating harmful substances. The method for treating a harmful substance according to claim 5, wherein a pH adjusting agent is added to and mixed with the treatment substance for the harmful substance in sludge or contaminated soil containing the harmful compound. The hazardous substance treating material according to any one of claims 1 to 4, wherein the harmful substance is soil containing a boron compound as a harmful compound .