JP2006233018A - Inorganic electrolytic coagulant capable of rendering heavy metal ion harmless and processing method for resource recycling using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inorganic electrolytic coagulant which can almost permanently sequester harmful heavy metals based on the geological balance of elements and further enables them to be used as resources and to provide a processing method for resources recycling. <P>SOLUTION: The inorganic electrolytic coagulant for rendering heavy metal ions harmless consists of, as the main agent, an aqueous solution which incorporates the following A and at least one of B and C, and as the combined agent, an aqueous solution which incorporates the following D. Here, A: sulfuric acid; B: at least one of aluminum sulfate and polyaluminum sulfate; C: at least one of polyferric sulfate and ferric chloride; and D: at least one of potassium silicate and sodium silicate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an inorganic electrolytic coagulant capable of detoxifying heavy metal ions contained in incineration ash such as municipal waste or heavy metal contaminated soil in a factory site, and a resource recycling method using the same.

JP 2000-198981 A

  In nature, various elements exist in the soil as compounds, and this is the same for elements harmful to humans. For example, it is said that lead is contained in soil at 2 to 200 mg / kg. However, there have been no reports of cases where lead in this soil has adversely affected human health. The reason may be that each element exists in the form of a complex compound.

For example, it forms complex compounds (chain ion bonds) with metals, calcium salts / silica, sulfates / phosphoric acid, sulfur salts, etc., and exists in a chemically very stable state. It is considered. Therefore, harmful elements that exist in nature do not dissolve in the human sphere of life, that is, in groundwater, rivers, and the ocean.
On the other hand, a lead compound in a deep formation that does not come into contact with oxygen exists in a state of lead sulfide, and when it comes into contact with oxygen, it easily elutes as lead ions. The same applies to elements other than lead. By the way, the mine pollution (mine poisoning) problem is caused by this.

Conventionally, a wide variety of treatment agents (chelating agents) have been developed for heavy metal ions that are harmful to humans, and are widely used for heavy metal immobilization treatment on harmful treatment objects such as contaminated soil and incinerated ash. Yes. For example, the invention described in Patent Document 1 can be mentioned.
However, this chelating agent is composed of an organic substance. For example, the main component is a pyrrolidine-based, imine-based, or carbamic acid-based organic agent. Such organic substances are easily denatured and deteriorated from the definition of organic substances, and their effects cannot be expected permanently. Therefore, at present, there is no choice but to landfill the harmful processing objects as described above at the final disposal site. In reality, most of the municipal waste incineration ash and more than half of the contaminated soil are landfilled.
However, recently it has become difficult to secure a final disposal site. Incineration ash has been put to practical use by making it into slag in a melting furnace and using it for concrete aggregates, etc., but it is difficult to say that adoption is progressing because enormous capital investment is required. The current situation is that it is a common problem for local governments nationwide.

  In view of the above, the present invention is based on the geological balance of elements, and can block harmful heavy metals almost permanently, and can also be used as a resource, an inorganic electrolytic coagulant, and a recycling process using the same It is an object to provide a method.

In order to solve the above-mentioned problem, the invention according to claim 1 of the present application includes an aqueous solution in which at least one of B and C is blended together with the following A as a main ingredient:
(A) sulfuric acid (B) at least one of aluminum sulfate and polysulfate (C) at least one of ferric sulfate and ferric chloride as a concomitant agent, and an aqueous solution containing the following D:
(D) An inorganic electrolytic coagulant capable of detoxifying heavy metal ions, comprising at least one of potassium silicate and sodium silicate.

The invention according to claim 2 of the present application is characterized in that the heavy metal ion according to claim 1, wherein at least one of the following E and F is further blended with the main agent: An inorganic electrolytic coagulant that can be rendered harmless is provided.
(E) at least one of ferric sulfate (F) magnesium chloride and magnesium sulfate

The invention according to claim 3 of the present application is characterized in that at least one of the following G and H is further blended with the above-mentioned combination agent, An inorganic electrolytic coagulant capable of detoxifying heavy metal ions is provided.
(G) at least one of sodium tripolyphosphate, sodium aluminate, and sodium hexametaphosphate (H) sodium polyacrylate

  The invention according to claim 4 of the present application is based on an aqueous solution in which the above A, B, C, E, and F are blended as a main agent, and an aqueous solution in which the above D, G, and H are blended as a concomitant agent. The weight blending ratio in the main agent is 100 to 250 for water, 2 to 5 for the above, 250 to 600 for the same B, 80 to 250 for the same C, 10 to 50 for the same E, and 10 to 10 for the same F. The weight blending ratio in the concomitant is 100 to 300 for water, 500 to 1000 for D, 10 to 40 for G, and 2 to 5 for H. An inorganic electrolytic coagulant capable of detoxifying heavy metal ions is provided.

  The invention according to claim 5 of the present application uses the inorganic electrolytic coagulant according to any one of claims 1 to 4, and first mixes the main agent with respect to the object to be treated. Then, the resource-recycling processing method using the inorganic electrolytic coagulant which can sequester the heavy metal ion in a process target object by further mixing a combined use agent is provided.

  The inorganic electrolytic coagulant according to the invention of the present application is a processing agent composed of a completely inorganic agent based on the definition of an inorganic substance, which is unprecedented and has excellent processing accuracy, natural geological Insoluble precipitated crystals very similar to providence contain harmful substances and can be made harmless almost permanently.

In addition, according to the resource recycling method using the inorganic electrolytic coagulant according to the present invention, detoxification can be achieved, and at the same time, the contaminated soil and incinerated ash that are the objects to be processed can be utilized as excellent resources. Therefore, it is not necessary to adopt a disposal method that only has to be landfilled at the final disposal site as in the past.
In addition, when the treatment agent according to the present invention is used for contaminated soil existing in the natural world such as land mud and seabed mud, it is possible to vigorously promote the propagation of soil microorganisms and activate the circulation of natural ecosystems. It can exert an extremely excellent effect on vegetation.
Therefore, the inorganic electrolytic coagulant according to the present invention includes general municipal waste and incineration ash of industrial waste, heavy metal contaminated soil in industrial sites, industrial wastewater treatment sludge, river and lake sludge, harbor sludge, sewage sludge, etc. It can be effectively used for various processing objects.

Hereinafter, an example of an embodiment of the present invention will be described.
The inorganic electrolytic coagulant according to the present invention is a synergistic effect of a hydration reaction that cannot be achieved with a single charge by synthesizing and blending several types of inorganic positively charged substances with different ionic valences in one solvent liquid. It is modified to a polyvalent metal positive charge coagulant with a very wide neutralization area and processing accuracy, and the combined agent is mainly composed of sodium silicate and has several metal ion sequestering ability and aggregation effect. It is a heavy metal immobilizing agent composed of two liquids in which sodium is synthesized and mixed in one solvent liquid.

  The components blended in the inorganic electrolytic coagulant of this example are as shown in Table 1.

In the main component, water is used as a solvent. The water used here is preferably water that is not mixed with chlorine, such as groundwater.
Sulfuric acid (component A in the table, hereinafter the same) keeps the main agent acidic and prevents separation and precipitation of each salt.
Aluminum sulfate (B) is a so-called “sulfuric acid band” which reacts with SiO ₂ , CaO or the like as active alumina and becomes a major component of various precipitated crystals. Instead of this aluminum sulfate, the same amount of polyaluminum sulfate can be used. Aluminum sulfate and polyaluminum sulfate can also be used in combination.
Polyferric sulfate (C) is a polymer that forms a polynuclear complex. It condenses even at low temperatures and reacts sensitively with SiO ₂ to build insoluble crystals. Instead of this ferric sulfate, the same amount of ferric chloride can be used. Further, polyferric sulfate and ferric chloride can be used in combination.
Note that the above-described aluminum sulfate (polyaluminum sulfate) and polyferric sulfate (ferric chloride) may be omitted.
Ferric sulfate (E) is a low molecular flocculant. In combination with the above-mentioned ferric polysulfate, which is a polymer, enables a wide range of condensation. About this ferric sulfate, you may abbreviate | omit a mixing | blending.
Magnesium chloride (F) is a so-called “garlic”, and plays a role of improving the dehydrating property of the object to be treated and the above coagulation reaction. Instead of this magnesium chloride, the same amount of magnesium sulfate can be used. Further, magnesium chloride and magnesium sulfate can be used in combination. Note that this magnesium chloride and magnesium sulfate may be omitted.

Water is also used as a solvent in the components of the combination agent. As in the case of the main agent, it is desirable that the water is free of chlorine, such as groundwater.
Potassium silicate (D) is the main component of the soil effect stabilizer. It reacts sensitively with polyvalent metal ions and CaO to construct various insoluble crystals. In this example, “industrial potassium silicate” which is a colorless or slightly colored viscous liquid is used. It is soluble in water and liberates gel-like silicic acid with acid. Instead of this potassium silicate, the same amount of sodium silicate can be used. Moreover, potassium silicate and sodium silicate can also be used together. This potassium silicate (sodium silicate) can be used alone as a combination agent.
Sodium tripolyphosphate (G) has the ability to sequester metal ions, improves the properties of the object to be treated, and improves the dispersibility of the inorganic agent during the treatment. Instead of this sodium tripolyphosphate, the same amount of sodium aluminate or sodium hexametaphosphate can be used. Moreover, sodium tripolyphosphate, sodium aluminate, and sodium hexametaphosphate can be used in combination by selecting at least two of them. About this sodium tripolyphosphate, sodium aluminate, and sodium hexametaphosphate, you may abbreviate | omit a mixing | blending.
Sodium polyacrylate (H) is a high molecular polymer and has the ability to electrostatically strongly attract and condense metal positively charged colloidal particles in the acidic region, so that it can be processed quickly. The blending of this sodium polyacrylate may be omitted.

  Next, the manufacturing method of the main ingredient is described. First, water with no chlorine contamination, such as groundwater, is heated to a specified amount of about 75 ° C. Then, a specified amount of magnesium chloride (F) is added and lightly stirred (around 3 minutes). After confirming that the magnesium chloride (F) has completely dissolved, add the specified amount of sulfuric acid (A), stir gently (around 2 minutes), and mix well. Next, the specified amount of aluminum sulfate (B) is added, and lightly mixed and stirred (around 2 minutes). At this point, it is confirmed that the temperature of the aqueous solution is maintained at around 75 ° C. Next, specified amounts of polyferric sulfate (C) and ferric sulfate (E) are added, and lightly mixed and stirred (around 2 minutes). At this time, it is confirmed that the temperature of the aqueous solution is maintained at around 75 ° C., and then the production of the main agent is completed. Thereafter, the main agent thus produced is allowed to stand, and after it reaches room temperature, it is sealed in a container and stored.

  Next, a method for producing a concomitant drug will be described. First, water with no chlorine contamination, such as groundwater, is heated to a specified amount of about 75 ° C. Thereafter, a specified amount of sodium polyacrylate (H) is added and stirred (around 10 minutes). After confirming that the sodium polyacrylate (H) is completely dissolved, the specified amount of sodium tripolyphosphate (G) is added and stirred (around 5 minutes). After confirming that sodium tripolyphosphate (G) is completely dissolved, a specified amount of potassium silicate (D) is added, and lightly mixed and stirred (around 2 minutes). At this point, after confirming that the temperature of the aqueous solution is maintained at around 75 ° C., the production of the combination agent is completed. Then, the resultant concomitant is allowed to stand, and after being at room temperature, sealed in a container and stored.

Next, a specific treatment method will be described for the treatment of sequestering heavy metal ions contained in artificial contaminants. The case where the treatment target is incinerated ash of general municipal waste or heavy metal contaminated soil in a factory site is exemplified here.
First, water is sprayed on the object to be treated and stirred so that the water is evenly distributed. The water content is about 95%. Then, the main agent is uniformly added to the processing target in this state, and well mixed and stirred for 10 to 15 minutes. Next, the concomitant agent is added uniformly in the specified amount, and mixed and stirred well for 10 to 15 minutes. The blending ratio of the inorganic electrolytic coagulant is 2.5% by weight with respect to the treatment target for both the main agent and the concomitant agent. This completes the heavy metal closing process for the object to be processed. Leave the object to be treated for 24 hours or more in a state where it is protected from rainwater by covering with a construction sheet.

Next, a specific processing method will be described with respect to the processing for recycling the processing target in the state where the above processing has been performed. First, the case where incineration ash of general municipal waste is used as the processing object will be exemplified here.
The above treated incineration ash is thoroughly mixed and agitated with mountain sand and construction soil. The mixing ratio is 60%, such as incineration ash 40%, mountain sand, etc. by weight. Next, water is added to the above mixture while stirring to obtain a slurry state. To this, 25% by weight of potassium silicate or sodium silicate is added and mixed and stirred for 10 to 15 minutes. Further, slaked lime or quick lime is added at 30% by weight, and mixed and stirred for 10 to 15 minutes. The reason why potassium silicate, slaked lime, etc. are added in this recycling process is to stimulate the latent hydraulic components in the incinerated ash and extract a stronger solidification strength in addition to the component adjustment. This completes the resource recycling process for the object to be processed. Leave the object to be treated for 24 hours or more in a state where it is protected from rainwater by covering with a construction sheet.
In addition, when the heavy metal contamination soil in a factory ruins etc. is used as a process target object, the process after the process of adding said water shall be performed.

  Processed materials that have been treated in this way are strengthened embankments such as rivers and lakes, improvements to prevent liquefaction of sandy land, deeper layers of soft ground, construction of waterway grounds, improvement of road infrastructure, law It can be used in various applications such as surface protection, reuse of factory-contaminated soil for backfilling, and construction of temporary roads.

Next, a specific treatment method will be described for the treatment of sequestering heavy metal ions contained in pollutants in nature. The case where bottom mud such as a river, a lake, a harbor, etc. is used as the processing object is illustrated here. In addition, the bottom mud to be used for the treatment is a mud-type bottom mud immediately after dredging, which is passed through a sieve having an eye of about 10 mm and shells, dust, stones, etc. are removed.
First, water is sprinkled on the bottom mud after the above sieve and stirred so that the water is evenly distributed. The water content is about 95%. Then, the main agent is uniformly added to the processing target in this state, and well mixed and stirred for 10 to 15 minutes. Next, the concomitant agent is added uniformly in the specified amount, and mixed and stirred well for 10 to 15 minutes. The blending ratio of the inorganic electrolytic coagulant is 20% by weight for both the main agent and the concomitant agent with respect to the bottom mud after the above sieve. This completes the heavy metal closing process for the object to be processed. Leave the object to be treated for 24 hours or more in a state where it is protected from rainwater by covering with a construction sheet.

  In addition, the bottom mud is very rich in organic matter due to the accumulation of animal and plant carcasses over the years. Therefore, the bottom mud that has been subjected to heavy metal closing treatment as described above is optimal as a mineral-activated organic fertilizer having soil reforming ability. In particular, offshore mud is suitable for field fertilization. Port bottom mud is suitable for fertilizing paddy fields.

  In addition, although the compounding rate of the inorganic electrolytic coagulant illustrated above is an example and can be appropriately changed according to the composition of the processing object, the weight ratio of both the main agent and the concomitant agent is 0.5 to It is used in the range of 30%, more preferably in the range of 2 to 10%.

  In addition, the inorganic electrolytic coagulant according to the present invention exhibits a sufficient heavy metal closing effect even when used alone, but may be used in combination with a chelating agent existing in the past. In that case, in the initial stage of the treatment, a synergistic effect of the effect of the chelating agent made of an organic substance and the effect of the inorganic electrolytic coagulant can be expected, and in addition to this, almost no modification or deterioration occurs due to the definition of the inorganic substance. With no inorganic electrolytic coagulant, the effect can be expected permanently.

Next, a verification test was performed using the inorganic electrolytic coagulant of this example, which will be described below.
Municipal waste incineration ash collected at the Sakai Environmental Sanitation Center was used as the treatment object.
First, the heavy metal content and elution amount of the object to be treated were measured. The content test was conducted based on the Environmental Agency notification, Ring Water Tube No. 127, Sediment Survey Method II, Content Test. The dissolution test was based on the Environmental Agency Notification No.13, dissolution test. The measurement of heavy metals in the elution water was performed according to JIS K-0102 “Factory drainage test method”. The results are shown in Table 2.

  The object to be treated was collected in a hemispherical plastic container having a diameter of about 20 cm, and a predetermined amount of an inorganic electrolytic coagulant was added. Specifically, after adding the main agent and mixing uniformly with a spatula, a concomitant agent was further added and mixed uniformly with a spatula. In this case, the blending ratio of the inorganic electrolytic coagulant was set to 2 types, 3% and 6% by weight in the main agent and the concomitant agent with respect to the object to be treated. And after leaving the process target object which added the inorganic electrolytic coagulant for 24 hours, the elution amount test similar to the above was done. As shown in Table 2, since the elution value of heavy metals and the like of the object to be treated (before treatment) was below the legal reference value except for lead, only elution of lead was measured in this elution amount test. The results are shown in Table 3.

  As shown in the above experimental results, no elution of lead was observed from the processing object to which the inorganic electrolytic coagulant was added. In addition, it was confirmed that the heavy metal was sufficiently fixed and detoxified with the weight ratio of the inorganic electrolytic coagulant to the object to be treated being 3%. Therefore, it can be said that the inorganic electrolytic coagulant according to the present invention can exhibit the effect sufficiently with a small amount of use and is excellent in economic efficiency.

  Next, a verification test was conducted with the object to be treated as bottom mud, which will be described below. Three types of treatment objects were used: lake mud, estuary mud, and harbor mud. In this case, the blending ratio of the inorganic electrolytic coagulant was 20% by weight with respect to the object to be treated. About the measuring method, it is the same as that of the case of said incineration ash. The results are shown in Table 4.

  As shown in the above experimental results, the treatment object to which the inorganic electrolytic coagulant is added has a dramatically reduced concentration in any analysis item, and the inorganic electrolytic coagulant according to the present invention is about bottom mud. It was also confirmed that the effect can be fully exhibited.

Claims (5)

As the main agent, the following A is blended, and an aqueous solution in which at least one of B and C is blended;
(A) sulfuric acid (B) at least one of aluminum sulfate and polysulfate (C) at least one of ferric sulfate and ferric chloride as a concomitant agent, and an aqueous solution containing the following D:
(D) An inorganic electrolytic coagulant capable of detoxifying heavy metal ions, comprising at least one of potassium silicate and sodium silicate. The inorganic electrolytic coagulant capable of detoxifying heavy metal ions according to claim 1, wherein at least one of the following E and F is further blended with the main agent.
(E) at least one of ferric sulfate (F) magnesium chloride and magnesium sulfate The inorganic electrolytic coagulant capable of detoxifying heavy metal ions according to claim 1 or 2, wherein at least one of the following G and H is further added to the combination agent.
(G) at least one of sodium tripolyphosphate, sodium aluminate, and sodium hexametaphosphate (H) sodium polyacrylate An aqueous solution containing the above A, B, C, E, and F as a main agent,
As a concomitant agent, it consists of an aqueous solution containing the above D, G, H,
The weight blending ratio in the main agent is 100 to 250 for water, 2 to 5 for the above, 250 to 600 for the same B, 80 to 250 for the same C, 10 to 50 for the same E, 5 to 10 for the same F,
The weight blending ratio in the concomitant agent is 100 to 300 for water, 500 to 1000 for D, 10 to 40 for G, and 2 to 5 for H. An inorganic electrolytic coagulant that can detoxify heavy metal ions. The inorganic electrolytic coagulant according to claim 1 is used,
A resource recycling method using an inorganic electrolytic coagulant capable of sequestering heavy metal ions in a treatment object by first mixing the main agent with the treatment object and then further mixing a combination agent.