JP2002326819A - Iron sulfide, its production method, iron sulfide composition, heavy metal treatment agent and treatment method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new iron sulfide and iron sulfide composition excellent in durability and treatment capability of heavy metals, to provide a method which synthesizes these new iron sulfides and to provide a method which treats heavy metals contained in ashes, soil and waste water and so on and renders it harmless by using the heavy metal treatment agent containing the iron sulfide as an active element and this treatment agent. SOLUTION: The iron sulfide excellent in durability having a maquinawate structure shown by Fe.Mx .Ny .Sz as an essential component of constituting element (in the formula, M shows an alkaline earth metal, N shows an alkali metal, x, y and z show mol ratio, 0.01<=x<=0.5, y<=0.2, 0.7<=z<=1.4), this production method, the iron sulfide composition and the heavy metal treatment agent whose active ingredient is this iron sulfide and the treatment method using it are used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel iron sulfide having excellent durability, a method for producing the same, an iron sulfide composition containing the same,
The present invention relates to a novel agent for treating heavy metals containing iron sulfide as an active ingredient, and a method for detoxifying waste containing various heavy metals using the agent for treating heavy metals.

[0002]

2. Description of the Related Art Reviews of Pure an
d Applied Chemistry, Volume 20, 1
On pages 75 to 206 (1970), the structure of iron sulfide is shown, and generally known industrial iron sulfide and iron sulfide produced by melting iron powder and sulfur have a pyrrhotite structure, Further, it is disclosed that iron sulfide formed by mixing a solution containing iron (II) ions and a solution containing sulfur ions has a makinawite structure.

It is widely known that iron sulfide is used to detoxify waste containing various heavy metals.
JP-B-49-43472, JP-A-47-3180
No. 6, JP-A-50-13294, JP-A-50-13294
No. 96053, JP-A-52-126885, JP-A-60-227881, etc., by using industrial iron sulfide (pyroite structure) or the like, Pb and C in an aqueous solution.
A method for treating harmful heavy metals such as d, Cr, Hg, and As is disclosed.

It is also known to treat heavy metals with iron sulfide (makinawite structure) prepared by mixing a solution containing iron (II) ions and a solution containing sulfur ions. It is known that the obtained iron sulfide has a higher ability to treat heavy metals than industrial iron sulfide.
For example, JP-A-48-11291, JP-A-49-11291
No. 31152, JP-A-52-113559,
JP-A-52-148473, JP-A-53-102
No. 273 discloses a method for treating harmful heavy metals using a solution containing iron (II) ions and a solution containing sulfur ions, or iron sulfide obtained by mixing these solutions. ing.

However, iron sulfide having a mackinawite structure is very easily oxidized, reacts with moisture and oxygen in the air to decompose into sulfur and iron (III) hydroxide, and the ability to treat heavy metals easily decreases. Would. Therefore, conventionally, a solution containing iron (II) ions and a solution containing sulfur ions are mixed to prepare a slurry containing iron sulfide, and the slurry is used as it is immediately mixed with an object to be treated such as wastewater. That was customary. Normally, sodium sulfide or sodium bisulfide aqueous solution is used for the solution containing sulfur ions because of its price and industrial availability.
The operation must be performed by a skilled person having knowledge of chemistry due to corrosiveness and odor, and general handling is difficult. Further, when used in a slurry, it is difficult to increase the concentration of iron sulfide in order to have a certain fluidity,
For example, when iron sulfide slurry is manufactured at a factory, transportation costs become large, and when used for wastewater treatment, etc., there is no problem, but for example, fly ash and soil containing high concentration heavy metals are treated. Therefore, when a large amount of iron sulfide is added, there is a problem that the water content of the object to be treated becomes too high, and subsequent handling becomes difficult.

On the other hand, in the case of preparing a makinawite-structured iron sulfide powder by filtering and drying the slurry, in order to prevent oxidation,
It was necessary to operate under an inert atmosphere or to add an antioxidant. The obtained iron sulfide powder had to be stored in a container impervious to oxygen and moisture or had to be added with a reducing agent for preventing oxidation so as not to cause oxidative deterioration. The addition of the reducing agent did not fundamentally solve the susceptibility to oxidative degradation, and the storage stability was extremely low because the oxidation of iron sulfide started when the reducing agent was consumed.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a novel iron sulfide having excellent durability and excellent heavy metal treatment properties, and an iron sulfide composition containing the novel iron sulfide. And a method for synthesizing them. Another object of the present invention is to provide a treating agent for heavy metals containing the iron sulfide as an active ingredient, and a method for treating and rendering harmless heavy metals contained in ash, soil, wastewater and the like using the treating agent. And

[0008]

Means for Solving the Problems The present inventors have solved the above problems,
That is, the conventional synthetic iron sulfide has a high heavy metal treatment activity but has a disadvantage of poor durability, and as a result of intensive studies to solve this, as a result, the alkaline sulfide metal was incorporated into the iron sulfide in a certain amount or more. , as an essential component of the constituting elements in _{Fe · M x · N y ·} S z ( wherein, M is alkaline earth metal, N represents an alkali metal, x, y and z are molar ratios,
0.01 <x ≦ 0.5, y ≦ 0.2, 0.7 ≦ z ≦ 1.
4 is shown. )), The durability can be drastically improved by using a novel composition of iron sulfide, and such an iron sulfide contains an aqueous solution of a divalent iron salt and sulfur ions. It has been found that an aqueous solution can be obtained by mixing an aqueous solution with an alkaline earth component and adjusting the pH of the slurry after mixing to 7.0 or more. In addition, they found that the novel heavy metal treatment agent containing iron sulfide as an active ingredient has dramatically superior processing characteristics for various heavy metals compared to conventional synthetic iron sulfide and iron sulfide having a pyrrhotite structure. The invention has been completed.

Hereinafter, the present invention will be described in detail.

[0010] the iron sulfide of the invention, as an essential component of the constituting elements in _{Fe · M x · N y ·} S z ( wherein, M is alkaline earth metal, N represents an alkali metal, x, y and z are mole Ratio, 0.01 <x ≦ 0.5, y ≦ 0.1, 0.7 ≦ z ≦
1.4 is shown. ) Is essential.

In general, it is known that the molar ratio of iron to sulfur in iron sulfide is non-stoichiometric, and the molar ratio can take an arbitrary value around 1. The iron sulfide of the present invention also has a molar ratio z of sulfur to iron of 0.7 or more and 1.4 or less, similarly to the iron sulfide of the conventional mackinawite structure. In order to obtain a more stable Mackinawite structure, the ratio is preferably 0.8 or more and 1.0 or less.

The amount of alkaline earth metal in the iron sulfide of the present invention is represented by a molar ratio x to iron, where x is 0.01 <x
≦ 0.5. When the molar ratio x is 0.01 or less, improvement in durability cannot be expected. On the other hand, when x exceeds 0.5, the obtained stabilization improving effect is less than that in the range. .

The alkaline earth metal-containing iron sulfide of the composition of the present invention exhibits different XRD depending on the order in which the alkaline earth metal is added during preparation. That is, after mixing an aqueous solution containing a ferrous salt and sulfur ions, an alkaline earth metal component is added and p
When it is H7 or more, it shows the XRD attributed to the mackinawite structure, and when an aqueous solution containing a ferrous salt and a sulfur ion is mixed in the presence of an alkaline earth metal component to make the pH 7 or more, 1 shows a modified mackinawite structure. The present inventors show that in any case, within the composition range of the present invention, no peak derived from the alkaline earth metal component is observed, and that the effect of improving the durability in this range is extremely large. It was found. Furthermore, when an alkaline earth metal component exceeding this composition range is added, a peak attributed to the compound of the alkaline earth metal component comes to be observed, and the effect of improving durability is less than that. It is almost equivalent to the composition. However, the optimum range for recognizing this effect is slightly different depending on the type of the alkaline earth metal, and is 0.04 ≦ x ≦ 0.5 for magnesium, 0.03 ≦ x ≦ 0.4 for calcium, and 0 for strontium. .02 ≦ x ≦ 0.3, and further, for barium, 0.0
1 ≦ x ≦ 0.2.

In the present invention, it is also possible to use a plurality of kinds of alkaline earth metals by arbitrarily combining the above four elements. In the present invention, the most preferred alkaline earth metals are calcium and magnesium among the above four elements. Calcium and magnesium are not only easily incorporated into iron sulfide,
It is readily available industrially, is not as expensive as strontium, and does not pose toxicity problems like barium.

In the amount of alkali metal in the iron sulfide of the present invention, the upper limit of the molar ratio y to iron is lower than that of iron sulfide having a makinawite structure which has been known so far, and is 0.2 or less. Is required. When the amount of the alkali metal is larger than 0.2, it is difficult to obtain iron sulfide having excellent durability, which is the object of the present invention, and improvement in durability can be expected as the amount of the alkali metal is small,
More preferably, the amount of alkali metal is 0.1 or less.
Incidentally, the iron sulfide of the present invention includes a case where no alkali metal is contained at all, and for example, y is set to 0 by manufacturing a material containing no alkali metal as a raw material or removing an alkali metal component by washing or the like. Thus, iron sulfide can be obtained. Since the type of alkali metal differs depending on the raw material used, it cannot be said unconditionally.For example, when sodium sulfide or sodium hydrosulfide, which is industrially easily available, is used as a raw material for sulfur ions, N in the above composition formula is sodium and Become.

In the present invention, the durability was evaluated by changing the temperature and the relative humidity. Decomposition of the iron sulfide having a makinawite structure by a conventional synthetic method progresses in one day at summer temperature (up to 30 ° C.) and relative humidity (up to 70%), and a peak of S starts to be observed in XRD, and complete in seven days. And the peak attributable to the mackinawite structure disappears. Further, under the conditions of 50 ° C. and 70% relative humidity, the compound is completely decomposed in one day, and the peak attributed to the mackinawite structure disappears. On the other hand, the iron sulfide of the present invention has a residual rate of 50% or more (decomposition rate is less than 50%) even when subjected to one-day durability treatment at 70 ° C. and 70% relative humidity. It is characterized by extremely improved durability.

By adding an alkaline earth metal,
It is not clear why the durability is improved, but the alkaline earth metal is incorporated into the iron sulfide and a layer that prevents oxidative decomposition is formed on the surface of the iron sulfide, or the alkaline earth metal progresses oxidative decomposition. Presumed to be preventing.

The alkaline earth metal incorporated in the iron sulfide is not replaced by the iron in the iron sulfide but is incorporated in the form of a hydroxide or oxide of the alkaline earth metal. It is estimated that there is.

In the present invention, the "makinawite structure"
JCPDS card (PowerDiffraction)
n File) 15-37, and its XRD diffraction pattern is as shown in Table 1 below.

[0020]

[Table 1] In addition, the modified makinawite structure referred to in the present specification means that in the XRD diffraction pattern of the makinawite structure shown in Table 1 above, the plane spacing of the 001 plane is 5.03 ° or more and 5.5 or more.
It spreads in the c-axis direction at 3 ° or less, and when the peak intensity from this 001 plane is set to 100, it means a structure characterized by the fact that the intensity ratio of diffraction peaks from other hkl planes is all 20 or less.

Although the cause of the modified makinawite structure is not clear, when an alkaline earth metal component is present when iron sulfide is formed, the alkaline earth metal is introduced into the iron sulfide by the c-axis, that is, the iron atomic layer. It is presumed that the distance between the silicon atom and the sulfur atom layer is widened, and that the atoms are incorporated so as to cause disorder in the arrangement of the a-axis and the b-axis, that is, the arrangement of iron atoms and sulfur atoms.

As a result of examining the above-mentioned iron sulfide having the modified makinawite structure, the iron sulfide having the modified makinawite structure was dispersed in water, added with a weak acid such as acetic acid, and then filtered and washed. It was found that a part of the alkaline earth metal was eluted and the XRD diffraction pattern reversibly changed to a mackinawite structure. Therefore, it is considered that the modified makinawite structure of the present invention is a special form of the known makinawite structure.

Next, the method for producing iron sulfide of the present invention will be described in detail.

In the method of the present invention, the aqueous solution of a divalent iron salt, the aqueous solution containing sulfur ions, and the alkaline earth metal component are mixed, and the pH of the slurry after mixing is adjusted to 7.0 or more. An iron sulfide having a makinawite structure having excellent properties is obtained.

In the method of the present invention, the mixing order of the above three components can be appropriately selected. An aqueous solution of a divalent iron salt and an aqueous solution containing sulfur ions are mixed, and then the alkaline earth metal component is mixed. Alternatively, an aqueous solution of a divalent iron salt and an alkaline earth metal component may be mixed and then mixed with an aqueous solution containing sulfur ions, or an aqueous solution containing sulfur ions and an alkaline earth metal component may be mixed. Alternatively, an aqueous solution of a divalent iron salt may be mixed, and an optimal method can be selected in terms of a production process. The inventor further proposes that, in the above-described mixing method, when an alkaline earth metal is present when iron sulfide is generated by mixing an aqueous solution of a divalent iron salt and an aqueous solution containing sulfur ions, a makinawite structure to be generated is formed. It has been found that iron sulfide has a modified mackinawite structure.

The aqueous solution of a divalent iron salt used in the method of the present invention is not particularly limited as long as it is a water-soluble divalent iron salt. Specifically, iron (II) chloride, iron (II) nitrate , Iron (II) sulfate and iron (II) acetate. Among these, iron (II) chloride is most preferable because it is industrially easily available and inexpensive, and a solution obtained by dissolving iron scraps and the like with hydrochloric acid and a waste liquid after washing an iron plate with hydrochloric acid are also preferably used. be able to. On the other hand, when the alkaline earth metal component is Ca, Sr, or Ba, iron (II) sulfate is liable to form a sparingly soluble salt with these components. ,
When the alkaline earth metal component is Mg, it can be suitably used.

The concentration of the aqueous solution of the divalent iron salt used is not particularly limited, but if the concentration is too low, the volume of the reaction tank becomes large, and the amount of slurry to be filtered increases, which is industrially disadvantageous. Sometimes. Conversely, if the concentration is too high, problems such as salt precipitation due to temperature fluctuations are likely to occur, and the viscosity of the resulting slurry will increase, making handling and uniform mixing difficult. Therefore, the specific concentration of the divalent iron salt is 1 to 2 as Fe.
A range of 5 wt%, more preferably 3 to 20 wt% can be exemplified.

The solution containing sulfur ions used in the method of the present invention is not particularly limited as long as the solution contains sulfur ions, and the sulfide or hydrosulfide of an alkali metal salt, the sulfide or hydrosulfide of an ammonium salt is used. Any one obtained by dissolving a sulfide or a hydrosulfide of an alkaline earth metal in water can be suitably used. Among them, sodium sulfide and sodium hydrosulfide are most preferable because they are industrially easily available and inexpensive, and a solution in which hydrogen sulfide obtained in a petroleum desulfurization step is absorbed in an aqueous alkali solution such as sodium hydroxide is also preferable. Can be used.

The concentration of the solution containing sulfur ions to be used is not particularly limited, but for the same reason as the concentration of the aqueous solution of a divalent iron salt. As a specific sulfur ion concentration, S
1 to 15 wt%, more preferably 2 to 10 wt%
Can be exemplified.

The alkaline earth metal component is not particularly limited as long as it is water-soluble. In addition, even if it does not show water-solubility such as carbonate, it is possible to use one which dissolves in an acidic solution. . Specific examples of alkaline earth metal components include chlorides, carboxylate salts, nitrates, hydroxides, and sulfides of alkaline earth metals.

The mixing ratio of the aqueous solution of a divalent iron salt and the aqueous solution containing sulfur ions is not particularly limited. However, if the amount of sulfur ions is too large, not only does the raw material cost increase, but also unreacted sulfur ions are removed from the mother liquor. It may remain inside and require wastewater treatment. Conversely, if too little, the excess iron will precipitate as iron hydroxide, resulting in a mixture of iron sulfide and hydroxide,
Although the characteristics of the iron sulfide do not deteriorate, the iron sulfide is diluted by the weight of the iron hydroxide, and the apparent characteristics deteriorate. Therefore, it is preferable to mix Fe and S in a molar ratio of 1: 0.7 to 1.8, more preferably 1: 0.8 to 1.5.

The mixing ratio of the aqueous solution of the divalent iron salt and the alkaline earth metal component varies depending on the type of the alkaline earth metal. If the amount of the alkaline earth metal is small, the durable makinawite structure of the present invention can be obtained. No iron sulfide can be obtained.
Therefore, when the alkaline earth metal component is magnesium (Mg)
In the case of, it is preferable that the molar ratio of Fe and Mg is 1: 0.04 or more. When the alkaline earth metal component is calcium (Ca), the molar ratio of Fe and Ca is
1: It is preferable to mix them so as to be 0.03 or more,
When the alkaline earth metal component is strontium (Sr), it is preferable to mix them so that the molar ratio of Fe and Sr is 1: 0.02 or more. When the alkaline earth metal component is barium (Ba), it is preferable to mix Fe and Sr. When the molar ratio of Ba is 1: 0.0
It is preferable to mix them so as to be at least one.

The mixing operation is not particularly limited, and a semi-batch method or a continuous method known in chemical engineering can be used.

The temperature at the time of mixing is not particularly limited, and there is no need to cool and heat. For example, a temperature of 10 to 60 ° C. can be exemplified.

The stirring at the time of mixing is not particularly limited, and there is no particular problem as long as the stirring intensity is such that the generated slurry containing iron sulfide does not stay.

The mixing speed of the raw materials is not particularly limited, but if the mixing is too slow, the productivity may decrease, and if the mixing is too fast, local stagnation and an increase in viscosity may occur.
Therefore, for example, in the case of a semi-batch system, the addition rate may be selected so that all the raw materials are mixed in 1 to 240 minutes, more preferably in 3 to 120 minutes. 10 to 240 minutes, more preferably 1
What is necessary is just to make it 5-120 minutes.

As described above, when the mixing operation is completed, the slurry containing the iron sulfide of the present invention is obtained. In the present invention, it is essential that the slurry pH at the end of the mixing operation is 7.0 or more. Although an alkali source may be added after the completion of mixing to make the slurry pH 7.0 or more, it is more preferable to add the alkali source to an aqueous solution containing sulfur ions in advance. The alkali source is not particularly limited, and examples thereof include hydroxides of alkali metals and hydroxides of alkaline earth metals. Specific examples include sodium hydroxide, potassium hydroxide, calcium hydroxide, and barium hydroxide. it can. When the slurry pH is less than 7.0, the alkaline earth metal is not taken into the iron sulfide, and the iron sulfide of the present invention cannot be obtained. The slurry pH is preferably as high as possible, more preferably 8.0 or more, more preferably 10.0 or more, and still more preferably 1 or more.
It is good to be around 2.0.

Further, after the mixing of the raw materials is completed, stirring may be continued and aging may be performed in order to make the entire slurry formed uniform. The aging time is not particularly limited, and may be, for example, a time of 0 to 300 minutes.

The slurry containing the iron sulfide of the present invention can be obtained by the above method. This slurry may be used as it is for the treatment of heavy metals, but the transportation cost becomes enormous,
In addition, if a large amount of iron sulfide is added to treat fly ash or soil containing high concentrations of heavy metals, the water content of the material to be treated may be too high and handling after that may be difficult. is there. Therefore, usually, after filtration and washing, drying is performed to obtain iron sulfide powder.

As a method of filtration and washing at this time, a known method can be used. However, if filtration and washing are insufficient, the alkali sulfide remaining in the iron sulfide has a high durability. It will be difficult to obtain. Therefore, the filtration and washing conditions are as follows: when the molar ratio of iron to alkali metal in the iron sulfide obtained after filtration and washing is 1, and the molar ratio of iron is 1,
Alkali metal value is 0.2 or less, more preferably 0.1
It is necessary to satisfy the following conditions.

Drying may be carried out by any conventionally known method, but in order to prevent oxidation of iron sulfide, drying in an inert atmosphere gas or vacuum drying can be more preferably used.

The iron sulfide of the present invention can be obtained by the above method.

The present inventors have further studied and found that by adding various alkaline earth metal compounds to the iron sulfide having the composition of the present invention, it can be used as a treating agent for heavy metals which is one of the objects of the present invention. It has been found that an iron sulfide composition that can be used more preferably can be obtained. This iron sulfide composition is prepared by preparing the iron sulfide of the composition of the present invention and separately adding and mixing the iron sulfide, for example, mechanically mixing with a ball mill or the like, or preparing the iron sulfide of the present invention. It is also possible to prepare using an excess of alkaline earth metal component beyond the range of iron.

Examples of the alkaline earth metal compound to be added or used in excess include hydroxide, carboxylate, phosphate, sulfite, sulfate, carbonate and the like of alkaline earth. More specifically, corresponding alkaline earth metal salts such as magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, acetic acid, formic acid, oxalic acid, citric acid, stearic acid, and, for example, hydrogen phosphate Phosphoric acid such as calcium, corresponding alkaline earth metal salt of polyphosphoric acid, magnesium carbonate, carbonate of alkaline earth metal such as calcium carbonate, sulfate of alkaline earth metal such as magnesium sulfate, calcium sulfate, barium sulfate, Further, examples thereof include alkaline earth metal salts such as sulfurous acid and ascorbic acid having an antioxidant function.

These alkaline earth metal compounds do not reduce the durability of the iron sulfide of the present invention and, depending on the type, improve the activity of heavy metal treatment by the carrier effect of iron sulfide and improve the durability. It has an action, an auxiliary agent in the treatment of heavy metals, an improvement in hand linkability, etc., and is used by adding one or more kinds of alkaline earth metal salts to the iron sulfide of the present invention depending on the purpose. You can also. For example, when treating acidic fly ash, it is preferable to add an alkaline agent as an auxiliary agent, in which case, a mixture of the iron sulfide of the present invention and an alkaline earth hydroxide can be suitably used, When a large amount of an oxidizing component such as hexavalent chromium is contained, the mixture of iron sulfide and sulfite of the present invention can be suitably used. Further, the iron sulfide of the present invention has excellent durability, but the present inventors have found that the durability is further improved by adding an alkaline earth carboxylate, particularly an acetate, and severe These can be added when suitable storage conditions are considered.

The amount of the alkaline earth metal compound to be added is not particularly limited, and varies depending on the purpose. For example, 0.1 to 100 parts by weight can be added to 100 parts by weight of the iron sulfide of the present invention.

The iron sulfide and the iron sulfide composition of the present invention are extremely excellent in durability, and exhibit extremely high performance when used as a "heavy metal treating agent" containing this as an active ingredient. Hereinafter, the heavy metal treating agent of the present invention will be described in detail.

In the agent for treating heavy metals of the present invention, the heavy metals that can be treated include Pb, Cd,
Cr, Hg, As, Se, Cu, Ni, Sb, and Mo can be shown. Needless to say, the treatment agent of the present invention can treat not only the heavy metals described above individually but also those containing arbitrary plural elements among them.

The agent for treating heavy metals of the present invention is extremely effective for treating incineration ash and fly ash containing heavy metals. Heavy metals contained in various types of waste are concentrated in the waste incineration ash and fly ash. This is particularly remarkable in fly ash and molten fly ash, and many of the molten fly ash contain heavy metals such as lead in the order of percent, and require detoxification treatment. Fly ash and molten fly ash are classified into alkaline fly ash, neutral fly ash, alkaline molten fly ash, neutral molten fly ash, etc., depending on the incinerator structure and operating method. It is known that the type and content of heavy metals contained in the ash vary greatly, but the heavy metal treating agent of the present invention can be used for any kind of fly ash. The heavy metal treating agent of the present invention and water are added to these waste incineration ash and fly ash and kneaded.

The amount of the heavy metal treating agent of the present invention cannot be specified unconditionally because it differs depending on the type and total amount of heavy metals contained in the incineration ash and fly ash. , 0.1 to 50 wt%, preferably 0.5 to 30 w
t%, and furthermore, sampling waste incineration ash and fly ash in advance to determine the minimum addition amount in a lab test, and taking into account fluctuations in the amount of heavy metals contained in waste incineration ash and fly ash It is preferable to determine the amount of addition. Even if excessive addition is performed, for example, a phenomenon that mercury (Hg) becomes polysulfide and becomes soluble does not occur, and there is no problem.

The amount of water added depends on the nature of the incineration ash and fly ash.
0 to 40 wt% can be exemplified. Kneading method,
The time is not particularly limited, and a conventionally known method can be used, and the soluble heavy metals are converted into insoluble sulfides or iron salts, and the treatment is performed.

The agent for treating heavy metals of the present invention is also effective for treating soil containing heavy metals. A heavy metal treating agent is further added to the soil containing heavy metals, if necessary, and kneaded.

The amount of the heavy metal treating agent of the present invention varies depending on the total amount of heavy metals contained in the soil and cannot be specified unconditionally.
%. Further, it is preferable to sample the soil in advance and determine the minimum addition amount by a lab test, and add a slight excess in view of safety. When the water content in the soil is low, it depends on the type of the soil, but water is added as necessary so that the water content in the soil is usually 10 to 60 wt%. The method and time of kneading are not particularly limited, and a conventionally known method can be used, and the soluble heavy metals are converted into insoluble sulfides or iron salts, and the treatment is performed.

Further, using the heavy metal treating agent of the present invention,
It is also possible to treat wastewater containing heavy metals. A heavy metal treating agent is added to and mixed with wastewater containing heavy metals. The addition amount of heavy metal treatment agent cannot be unconditionally specified because it differs depending on the total amount of heavy metals contained in wastewater.Sampling wastewater in advance and finding the minimum addition amount in a lab test, and adding a slight excess in anticipation of safety Is preferred. At this time, if the pH of the wastewater is low, iron sulfide may be decomposed and hydrogen sulfide may be generated. Therefore, it is preferable to adjust the pH of the wastewater in advance.
0 or more, more preferably 6.0 or more.
The method and time for mixing are not particularly limited, and a conventionally known method can be used. The heavy metals in the wastewater are converted into insoluble sulfides or iron salts, and the treatment is performed. In addition, usually, an inorganic coagulant / precipitant used in the coagulation / precipitation treatment,
For example, ferric chloride, polyaluminum chloride, a sulfuric acid band, or the like can be used in combination, or a polymer coagulant for increasing the coagulation rate can be used in combination.

[0055]

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to only these examples. In addition, each measuring method in an Example is as follows.

(1) Method for Measuring Chemical Composition Fe, S, Ca, Sr, and Ba were measured using a fluorescent X-ray analyzer (Model JSX-3200, manufactured by JEOL Ltd.). Na, Mg, and Fe were measured using an ICP emission spectrometer (Perkin Elmer, model: optima 3000) after dissolving the sample with hydrochloric acid. After the measurement, the molar ratio of alkaline earth metal element, alkali metal element, and sulfur was determined based on iron.

(2) Method of measuring crystal structure X-ray diffractometer (manufactured by Mac Science, Model: MXP-
3, Cu target).

(3) Residual rate of iron sulfide Assuming that the main peak intensity of the iron sulfide before the durability treatment is I1 and the main peak intensity of the iron sulfide after the durability treatment is I2, the residual rate of iron sulfide (%) = I2 / I1 × Calculated as 100.

Example 1 A continuous stainless steel reaction vessel having an effective internal volume of 750 mL
An aqueous solution of iron (II) chloride (0.
5 mol / L) and aqueous sodium sulfide solution (1.0 mol
/ L) were continuously added at 500 ml / h and 250 ml / h, respectively, to prepare an iron sulfide slurry.

1000 m of the obtained iron sulfide slurry
was placed in a glass reaction vessel having an internal volume of 2 L, and 83 mmol of calcium chloride was added thereto with stirring.
An aqueous NaOH solution was added to adjust the slurry pH to 12.8. Stirring was continued for 60 minutes for aging. The slurry obtained after aging was filtered and washed, dried, and pulverized to obtain iron sulfide powder. The obtained iron sulfide powder is X
As a result of a line diffraction, it was a makinawite structure. X at this time
The charts of the line diffraction are shown in FIGS. As a result of the composition analysis, the molar ratio of each component was _Fe.Ca 0.22.Na
It was _0.016 · S _1.00 .

Next, a part of the obtained iron sulfide powder was
The sample was placed in a thermo-hygrostat at 70 ° C. and a relative humidity of 70%, and subjected to durability treatment for one day. As a result of X-ray diffraction, the powder after the durability treatment had a mackinawite structure, and no peaks of sulfur, which is a decomposition product of iron sulfide, and iron (III) oxide were observed. FIG. 1 shows a chart of X-ray diffraction at this time. As a result of calculating the residual ratio of iron sulfide based on the intensity ratio of the main peak before and after the durability treatment, it was 85%.

Example 2 The same operation as in Example 1 was carried out except that the slurry pH was changed to 11.7, to obtain iron sulfide powder. The obtained iron sulfide powder had a Mackinawite structure as a result of X-ray diffraction. A chart of the X-ray diffraction at this time is shown in FIG. As a result of the composition analysis, the molar ratio of each component was _{Fe.Ca 0.073.Na 0.032.}
-S was _0.99 .

Next, a part of the obtained iron sulfide powder was
The sample was placed in a thermo-hygrostat at 70 ° C. and a relative humidity of 70%, and subjected to durability treatment for one day. As a result of X-ray diffraction, the powder after the durability treatment had a mackinawite structure, and a slight peak of sulfur, which was a decomposition product of iron sulfide, was observed. As a result of calculating the residual ratio of iron sulfide based on the intensity ratio of the main peak before and after the durability treatment, it was 71%.

Example 3 The same operation as in Example 1 was performed except that the slurry pH was changed to 10.3, to obtain iron sulfide powder. The obtained iron sulfide powder had a Mackinawite structure as a result of X-ray diffraction. A chart of the X-ray diffraction at this time is shown in FIG. Further, as a result of composition analysis, the molar proportions of the respective components, Fe · Ca _0.035 · Na _0.077
-S was _0.99 .

Next, a part of the obtained iron sulfide powder was
The sample was placed in a thermo-hygrostat at 70 ° C. and a relative humidity of 70%, and subjected to durability treatment for one day. As a result of X-ray diffraction of the powder after the durability treatment, a peak attributable to sulfur, which is a decomposition product, was observed other than the iron sulfide having the makinawite structure. The residual ratio of iron sulfide calculated based on the intensity ratio of the main peak before and after the durability treatment was 53%.

Example 4 The amount of calcium chloride added was 220 mmol,
Exactly the same operation as in Example 1 except that the pH was changed to 12.6
To obtain iron sulfide powder. The obtained iron sulfide powder is X
As a result of X-ray diffraction, hydroxylation other than iron sulfide having a makinawite structure
A calcium peak was observed. As a result of the composition analysis,
The molar ratio of the components is Fe.Ca_0.43・ Na _0.004・ S_0.98
Met.

Next, a part of the obtained iron sulfide powder was
The sample was placed in a thermo-hygrostat at 70 ° C. and a relative humidity of 70%, and subjected to durability treatment for one day. As a result of X-ray diffraction of the powder after the durability treatment, peaks of calcium hydroxide and calcium carbonate were observed in addition to the iron sulfide having the makinawite structure. As a result of calculating the residual ratio of iron sulfide based on the intensity ratio of the main peak before and after the durability treatment, it was 87%.

Comparative Example 1 An iron sulfide slurry continuously prepared in the same manner as in Example 1 was filtered, washed, dried, and pulverized to obtain iron sulfide powder. The obtained iron sulfide powder had a Mackinawite structure as a result of X-ray diffraction. FIG. 3 shows a chart of X-ray diffraction at this time. Further, as a result of composition analysis, the molar ratio of each component was Fe · Na _0.22 · S _0.99.

Next, a part of the obtained iron sulfide powder was
The sample was placed in a thermo-hygrostat at 70 ° C. and a relative humidity of 70%, and subjected to durability treatment for one day. As a result of X-ray diffraction, the powder after the durability treatment was a mixture of sulfur, which is a decomposition product of iron sulfide, and iron (III) oxide, and no peak attributed to iron sulfide was observed. FIG. 3 shows a chart of X-ray diffraction at this time.

Comparative Example 2 4 g of calcium hydroxide was added to 30 g of the iron sulfide powder prepared in Comparative Example 1 and mixed by a ball mill for 30 minutes to prepare a mixed composition of iron sulfide and calcium hydroxide. As a result of X-ray diffraction, this composition was a mixture of iron sulfide having a mackinawite structure and calcium hydroxide. Further, as a result of composition analysis, the molar ratio of each component was _{Fe · Ca 0.19 · Na 0. 22} · S 0.99.

Next, a part of the obtained iron sulfide powder was
The sample was placed in a thermo-hygrostat at 70 ° C. and a relative humidity of 70%, and subjected to durability treatment for one day. As a result of X-ray diffraction, the powder after the durability treatment was a mixture of sulfur and iron oxide (III), which are decomposition products of iron sulfide, and calcium hydroxide and calcium carbonate, and no peak attributed to iron sulfide was observed. .

Comparative Example 3 A massive commercial reagent iron (II) sulfide was pulverized to obtain iron sulfide powder. The obtained iron sulfide powder had a pyrotite structure as a result of X-ray diffraction. The X-ray diffraction chart at this time is shown in FIG.
Shown in

Next, a part of the obtained iron sulfide powder was
The sample was placed in a thermo-hygrostat at 70 ° C. and a relative humidity of 70%, and subjected to durability treatment for one day. As a result of X-ray diffraction of the powder after the durability treatment, a 1-pilotite structure and a peak attributed to sulfur, which is a decomposition product of iron sulfide, were observed. The X-ray diffraction chart at this time is shown in FIG.

From the results of Example 1 and Comparative Examples 1, 2, and 3,
The durability of the iron sulfide in the present invention is greatly improved compared to conventionally known synthetic iron sulfide, and it can be determined that the added calcium is not a mere mixture but is incorporated in the iron sulfide. The results of Examples 1 to 4 show that the higher the slurry pH, the easier calcium is taken into iron sulfide, and the larger the amount of calcium taken in, the better the stability of iron sulfide. Furthermore, there is an upper limit to the amount of alkaline earth metal that can be incorporated into iron sulfide. In the case of calcium, it can be estimated to be around 0.4. It turns out that it becomes a composition. From the above, it can be determined that when the alkaline earth metal is calcium, iron sulfide with improved durability of the present invention can be obtained in a region where the molar ratio of calcium to iron is 0.03 to 0.4.
Further, in FIG. 2, the diffraction peak of iron sulfide obtained in Example 1 was shifted to a lower angle side than those obtained in Examples 2 and 3, and more calcium was incorporated into iron sulfide. Conceivable.

Example 5 1000 ml of the iron sulfide slurry continuously prepared in the same manner as in Example 1 was placed in a glass reaction vessel having an internal volume of 2 L, and 83 mmol of barium chloride was added thereto with stirring, followed by 48% NaOH aqueous solution is added and slurry pH
Was set to 13.0. Stirring was continued for 60 minutes for aging. The slurry obtained after aging was filtered and washed, dried, and pulverized to obtain iron sulfide powder. The obtained iron sulfide powder had a Mackinawite structure as a result of X-ray diffraction. A chart of the X-ray diffraction at this time is shown in FIG. As a result of composition analysis, the molar ratio of each component was _{Fe.Ba 0.078
-It} was Na _0.014 * S _0.96 .

Next, a part of the obtained iron sulfide powder was
The sample was placed in a thermo-hygrostat at 70 ° C. and a relative humidity of 70%, and subjected to durability treatment for one day. The powder after the durability treatment has a mackinawite structure, and sulfur, which is a decomposition product of iron sulfide, and iron oxide (I
No peak of II) was observed. A chart of the X-ray diffraction at this time is shown in FIG. The residual ratio of iron sulfide calculated based on the intensity ratio of the main peak before and after the durability treatment was 93%.

Example 6 1000 ml of the iron sulfide slurry continuously prepared in the same manner as in Example 1 was placed in a glass reactor having an internal volume of 2 L, and strontium chloride (66 mmol) was stirred.
Was added, and a 48% aqueous NaOH solution was further added to adjust the slurry pH to 13.1. Stirring was continued for 60 minutes for aging. The slurry obtained after aging was filtered and washed, dried, and pulverized to obtain iron sulfide powder. The obtained iron sulfide powder had a Mackinawite structure as a result of X-ray diffraction. As a result of composition analysis, the molar ratio of each component was Fe
_{-It was} Sr _0.095 * Na _0.023 * S _0.98 .

Next, a part of the obtained iron sulfide powder was
The sample was placed in a thermo-hygrostat at 70 ° C. and a relative humidity of 70%, and subjected to durability treatment for one day. The powder after the durability treatment had a mackinawite structure as a result of X-ray diffraction, and no sulfur or iron (III) oxide peak was observed. As a result of calculating the residual ratio of iron sulfide based on the intensity ratio of the main peak before and after the durability treatment, it was 88%.

Example 7 1000 ml of the iron sulfide slurry continuously prepared in the same manner as in Example 1 was placed in a glass reactor having an internal volume of 2 L, and stirred with 130 mmol of magnesium chloride.
Was added, and a 48% aqueous NaOH solution was further added to adjust the slurry pH to 12.9. Stirring was continued for 60 minutes for aging. The slurry obtained after aging was filtered and washed, dried, and pulverized to obtain iron sulfide powder. The obtained iron sulfide powder had a Mackinawite structure as a result of X-ray diffraction. As a result of composition analysis, the molar ratio of each component was Fe
· Mg was _0.37 · Na _0.068 · S _0.95.

Next, a part of the obtained iron sulfide powder was
The sample was placed in a thermo-hygrostat at 70 ° C. and a relative humidity of 70%, and subjected to durability treatment for one day. As a result of X-ray diffraction, the powder after the durability treatment had a mackinawite structure, and a slight peak attributable to sulfur, which is a decomposition product of iron sulfide, was slightly observed. As a result of calculating the residual ratio of iron sulfide based on the intensity ratio of the main peak before and after the durability treatment, it was 72%.

From the results of Examples 5 to 7, it can be seen that alkaline earth metals other than calcium have an effect of improving the durability of synthetic iron sulfide.

Example 8 A commercially available reagent (480 mmol) of sodium hydrosulfide and 720 mL of sodium hydroxide were placed in a glass reactor having an internal volume of 2 liters.
mmol and 1000 g of water were added, and the mixture was kept at 25 ° C. using a water bath while stirring and dissolving. To this solution is added water 60
A solution in which 480 mmol of iron (II) chloride and 120 mmol of calcium chloride were dissolved in 0 g was added over 40 minutes. The pH of the slurry after the addition was 12.3. Stirring was continued for 30 minutes for aging. The slurry obtained after aging was filtered and washed, dried, and pulverized to obtain iron sulfide powder. The obtained iron sulfide powder is X
As a result of the line diffraction, it was a modified mackinawite structure having a broad peak around 17 to 18 °. The X-ray diffraction charts at this time are shown in FIGS. Further, as a result of composition analysis, the molar proportions of the respective components, Fe · Ca _0.16 · Na _0.006
S was _0.90 .

Next, a part of the obtained iron sulfide powder was
The sample was placed in a thermo-hygrostat at 70 ° C. and a relative humidity of 70%, and subjected to durability treatment for one day. The powder after the endurance treatment was analyzed by X-ray diffraction.
It has a modified makinawite structure having a broad peak around １８18 °, and no peak of sulfur, which is a decomposition product of iron sulfide, and iron (III) oxide was observed. FIG. 6 shows a chart of the X-ray diffraction at this time. As a result of calculating the residual ratio of iron sulfide based on the intensity ratio of the main peak before and after the durability treatment, it was 91%.

A part of the obtained iron sulfide powder was subjected to a three-month indoor storage test from summer to autumn. The powder after the storage test had a modified mackinawite structure as a result of X-ray diffraction, and no peaks of sulfur, which is a decomposition product of iron sulfide, and iron (III) oxide were not observed.

Example 9 A commercially available reagent of sodium hydrosulfide 480 mmol and sodium hydroxide 720 were placed in a glass reactor having an internal volume of 2 liters.
mmol and 1000 g of water were added, and the mixture was kept at 25 ° C. using a water bath while stirring and dissolving. To this solution is added water 60
480 mmol of iron (II) chloride and 1 barium chloride in 0 g
A solution in which 20 mmol was dissolved was added over 40 minutes.
The pH of the slurry after the completion of the addition was 12.6. Stirring was continued for 30 minutes for aging. The slurry obtained after aging was filtered and washed, dried, and pulverized to obtain iron sulfide powder. The obtained iron sulfide powder had a broad peak around 17 to 18 ° as a result of X-ray diffraction.
It had a modified mackinawite structure. FIG. 7 shows a chart of X-ray diffraction at this time. Further, as a result of composition analysis, the molar ratio of each component was _{Fe · Ba 0.083 · Na 0.028 ·} S 0.88.

Next, a part of the obtained iron sulfide powder was
The sample was placed in a thermo-hygrostat at 70 ° C. and a relative humidity of 70%, and subjected to durability treatment for one day. The powder after the endurance treatment was analyzed by X-ray diffraction.
It has a modified makinawite structure having a broad peak around １８18 °, and a slight peak attributable to sulfur, which is a decomposition product of iron sulfide, was observed. FIG. 7 shows a chart of X-ray diffraction at this time. As a result of calculating the residual ratio of iron sulfide based on the intensity ratio of the main peak before and after the durability treatment, it was 87%.

Example 10 A commercially available reagent (480 mmol) of sodium bisulfide and 720 mL of sodium hydroxide were placed in a glass reactor having an internal volume of 2 liters.
mmol and 1000 g of water were added, and the mixture was kept at 25 ° C. using a water bath while stirring and dissolving. To this solution is added water 60
A solution in which 480 mmol of iron (II) chloride and 120 mmol of strontium chloride were dissolved in 0 g was added over 40 minutes. The pH of the slurry after the completion of the addition was 12.4. Stirring was continued for 30 minutes for aging. The slurry obtained after aging was filtered and washed, dried, and pulverized to obtain iron sulfide powder. The obtained iron sulfide powder is X
As a result of the line diffraction, it was a modified mackinawite structure having a broad peak around 17 to 18 °. Further, as a result of composition analysis, the molar proportions of the respective _{components, Fe · Sr 0.097 · Na 0} .019
S was _0.92 .

Next, a part of the obtained iron sulfide powder was
The sample was placed in a thermo-hygrostat at 70 ° C. and a relative humidity of 70%, and subjected to durability treatment for one day. The powder after the endurance treatment was analyzed by X-ray diffraction.
It has a modified makinawite structure having a broad peak around １８18 °, and no peak of sulfur, which is a decomposition product of iron sulfide, and iron (III) oxide was observed. The residual ratio of iron sulfide calculated based on the intensity ratio of the main peak before and after the durability treatment was 93%.

Example 11 A commercially available reagent (420 mmol) of sodium hydrosulfide and sodium hydroxide (780) were placed in a glass reactor having an internal volume of 2 liters.
mmol and 1000 g of water were added, and the mixture was kept at 25 ° C. using a water bath while stirring and dissolving. To this solution is added water 60
A solution in which 420 mmol of iron (II) sulfate and 180 mmol of magnesium sulfate were dissolved in 0 g was added over 40 minutes. The pH of the slurry after the addition was 10.5. Stirring was continued for 30 minutes for aging. The slurry obtained after aging was filtered and washed, dried, and pulverized to obtain iron sulfide powder. The obtained iron sulfide powder is X
As a result of the line diffraction, it was a modified mackinawite structure having a broad peak around 17 to 18 °. The results of the composition analysis, the molar proportions of the respective _{components, Fe · Mg 0.37 · Na 0.07} 9
-S was _0.94 .

Next, a part of the obtained iron sulfide powder was
The sample was placed in a thermo-hygrostat at 70 ° C. and a relative humidity of 70%, and subjected to durability treatment for one day. The powder after the endurance treatment was analyzed by X-ray diffraction.
In addition to the modified makinawite structure having a broad peak around １８18 °, a slight peak attributable to sulfur, which is a decomposition product of iron sulfide, was observed. As a result of calculating the residual ratio of iron sulfide based on the intensity ratio of the main peak before and after the durability treatment, it was 78%.

According to the results of Examples 8 to 11, when an aqueous solution of a divalent iron salt and an aqueous solution containing sulfur ions were mixed in the presence of an alkaline earth metal component, iron sulfide having a modified mackinawite structure was obtained. It is understood that it is possible.

Example 12 The amount of sodium hydrosulfide used was 420 mmol, the amount of sodium hydroxide was 780 mmol, the amount of iron (II) chloride was 420 mmol, and the amount of calcium chloride was 180 mmol.
The same operation as in Example 8 was performed.

[0093] The slurry pH after completion of the addition 12.6, iron sulfide of the resulting powder modified Makinawaito structure, the molar ratio of each component was _{Fe · Ca 0.28 · Na 0.002 ·} S 0.88. FIG. 8 shows a chart of the X-ray diffraction at this time. Further, the powder after the durability treatment was iron sulfide having a modified mackinawite structure, and the residual ratio of iron sulfide was 88%.

Example 13 The amount of sodium hydrosulfide used was 360 mmol, the amount of sodium hydroxide was 840 mmol, the amount of iron (II) chloride was 360 mmol, and the amount of calcium chloride was 240 mmol.
The same operation as in Example 8 was performed.

The pH of the slurry after the addition was 12.5, and the obtained powder was iron sulfide having a modified mackinawite structure. A trace of calcium hydroxide was observed in the trace amount, and the molar ratio of each component was Fe.Ca _0.39. Na _0.001 · S _0.91 . FIG. 8 shows a chart of the X-ray diffraction at this time. In addition, the powder after the durability treatment was iron sulfide having a modified mackinawite structure, peaks of trace amounts of calcium hydroxide and calcium carbonate were observed, and the residual ratio of iron sulfide was 93%.

Example 14 The amount of sodium hydrosulfide used was 300 mmol, the amount of sodium hydroxide was 900 mmol, the amount of iron (II) chloride was 300 mmol, and the amount of calcium chloride was 300 mmol.
The same operation as in Example 8 was performed.

The pH of the slurry after the addition was 12.5, and the obtained powder was a mixture of iron sulfide and calcium hydroxide having a modified mackinawite structure. The molar ratio of each component is Fe
was _{a 0. 66 · Na 0.001 · S} 0.88. FIG. 8 shows a chart of the X-ray diffraction at this time. The powder after the durability treatment was a mixture of iron sulfide having a modified mackinawite structure, calcium hydroxide and calcium carbonate, and the residual ratio of iron sulfide was 93%.
%Met.

Example 15 The same operation as in Example 8 was performed except that the amount of sodium hydrosulfide used was 540 mmol, the amount of sodium hydroxide was 660 mmol, the amount of iron (II) chloride was 270 mmol, and the amount of calcium chloride was 60 mmol.

[0099] The slurry pH after completion of the addition 11.1, powder obtained is iron sulfide modified Makinawaito structure, the molar ratio of each component was _{Fe · Ca 0.038 · Na 0.089 ·} S 0.85. FIG. 8 shows a chart of the X-ray diffraction at this time.
The powder after the durability treatment was a mixture of iron sulfide having a modified mackinawite structure and sulfur as a decomposition product thereof, and the residual ratio of iron sulfide was 56%.

Comparative Example 4 The same operation as in Example 5 was performed except that the amount of sodium hydrosulfide used was 600 mmol, the amount of sodium hydroxide was 600 mmol, the amount of iron (II) chloride was 600 mmol, and the amount of calcium chloride was 10 mmol.

[0102] The slurry pH after completion of the addition 6.8, the resulting powder is iron sulfide Makinawaito structure, the molar ratio of each component was _{Fe · Ca 0.008 · Na 0.14 ·} S 0.94. The powder after the durability treatment was a mixture of sulfur, which is a decomposition product of iron sulfide, and iron (II), and no peak attributed to iron sulfide was observed.

From the results of Examples 1 to 5 and 12 to 15, it is considered that the modified makinawite structure has higher durability than the iron sulfide having the makinawite structure. In addition, the results of Comparative Example 4 show that when the pH of the slurry after completion of the addition is less than 7, even if iron sulfide is prepared in the presence of calcium, calcium is not taken in and the durability is not improved.

Next, the results of treating heavy metals using the iron sulfide of the present invention will be described.

Example 16 Using alkaline fly ash containing 2400 ppm of lead, 160 ppm of chromium, and 2.1 ppm of mercury, treatment characteristics of heavy metals were examined. To 100 parts by weight of alkaline fly ash, 30 parts by weight of water and iron sulfide prepared in Examples and Comparative Examples were added, kneaded and subjected to heavy metal treatment. The obtained treated fly ash was subjected to a 13th dissolution test (1973) notified by the Environment Agency, and the results are shown in Table 2.

[0105]

[Table 2] As is evident from the results in Table 2, the iron sulfide obtained in the examples had almost the same treatment characteristics as heavy iron sulfides before the durability treatment, and the pitrotite type sulfide obtained in the comparative example had the same treatment characteristics as the makinawite type iron sulfide. It turns out that it is much better than iron. Furthermore, conventional mackinawite-type iron sulfide deteriorates the processing characteristics of heavy metals when subjected to a durability treatment at 70 ° C. and a relative humidity of 70% for one day, whereas iron sulfide in the present invention has a durability treatment. It can be seen that the processing characteristics of heavy metals are maintained afterwards.

Example 17 Using neutral fly ash containing 1900 ppm of lead, 1100 ppm of chromium, and 100 ppm of cadmium, the treatment characteristics of heavy metals were examined. To 100 parts by weight of neutral fly ash, 30 parts by weight of water and iron sulfide prepared in Examples and Comparative Examples were added, kneaded and subjected to heavy metal treatment. The obtained fly ash was subjected to a 13th dissolution test (197
3 years), and the results are shown in Table 3 .

[0107]

[Table 3] As is clear from the results in Table 3, the iron sulfide obtained in Examples 8 and 9 can also treat heavy metals contained in neutral fly ash, and the conventional synthetic iron sulfide obtained in Comparative Example 1 It can be seen that it has almost the same initial characteristics as that of, and has much more excellent durability.

Example 18 A model contaminated soil containing 7700 ppm of lead, 470 ppm of cadmium, 1800 ppm of hexavalent chromium, 96 ppm of arsenic, and 2200 ppm of selenium (water content: 50
%), The processing characteristics of heavy metals were examined. Iron sulfide prepared in Examples and Comparative Examples was added to 100 parts by weight of soil, kneaded, and treated with heavy metals. The obtained soil was subjected to a dissolution test according to the Environment Agency Notification No. 46 (1991).
Year), and the results are shown in Tables 4 and 5.

[0109]

[Table 4]

[Table 5] As is clear from the results of Tables 4 and 5, the iron sulfide obtained in Examples 1 and 8 can also treat heavy metals contained in soil, and is substantially the same as the makinawite-type iron sulfide obtained in Comparative Example 1. It can be seen that they have the same initial properties and are much more durable than the Makinawite-type iron sulfide.

Example 19 A solution containing 10 ppm of lead, a solution containing 10 ppm of cadmium, a solution containing 1 ppm of mercury, and 10 ppm of hexavalent chromium
Solution, arsenic 10ppm solution, selenium 10p
Example 1 for six types of model drainage of a solution containing pm
0.2 parts by weight of the iron sulfide prepared in Steps 8 and 8 were added, and the treatment characteristics of heavy metals with iron sulfide were examined. After iron sulfide was added to the model wastewater, the mixture was mixed for 30 minutes, filtered through a glass filter paper (GS-25 manufactured by Advantech Toyo), and the amount of each component contained in the filtrate was measured. Table 6 shows the results.
It was shown to.

[0111]

[Table 6] As is clear from the results in Table 6, the iron sulfide of the present invention can also treat heavy metals in wastewater.

[0112]

According to the present invention, the following effects can be obtained. 1) The iron sulfide of the present invention has a mackinawite structure having a novel composition which has not been known so far, and has excellent treatment properties for heavy metals and excellent durability. 2) The manufacturing method of the present invention can easily manufacture this excellent iron sulfide. 3) The agent for treating heavy metals of the present invention contains this excellent iron sulfide as an active ingredient. By using this treating agent, heavy metals contained in ash, soil, wastewater, etc. can be treated and made harmless. .

[Brief description of the drawings]

FIG. 1 shows the results of X-ray diffraction after iron sulfide powder prepared in Example 1 and its durability treatment at 70 ° C. and 70% relative humidity for 1 day. The X axis (horizontal axis) indicates the diffraction angle 2θ (unit is degree), and the Y axis (vertical axis) indicates the X-ray intensity (unit is cps).

FIG. 2 shows the results of X-ray diffraction of the iron sulfide powders prepared in Examples 1, 2 and 3. The X axis (horizontal axis) indicates the diffraction angle 2θ (unit is degree), and the Y axis (vertical axis) indicates the X-ray intensity (unit is cps).

FIG. 3 shows the results of X-ray diffraction after the iron sulfide powder prepared in Comparative Example 1 and its durability treatment at 70 ° C. and 70% relative humidity for one day. The X axis (horizontal axis) indicates the diffraction angle 2θ (unit is degree), and the Y axis (vertical axis) indicates the X-ray intensity (unit is cps).

FIG. 4 shows the results of X-ray diffraction after the iron sulfide powder prepared in Comparative Example 3 and its durability treatment at 70 ° C. and 70% relative humidity for one day. The X axis (horizontal axis) indicates the diffraction angle 2θ (unit is degree), and the Y axis (vertical axis) indicates the X-ray intensity (unit is cps).

FIG. 5 shows the results of X-ray diffraction after iron sulfide powder prepared in Example 5 and its durability treatment at 70 ° C. and 70% relative humidity for one day. The X axis (horizontal axis) indicates the diffraction angle 2θ (unit is degree), and the Y axis (vertical axis) indicates the X-ray intensity (unit is cps).

FIG. 6 shows the results of X-ray diffraction after the iron sulfide powder prepared in Example 8 and its durability treatment at 70 ° C. and 70% relative humidity for one day. The X axis (horizontal axis) indicates the diffraction angle 2θ (unit is degree), and the Y axis (vertical axis) indicates the X-ray intensity (unit is cps).

FIG. 7 shows the results of X-ray diffraction after iron sulfide powder prepared in Example 9 and its durability treatment at 70 ° C. and 70% relative humidity for 1 day. The X axis (horizontal axis) indicates the diffraction angle 2θ (unit is degrees), and the Y axis (vertical axis) indicates the X-ray intensity (unit is cps).

FIG. 8 is a diagram illustrating an eighth embodiment, a twelfth embodiment, a thirteenth embodiment, and a first embodiment.
4 shows the results of X-ray diffraction of the iron sulfide powder prepared in Example 15. X axis (horizontal axis) is diffraction angle 2θ (unit is degr
ee), and the Y-axis (vertical axis) represents the intensity of X-rays (unit is cp).
s).

[Explanation of symbols]

1: X-ray diffraction pattern of iron sulfide powder prepared in Example 1 2: X-ray diffraction pattern of iron sulfide powder prepared in Example 1 after durable treatment 3: X of iron sulfide powder prepared in Example 1 X-ray diffraction pattern 4: X-ray diffraction pattern of iron sulfide powder prepared in Example 2 5: X-ray diffraction pattern of iron sulfide powder prepared in Example 3 6: X-ray diffraction of iron sulfide powder prepared in Comparative Example 1 Pattern 7: X-ray diffraction pattern of iron sulfide powder prepared in Comparative Example 1 after durable treatment 8: X-ray diffraction pattern of iron sulfide powder prepared in Comparative Example 3 9: Iron sulfide powder prepared in Comparative Example 3 X-ray diffraction pattern after endurance treatment 10: X-ray diffraction pattern of iron sulfide powder prepared in Example 5 11: X-ray diffraction pattern after endurance treatment of iron sulfide powder prepared in Example 5 12: Example X-ray of iron sulfide powder prepared in 8 Folding pattern 13: X-ray diffraction pattern of iron sulfide powder prepared in Example 8 after endurance treatment 14: X-ray diffraction pattern of iron sulfide powder prepared in Example 9 15: Iron sulfide powder prepared in Example 9 X-ray diffraction pattern of iron sulfide powder prepared in Example 14 16: X-ray diffraction pattern of iron sulfide powder prepared in Example 13 18: Prepared in Example 12 X-ray diffraction pattern of iron sulfide powder 19: X-ray diffraction pattern of iron sulfide powder prepared in Example 8 20: X-ray diffraction pattern of iron sulfide powder prepared in Example 15

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C02F 1/58 C02F 1/62 D 1/62 EZ B09B 3/00 304G 304K F-term (Reference) 2E191 BA02 BB00 BB01 BC01 BD11 4D004 AA36 AA37 AA41 AB03 CA15 CA34 CC03 4D038 AA08 AB65 AB67 AB68 AB69 AB70 AB71 AB72 AB73 AB74 BB17 4G002 AA06 AA08 AA12 AB02 AD04 AE05

Claims (16)

[Claims] As an essential component of claim 1] constituent elements, Fe · M _x ·
N _y · S _z (where M is an alkaline earth metal, N is an alkali metal, x, y and z are molar ratios, and 0.01 <x ≦
0.5, y ≦ 0.2, 0.7 ≦ z ≦ 1.4. Durable iron sulfide having a makinawite structure represented by). 2. The makinawite structure according to claim 1, wherein the XRD diffraction pattern has a 001 plane spacing of 5.
Spread in the c-axis direction from 03 ° to 5.53 °,
When the peak intensity from the 01 plane is 100, other hk
Iron sulfide excellent in durability, having a modified Mackinawite structure in which the intensity ratios of diffraction peaks from the l-plane are all 20 or less. 3. An aqueous solution of a divalent iron salt, an aqueous solution containing sulfur ions, and an alkaline earth metal component, and the pH of the slurry after mixing is adjusted to 7.0 or more. The method for producing iron sulfide described above. 4. The method for producing iron sulfide according to claim 3, wherein the alkaline earth metal is calcium (Ca) and / or magnesium (Mg). 5. A slurry is produced by mixing an aqueous solution of a divalent iron salt and an aqueous solution containing sulfur ions in the presence of an alkaline earth metal component, and adjusting the pH of the slurry after mixing to 7.0 or more. 3. The method for producing iron sulfide according to claim 2, wherein: 6. The method for producing iron sulfide according to claim 5, wherein the alkaline earth metal is calcium (Ca) and / or magnesium (Mg). 7. An iron sulfide composition comprising the iron sulfide according to claim 1 and an alkaline earth metal compound. 8. The sulfide according to claim 7, wherein the alkaline earth metal compound is at least one compound selected from the group consisting of an alkaline earth metal hydroxide, carboxylate, phosphate and sulfite. Iron composition. 9. A heavy metal treating agent comprising the iron sulfide according to claim 1 or 2 as an active ingredient. 10. A heavy metal treating agent comprising the iron sulfide composition according to claim 7 or 8 as an active ingredient. 11. A detoxifying method comprising adding the heavy metal treating agent according to claim 9 to any of incineration ash, fly ash or molten fly ash containing heavy metals and kneading them. Processing method. 12. The detoxifying method according to claim 11, wherein water is further added to the heavy metal treating agent, followed by kneading. 13. A detoxification method comprising adding the heavy metal treating agent according to claim 9 to a soil containing heavy metals and kneading the mixture. 14. The detoxification treatment method according to claim 13, wherein water is further added to the heavy metal treating agent, followed by kneading. 15. A detoxification method comprising adding the heavy metal treating agent according to claim 9 or 10 to waste water containing heavy metals and mixing. 16. The method according to claim 16, wherein the heavy metals are Pb, Cd, Hg, Zn,
The detoxification method according to any one of claims 11 to 15, wherein the method is one or more elements selected from the group consisting of Cu, Ni, Cr, As, Se, Sb, and Mo.