JPH0880490A - Treatment of antimony-containing waste water - Google Patents

Abstract

PURPOSE: To highly the antimony contained in waste water. CONSTITUTION: An antimony-contg. waste water is subjected successively to a reaction condition forming treatment and a precipitate forming treatment, and the precipitate formed in the waste water is separated from the treated water by solid-liq. separation. In the reaction condition forming treatment, ferric chloride is added to the antimony-contg. waste water to keep the waste water at <=pH 3.5, and iron ion is uniformly dissolved in the waste water. In the precipitate forming treatment, an alkali agent is added to the waste water subjected to the reaction condition forming treatment. A good iron precipitate is produced in the waste water in the range >=pH 6 by the addition of the alkali agent, and the antimony in the waste is fetched into the precipitate and removed from the waste water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating antimony-containing wastewater for highly treating antimony contained in wastewater.

[0002]

2. Description of the Related Art Ultra-high purity antimony is InSb, Al
It has come to be used as a raw material for compound semiconductors such as Sb and electronic parts such as varistors, and as an activator.
The concentration of antimony contained in factory effluent has come to be taken up as a social problem due to the strong toxicity of its simple substance and compound.

As a method of removing antimony from antimony-containing wastewater, a coprecipitation method of coprecipitating with other metals coexisting in the liquid, iron chloride, iron sulfate and the like are added and treated in an alkaline region to coagulate and precipitate. Although the coagulation-precipitation method and the like have been known, none of them are effective methods, and a method of producing an insoluble precipitate by adjusting the liquid pH to 4 to 7 after adding an iron salt has been proposed (JP Sho 63-236592
issue).

This method is, in essence, obtained by treating antimony-containing wastewater in the presence of a ferric salt to a pH of 4 to 7, preferably pH.
When adjusted to 4 to 6 and reacted for about 5 to 30 minutes, antimony is deposited as an insoluble precipitate.

It is considered that this method is characterized in that it is processed in an acidic region, whereas the conventional method in which an iron salt is added and coagulated and precipitated is processed in an alkaline region. In an example in which 1 g of antimony chloride was added to 10 L (liter) of water and stirred for 30 minutes, 1000 mg / L of ferric chloride was added to this antimony-containing water, and the pH value was adjusted using sodium hydroxide or hydrochloric acid, Filter paper NO.
With respect to the filtrate of the supernatant liquid filtered at 5A, an antimony concentration of 0.02 mg / L was achieved in the range of pH 4 to 7,
The data show that the antimony concentration of 0.01 mg / L was achieved in H5 to H6. In this experimental example, when the pH is 7 or more, the processing capacity is sharply reduced.

[0006]

However, since the precipitate produced by the above treatment method is treated in the acidic region of the liquid, the iron precipitate is not sufficiently formed, and solid-liquid separation of the generated sludge is troublesome. Is. In addition, although the mechanism by which antimony is precipitated and removed by this method is not clear, if it is assumed that co-precipitation is used, there is a risk that antimony will be re-eluted from the precipitate, and In order to treat antimony at a low concentration, it is necessary to add a large amount of iron salt, and as a result, a large amount of sludge is generated, which causes new problems in the treatment.

An object of the present invention is to provide a method for treating antimony-containing wastewater capable of reducing the concentration of antimony by forming conditions for forming iron precipitates in the wastewater containing antimony and reducing the amount of sludge generated. It is in.

[0008]

In order to achieve the above object, the method for treating antimony-containing wastewater according to the present invention contains antimony having a reaction condition forming treatment, a precipitation forming treatment, and a solid-liquid separation treatment. A method for treating wastewater, which is a reaction condition formation treatment, is a treatment in which ferric chloride is added to water containing antimony to form reaction conditions in the wastewater for producing a precipitate containing antimony. The treatment is to add an alkaline agent to the wastewater containing antimony,
The precipitate is generated in water, and the solid-liquid separation treatment is a treatment for removing the generated insoluble precipitate from the waste water.

The reaction conditions for forming a precipitate formed in antimony-containing wastewater by adding ferric chloride are as follows:
Addition amount of ferric chloride to antimony 1: 1 by weight
It is 0 or more, and the pH of the antimony-containing water is set to 3.5 or less in a state in which ferric chloride is dissolved in water.

In the precipitation treatment, the pH value of the antimony-containing wastewater adjusted by adding an alkaline agent is 7 or more.

Further, it has an adsorption treatment, and the adsorption treatment is a treatment for adsorbing antimony remaining in the wastewater from which the insoluble precipitate is removed by the solid-liquid separation treatment, to the chelate resin.

[0012]

When the ferric chloride salt is added to the antimony-containing wastewater, the pH of the wastewater naturally becomes acidic. When the pH of the waste water is agitated for 5 minutes or more, preferably 30 minutes or more in the region of 3.5 or less, reaction conditions for forming a precipitate containing antimony in the waste water are formed.

As described above, since the ferric chloride solution itself is acidic, it is possible to adjust the pH of the wastewater to 3.5 or less simply by adding the ferric chloride solution to the wastewater. Etc. may be added separately to adjust the pH to 3.5 or less. It is desirable that the pH of the waste water is as low as 3.5 or less. When the pH is 3.5 or higher, the precipitate containing antimony is not effectively generated by the subsequent precipitation generation treatment.

The amount of ferric salt added varies depending on the concentration of antimony contained in the wastewater.
A weight ratio of 10 or more as Fe ²⁺ is a rough standard. The greater the amount of ferric salt added, the higher the reactivity with antimony, but it also lowers the water quality of the wastewater. Therefore, an appropriate amount should be set in consideration of the balance with the treated water quality.

When ferric chloride and antimony are allowed to coexist at a pH of 3.5 or less and an alkaline agent is added to the effluent, iron precipitates are formed. The precipitate containing antimony is p
Although it is generated in the vicinity of H4 or higher, the iron precipitate is not sufficiently generated in the acidic region of the liquid. Therefore, when the treatment is carried out in an alkaline region having a pH of 7 or higher, a precipitate suitable for the coagulating sedimentation treatment can be produced.

The precipitation treatment is carried out by adding an alkaline agent such as sodium hydroxide depending on the pH of the waste water. However, an acid such as hydrochloric acid or sulfuric acid may be added to the waste water to adjust the pH.

Precipitates generated in the wastewater can be separated and removed from the wastewater by a method such as sedimentation, filtration and centrifugation. In solid-liquid separation treatment, a polymer flocculant is added to the wastewater to separate the precipitates. It is preferable to promote it.

For the adsorption treatment of antimony remaining in the treated water after solid-liquid separation, a chelating resin for trapping antimony,
For example, Chelate SB (trade name) manufactured by Hokuetsu Carbon Industry Co., Ltd.,
Uniselec (trade name) manufactured by Unitika Ltd., Lead F
(Product name) Asahi Engineering Co., Ltd. etc. are used. By using the chelate resin for the adsorption treatment of antimony, the iron salt concentration necessary for generating the precipitate can be reduced, and the amount of iron sludge generated can be reduced.

[0019]

EXAMPLES Examples of the present invention will be shown below.

Example 1 Sb ₂ O ₃ was dissolved in distilled water as water to be treated to prepare a solution containing 2 mg / L of Sb.
FeCl ₃ was added to this solution, and the addition amounts of FeCl ₃ were 100 mg / L (pH 2.8) and 300 mg / L, respectively.
(PH 2.75), 500 mg / L (pH 2.7) 3
After making various kinds of solutions and stirring each solution for 30 minutes, an alkaline agent was added and various pH values were changed to cause iron precipitation in the solution. Next, a polymer flocculant was added to each solution so as to have a concentration of 1 mg / L.
The mixture is allowed to stand for 5 minutes to precipitate the precipitate in the liquid, and the supernatant is added with NO. 5
The antimony concentration contained in the treated water filtered with the A filter paper was measured. The results are shown in Fig. 1.

Example 2 SbCl ₃ as water to be treated was dissolved in distilled water to prepare a solution containing 2 mg / L of Sb. FeCl ₃ was added to this solution to obtain FeCl ₃
Of 100mg / L (pH 2.8), 300mg
/ L (pH 2.75), 500 mg / L (pH 2.7)
3 types of solutions were prepared, and each solution was stirred for 30 minutes, and then an alkaline agent was added to change the pH value in various ways to cause iron precipitation in the solution. Next, a polymer flocculant was added to each solution so as to be 1 mg / L, and then 3
The mixture is allowed to stand for 0 minutes to precipitate the precipitate in the liquid, and the supernatant is added with NO.
The concentration of antimony contained in the treated water filtered with 5A filter paper was measured. The results are shown in Figure 2.

As described above, according to the first and second embodiments, FIG.
As is clear from the above, as long as the reaction conditions for generating a precipitate having a pH of 3.5 or less are formed in water in advance, if the treatment for increasing the pH by adding the alkaline agent is performed, the pH is 6 or more,
Furthermore, even in the alkaline region of pH 7 or higher, the concentration of antimony in the treated water from which the precipitate has been removed becomes low,
It can be seen that antimony in the liquid to be treated is taken into the iron precipitate and removed from the water to be treated.

This result shows that when treating antimony-containing water, if a predetermined amount or more of ferric chloride is added in advance to the water to be treated and it is sufficiently contacted with antimony, the precipitation formation treatment is carried out. Has a pH of 4 to 7, preferably 4 to
Even if it is not within the range of 6, precipitation occurs, indicating that antimony in the water to be treated can be removed. The reason for this is not clear, but it is suspected that the intermediate product produced by the reaction of antimony in the water to be treated with ferric chloride may trigger the precipitation of the solution by increasing the pH of the solution. Seem. The precipitate generated in the alkaline region of pH 7 or more has a large particle size and is a solid floc, and solid-liquid separation is facilitated. Therefore, in the present invention, the precipitation generation treatment is performed in the alkaline region of pH 7 or more. It is preferable.

(Example 3) A Sb ₂ O ₃ solution with a concentration of 50
FeCl ₃ was added to 0 mg / L and the precipitate formed in the solution was removed to obtain treated water having an antimony concentration of 0.1 mg / L. In the water flow test of the treated water, a glass column having an inner diameter of 10 mm filled with 5 mL of the chelating resin for antimony treatment was used, and the treated water was passed at a space velocity of 10. The concentration of antimony in the water flow is 200 for every 1,000 mL of water flow.
Measured up to 00 mL, all antimony concentrations are 0.0
It was 005 mg / L or less.

[0025]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, when removing antimony in wastewater, antimony and ferric chloride are allowed to coexist in advance under the condition of pH 3.5 or less to prevent the precipitation of iron. The production conditions are hardly restricted, and the precipitate can be produced substantially only by adding the alkaline agent. Therefore, if the precipitation generation treatment is carried out at pH 7 or higher, the separation of the generated iron precipitate becomes extremely easy, antimony is taken into the precipitate, and the antimony-containing wastewater can be effectively treated without re-elution. In addition to the advanced treatment of wastewater containing antimony, it also has the effect of reducing the amount of iron sludge generated.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a processing example according to a first embodiment.

FIG. 2 is a diagram illustrating a processing example according to a second embodiment.

Claims (4)

[Claims] 1. A reaction condition forming process, a precipitate forming process,
A method for treating wastewater containing antimony, comprising solid-liquid separation treatment, wherein the reaction condition forming treatment is carried out by adding ferric chloride to water containing antimony to prepare reaction conditions for producing a precipitate containing antimony. This is a process that forms in wastewater.Precipitate formation is a process that adds an alkaline agent to antimony-containing wastewater to form a precipitate in water.Solid-liquid separation treatment is a process that drains the formed insoluble precipitate. A method for treating antimony-containing wastewater, characterized in that it is a treatment for removing it from the inside. 2. The reaction condition for the formation of a precipitate formed in the antimony-containing wastewater by adding ferric chloride is that the addition amount of ferric chloride is 10 or more per 1 weight of antimony, 2. The method for treating antimony-containing wastewater according to claim 1, wherein the pH of the antimony-containing water is set to 3.5 or less in a state in which ferric chloride is dissolved therein. 3. The method for treating antimony-containing wastewater according to claim 1, wherein the precipitation generation treatment has a pH value of the antimony-containing wastewater adjusted by the addition of an alkaline agent of 7 or more. 4. An adsorption treatment, wherein the adsorption treatment is a treatment for adsorbing antimony remaining in the wastewater from which insoluble precipitates have been removed by the solid-liquid separation treatment, to the chelate resin. The method for treating wastewater containing antimony according to 1, 2, or 3.