TW201509829A - Treating method of low-concentrated cyanogen-containing water including iron-cyano complex and treating device thereof - Google Patents

Abstract

This invention effectively decomposes and removes cyanogenin low-concentrated cyanogen-containing water including an iron-cyano complexwitha treatment in a relatively low temperature without needs of large-scale equipment. A treating method of the low-concentrated cyanogen-containing water including the iron-cyano complex ofthis invention includes addingan alkali agent and a chlorine source to the low-concentrated cyanogen-containing water including the iron-cyano complex, and maintainingthe water under a condition that a pH is 11 to 13, a free chlorine concentration is 10 mg/L or more, a water temperature is from 40 DEG C to 100 DEG C, preferably from 40 DEG C to less than 80 DEG C, more preferably from 60 DEG C to less than 80 DEG C for a certain time. If necessary, the water temperature is heated to 40 DEG C to 100 DEG C by adding a heat source.

Description

Low concentration cyanide-containing water treatment method containing ferricyanide complex

This invention relates to a process for the decomposition of cyanide in low concentration cyanide-containing water containing a ferricyanide complex. In particular, the present invention relates to a low concentration by containing a ferricyanide complex (iron (II) ferrocyanide complex, iron (III) cyanide complex, etc.) A method in which the pH of the cyanide-containing water, the water temperature, and the free chlorine concentration are maintained within a predetermined range for a predetermined period of time to decompose the total cyanide in the drainage.

Low-concentration cyanide-containing drains containing ferricyanide complexes are discharged from furnaces for processing coal, beneficiation refineries, and coke manufacturing plants. When iron (II) cyanide complex or the like is used for adsorption, aggregation treatment, or the like of a radioactive contaminant or the like, such drainage is also discharged.

Since the ferric cyanide complex has difficulty in decomposition, it is difficult to carry out oxidative decomposition treatment. In the method of separating and separating the ferricyanide complex by the prussian blue method or the total cyanide method, the apparatus becomes large, and it is necessary to contain the precipitate due to separation. Cyanide sludge is treated. therefore, The iron blue method or the total cyanide method cannot immediately deal with the sudden generation of low-concentration wastewater containing ferricyanide complex.

Patent Document 1 and Patent Document 2 disclose a treatment method for cyanide-containing drainage which can also decompose and remove a ferric cyan complex.

Patent Document 1 discloses a simultaneous continuous treatment method for a cyanide-containing ammonia waste liquid, which comprises: a first oxidation step of maintaining a waste liquid containing free cyanogen, a cyanide complex, and ammonia at a normal temperature or less than 80 ° C and adding Hypochlorite, which decomposes free cyanide and a part of ammonia; in the second oxidation step, the first oxidation step treatment liquid is maintained at 80 ° C or higher and hypochlorite is added to decompose the cyanide complex and the remaining ammonia; In the aging step, the second oxidation step treatment liquid is maintained at 80 ° C or higher to completely decompose the cyanide complex and decompose ammonia.

In this method, the concentration of hypochlorous acid in the first oxidation step and the second oxidation step is controlled by an Oxidation-Reduction Potential (ORP). The residence time in the first oxidation step is from 10 minutes to 120 minutes, and the residence time in the second oxidation step is from 20 minutes to 150 minutes.

Patent Document 2 discloses a method for treating a cyanide waste liquid, which is a method of adding hypochlorite to a waste liquid containing a cyanide complex under alkaline conditions to carry out an oxidative decomposition treatment, and containing iron and gold. The above waste liquid of at least one cyanide complex is heated from room temperature to a range of 80 ° C to the boiling point and the temperature is maintained within the above range, and the redox potential of the waste liquid is measured from room temperature, and continuously or intermittently from room temperature. The hypochlorite is added until the redox potential of the waste liquid reaches the oxidation-reduction potential of hypochlorite in the above range.

[Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2006-334508

[Patent Document 2] Japanese Patent No. 4291151

In the method described in Patent Document 1, when the low-concentration cyanide-containing drainage having a total cyanide concentration of 300 mg/L or less is treated, the inflection of the ORP caused by the addition of hypochlorite cannot be clearly confirmed (inflection) Point), and it is difficult to use ORP for drug dosage control. Therefore, the method of Patent Document 1 is not suitable for the treatment of a low concentration cyanide-containing drainage.

In any of the methods of Patent Document 1 and Patent Document 2, the treatment under the condition of a water temperature of 80 ° C or higher is required, and the piping and the treatment tank which can withstand the temperature conditions of 80 ° C or higher are provided, thereby causing the equipment cost. Becomes high.

An object of the present invention is to solve the above conventional problems and to provide a method for efficiently decomposing and removing cyanide in a low-concentration cyanide-containing water containing a ferricyanide complex by a relatively low-temperature treatment.

In order to solve the above problems, the inventors of the present invention have conducted intensive studies and found that an alkali agent and a chlorine source are added to a low-concentration cyanide-containing water containing a ferric cyanide complex, and the pH is lowered at a predetermined pH, water temperature, and free. When the chlorine concentration is maintained for a predetermined period of time, a simple device such as a water tank, a simple drug dosing unit, and a heating unit can be used, and a low-concentration cyanide-containing water can be treated by relatively low-temperature treatment without complicated chemical administration. The total cyanide containing the ferricyanide complex is efficiently decomposed and removed, and can also sufficiently cope with the treatment of the low-concentration drainage containing the ferric cyanide compound which is suddenly generated.

The present invention has been completed based on the above findings, and the following matters are intended.

[1] A method for treating a low concentration cyanide-containing water containing a ferricyanide complex, which is a method for decomposing cyanide in a low concentration cyanide-containing water containing a ferricyanide complex, characterized in that the cyanide is contained The alkaline agent and the chlorine source are added to the low-concentration cyanide-containing water of the complex, and are maintained at a pH of 11 to 13, a free chlorine concentration of 10 mg/L or more, and a water temperature of 40 ° C or more and 100 ° C or less for a predetermined period of time.

[2] The method for treating a low concentration cyanide-containing water containing a ferricyanide complex according to [1], wherein the predetermined time is one of the following i) to iv) according to the water temperature:

i) 300 hours or more when the water temperature is 40 ° C or more and less than 50 ° C

Ii) 48 hours or more when the water temperature is 50 ° C or more and less than 60 ° C

Iii) 6 hours or more when the water temperature is 60 ° C or more and less than 80 ° C

Iv) When the water temperature is 80 ° C or more and 100 ° C or less, it is 3 hours or longer.

[3] The method for treating a low concentration cyanide-containing water containing a ferricyanide complex according to [1] or [2], wherein the low concentration cyanide-containing water containing the ferricyanide complex Warming to 40 ° C or more and 100 ° C or less.

[4] The method for treating a low concentration cyanide-containing water containing a ferricyanide complex according to any one of [1] to [3], wherein the low concentration containing the above-mentioned ferricyanide complex is contained The cyanide water is maintained in the water tank provided with the water surface covering material for the predetermined period of time.

[5] The method for treating a low concentration cyanide-containing water containing a ferricyanide complex according to any one of [1] to [4] wherein the low concentration cyanide containing the ferricyanide complex The total cyanide concentration of water is below 300 mg/L.

According to the present invention, the treatment can be carried out at a relatively low temperature of 40 ° C or more and 100 ° C or less, preferably 40 ° C or more and less than 80 ° C, more preferably 60 ° C or more and less than 80 ° C, without requiring an expensive heat-resistant apparatus. Since the method of the present invention can be carried out using only a water tank and a simple drug dosing unit or a heating unit, it can be easily implemented by using an existing device.

In the present invention, since the cyanide-containing water is treated by managing the pH value, the water temperature, and the free chlorine concentration and the maintenance time, it is not necessary to perform complicated drug administration or the like.

Since the method of the present invention does not require the treatment of the generated sludge, and can be carried out by simple equipment and simple operation, it is possible to quickly cope with the treatment of the low-concentration drainage containing the ferric cyanide compound which is suddenly generated.

According to the present invention, total cyanide in a low concentration cyanide-containing water containing a ferricyanide complex can be efficiently decomposed to a low concentration of less than 0.1 mg/L.

1‧‧‧Sink

2‧‧‧Surface covering materials

3‧‧‧Alkaline tank

4‧‧‧ Chlorine source storage tank

11‧‧‧pH meter

12‧‧‧Free chlorine meter

13‧‧‧ thermometer

14‧‧‧Injection nozzle for heating steam

15‧‧‧Mixer

P ₁ , P ₂ ‧ ‧ pumps

Fig. 1 is a schematic view showing a treatment apparatus of an embodiment of a method for treating a low-concentration cyanide-containing water containing a ferricyanide complex according to the present invention.

Hereinafter, embodiments of the method for treating a low concentration cyanide-containing water containing a ferricyanide complex of the present invention will be described in detail.

In the method for treating a low concentration cyanide-containing water containing a ferricyanide complex according to the present invention, the iron cyanide complex containing iron (II) cyanide complex or iron (III) cyanide complex is low. Cyanide decomposition in cyanide-containing water (hereinafter sometimes referred to as "raw water"). An alkali agent and a chlorine source are added to the raw water at a pH of 11 to 13, a free chlorine concentration of 10 mg/L or more, a water temperature of 40 ° C or more and 100 ° C or less, preferably 40 ° C or more and less than 80 ° C, more preferably It is maintained at a temperature of 60 ° C or more and less than 80 ° C for a predetermined period of time.

The cyanide-containing water has a pH value, a water temperature, and a free chlorine concentration as the above conditions, and the cyanide-containing water is maintained in a water tank or the like for a predetermined period of time to decompose the total cyanide containing the ferric cyanide complex in the raw water. . Under the conditions of a water temperature of 40 ° C or more, a pH of 11 or more, and a free chlorine concentration of 10 mg / L or more, the oxidative decomposition reaction of cyanogen becomes active, and the hardly decomposable ferric cyanide complex is gradually decomposed.

In the present invention, the ferric cyanide compound concentration can be 407 mg/L or less, for example, 0.7 mg/L, by setting the water temperature, the pH value, and the free chlorine concentration to a predetermined range and ensuring a predetermined reaction time. The total cyanide decomposition in the low cyanide concentration of ~407 mg/L and the total cyanide concentration of 300 mg/L or less, for example 0.5 mg/L to 300 mg/L, is removed to less than 0.1 mg/L.

The alkali agent added to the raw water may be sodium hydroxide (NaOH), potassium hydroxide (KOH) or the like. The alkaline agent is usually used in the form of an aqueous solution of about 10% by weight to about 48% by weight.

When the pH of the raw water is 6 to 10, the raw water is adjusted to have a pH of 11 to 13, preferably 11 to 12.5, more preferably 11 to 12 by adding an alkali agent. If the adjusted pH value is less than 11, the ferric cyanide complex cannot be sufficiently decomposed and removed. Even if the adjusted pH value exceeds 13, the effect of improving the decomposition and removal of the ferric cyan complex is not obtained, and the use amount of the alkali agent is increased, and the operation of the device is resistant to alkali and high pH water. Problems such as sex are practically disadvantageous in terms of economy and safety.

The chlorine source added to the raw water may be a chlorine source which is a source of free chlorine such as sodium hypochlorite (NaClO), bleaching powder, or chlorine. The chlorine source is preferably used in the form of an aqueous solution of about 10% by weight to about 13% by weight.

The raw water is adjusted to have a free chlorine concentration of 10 mg/L or more, preferably 10 mg/L to 1000 mg/L, by adding a chlorine source. If the adjusted free chlorine concentration is less than 10 mg/L, the ferricyanide complex cannot be sufficiently decomposed and removed. Even if the concentration of free chlorine is excessively increased, the effect of improving the decomposition and removal effect of the ferric cyan complex is not obtained, and it is practically disadvantageous in terms of an increase in the amount of use of the chlorine source, economy, and safety. The corrosion rate of the steel material in the water having a pH of 11 or more and the free chlorine concentration exceeding 1000 mg/L is smaller than the corrosion rate of the steel material in the raw water. Therefore, the method of the present invention makes the steel less susceptible to corrosion.

In the present invention, the water temperature of the raw water is maintained at 40 ° C or more and 100 ° C or less, preferably 40 ° C or more and less than 80 ° C, more preferably 60 ° C or more and less than 80 ° C. If the water temperature is less than 40 ° C, the ferric cyanide complex cannot be sufficiently decomposed and removed. The water temperature may be from 80 ° C to 100 ° C, but the water temperature is preferably less than 80 ° C from the viewpoints of economy, safety, durability of equipment, and the like.

In order to set the water temperature of the raw water to 40° C. or more, steam may be blown into the raw water, or a water tank having a heating device such as a heater may be used, or the raw water may be heated by a heat exchanger. By the blowing of steam, the water temperature can be adjusted using only a simple steam blowing nozzle. The pH of the raw water after the steam is blown and the concentration of the free chlorine must be in the above range.

In order to maintain the water temperature of the raw water in the water tank, a heat preservation unit such as a jacket may be provided in the water tank. In particular, it is possible to set up the following Fine Ball (registered trademark of Nippon Paper-Pak Co., Ltd.) The water surface is coated to prevent the water temperature from being lowered due to heat release from the water surface. The surface covering material can be easily laid and disassembled. The steam blowing nozzle for heating is easily inserted into the water covered by the water surface covering material.

In the present invention, the raw water adjusted to a predetermined water temperature, pH value, and free chlorine concentration is maintained for a predetermined period of time, and the predetermined time is preferably as follows.

i) 300 hours or more, preferably 300 hours to 1440 hours, more preferably 300 hours to 720 hours, when the water temperature is 40 ° C or more and less than 50 ° C.

Ii) in the case where the water temperature is 50 ° C or more and less than 60 ° C, it is 48 hours or more, preferably 48 hours to 300 hours, more preferably 150 hours to 250 hours.

Iii) in the case where the water temperature is 60 ° C or more and less than 80 ° C, it is 6 hours or longer, preferably 6 hours to 48 hours, more preferably 24 hours to 48 hours.

Iv) When the water temperature is 80 ° C or more and 100 ° C or less, it is 3 hours or longer, preferably 3 hours to 6 hours, more preferably 4 hours to 6 hours.

The predetermined time is determined by the relationship between the concentration of the ferric cyanide compound and the total cyanide concentration of the raw water, the water temperature of the raw water, the pH value, and the free chlorine, so that the total cyanogen in the raw water is sufficiently decomposed.

A specific embodiment of the cyanide decomposition treatment of the present invention will be described below with reference to Fig. 1 .

In Fig. 1, reference numeral 1 denotes a water tank for holding raw water, and a pH meter 11, a free chlorine meter 12, and a thermometer 13 are provided. The blowing nozzle 14 for heating the steam and the agitator 15 are inserted into the water. In the water tank 1, the water surface covering material 2 is provided so as to cover the water surface in the tank.

For the raw water in the water tank 1, an alkali agent and a chlorine source are respectively added from the alkali agent storage tank 3 and the chlorine source storage tank 4. Alkali agent 11 is linked by a pump P ₁ while adjusting the addition amount of a pH meter. The chlorine source is adjusted by the pump P _{2 in} conjunction with the free chlorine meter 12. The amount of steam blown into the blowing nozzle 14 for the steam for warming is adjusted by a valve (not shown) or the like that is interlocked with the thermometer 13.

The raw water is kept in the water tank 1 for a predetermined period of time in the following state: the pH is adjusted to 11 to 13 by adding an alkali agent and a chlorine source while stirring with a stirrer 15, and the free chlorine concentration is adjusted to 10 mg/L or more. The water temperature is adjusted to 40° C. or more and 100° C. or less, preferably 40° C. or more and less than 80° C., more preferably 60° C. or more and less than 80° C. by blowing steam.

In the holding period, since the water surface of the raw water is covered by the water surface covering material 2, it is possible to prevent the water temperature from being lowered due to the heat release from the water surface, and to reduce the amount of steam blowing for heating.

The water-repellent covering material 2 is preferably provided by arranging a granular body of a synthetic resin having a specific gravity of less than 1, preferably a resin hemisphere such as polyethylene. As the water surface covering material, for example, a material commercially available as a fine ball (registered trademark of Nippon Paper Packaging Co., Ltd.) can be used.

The treated water in which the total cyanide in the water is decomposed and removed in the water tank 1 for a predetermined period of time is discharged to the outside of the system. The present invention is not limited to the batch type, and may be continuously processed. In the case of the continuous type, it may be designed such that the residence time of the water tank becomes the predetermined time.

The treatment method of the low-concentration cyanide-containing water containing the ferricyanide complex of the present invention is effective for the treatment of the low-concentration wastewater containing the ferricyanide complex discharged from a wide range of fields: in the furnace for treating coal, the beneficiation refining, and the coke Drainage containing ferricyanide complex produced by the use of iron (II) cyanide complex or the like in the production of a plant such as a ferric-cyanide-containing compound, and the use of an iron (II) cyanide complex or the like in the adsorption or aggregation treatment of a radioactive contaminant or the like. Wait.

[Examples]

The present invention will be more specifically described below by way of examples and comparative examples.

Moreover, in the following examples and comparative examples, the test water of the following water quality was used as raw water. The test water is dust collecting water simulating a coal-fired power generation facility. The alkaline agent used was a 48% by weight aqueous NaOH solution, and the chlorine source was a 12% by weight aqueous NaClO solution.

<test water quality>

pH: 9.2

Total cyanide: 11mg/L

(Iron (II) cyano reagent: 5.5mg/LasCN, iron (III) cyano reagent: 5.5mg/LasCN)

The analysis method of total cyanide and free chlorine concentration in water is as follows.

Total cyanide: After adding L(+)-ascorbic acid to the test water and reducing the residual chlorine in the water, the pH was adjusted to 12 by NaOH, and the 4-pyridine-pyrazolone according to JIS K 0102 was used without filtration. The total cyanogen was determined by spectrophotometry.

Free chlorine: The test water was filtered through a filter paper made of a glass filter, diluted with pure water to a predetermined concentration, and measured by a DPD method according to JIS K 0102.

[Test No. 1 to No. 21]

The test water was obtained by blowing steam into a glass container with a lid (sample capacity: 500 mL), and adding an alkali agent and a chlorine source to the water temperature, pH value, and free chlorine concentration shown in Table 1. Maintain the specified time shown in Table 1. The total cyanide concentration of the test water after the predetermined time was measured, and the results are shown in Table 1.

As is apparent from Table 1, according to the present invention, the ferric cyanide complex in water can be efficiently decomposed and removed at a temperature of less than 80 ° C (Test No. 1 to No. 8).

On the other hand, Test No. 10 to No. 13 having a free chlorine concentration of less than 10 mg/L, Test No. 14 and No. 15 having a pH of less than 11, and Test No. 16 and No. having a water temperature of less than 40 ° C. In the case of 17, the ferric cyanide complex could not be sufficiently decomposed, and it was found that the water temperature, the pH value, and the free chlorine concentration must satisfy the conditions of the present invention.

It is known from Test No. 7 and No. 8 that even under the conditions of a water temperature of 40 ° C or 50 ° C, the reaction time can be prolonged by prolonging the reaction time under the condition of a free chlorine concentration of 10 mg/L or more. The substance is fully decomposed.

It is known from Test No. 9 that even at a water temperature of 90 ° C, it can be borrowed. The total cyanide concentration was made less than 0.1 mg/L under the conditions of a free chlorine concentration of 10 mg/L or more for a predetermined period of time of 4 hours or longer.

As shown in Test No. 18 to No. 21, when the reaction time was short, the ferric cyanide complex could not be sufficiently decomposed. Therefore, it is preferable to determine the predetermined time required for the treatment based on the test results of Table 1 or the additional test results based on the processing conditions performed by the water temperature or the like.

The present invention has been described in detail with reference to the preferred embodiments thereof.

The present application is based on Japanese Patent Application No. 2013-175823, filed on-

1‧‧‧Sink

2‧‧‧Surface covering materials

3‧‧‧Alkaline tank

4‧‧‧ Chlorine source storage tank

11‧‧‧pH meter

12‧‧‧Free chlorine meter

13‧‧‧ thermometer

14‧‧‧Injection nozzle for heating steam

15‧‧‧Mixer

P ₁ , P ₂ ‧ ‧ pumps

Claims (8)

A method for treating low-concentration cyanide-containing water containing a ferricyanide complex, which is a method for decomposing cyanide in a low-concentration cyanide-containing water containing a ferricyanide complex, characterized in that the mixture contains a ferricyanide complex The low-concentration cyanide-containing water is added with an alkali agent and a chlorine source, and is maintained at a pH of 11 to 13, a free chlorine concentration of 10 mg/L or more, and a water temperature of 40 ° C or more and 100 ° C or less. The method for treating a low concentration cyanide-containing water containing a ferricyanide complex according to claim 1, wherein the predetermined time is any one of the following i) to iv) according to the water temperature: i) When the water temperature is 40° C. or more and less than 50° C., it is 300 hours or more ii) When the water temperature is 50° C. or more and less than 60° C., it is 48 hours or more iii) The water temperature is 60° C. or more and less than 80° C. In the case of 6 hours or more, iv) is 3 hours or more when the water temperature is 80° C. or more and 100° C. or less. A method for treating a low concentration cyanide-containing water containing a ferricyanide complex according to claim 1 or 2, wherein the temperature of the low concentration cyanide-containing water containing the ferricyanide complex is heated To 40 ° C or more and 100 ° C or less. A method for treating a low-concentration cyanide-containing water containing a ferricyanide complex according to claim 3, wherein the low-concentration cyanide-containing water containing the ferricyanide complex is heated by blowing a vapor . The method for treating a low concentration cyanide-containing water containing a ferricyanide complex according to any one of claims 1 to 4, wherein the low concentration cyanide-containing water containing the ferricyanide complex is The predetermined time is maintained in the water tank provided with the surface covering material. The ferric cyanide according to any one of claims 1 to 5 A method for treating a low concentration cyanide-containing water of a complex compound, wherein the total cyanide concentration of the low concentration cyanide-containing water containing the ferricyanide complex is 300 mg/L or less. The method for treating a low concentration cyanide-containing water containing a ferricyanide complex according to any one of claims 1 to 6, wherein the concentration of the ferricyanide complex is 0.7 mg/L to 407 mg/ The low-concentration cyanide-containing water having a total cyanide concentration of 0.5 mg/L to 300 mg/L is treated to obtain treated water having a total cyanide concentration of less than 0.1 mg/L. A low-concentration cyanide-containing water treatment device containing a ferricyanide complex by adding an alkali agent and a chlorine source to a low-concentration cyanide-containing water containing a ferricyanide complex, and at a prescribed pH, free chlorine a device for decomposing cyanide in the low concentration cyanide water under the conditions of concentration and water temperature, and comprising: a water tank for holding the low concentration cyanide water; a mixer for stirring the water in the water tank a pH meter for measuring the pH of the water in the water tank, a free chlorine meter for measuring the concentration of free chlorine, and a thermometer for measuring the water temperature; a water surface covering material covering the water surface of the water in the water tank; and being inserted into the water tank a blowing nozzle for heating steam in water; an alkali agent adding unit linked to the pH meter; a chlorine source adding unit linked to the free chlorine meter; and adjusting the blowing into the heating steam in conjunction with the thermometer A unit that blows a vapor injecting amount into the nozzle.