JPH07116671A - Method for treating cyanide-containing wastewater containing metal cyanide complex ions - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a new technique capable of substantially completely and inexpensively decomposing cyanide in a cyanide-containing wastewater containing metal cyanide complex ions without requiring additional treatment. The main purpose is that. [Structure] I. In the reaction vessel, the cyanide-containing wastewater containing metal cyanide complex ions is maintained at a temperature of 100 to 370 ° C. and a pressure at which the wastewater maintains a liquid phase, and a cyanide compound, a nitrogen compound, an organic substance and an inorganic substance in the wastewater. A method for treating a cyanide-containing wastewater containing a metal cyanide complex ion, which comprises performing a wet oxidation treatment in the presence of oxygen in an amount less than the theoretical amount of oxygen required for decomposing hydrogen. II. The method of I above, wherein at least one of a metal oxide support and a metal support is further present in the reaction vessel. III. The method of I above, wherein sulfuric acid is added to the wastewater in advance. IV. The method of the above item I, wherein sulfuric acid is added to the wastewater in advance and at least one of a metal oxide carrier and a metal carrier is further present in the reaction vessel.

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 cyanide-containing wastewater containing metal cyanide complex ions (hereinafter, this wastewater may be simply referred to as cyanide-containing wastewater).

[0002]

2. Description of the Related Art Various methods have been proposed as a method for decomposing cyan in waste water containing cyan.
There are the thermal decomposition method and the thermal hydration method.

For example, Japanese Patent Publication No. 52-45679,
"A method for treating a tetracyanonickelate / cyan waste liquid, which is characterized by performing a heat treatment at a temperature of 150 ° C or higher" is disclosed.

Japanese Examined Patent Publication No. 55-50718 discloses that "cyan waste liquid containing iron cyanide complex ions is heated to 140 ° C. or higher in the presence of 2 mol or more of alkali metal hydroxide per iron cyanide complex ion / mol of the waste liquid. A method for treating a cyan waste liquid containing iron cyanide complex ions, which is characterized by performing heat treatment at a temperature ".

Japanese Unexamined Patent Publication (Kokai) No. 1-115490 basically discloses a method of pre-heating a cyan waste liquid and then thermally hydrolyzing it by heating steam under high temperature and high pressure.

Japanese Unexamined Patent Publication (Kokai) No. 1-194997 discloses that "a thermally decomposed solution obtained by thermally decomposing cyan in a cyan-containing solution is treated with an aerobic bacterium in which a facultative anaerobic bacterium is acclimatized and modified. The method of treating the contained liquid "is disclosed.

However, in such a thermal decomposition method,
(A) The treated water and cyan in the sludge cannot be sufficiently treated. (B) Therefore, a method for further biological treatment of the treated water has been proposed (JP-A-1-1-1).
(See No. 94997), this method requires treatment with specific bacterial cells, further lacks stability of treatment, and management of the treatment system is difficult. (C) Cyan-containing sludge is treated as hazardous waste. (D) Generally, the process of treating waste liquid containing cyan complex ion is complicated,
There are problems such as high cost.

Various cyanide-containing wastewater methods have been proposed in addition to the above-mentioned thermal decomposition methods, but any of them has problems and is said to be superior to the thermal decomposition method. hard.

[0009]

Therefore, the present invention provides a new technique capable of decomposing substantially completely and inexpensively cyanogen in cyanide-containing wastewater without the need for additional treatment. The main purpose is that.

[0010]

The present inventor has conducted various studies in view of the current state of the art as described above, and as a result, in the case of performing wet oxidation treatment of cyanide-containing wastewater under specific conditions, It was found that the task could be almost achieved.

That is, the present invention provides the following methods: I. In the reaction vessel, the cyanide-containing wastewater containing metal cyanide complex ions is maintained at a temperature of 100 to 370 ° C. and a pressure at which the wastewater maintains a liquid phase, and a cyanide compound in the wastewater,
A method for treating a cyanide-containing wastewater containing a metal cyanide complex ion, which comprises performing a wet oxidation treatment in the presence of oxygen in an amount less than the theoretical oxygen amount necessary for decomposing a nitrogen compound, an organic substance and an inorganic substance (hereinafter referred to as “the present application”). The first invention).

II. In the reaction vessel, the cyanide-containing wastewater containing metal cyanide complex ions is maintained at a temperature of 100 to 370 ° C. and a pressure for maintaining the liquid phase of the wastewater, while the cyanide compound, the nitrogenated rods, the organic substance and the inorganic substance in the wastewater are maintained. Cyanide containing metal cyanide complex ion characterized by performing wet oxidation treatment in the presence of oxygen in an amount less than the theoretical amount of oxygen required for decomposing a volatile substance and in the presence of at least one of a metal oxide carrier and a metal carrier Wastewater treatment method
Invention).

III. In the reaction vessel, the cyanide-containing wastewater containing the metal cyanide complex ion to which sulfuric acid had been added in advance was used.
While maintaining the temperature of 0 to 370 ° C. and the pressure at which the wastewater maintains the liquid phase, the amount of oxygen less than the theoretical oxygen amount necessary for decomposing the cyanide compounds, nitrogenated rods, organic substances and inorganic substances in the wastewater is A method for treating a cyanide-containing wastewater containing metal cyanide complex ions, which comprises performing a wet oxidation treatment in the presence thereof (hereinafter referred to as a third invention of the present application).

IV. In the reaction vessel, the cyanide-containing wastewater containing the metal cyanide complex ion to which sulfuric acid had been added in advance was used.
While maintaining the temperature of 0 to 370 ° C. and the pressure at which the wastewater maintains the liquid phase, the amount of oxygen less than the theoretical oxygen amount necessary for decomposing the cyanide compounds, nitrogenated rods, organic substances and inorganic substances in the wastewater is A method for treating a cyanide-containing wastewater containing a metal cyanide complex ion, which comprises performing a wet oxidation treatment in the presence of at least one of a metal oxide carrier and a metal carrier (hereinafter referred to as a fourth invention of the present application).

The cyanide-containing wastewater containing metal cyanide complex ions, which is the object of the present invention, is not particularly limited, and various cyanide-containing waste liquids discharged from the plating industry, soft nitriding treatment of steels, liquid carburizing treatment, chemical conversion treatment. Examples of the cyan liquid used for the surface treatment such as or a cyan waste liquid discharged from these surface treatment processes are exemplified. These cyan-containing wastewaters further include various organic and inorganic substances (organic acids such as formic acid and acetic acid), various nitrogen compounds such as ammonia (in this specification, nitrogen such as ammonia other than cyan compounds). The compound may be simply referred to as a nitrogen compound), or an organic chlorine compound such as trichlorethylene may also be contained.

The first to fourth applications of the present application will be described below with reference to the drawings.
The invention will be described in detail.

I. First Invention of the Present Application FIG. 1 is a flow sheet showing an outline of the first invention of the present application.

The cyan-containing waste liquid is pressurized from the waste water storage tank 1 to a predetermined pressure by the pump 2 and further mixed with the oxygen-containing gas whose pressure is previously boosted by the compressor 7, and then passed through the heat exchanger 3 to the reaction tower 4. Supplied. As the heat source of the heat exchanger 3, the high temperature treated liquid from the reaction tower 4 is circulated and used. When it is not possible to maintain a predetermined reaction temperature during the reaction such as in winter, steam can be supplied from the steam generator 8 to the reaction tower 4. Although not shown, a heating device may be provided between the heat exchanger 3 and the reaction tower 4 in order to bring the temperature inside the reaction tower to a predetermined temperature at the time of startup.

The temperature during the reaction is usually about 100 to 370 ° C, more preferably about 150 to 300 ° C. The higher the temperature during the reaction, the higher the rate of decomposition and removal of cyanide compounds,
In addition, the retention time of wastewater in the reaction tower will be shortened, but on the other hand, the equipment cost will increase.Therefore, comprehensively consider the concentration of cyanide compounds in the wastewater, the required treatment level, operating costs, construction costs, etc. And set it. The pressure during the reaction may be equal to or higher than the pressure at which the waste water can maintain the liquid phase at a predetermined temperature.

The amount of oxygen added to the cyanide-containing wastewater is less than the theoretical amount of oxygen required to decompose cyanide compounds, nitrogen compounds, organic and inorganic substances into harmless products,
More preferably, it is about 0.01 to 0.5 times the theoretical oxygen amount. When the amount of oxygen is less than 0.01 times the theoretical amount of oxygen, the decomposition of cyanide compounds will be insufficient, while even if it exceeds 0.5 times, the further improvement of the decomposition efficiency is recognized. I can't. As an oxygen source, air, oxygen-enriched air, oxygen, and oxygen containing one or more of hydrogen cyanide, hydrogen sulfide, ammonia, sulfur oxides, organic sulfur compounds, nitrogen oxides, hydrocarbons, etc. as impurities Waste gas etc. are illustrated.

The treated liquid from the reaction tower 4 is, as described above,
After preheating the cyan-containing wastewater in the heat exchanger 3, it is sent to the cooling tower 5 to be cooled, and then enters the gas-liquid separator 6,
It is separated into a gas phase component 9 and a liquid phase component 10. Liquid phase component 1
0 is sent to a solid-liquid separator 11 and separated into a final treated liquid 12 and a solid content (sludge) 13. Solid-liquid separation can be carried out by a method such as separation by gravity settling, separation by a magnet, separation by a filter press, and separation by coagulation sedimentation.

The reaction can be promoted by providing a plurality of trays inside the reaction tower 4.

Sludge (eg, black Fe ₃ O ₄ as a main component when the wastewater is iron cyanide complex ion-containing wastewater) may be accumulated in the reaction tower 4 with the passage of time. . In such a case, for example, it is preferable to clean or wash the inside of the reaction tower with air, water, steam, chemicals or the like, and periodically remove the accumulated sludge. Similar cleaning or washing can be performed on other devices such as the heat exchanger 3 if necessary.

The cyanide-containing wastewater tends to form sludge at a temperature of about 150 ° C. or above, especially because the decomposition reaction of cyanide is promoted. Therefore, in order to suppress the accumulation of sludge in the heat exchanger 3, a part of the cooled final treated liquid 12 is circulated and mixed with the treated liquid from the reaction tower 4 used for heat exchange, and heat exchange is performed. It is preferable to suppress the temperature of the cyan-containing wastewater in the vessel 3 to about 150 ° C.

Since the final treated liquid 12 from the solid-liquid separator 11 contains decomposition products such as ammonia and formic acid, they are subjected to biological treatment such as removal of ammonia and activated sludge treatment according to a conventional method. May be. In addition, by flushing the treated liquid that has finished heat exchange in the heat exchanger 3, ammonia contained in the treated liquid is absorbed and removed by sulfuric acid-containing water, water, or the like, or by using a known catalyst. After decomposition under phase, it can be subjected to biological treatment.

II. Second Invention of the Present Application FIG. 2 is a flow sheet showing an outline of the second invention of the present application.

The second invention of the present application is substantially the same as the first invention of the present application in that the reaction tower 14 is filled with at least one of a metal oxide carrier and a metal carrier.

By filling such a metal oxide carrier and / or a metal carrier, a reaction promoting effect by a piston flow flow is achieved. Therefore, it becomes possible to relax the reaction conditions as compared with the case where no carrier is used, and under the same reaction conditions, the treatment efficiency of the cyanide-containing wastewater is improved and the treatment time is shortened.

As the metal oxide carrier and the metal carrier,
There is no particular limitation, and a known catalyst carrier can be used. As the metal oxide carrier, alumina, silica, zirconia, titania, a composite metal oxide containing these metal oxides (alumina-silica,
(Alumina-silica-zirconia, titania-zirconia, etc.), metal oxide-based carriers containing these metal oxides or complex metal oxides as main components, and the like, and examples of the metal carrier include iron and aluminum. Among these, zirconia, titania, and titania-zirconia, which have excellent durability, are more preferable.

The shape of the metal oxide support and the metal support is also
The shape is not particularly limited, and examples thereof include spherical shape, pellet shape, cylindrical shape, crushed piece shape, powder shape, and honeycomb shape. In the case of using a fixed bed, the volume of the reaction tower in the case where such a carrier is packed and used is such that the space velocity of the liquid is about 0.5 to 10 hr ^-1 , more preferably about ¹ to 5 hr ^-1. Is good. The size of the carrier used in the fixed bed is usually 3 to 50 m when it is spherical, pellet-like, columnar, crushed piece-like, powder-like or the like.
It is about m, more preferably about 5 to 25 mm. In addition, as the honeycomb structure when the carrier is used in a honeycomb shape, an opening having an arbitrary shape such as a quadrangle, a hexagon, and a circle is used. The area per unit volume, the aperture ratio, etc. are not particularly limited, but usually the area per unit volume is 200 to 800 m ² / m ³ , the aperture ratio 4
The thing of about 0 to 80% is used. Examples of the material for the honeycomb structure include the same metal oxides and metals as those described above, and zirconia, titania, and titania-zirconia having excellent durability are more preferable.

When a fluidized bed is formed in the reaction tower,
The amount of the carrier that can form a fluidized bed in the reaction tower, that is, about 0.01 to 20%, more preferably about 0.05 to 10%, based on the weight of the cyanide-containing wastewater, is slurry-like in the cyanide-containing wastewater. Suspend in and use. When a fluidized bed is used, the metal oxide carrier is suspended in the waste water in a slurry state and supplied to the reaction tower, and the catalyst is precipitated and centrifuged from the treated liquid discharged outside the tower after the reaction is completed. Separate and collect by an appropriate method such as separation, and reuse. Therefore, considering the ease of separation and recovery of the catalyst from the treated liquid, the particle size of the metal oxide support used in the fluidized bed is 0.1
More preferably, it is about 5 to 0.5 mm.

III. Third Invention of the Present Application FIG. 3 is a flow sheet showing an outline of the third invention of the present application.

In the third invention of the present application, sulfuric acid from the sulfuric acid storage tank 15 is added to the cyanide-containing wastewater supplied into the reaction tower 4,
Except for being subjected to the reaction, there is substantially no difference from the first invention of the present application.

The cyanide-containing wastewater may contain a considerably large amount of alkali metal compound depending on the generation site. Therefore, it is preferable to add sulfuric acid to such cyan-containing wastewater prior to the wet oxidative decomposition reaction. Sulfuric acid is preferably added between the pump 2 and the inlet of the reaction tower 4.

The addition amount of sulfuric acid is 0.25 to 1 times per 1 mol of the total amount of alkali metal in the waste water. When the wastewater to be treated in the third invention of the present application is iron cyanide complex ion-containing wastewater, sludge containing red Fe ₂ O ₃ as a main component is formed.

IV. Fourth Invention of the Present Application FIG. 4 is a flow sheet showing an outline of the fourth invention of the present application.

The fourth invention of the present application is substantially different from the second invention of the present application in the point that the sulfuric acid from the sulfuric acid storage tank 15 is added to the cyanide-containing wastewater supplied into the reaction tower 14 to be used for the reaction. There is no.

The amount of sulfuric acid added is the same as in the case of the third invention of the present application. When the wastewater to be treated is iron cyanide complex ion-containing wastewater as well, red sludge containing Fe ₂ O ₃ as the main component is added. It is formed.

[0039]

According to the method of the present invention, the cyan complex ions and cyan are decomposed substantially completely, and they are hardly contained in the final treated liquid and the sludge produced.

Further, substantially no harmful components are found in either the gas phase or the liquid phase after gas-liquid separation. When an oxygen-containing waste gas is used as an oxygen source, the presence of harmful components derived from the waste gas is substantially not recognized in either the gas phase or the liquid phase.

Furthermore, according to the method of the present invention, since the processing flow is extremely simple, the processing cost (equipment cost, operating cost, etc.) is significantly reduced.

[0042]

EXAMPLES Examples and comparative examples will be shown below to further clarify the features of the present invention.

Example 1 According to the flow shown in FIG. 1, a cyan complex ion-containing waste liquid having the composition (the unit of concentration is mg / l) shown in Table 1 was treated according to the first invention of the present application.

[0044]

[Table 1]

Cyan-containing wastewater having a pH of 10.6 was subjected to a space velocity of 1.0 Hr ^-1 (based on empty column) and a mass velocity of 14.15 m.
Air was supplied at a space velocity of 3.2 Hr ^-1 (empty tower standard, standard state conversion) while supplying ³ m- ² Hr ^-1 to the reaction tower 4. The air supply amount was an amount corresponding to 0.023 times the theoretical oxygen amount.

In the reaction, waste water and air are introduced into the inlet side of the heat exchanger 3, and the temperature of the gas-liquid mixture at the outlet side of the heat exchanger 3 (the inlet side of the reactor 4) is 150 ° C.
Thus, a part of the final treated liquid 12 was circulated and mixed with the treated liquid from the reactor 4 to control the temperature. Also,
By supplying steam from the steam generator 8 to the reactor 4, the temperature inside the reaction tower 4 is 220 ° C. and the pressure is 30 kg · cm.
^Held at ^-2 . It should be noted that the reaction tower 4 was equipped with a tray tower every 70 cm.

Table 2 shows the composition (concentration unit: mg / l) of the treated liquid having a pH of 10.6 from the reaction tower 4. In addition,
The metal components in the initial wastewater become sludge, and the reaction tower 4
And the lower part of the solid-liquid separator 11 (filter press in this example).

[0048]

[Table 2]

As is clear from the comparison between Tables 1 and 2, the cyan component was substantially completely decomposed and converted into ammonia and formic acid. Cyan and ammonia were not detected in the exhaust gas 9, and the exhaust gas 9 consisted essentially of O ₂ and N ₂ and CO ₂ produced by the decomposition of the cyan component.

The sludge extracted from the lower part of the reaction tower 4 has a black color and contains Fe ₂ O ₃ and Fe ₃ O ₄ as main components, and P ₂ O ₅ , Na ₂ O, and other components.
Containing ZnO, SiO _2, etc., CN content is 1 mg · k
It was a precipitate having a good sedimentation property at g ^-1 or less.

Comparative Example 1 Cyan-containing wastewater was treated in the same manner as in Example 1 except that air was not supplied.

T-CN in the treated liquid from the reaction tower 4 is
0.5 mg · l ⁻¹ , cyan is not completely processed. Moreover, NH ₃ -N in the treated liquid is 9771 m.
The g · l ⁻¹ and TOC were 6185 mg · l ⁻¹ .

On the other hand, the exhaust gas contains cyan 1.5 mg · N
It contained m ^-3 and 2.9 mg of ammonia-Nm ^-3 .

The sludge extracted from the lower part of the reaction tower 4 has a black color and contains Fe ₃ O ₄ as a main component and P ₂ O ₅ , Na ₂ O, ZnO, SiO ₂ etc. as other components, The CN content was 185 mg · kg ⁻¹ , and the precipitate had a low sedimentation property.

Example 2 and Comparative Examples 2 to 7 By controlling the circulating amount of the final treated liquid, as shown in Table 3, gas-liquid at the outlet side of the heat exchanger 3 (inlet side of the reactor 4). A wet oxidation treatment of cyanide-containing wastewater was performed in the same manner as in Example 1 except that the temperature of the mixture was adjusted variously.

[0056]

[Table 3]

The amount of sludge produced in the heat exchanger, the heater and the pipes thereof due to the decomposition of the cyan complex component is based on the amount produced in Example 1 (the outlet side temperature of the heat exchanger 3 is 150 ° C.) (100). Is shown in Table 4.

[0058]

[Table 4]

When the cyanide-containing wastewater is heated so that the outlet temperature of the heat exchanger exceeds 150 ° C., the amount of sludge produced in the heat exchanger, the heater and these pipes increases, so that the pressure loss is reduced. growing. Therefore, it is necessary to regularly remove the generated sludge from these devices by jet cleaning, chemical cleaning or the like.

That is, the time during which stable operation can be continuously performed is about 1/200 in Comparative Example 7 as compared with Example 1.
Nothing more than. In other words, the outlet side temperature of the heat exchanger 3 is set to 1
By adjusting the temperature to 50 ° C. or lower, the operation of the entire apparatus can be stably performed for a long period while suppressing the generation of sludge.

Comparative Example 8 and Examples 3 to 6 As shown in Table 5, except that the amount of air supplied to the reaction column 4 (the amount corresponding to the relative oxygen amount when the theoretical oxygen amount is 1) is variously changed. Was subjected to wet oxidation treatment of cyanide-containing wastewater in the same manner as in Example 1.

[0062]

[Table 5]

In the case of Comparative Example 8 in which the air supply amount was less than 0.01 times the theoretical oxygen amount, 0.3 mg · l ⁻¹ of T-CN was detected in the treated liquid. In contrast,
In Examples 3 to 6, T-CN in the treated liquid was 0.1 m.
It was below g · l ⁻¹ .

Even when air is supplied in an amount equal to or more than 0.5 times the theoretical oxygen amount, T-CN in the treated liquid is also supplied.
Was 0.1 mg · l ^-1 or less, but it is not preferable because it has disadvantages such as an increase in compression power cost and an increase in heating fuel (or vapor amount) due to an increase in liquid evaporation amount in the system. .

Example 7 The cyan complex ion-containing waste liquid having the composition shown in Table 1 was treated according to the second invention of the present application according to the flow shown in FIG.

That is, the reaction was carried out in the same manner as in Example 1 except that the reaction tower 14 was filled with titania spheres having a diameter of 5 mm.

The water quality of the treated liquid from the reaction tower 14 and the sludge after gas-liquid separation were the same as those in Example 1 (T-CN of treated liquid = 0.1 mg · l ⁻¹ or less, C in sludge).
The residence time in the reaction tower 14 required for the N content = 1 mg · kg ⁻¹ or less) is about 1 as compared with Example 1.
It was shortened by 5%. Further, the black sludge 13 obtained by the solid-liquid separator 11 was a precipitate having a good sedimentation property.

Examples 8 to 11 The cyan complex ion-containing waste liquid having the composition shown in Table 1 was treated in the same manner as in Example 7 except that the treatment temperature in the reaction tower 14 was changed variously. Table 6 shows the results when the residence time in the reaction tower in Example 7 was 100.

[0069]

[Table 6]

Example 12 The cyan complex ion-containing waste liquid having the composition shown in Table 1 was treated according to the third invention of the present application according to the flow shown in FIG. The waste water is Na 1.35 mol·l ⁻¹ and K 0.36 mol ·
It contained alkali metal total 1.71 mole · l ^-1 of l ^-1.

That is, in the apparatus shown in FIG. 3, Example 1 was carried out except that sulfuric acid from the sulfuric acid storage tank 15 was added to the wastewater from the booster pump 2 at a rate of 0.86 mol / l, and this was treated in the reaction tower 4. Wet oxidation treatment was carried out in the same manner as in.

T-CN in the treated solution was 0.1 mg · l ⁻¹
Hereafter, NH ₃ -N is 8610 mg · l ⁻¹ and TOC is 66.
It was 00 mg · l ⁻¹ .

Cyan and ammonia were not detected at all in the exhaust gas 9, and the exhaust gas 9 consisted essentially of O ₂ and N ₂ and CO ₂ produced by the decomposition of the cyan component.

The sludge extracted from the lower part of the reaction tower 4 has a reddish brown color and contains Fe ₂ O ₃ as a main component and P ₂ O ₅ , Na ₂ O, ZnO, SiO ₂ etc. as other components. The CN content was 1 mg · kg ⁻¹ or less, and the precipitate had a good sedimentation property.

Comparative Example 9 Cyan-containing wastewater was treated in the same manner as in Example 12 except that air was not supplied.

T-CN in the treated liquid from the reaction tower 4 is
It was 0.48 mg · l ⁻¹ and cyan was not completely processed.

On the other hand, the exhaust gas 9 contained 1.8 mg of cyan.
It contained Nm ^-3 and ammonia 1.5 mg Nm ^-3 .

The sludge extracted from the lower part of the reaction tower 4 has a reddish brown color and contains Fe ₂ O ₃ as a main component and P ₂ O ₅ , Na ₂ O, ZnO, SiO ₂ etc. as other components. , CN content was 150 mg · kg ⁻¹ , which was a precipitate with low sedimentation property.

Example 13 and Comparative Examples 10 to 15 Table 7 was obtained by controlling the circulating amount of the final treated liquid 12.
As shown in, the outlet side of the heat exchanger 3 (the inlet side of the reactor 4)
The wet oxidation treatment of cyanide-containing wastewater was performed in the same manner as in Example 12 except that the temperature of the gas-liquid mixture in Example 2 was adjusted variously.

[0080]

[Table 7]

The amount of sludge produced in the heat exchanger, the heater and the pipes thereof due to the decomposition of the cyan complex component etc. is based on the amount produced in Example 12 (outlet side temperature 150 ° C. of the heat exchanger 3) (100). Is shown in Table 8.

[0082]

[Table 8]

When the waste water containing cyanide is heated so that the outlet temperature of the heat exchanger exceeds 150 ° C., the amount of sludge produced in the heat exchanger, the heater and these pipes is increased even when sulfuric acid is added. , The pressure loss increases. Therefore, it is necessary to regularly remove the generated sludge from these devices by jet cleaning, chemical cleaning or the like.

That is, the time during which stable operation can be continuously performed is about 1/2 in Comparative Example 15 as compared with Example 12.
It was only 05. These results indicate that by setting the outlet temperature of the heat exchanger 3 to 150 ° C. or lower, the operation of the entire device can be stably performed for a long period of time.

Comparative Example 16 and Examples 14 to 17 As shown in Table 9, except that the amount of air supplied to the reaction tower 4 (the amount corresponding to the relative oxygen amount when the theoretical oxygen amount is 1) was variously changed. Was subjected to wet oxidation treatment of cyanide-containing wastewater in the same manner as in Example 12.

[0086]

[Table 9]

In the case of Comparative Example 16 in which the air supply amount is less than 0.01 times the theoretical oxygen amount, T-CN is contained in the treated liquid at a ratio of 0.3 mg · l ^−1. was detected.
On the other hand, in Examples 14 to 17, T- in the treated liquid was
The CN was 0.1 mg · l ⁻¹ or less.

Even when air is supplied in an amount equal to or more than 0.5 times the theoretical oxygen amount, T-CN in the treated liquid is also supplied.
Was 0.1 mg · l ⁻¹ or less, but it also had disadvantages such as an increase in compression power ratio and an increase in heating fuel (or vapor amount) due to an increase in liquid evaporation in the system. Not preferable.

Example 18 According to the flow shown in FIG. 4, the cyan complex ion-containing waste liquid having the composition shown in Table 1 was treated according to the fourth invention of the present application.

That is, the wet oxidation treatment of the cyan complex ion-containing waste liquid was performed in the same manner as in Example 12 except that the reaction tower 14 was filled with titania spheres having a diameter of 5 mm.

The water quality of the treated liquid from the reaction tower 14 and the sludge after gas-liquid separation were the same as those in Example 12 (T-CN of treated liquid = 0.1 mg · l ⁻¹ or less, CN in sludge). The retention time in the reaction tower 14 required for the content = 1 mg · kg ⁻¹ or less) is
It was reduced by about 16%. Further, the obtained reddish brown sludge was a precipitate having a good settling property.

Examples 19 to 22 The cyan complex ion-containing waste liquid having the composition shown in Table 1 was treated in the same manner as in Example 18 except that the treatment temperature in the reaction tower 14 was changed variously. Table 10 shows the results when the reaction tower residence time in Example 14 was set to 100.

[0093]

[Table 10]

[Brief description of drawings]

FIG. 1 is a flow sheet showing an outline of the first invention of the present application.

FIG. 2 is a flow sheet showing an outline of the second invention of the present application.

FIG. 3 is a flow sheet showing an outline of a third invention of the present application.

FIG. 4 is a flow sheet showing an outline of a fourth invention of the present application.

[Explanation of symbols]

 1 ... Waste water storage tank 2 ... Pump 3 ... Heat exchanger 4 ... Reaction tower 5 ... Cooler 6 ... Gas-liquid separator 7 ... Compressor 8 ... Steam generator 9 ... Gas phase component 10 ... Liquid phase component 11 ... Solid-liquid separation Container 12 ... Final treated liquid 13 ... Solid content (sludge) 14 ... Reaction tower 15 ... Sulfuric acid storage tank

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[Procedure amendment]

[Submission date] November 17, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0002

[Correction method] Change

[Correction content]

As a method for decomposing cyanide in waste water containing cyanide, various methods such as a thermal decomposition method and a thermal hydration method have been proposed, in addition to a treatment method with a chemical such as a chlorine-based chemical, ozone and iron salt.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

However, the treatment with a chemical has a limit to the cyanide concentration in the waste water which can be applied from the economical aspect, and the method of adding an iron salt to form a sparingly soluble complex salt requires treatment of sludge containing cyanide. And Furthermore, the thermal decomposition method requires a long time to completely decompose the cyan compound depending on the type of the (a) cyanide complex ion.
In the ordinary treatment method, a part of cyan remains in the sludge after treatment. (B) Therefore, a method of further biological treatment of treated water has been proposed (Japanese Patent Laid-Open No. 19499/1990).
(See No. 7), this method requires treatment with specific bacterial cells, and when nitrogen removal is required, an ammonia stripper or biological denitrification equipment is required. If the method is a batch method, there is a problem that it is not suitable for treating a large amount of wastewater.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

Generally, sludge containing cyanide needs to be treated as hazardous waste. In addition, according to the conventional processing method, there is a problem that the processing of the waste liquid containing high-concentration cyanide containing the cyan complex ion complicates the process and increases the processing cost.

 ─────────────────────────────────────────────────── ─── Continued front page (72) Yoshiaki Harada, 1-2 1-2 Hirano-cho, Chuo-ku, Osaka-shi, Osaka Prefecture Osaka Gas Co., Ltd. (72) Ken-ichi Yamazaki 4-chome, Hirano-cho, Chuo-ku, Osaka-shi, Osaka 1-2 In Osaka Gas Co., Ltd. (72) Inventor Fuyuki Noguchi 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi, Osaka Prefecture In Osaka Gas Co., Ltd. (72) Masakatsu Hiraoka 39, Kibata Mikurayama, Uji-shi, Kyoto Prefecture −763 (72) Inventor Heihachi Takahashi 1-15-1 Nihonbashi, Chuo-ku, Tokyo Within Japan Parkerizing Co., Ltd. (72) Inventor Gennosuke Inoue 656-1 Oto, Yono-shi, Saitama 1-403

Claims (24)

[Claims] 1. A cyan compound, a nitrogen compound, or an organic compound in waste water, which is maintained in a reaction vessel at a temperature of 100 to 370 ° C. and a pressure at which the waste water maintains a liquid phase, while maintaining a temperature of 100 to 370 ° C. A method for treating cyanide-containing wastewater containing a metal cyanide complex ion, which comprises performing a wet oxidation treatment in the presence of oxygen in an amount less than the theoretical oxygen amount required for decomposing substances and inorganic substances. 2. The amount of oxygen is 0.01 to 0.5 of the theoretical amount of oxygen.
The method for treating wastewater according to claim 1, wherein the amount is double. 3. The method for treating wastewater according to claim 1, wherein the treatment temperature is 150 to 300 ° C. 4. The method for treating wastewater according to claim 1, wherein the cyanide-containing wastewater containing metal cyanide complex ions is preheated to 150 ° C. by heat exchange with the treated liquid and then subjected to wet oxidation treatment. 5. The method for treating wastewater according to claim 1, wherein steam is fed into the reaction vessel to raise the temperature. 6. A cyan compound, a nitrogen compound, an organic compound in the waste water, while maintaining the temperature of the cyan-containing waste water containing metal cyanide complex ions at 100 to 370 ° C. and the pressure at which the waste water maintains a liquid phase in the reaction vessel. A metal cyanide complex ion characterized by performing a wet oxidation treatment in the presence of oxygen in an amount less than the theoretical oxygen amount necessary for decomposing substances and inorganic substances and in the presence of at least one of a metal oxide support and a metal support. Method for treating wastewater containing cyanide containing. 7. The amount of oxygen is 0.01 to 0.5 of the theoretical amount of oxygen.
The method for treating wastewater according to claim 6, wherein the amount is double. 8. The method for treating wastewater according to claim 6, wherein the treatment temperature is 150 to 300 ° C. 9. The method for treating wastewater according to claim 6, wherein the cyanide-containing wastewater containing metal cyanide complex ions is preheated to 150 ° C. by heat exchange with the treated liquid and then subjected to wet oxidation treatment. 10. The method for treating wastewater according to claim 6, wherein steam is fed into the reaction vessel to raise the temperature. 11. The method for treating wastewater according to claim 6, wherein the metal oxide carrier contains at least one of titania and zirconia. 12. 100 to 3 of cyanide-containing wastewater containing metal cyanide complex ions to which sulfuric acid has been added in advance in a reaction vessel.
Wet in the presence of oxygen below the theoretical oxygen amount required to decompose the cyanide compounds, nitrogen compounds, organic substances and inorganic substances in the wastewater while maintaining the temperature of 70 ° C and the pressure at which the wastewater maintains the liquid phase. A method for treating a cyanide-containing wastewater containing a metal cyanide complex ion, characterized by performing an oxidation treatment. 13. The method according to claim 12, wherein the added amount of sulfuric acid is 0.25 to 1 mol per 1 mol of the total amount of alkali metals in the cyan-containing waste water containing metal cyan complex ions. 14. The amount of oxygen is 0.01-0.
The method for treating wastewater according to claim 12, wherein the amount is 5 times. 15. The method for treating wastewater according to claim 12, wherein the treatment temperature is 150 to 300 ° C. 16. The method for treating wastewater according to claim 12, wherein the cyanide-containing wastewater containing metal cyanide complex ions is preheated to 150 ° C. by heat exchange with the treated liquid and then subjected to wet oxidation treatment. 17. The method for treating wastewater according to claim 12, wherein steam is fed into the reaction vessel to raise the temperature. 18. 100 to 3 of cyanide-containing wastewater containing metal cyanide complex ions to which sulfuric acid has been added in advance in a reaction vessel.
In the presence of oxygen in an amount less than the theoretical oxygen amount necessary for decomposing cyanide compounds, nitrogen compounds, organic substances and inorganic substances in the waste water while maintaining the temperature of 70 ° C. and the pressure for maintaining the liquid phase of the waste water, and the metal. A method for treating a cyanide-containing wastewater containing a metal cyanide complex ion, which comprises performing a wet oxidation treatment in the presence of at least one of an oxide carrier and a metal carrier. 19. The method according to claim 18, wherein the added amount of sulfuric acid is 0.25 to 1 mol per 1 mol of the total amount of alkali metal in the cyan-containing wastewater containing metal cyan complex ions. 20. The amount of oxygen is 0.01 to 0.
The method for treating wastewater according to claim 18, wherein the amount is 5 times. 21. The method for treating wastewater according to claim 18, wherein the treatment temperature is 150 to 300 ° C. 22. The method for treating wastewater according to claim 18, wherein the cyanide-containing wastewater containing metal cyanide complex ions is preheated to 150 ° C. by heat exchange with the treated liquid, and then subjected to wet oxidation treatment. 23. The method for treating wastewater according to claim 18, wherein steam is fed into the reaction vessel to raise the temperature. 24. The method for treating wastewater according to claim 18, wherein the metal oxide carrier contains at least one of titania and zirconia.