JPH07124570A - Removal of cyan and heavy metal from waste water containing iron cyan complex salt and heavy metal salts by sedimentation and flocculation separation - Google Patents

Abstract

PURPOSE:To separate and remove cyan and heavy metals from waste water containing an iron cyan complex salt and heavy metal salts by the injection of a manganeous compd. CONSTITUTION:Waste water containing an iron cyan complex salt is sent into a reaction tank 2 and a manganeous compd. soln. 6 is injected into the waste water to sediment manganese ferrocyanide or ferricyanide and a sodium hydroxide soln. 7 is injected to adjust the pH value of the treated water. Next, manganese ferrocyanide or ferrocyanide is flocculated in a flocculation tank 3 to be sedimented and separated in a sedimentation tank 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of manufacturing wastewater treatment equipment for removing cyanide and heavy metals from wastewater containing a mixture of iron cyanide complex salts and heavy metal salts, and managing wastewater treatment.

[0002]

2. Description of the Related Art As a method for removing cyanide and heavy metals in waste water containing iron cyanide complex salts, zinc ions are added at pH 9.5 or less to form precipitates as zinc ferrocyanide, which is then aggregated and separated. In addition, ferricyan ion is added with a reducing agent to reduce it to ferrocyan ion, and then zinc ion is added to form a precipitate, which is aggregated and separated.

[0003]

In the conventional method, when the ferricyanide was removed, it was necessary to inject a reducing agent such as sodium bisulfite to reduce the ferricyanide.
Further, there is a problem that the zinc ferrocyanide precipitate begins to dissolve and cannot be completely separated and removed from the waste water for which the PH value is required to be 9.5 or more because other substances are mixed.

The present invention does not require injection of a reducing agent and produces precipitates from both ferrocyanide and ferricyanide, and even at pH 9.50 or higher, these precipitates do not dissolve, and a simple and easy waste water treatment system is provided. The purpose is to provide simplification of manufacturing method and wastewater treatment management work.

[0005]

In order to achieve the above object, a primary manganese compound is used as a chemical to be injected into the precipitation formation of the present invention, and a manganese ferrocyanide or a manganese ferricyanide as shown in Chemical formulas 1 and 2 is used. To form a precipitate.

[0006]

[Chemical 1]

[0007]

[Chemical 2]

The PH value for the precipitation of manganese ferrocyanide or manganese ferricyanide by injecting a primary manganese compound is in a wide range of PH 4.5 to 14.0, but the excess manganese ion injected is sodium hydroxide. A pH value of 9.0 to 10.5 is suitable for injecting the solution and forming and removing a precipitate of manganese hydroxide as shown in Chemical formula 3.

[0009]

[Chemical 3]

When other heavy metal salts and surfactants are mixed in the waste water, the pH value is preferably pH 9.0 to 10.5 in order to enhance the effect when precipitation formation or aggregation is incomplete.

The injection amount of the first manganese-based material is appropriately 6 g to 10 g as manganese with respect to 1 m ³ of waste water having a cyanide concentration of 10 mg / 1000 cm ³ .

The cyan concentration of the waste water is 10 to 20 mg / 10.
In the case of 00 cm ³ , the concentration of the injected first manganese compound solution is 0.3 to 0.5 g / 1000 cm as manganese.
³ is appropriate.

When the wastewater is treated continuously, the method for injecting the solution of the first manganese compound is the water supply pump 9 for the wastewater containing the iron cyanide complex salt and the injection pump 1 for the solution of the first manganese compound.
It is preferable that 0 works in conjunction and injects.

[0014]

As described above, the primary manganese ion acts on the ferrocyanide and ferricyanide to form a water-insoluble precipitate.

Then, other heavy metal ions mixed by the injection of the sodium hydroxide solution and the excess manganese ions injected are precipitated as hydroxides.

Further, when a surfactant is mixed, there is a place where the coagulation effect is hindered.
A high value of promotes the agglomeration effect.

[0017]

EXAMPLES Examples will be described with reference to the drawings.
In FIG. 1, the wastewater that has flowed into the wastewater storage tank 1 is the water pump 9
Then, water is sent to the reaction tank 2 and the primary manganese compound solution 6 and the sodium hydroxide solution 7 are injected by the metering pumps 10 and 11. As manganese sulphate is used as the manganese manganese compound, it proceeds into the precipitation tank 3 while advancing the reaction of precipitation generation, and the coagulant solution 8 is injected by the metering pump 12 to agglomerate the precipitate and flow into the precipitation tank 4. In the settling tank 4, the precipitates of cyan and heavy metals are separated and separated from the supernatant water, and the settled precipitates are taken out from the settling valve 17 and disposed of by a sludge dehydrator.

The flow rate of the waste water is adjusted by the flow rate control valve 18 to keep the flow rate constant. For the injection amount of the first manganese compound solution, the cyan concentration in the wastewater is analyzed and weighed in advance, and

Metering pump 1 to inject at the stated rate
0 and the water feed pump 9 are operated in conjunction.

The injection amount of the sodium hydroxide solution is instructed by the PH adjustment indicator to operate the metering pump 11, and the pH is adjusted to 9.0.
Inject to ~ 10.5.

The injection amount of the coagulant is set by operating the water feed pump 9 and the metering pump 12 in conjunction with each other to set an appropriate amount at which the coagulating effect appears.

[0021]

Since the present invention is constructed as described above, it has the following effects.

Cyan can be separated and removed from wastewater containing a ferrocyanine compound or a ferricyanide compound by forming a precipitate of these complex cyanide compounds.

Precipitation is generated in wastewater containing ferricyanide without being reduced to ferrocyanide.

The precipitation of iron cyanide complex salt has a wide PH value range, and precipitation separation can be carried out within a range common to the PH value of precipitation of other heavy metal ions as hydroxides.

[Brief description of drawings]

FIG. 1 is a process diagram of removing cyanide and heavy metals from wastewater containing ferrocyanide, ferricyanide and heavy metal salts.

[Explanation of symbols]

 1. Wastewater storage tank 2. Reaction tank 3. Coagulation tank 4. Settling tank 5. Clear water 6. First manganese compound solution 7. Sodium hydroxide solution 8. Flocculant solution 9. Water pump 10. Metering pump 11. Metering pump 12. Metering pump 13. Reaction tank agitator 14. Aggregator agitator 15. PH adjustment indicator 16. PH electrode 17. Sediment extraction valve 18. Liquid level sensor 19. Flow control valve

Claims (7)

[Claims] 1. A wastewater containing ferrocyanide or ferricyanide and a salt of a heavy metal is sent to a reaction tank (2), a primary manganese compound solution (6) is injected, and a sodium hydroxide solution (7) is injected to obtain a PH9. It is adjusted to 0.0 to 14.0 to produce a precipitate of manganese ferrocyanide or manganese ferricyanide and a precipitate of heavy metal hydroxide. Next, a method in which coagulation is performed in the coagulation tank (3) and sedimentation separation is performed in the sedimentation tank (4). 2. A method for producing a precipitate of manganese ferrocyanide or manganese ferricyanide by using a solution of manganese sulphate in the solution of the manganese compound of claim 1, and performing coagulation sedimentation separation. 3. A method of producing a precipitate of manganese ferrocyanide or manganese ferricyanide by using a solution of primary manganese chloride in the solution of the primary manganese compound according to claim 1, and performing the aggregation precipitation separation. 4. A method of producing a precipitate of manganese ferrocyanide or manganese ferricyanide by using a solution of manganese ferrous nitrate in the solution of the first manganized oxide solution according to claim 1, and performing coagulation sedimentation separation. 5. A method of producing a precipitate of manganese ferrocyanide or manganese ferricyanide by using a solution of manganese acetate in the solution of the manganese compound of claim 1, and performing coagulation sedimentation separation. 6. A method of producing a precipitate of manganese ferrocyanide or manganese ferricyanide by using a solution of manganese thiosulfate in the solution of the first manganized oxide solution according to claim 1, and performing coagulation sedimentation separation. 7. A method of producing a precipitate of manganese ferrocyanide or manganese ferricyanide by using a solution of manganese ferrous carbonate in the solution of the manganese compound of claim 1, and carrying out the aggregation sedimentation separation.