JPH0324298A - Treatment of ferrous ion in aqueous acidic solution - Google Patents

Abstract

PURPOSE:To easily reduce the Fe ion content of an aq. acidic soln. by bubbling oxygen or ozone through the soln. having a high content of ferrous ion to oxidize the ferrous ion to ferric ion and removing the ferric ion with a chelating resin. CONSTITUTION:A band steel 3 with the surface cleaned in a pretreating device 4 is passed through a Zn electroplating bath 5, and the surface is plated with Zn. The ferrous ion content of the plating soln. in the plating bath 5 is increased, and the plating soln. is deteriorated. Accordingly, a part of the plating soln. is introduced into a first iron removing device 7 via a pipeline 8, oxygen or ozone is blown into the soln. to oxidize the ferrous ion to ferric ion, and excess oxygen and ozone are removed. The soln. is introduced into a second iron removing device 10, the ferric ion is adsorbed on a chelating ion-exchange resin packed in the device, and the plating soln. with the Fe content reduced is returned to the plating bath 5 through a pipeline 16 and used in plating.

Description

[Detailed description of the invention] [Industrial application field] The present invention oxidizes divalent iron ions (Fe'') in an acidic aqueous solution (especially electrogalvanizing solution) with a high concentration of divalent iron ions, This invention relates to a method of reducing the concentration of divalent iron ions by replacing trivalent iron ions (Fe'') with established processing technology.

(Prior art) Conventionally, as a means to separate trivalent iron ions in an acidic aqueous solution with a high concentration of trivalent iron ions, a neutralizing agent such as calcium hydroxide is added, and the hydroxide is separated from the aqueous solution. In recent years, a method has also been considered in which an organic extractant containing a water-insoluble dialkyl phosphoric acid is brought into contact with an acidic aqueous solution to separate it (Japanese Patent Publication No. 1983-1999).
(Refer to Publication No. 53410). However, a separation method using a chelate resin has been developed to separate iron ions from an electrolytic galvanizing solution, and is now in general use. This method removes trivalent iron ions by passing the plating solution through an exchange column filled with a chelating ion exchange resin that has selective adsorption properties for trivalent iron ions ( (See Japanese Patent Publication Nos. 57-27460 and 57-51479) and is quite effective in removing trivalent iron ions.

[Problem to be solved by the invention]

However, during the method for separating iron ions from the electrolytic galvanizing solution, a large amount of divalent iron ions enter the plating solution from auxiliary raw materials due to elution from the iron plate to be plated, electrolytic tank, etc. It was not effective against plating, and it was not possible to reduce the iron ion concentration in the plating solution. As a result, the surface characteristics of the electrolytic galvanized iron plate of the product deteriorate, and metal materials such as electrolytic tanks, piping, pumps, etc. are subject to accelerated damage.

(Object of the Invention) The present invention has been made to solve the above-mentioned problems, and it makes it possible to efficiently oxidize divalent iron ions to trivalent iron ions by oxygen or ozone, and also to make it possible to efficiently oxidize divalent iron ions to trivalent iron ions remaining in the liquid. The purpose of this method is to ensure that oxygen or ozone is removed to ensure that trivalent iron ions are removed using a chelate resin in the next step.

[Means to solve the problem]

The present invention enables the production of iron from an acidic aqueous solution with a high concentration of divalent iron ions.
This is a method for removing valent iron ions, in which the acidic aqueous solution is bubbled with oxygen or ozone to oxidize and remove the divalent iron ions, and then the blown oxygen or ozone is removed from the acidic aqueous solution using a semipermeable membrane. It is characterized by
This structure achieves the above objective.

[Example] First, an example of equipment for implementing the method of the present invention will be described with reference to FIG.

1 in the figure is an electrogalvanizing equipment, in which a thin steel plate 3 is supplied from a thin steel plate coil 2, its surface is conditioned in a pre-treatment tank 4, the surface is galvanized in an electro-galvanized tank 5, and then post-treated. It is configured to be post-processed in a tank to become a product coil 6.

7 is the first iron removal device for removing divalent iron ions;
The inlet of the first iron removing device 7 is connected to the electrogalvanizing tank 4 via a valve 9 by a pipe 8.

10 is a second iron removal device (
The second iron removing device 10 is filled with a chelating ion exchange resin that adsorbs trivalent iron ions in the electrolytic galvanizing solution, and is removed by a regenerating acid aqueous solution flow system (not shown). The chelating ion exchange resin can be regenerated by passing a regenerated acid aqueous solution through it.

The discharge side of a pump l1 is connected to the inlet of the second iron removal device 10, and the first iron removal device 7 is connected to the suction side of the pump II via a valve 13 via a pipe 12, and
Bypass piping 14 is directly connected to electrogalvanizing tank 4 via valve 15 . Further, the outlet of the second iron removing device 10 is connected to the electrogalvanizing tank 5 via a return pipe 16 and a valve 17.

The first iron removal device 7 has a pipe-shaped processing tank 18 through which the electrolytic galvanizing solution flows in one direction, and the processing tank 18 includes:
The inlet side end and the outlet side end are connected, and a return pipe 22 with a pump 19 provided in the middle and valves 20 and 21 at both ends is connected, and when the valves 20 and 21 are open, the return pipe 22 is connected. It is possible to flow the electrogalvanizing solution into the processing tank 18 multiple times by the bomb 19 through the piping 22.

A blowing pipe 23 is connected to the artificial side of the processing tank 18 so as to be able to blow oxygen or ozone into it.
The electrolytic galvanizing solution in the processing tank 18 can be hubbed with oxygen or ozone blown into the processing tank 18 through the tank 3.

In addition, the exit side of the processing tank 18 is provided with a semipermeable membrane 24 (
The entire periphery of the membrane is covered with a hood 25 connected to an exhaust device, and the exhaust action of the exhaust device is exerted on the entire semipermeable membrane 24 through the hood 25. Utilizing the properties of the film, it is possible to degas the oxygen or ozone blown into the electrolytic galvanizing solution.

In such equipment, with valve 15 closed, valves 9, l3, and l7 are opened to drive bomb 1l, a portion of the electrolytic galvanizing solution is extracted from electrogalvanizing tank 5, and valves 9, l3, and l7 are opened. When a predetermined amount of iron is supplied into the processing tank 18 of the first iron removal device 7 by opening and closing operations,
As a result, the treated electrogalvanizing solution discharged from the processing tank 18 is supplied to the second iron removal device 10 via the pipe 12, and the treated electrogalvanizing solution discharged from the second iron removal device 10 is returned. It is returned to the electrogalvanizing tank 5 via piping 16. Then, in the first iron removing device 7, a process of oxidizing divalent iron ions and degassing, which will be described later, is performed. Further, a step of removing trivalent iron ions is performed in the second iron removing device 10.

In the first iron removal device 7, the pump I9 is driven with the valves 20 and 21 open, and the electrolytic galvanizing solution is passed into the processing tank 18 multiple times through the return pipe 22, while the exhaust device is driven. At the same time, oxygen or ozone is blown into the electrolytic galvanizing solution in the processing tank 18 via the blowing pipe 23. Then, the electrogalvanizing solution flows through the processing tank 18 multiple times, and each time the electrogalvanizing solution is bubbled with oxygen or ozone, and the divalent iron ions in the electrolytic galvanizing solution are It is oxidized to trivalent iron ions according to formula (2). Further, oxygen or ozone remaining in the electrogalvanizing solution without being used for oxidizing divalent iron ions passes through the semipermeable membrane 24 and is discharged into the hood 25, where it is collected and exhausted.

(1) F e"+Oz +2 H' +3 e-+
Fe"+20H (2) Fe"+Ot +3 H"+5 e-
→F e"+30H
Inside the electrolytic galvanizing solution, divalent iron ions are bubbled with oxygen or ozone to oxidize and convert them into trivalent iron ions. Semi-permeable membrane 24 removes remaining oxygen or ozone.
It is removed (gas degassed) by

Oxygen or ozone remaining in the electrogalvanizing solution corrodes the chelate resin effective in removing trivalent iron ions in the second iron removal device 10 and weakens the suction power of the bombs 11 and 19. The removal not only ensures the flow of the plating solution treatment but also guarantees the ability of the second iron removal device 10 to remove trivalent iron ions. Although the electrogalvanizing solution treatment process has been described, it is of course applicable to oxidation sterilization processes in small water supply facilities.

〔Effect of the invention〕

As described above, the present invention can reliably oxidize divalent iron ions in an acidic aqueous solution to trivalent iron ions.

Furthermore, since divalent iron ions are oxidized by bubbling with oxygen or ozone and no neutralizing agent is added, there is no effect on the composition of the acidic aqueous solution. Furthermore, the semipermeable membrane can reliably remove oxygen or ozone remaining in the acidic aqueous solution. Therefore, the removal treatment of trivalent iron ions using the chelate resin in the next step can be ensured, and iron ions in the acidic aqueous solution can be removed. Furthermore, since it can be carried out in a flow system, efficient treatment can be performed with small equipment, and the treatment process can be simplified.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of the equipment for carrying out the method of the present invention, and Figure 2 is the
FIG. 2 is a schematic cross-sectional view showing the main part of the figure in detail. l...Electrogalvanizing equipment, 5...Electrogalvanizing tank, 7...First iron removal device, 8
...Piping, 9...Valve, 10...
...Second iron removal device, 11...Pump, l2.
...Piping, l3...Valve, 14...
...Bypass piping, 15...Valve, 16.
...Return piping, 17...Valve, 18.
...Processing tank, l9...Pump, 20
, 2l...Valve, 22...Return piping, 23...Blowing piping, 24...Semipermeable membrane, 25...Hood.

Claims (1)

[Claims] (1) is a method for removing divalent iron ions from an acidic aqueous solution with a high concentration of divalent iron ions, in which the acidic aqueous solution is bubbled with oxygen or ozone to oxidize and remove the divalent iron ions, and then the A method for treating divalent iron ions in an acidic aqueous solution, which comprises removing blown oxygen or ozone from the acidic aqueous solution using a semipermeable membrane.