JPS6360833B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] This invention relates to a method for regenerating an etching solution containing iron chloride as a main component. [Prior art] Ferric chloride (FeCl ₃ ) is used instead of conventional nitric-fluoric acid as an etching solution for materials to be treated such as iron alloys and alloy steels, and HCl and/or
Etching treatment with excellent descaling properties and surface smoothness has been carried out by adding H ₂ SO ₄ alone or a mixed acid, but as the amount of etching processing of the material to be treated increases, the etching solution deteriorates and FeCl ₃ decreases, FeCl ₂ increases, and the descalability and surface smoothness of the treated material deteriorate. For this reason, conventional methods for regenerating the etching treatment solution include injecting ozone and Cl ₂ gas, adding oxidizing agents such as hydrogen peroxide and bleaching powder, and electrolytic oxidation using a diaphragm. The method of blowing in , ozone, or Cl ₂ gas requires a large amount of equipment costs, and there are environmental problems and major problems in handling. Furthermore, the above-mentioned method of adding an oxidizing agent increases costs, and in the case of hydrogen peroxide, a large amount of water is generated, and in the case of bleached powder, Ca ions may remain as impurities in the regenerating liquid. Furthermore, the electrolytic oxidation method requires high equipment costs, and there is a risk of explosion if a large amount of hydrogen is generated. [Object of the invention] The object of the present invention is to eliminate the drawbacks of the above conventional method,
It is an object of the present invention to provide a method for regenerating an etching solution that has high regeneration efficiency using an inexpensive device. [Structure of the Invention] The present invention relates to a method of treating an etching solution with an oxidizing gas containing _O2 . Generally, the etching solution is regenerated according to the following reaction formula (1). 4Fe ²⁺ +4H ⁺ +O ₂ →4Fe ³⁺ +2H ₂ O ...(1) As a result of various studies on cheap, simple, and efficient methods for making the reaction equation (1) proceed from the left side to the right side, the inventor came up with the first method. Hydrochloric acid is added as H ⁺ to the etching solution containing iron ions. In order to supply O ₂ to this hydrochloric acid-containing etching solution, an oxidizing gas containing O ₂ is fed into a regeneration tank filled with an acid-resistant and heat-resistant filler made of glassy Raschig rings or Lessing rings. However, it has been found that by promoting the contact reaction through the mixed treatment liquid and heating the mixed treatment liquid to a specific temperature, the reaction from the left side to the right side of the formula (1) can be promoted. The present invention is based on the above knowledge, and the etching solution to be regenerated is stored together with added hydrochloric acid in a regeneration tank filled with a filler for promoting gas-liquid contact made of glassy Raschig ring or Lessing ring, and the etching solution is mixed with hydrochloric acid. It is characterized by a method of regeneration by blowing an oxidizing gas containing O ₂ into the liquid and stirring it under heating at 60°C to 95°C. The method of the invention is further explained by means of exemplary figures. In FIG. 1, a regeneration tank 1 is filled with a vitreous filler 2 for promoting gas-liquid contact, and contains an etching solution. Hydrochloric acid added to the etching solution is supplied from a hydrochloric acid supply pipe 4. An O2 _- containing oxidizing gas blowing pipe 5 for blowing air, oxygen, etc. into the mixed treatment liquid 3 in the regeneration tank 1 is inserted to blow the O2 _- containing oxidizing gas into the mixed treatment liquid 3. The mixed treatment liquid 3 is heated to 60° C. to 95° C. by the inserted heater 6, and the liquid 3 is stirred and regenerated by the blown gas. The regenerating liquid is sprayed onto the upper part of the mixed processing liquid 3 in the regenerating tank 1 through a circulation pipe 8 from the regenerating liquid outlet 7 in the lower part of the regenerating tank 1, thereby being circulated and regenerated. In this invention, the material of the filler 2 to be filled in the regeneration tank 1 is preferably glassy Raschig ring or Lessing ring, which does not cause any chemical reaction with the mixed treatment liquid, and the size is 3 mm to 100 mm. can. Furthermore, in the present invention, the reason why hydrochloric acid is added to the etching treatment solution is to supply H ⁺ in reaction formula (1) as described above, and therefore the amount of hydrochloric acid added is equal to or more than the equivalent amount to the amount of Fe ²⁺ . The amount of hydrochloric acid that supplies H ⁺ is required. The oxidizing gas containing _O2 to be blown into the processing liquid 3 may be oxygen, but air is most preferable in terms of cost.The blowing pressure is 0.5Kg/ ^cm2 to 5Kg/ ^cm2 , and the blowing flow rate is O2. _The amount is preferably 5 l/min to 20 l/min. Furthermore, as a means for heating the mixed treatment liquid 3 to 60°C to 95°C, the mixed treatment liquid may be heated directly or indirectly with a heater as described above, or the O ₂ -containing oxidizing gas may be preheated and blown. It can be crowded,
Alternatively, the regeneration liquid may be heated during circulation. If the heating temperature is 60°C or lower, the reaction rate from Fe ²⁺ to Fe ³⁺ will be slow, and if it exceeds 95°C, the treatment liquid will evaporate, which is not preferable. [Example] Next, Figure 2 shows the treatment solution (composition: FeCl ₃ 5wt%, FeCl 2 11.5wt%, FeCl ₂ 11.5wt%,
Oxidation of the treated liquid when air is blown as an oxidizing gas containing O ₂ into HCl 1.5wt%, H ₂ SO ₄ 5wt% at a pressure of 1.0Kg/mm ² and a flow rate of 15l/min, and the liquid circulation is set to 1lmin. The relationship between time and the amount of FeCl ₂ in the treatment solution changed to FeCl ₃ (regeneration amount) is shown. In the figure, curve 5 represents the method of the present invention, and curves 1, 2, 3, and 4 do not belong to the present invention.

〔Effect of the invention〕

A 5 mm vitreous Raschig ring 2 is made by applying the treatment solution 2 which was used to etch the Fe-42Ni alloy for 20 hours before regeneration.
After adding 150ml of 12NHCl to the treated solution in this tank, a 5mm gas blowing pipe was inserted into the regeneration tank, and air heated to 80°C was pumped through the tank at a pressure of 1.0Kg. /mm ² , flow rate 15/min
By the method of the present invention, the regenerating liquid is sprayed from above through a circulation pipe after treatment in the tank, and is circulated at a rate of 1/min. A comparison of the treated solution after regeneration with that before regeneration is as shown in the table below, which shows that the method of the present invention requires almost no equipment cost and has extremely excellent regeneration efficiency.

【table】 [Brief explanation of drawings]

Fig. 1 is an explanatory diagram of an example of an apparatus for carrying out the method of the present invention, and Fig. 2 shows the oxidation time of the processing liquid and FeCl ₂ in the processing liquid when air is blown into the processing liquid and the liquid is circulated.
Fig. 3 is a diagram showing the relationship between the amount of regeneration and the amount of FeCl 3 changed into FeCl ₃ . 1: Regeneration tank, 2: Filler, 3: Mixed treatment liquid,
4: Hydrochloric acid supply pipe, 5: Oxidizing gas blowing pipe, 6: Heater, 7: Regeneration liquid outlet, 8: Circulation pipe.

Claims (1)

[Claims] 1. The etching solution to be regenerated is stored together with added hydrochloric acid in a regeneration tank filled with a filler for promoting gas-liquid contact consisting of vitreous Raschig rings or Lessing rings, and an oxidizing gas containing O ₂ is added to the mixed solution. A method for regenerating an etching treatment solution, which comprises blowing the etching solution into the solution and regenerating it by stirring in a heated state of 60°C to 95°C.