JPH05125562A - Treatment of waste etchant of ferric chloride solution - Google Patents

Abstract

PURPOSE:To separate and recover heavy metals as much as possible and to regenerate a ferric chloride soln. by treating the mixture of the waste etchant from the production of electronic parts and the waste etchant of a shadow mask that is the waste ferric chloride soln. contg. the valuable heavy metals such as copper, chromium and nickel as the object. CONSTITUTION:A waste ferric chloride soln. is added with a specified amt. of iron material and controlled to pH<1.5 to deposit and remove copper in the first stage. The soln, is mixed with a specified amt. of iron material and controlled to pH 1 to 3 to deposit and remove chromium in the second stage. The soln. is mixed with a specified amt. of the iron powder produced from Hoeganes ore and controlled to pH<3.5 to deposit and remove nickel in the third stage. The soln. treated in the third stage is chlorinated to regenerate ferric chloride in the fourth stage. Consequently, the valuable heavy metals are separated and removed, and the ferric chloride soln. is regenerated at a low cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing and recovering heavy metals, particularly copper, chromium and nickel contained in a ferric chloride solution used for etching treatment from the waste solution, and to The present invention relates to a treatment method for regenerating an etching waste liquid as a ferric chloride liquid.

[0002]

BACKGROUND OF THE INVENTION In recent years, ferric chloride liquid (hereinafter simply referred to as "ferric chloride solution") used for etching treatments of printed wiring boards, shadow masks of color televisions, or IC lead frames. The etching treatment liquid is abbreviated as “salt iron liquid”), the amount of use of which is rapidly increasing year by year with the development of the electronic industry, etc., and a technology for treating a large amount of etching waste liquid generated with this, or It has become important to develop a technology for more actively recycling the treated liquid.

By the way, there are the following problems with the treatment of waste liquid generated by using ferric chloride liquid for etching treatment (hereinafter abbreviated as "salt iron waste liquid") and regeneration treatment. One is that due to the nature of the etching process, the substances (heavy metals) eluted from the material to be etched and contained in the waste liquid differ depending on the type of material to be etched. It is rare that it can be applied to the same type of heavy metal treatment method, and that the waste liquid contains multiple types of heavy metals instead of one type, for example, two types (for example, both copper and nickel) or more types. Removal of a single type of heavy metal (eg copper, chromium, nickel), if
Even if a method effective for recovery is used, appropriate removal is often impossible.

Furthermore, another important problem in the treatment of the salt iron waste liquid after the etching treatment is the increase of sludge if the precipitation of iron is not suppressed when the heavy metals contained therein are removed. There is also a point that the amount of ferric chloride solution to be regenerated decreases and effective treatment in an industrial sense cannot be realized.

Due to these various problems, various proposals have hitherto been made for treating salt iron waste liquid. As a conventional technique known as a method for removing heavy metals in waste liquid,
There is a long-known method of precipitating heavy metals in an etching waste liquid as hydroxides by an alkali neutralization method and then filtering and removing the heavy metals. It is excellent in that most of the heavy metals can be removed. On the other hand, however, even if there are multiple types of heavy metals in the precipitate, they cannot be separated and recovered, so valuable metals cannot be recovered, and the amount of alkali consumed is large and the amount of sludge is large.

Further, in the field of electronics industry, an ion exchange method is used for depositing and removing with a metallic iron or iron filter a waste liquid containing copper generated when a circuit pattern is exposed and etched on a substrate whose surface is covered with a photoresist. Processing technology called "(JP-A-47-29236 and JP-A-48-671)"
No. 37) is known, but this method can be applied only to copper etching waste liquid.

Further, a method of depositing heavy metals in the etching waste liquid on the cathode side by electrolysis is also proposed (for example, JP-A-51).
No. 508368). This is because it is not necessary to add a large amount of alkali as in the alkali neutralization method,
It is excellent in that it can collect valuable metals in the waste liquid, but on the other hand, the problem that toxic Cl ₂ gas is generated at the anode,
Since the target waste liquid is a salt iron waste liquid containing a large amount of iron ions, there is a disadvantage in that a metal that is less base than iron (for example, chromium) cannot be removed due to the ionization tendency. In order to solve this problem, an alkali such as caustic soda is added to the anode side to neutralize Cl ₂ and a heavy metal is deposited on the cathode side by a diaphragm electrolysis method (JP-A-51-23447 or JP-A-5353).
No. 34639) has also been proposed, but this method not only cannot remove metal elements that are less base than iron elements,
Another problem is that the regeneration efficiency of the etching waste liquid becomes low, and it has not been industrially implemented. Furthermore, as an improved technique of this diaphragm electrolysis method, a method of using an anion exchange membrane for the diaphragm is also proposed (for example, JP-A-61-140909).
No. 2) has been implemented, but there is a problem in terms of equipment costs, etc. as an implementation technology.

Furthermore, a method classified into a solvent extraction method for selectively extracting iron ions from a salt iron waste liquid (Japanese Patent Laid-open No. Sho 53-53)
No. 90423, JP-A-59-196723, JP-A-59-219471, etc.), this method is excellent in the removal efficiency of heavy metals such as Zn, Cr and Ni, but is equivalent to extraction. It requires a large amount of water and the concentration of the regenerating solution becomes thin, so it is not suitable as a method for regenerating salt iron solution, and it is not suitable for industrial implementation because it requires wastewater treatment equipment. Has the drawback that it requires additional recovery equipment.

As described above, each of the various etching waste liquid treatment techniques that have been proposed so far mainly for the purpose of regenerating the salt iron liquid has been pointed out to have many technical drawbacks and insufficient points. Not suitable for implementation.

In addition to the above-mentioned conventional techniques, a method of regenerating an etching waste liquid of a salt iron solution and recovering valuable heavy metals contained therein by precipitation, precipitation, adsorption, etc. In order to make a distinction, in the following description, a “metal iron reduction method” has been proposed, and has been attracting attention together with its characteristic of excellent removal efficiency.

The operation principle of the metallic iron reduction method is that a step of giving a reducing action by adding an iron source to an etching waste liquid of ferric chloride and a step of precipitating and precipitating iron and other heavy metals by this reduction are carried out. It is a combination. However, in the actual reaction, the reaction mechanism has not been clarified because precipitation, precipitation, coprecipitation, adsorption, etc. are complicatedly intertwined, and the etching waste liquid to which this technique is applied is not a chloride solution. Not only diiron and ferrous chloride reduced by it, but also heavy metal chlorides derived from the components of the material to be etched (for example, IC substrate and shadow mask) are included, and the ionization tendency and chemical nature of the specific heavy metal coexisting with iron. Due to differences in properties, common treatment cannot be applied to all heavy metals. Therefore, regarding the “metal iron reduction method”, various proposals have heretofore been made regarding the case where the etching waste liquid of the salt iron solution contains one kind of heavy metal or the case where it contains a plurality of kinds of heavy metals.

Of the conventionally proposed metal reduction methods,
In the waste iron salt solution containing one kind of heavy metal other than iron, the other heavy metal is chromium (Japanese Patent Publication No. 60-8979, Japanese Patent Publication No. 60-8980), and the other heavy metal is copper. (Japanese Patent Publication No. 60-34501) and another heavy metal is nickel (Japanese Patent Laid-Open No. 62-1914).
No. 28), and as a target for a salt iron waste liquid containing two or more kinds of heavy metals other than iron, JP-B-57-37533, JP-B-56-36127, and JP-B-61- 44814 and Japanese Patent Publication No. 63-66908. In addition, as a specification of two kinds of heavy metals, Japanese Patent Application Laid-Open No. 62-19255 relates to chromium and nickel.
No. 8 and JP-A-1-167235 concerning copper and nickel are proposed.

[0013]

By the way, salt iron waste liquids which are generated as waste liquids in the field of electronic component manufacturing for etching circuit patterns as described above and which are generated by the etching treatment of shadow masks in color televisions, are described below. Since it is not economically advantageous to provide equipment for individually regenerating salt iron liquid by treating each waste liquid generated in each field, it would be extremely industrially difficult if a technology for collectively treating salt iron waste liquid in various fields could be realized. Be beneficial.

However, the salt iron waste liquid eluted by the etching of the copper substrate and the salt iron waste liquid eluted by the etching of the metal material such as stainless steel and nickel alloy (42 alloy, amber) are collectively contained, for example, three kinds of copper, chromium and nickel. No proposal has been made so far for a method of separating and recovering a valuable salt metal from a salt iron waste liquid containing several hundred to tens of thousands ppm and further regenerating the salt iron liquid.

This is because the valuable metals such as copper, chromium and nickel contained in the salt iron waste liquid are removed from the salt iron waste liquid containing one kind of heavy metal by the metal reduction method in a simple combination. This is also because it is difficult to separate the individual heavy metals to be recovered, and the regenerating treatment of the salt iron solution cannot be effectively realized on an industrial scale.

For example, in the method of Japanese Patent Publication No. 60-8979, in which chromium is selectively removed, the ferric ion is added and the waste liquid having a pH of <1 is added with caustic soda to give a pH of 1.7.
It is difficult to separate and recover copper and chromium by applying the same method when the waste liquid contains copper at the same time as well as the complicated operation of adjusting to 4.5. These cannot be separated and recovered from the iron waste liquid. In addition, when iron material is present in the salt iron waste liquid, the pH is 1.5.
The method of Japanese Examined Patent Publication No. Sho 60-8980, in which iron oxide is generated by blowing oxygen until it reaches ~ 3.5, has the same problem.

In the method of Japanese Patent Publication No. 60-34501 for depositing and removing copper under the conditions of pH 2 to 4, and the method of Japanese Patent Laid-Open No. 62-191428 for removing nickel, the case where other heavy metals are contained at the same time is taken into consideration. I haven't.

As described above, the conventional methods for removing one kind of specific heavy metal from the salt iron waste liquid are common in that the impurities other than iron are removed by introducing the iron material and adjusting the pH. This method cannot be applied to the method of separately separating heavy metals from the waste liquid and recovering them from the waste liquid, and even if these individual methods are combined, the target multiple heavy metals cannot be individually recovered.

Further, from the standpoint of individually recovering a plurality of types of heavy metals, a method for regenerating a salt iron waste liquid containing chromium and nickel, for example, has been proposed.
In the method of No. 58, a two-step process of removing nickel after removing chromium at a pH of about 1 is performed, but the case where copper is further included is not taken into consideration, and the method includes chromium, nickel and copper. When applied to the treatment of salt iron waste liquid, it is not possible to separate and recover copper and chromium. On the other hand, in JP-A-1-167235 proposed as a method for separating and recovering a salt iron waste liquid containing copper and nickel, nickel is first removed by depositing and removing copper at pH 0-1 and then crushing the iron material. However, it is not appropriate to perform strong stirring with an industrial facility, and no consideration is given to the case of containing chromium together.

When regenerating a salt iron waste liquid containing a large number of heavy metals, it is difficult to regenerate the salt iron liquid while separating and recovering the heavy metals separately. Proposal for the purpose of, for example, Japanese Patent Publication No. 61-44
No. 814, Japanese Patent Publication No. 57-37533, Japanese Patent Publication No. 56-3
It can be understood from the proposals of the methods such as No. 6127 and Japanese Examined Patent Publication No. 63-66908 that a method of collectively removing these heavy metals as a filter while using the "metal iron reduction method" is adopted.

In view of the current state of the art as described above, the present inventor typically mixes a salt iron waste liquid generated from the electronic industry field and a salt iron waste liquid generated from the etching process of a shadow mask and collectively processes them. For the salt iron waste liquor containing copper, chromium and nickel, which is considered to be the case, we have conducted intensive studies with the objective of efficiently regenerating the salt iron liquor while separating and recovering valuable heavy metals as separately as possible.

The object of the present invention, which is provided from such a viewpoint, is to separate these heavy metals in high purity from an etching waste liquid of ferric chloride containing copper, chromium and nickel with high purity and with high yield. An object of the present invention is to provide a method capable of regenerating ferric chloride solution. Another object of the present invention is to separate and recover copper, chromium and nickel from the above-mentioned etching waste liquid so that a valuable metal can be reused, and to recycle the salt iron waste liquid into a salt iron liquid. It is to provide a method that can reduce the cost of doing.

[0023]

In order to achieve the above object, the inventor of the present invention has completed the present invention including a method for treating an etching waste liquid described in each of the claims.

In the method of the present invention, as the first step, ferric chloride present in the salt iron waste liquid is reduced to ferrous chloride, and copper ions in the liquid are reduced to precipitate as metallic copper. In order to do so, a sufficient amount of iron material necessary for the reaction is put into the etching waste liquid and heated and stirred, and a first step of precipitating metallic copper without solidifying chromium to perform solid-liquid separation, The iron material is added to the liquid that has undergone the process of (2) to precipitate the chromium in the liquid and the solid-liquid separation is performed, and the iron material is added to the liquid that has passed the second step to precipitate the nickel, and this is solid-liquid separated. It comprises a third step of separating and a step of chlorinating the liquid which has passed through the third step and regenerating it as ferric chloride liquid.

The third step in the above method can be carried out by adding the total amount of iron material to be added to the liquid at one time, but it is divided into two parts at the beginning of the total reaction time and about an intermediate time point or more. It is preferable to divide the mixture into two and add them. The ratio of dividing into two is not limited, but the iron material to be used can be used after being divided substantially evenly. When the addition time is divided into two, the addition timing of the iron material is preferably at the beginning and the middle of the entire treatment period of the third step as described above (for example, when 40 to 60% of the total treatment period has elapsed). To be selected.

The iron material added in the third step is preferably added after being brought into contact with the ferric chloride solution before being added to the solution. This activates the surface of the iron material to be charged, and the reaction progresses quickly and smoothly.

In the method of the present invention, the iron material used in the first step of reacting the added iron material with ferric chloride to convert it to ferrous chloride is not particularly limited as long as it is metallic iron. Iron pieces with a large surface area are generally economical. However, in order to suppress the excessive reaction, the iron powder has an excessively large surface area, which is not preferable. Therefore, iron pieces are preferably used in the first step, and the iron pieces are contained in the etching waste liquid in an amount necessary for reducing ferric chloride contained in the etching waste liquid to ferrous chloride. An equimolar amount is used relative to the total amount required to reduce copper ions to metallic copper. The liquid to which this iron piece is added is 50 to 90 ° C,
While stirring at a temperature of preferably 70 to 90 ° C., pH <
The reaction is carried out for 1 to 15 hours, preferably 1 to 5 hours while maintaining the pH at 1.5, preferably 0.5 to 1.2, to suppress the precipitation of nickel and chromium, and 99% of the copper ion in the liquid.
The above can be deposited (de-Cu reaction) and recovered according to the following formula.

Reduction: 2FeCl ₃ + Fe → 3FeCl ₂ Precipitation: Fe + Cu ²⁺ → Fe ²⁺ + Cu ↓ If the pH exceeds 1.5 in the above reaction, precipitation of chromium tends to occur, which is not preferable. In this first step, copper tends to interfere with the continuation of the reaction because it occurs so as to cover the surface of the added iron piece, so the copper precipitated on the iron piece surface is exposed to expose the iron surface. It is desirable to stir to such an extent that The above reaction can be carried out in an air atmosphere or a nitrogen gas atmosphere.

The copper-containing sludge collected by filtration in the first step has a high copper content and can be industrially reused as a valuable resource.

The second step of the method of the present invention is carried out by adding new iron material to the liquid and keeping the pH at 1 to 3. The iron material used in the second step is not particularly limited as long as it is metallic iron, and iron pieces having a large surface area are economical, but are not iron powder for the same reason as in the case of the first step. It is preferable to use iron pieces. The amount of iron material used depends on the amount of copper and chromium contained in the etching waste liquid,
Usually, about half or a little less than the amount of iron material used in the first step is sufficient. The liquid to which the iron pieces are added keeps the pH at 1 to 3, and the reaction is performed at a temperature of 50 to 90 ° C., preferably 70 to 90 ° C. with stirring for 1 to 15
The precipitation of chromium other than nickel (removing Cr reaction) can be performed for about 1 to 5 hours, and 95% or more of chromium in the liquid can be removed as sludge by filtration. If the pH of the solution is less than 1, the chromium removal rate tends to decrease, and if the pH exceeds 3, loss of the salt iron solution tends to increase, which is not preferable.

This reaction can be carried out in an air atmosphere or a nitrogen gas atmosphere.

In the third step of the method of the present invention, in addition to adding new iron material to the solution, ferric chloride solution is also added. As the iron material, it is preferable to use iron powder in order to avoid a large amount of waste and waste of performing crushing treatment. Especially, iron powder having porous, needle-like crystals and a large surface area is suitable. ing. According to the study of the present inventor, porous and needle-shaped iron powder (M
-100) is the most suitable. Electrolytic iron powder brings about the same effect as this, but it is very expensive and therefore costly and not industrially advantageous.

In the third step of the present invention, the iron material is preliminarily subjected to the second chloride treatment.
It can also be carried out in the following manner, in which it is added after being treated with an iron solution. That is, a predetermined amount of ferric chloride solution (or hydrochloric acid) used as a reaction accelerator and this (ferric chloride solution
(The iron material necessary for converting to iron) + (1 time mole of iron material relative to nickel) is mixed and reacted in a separate container in advance, and the reaction mixture is charged into a filtrate from which copper and chromium have been removed. .5
And the mixture is heated and stirred for 14 hours, for example, so that the liquid temperature becomes 70 ° C.
Nickel can be removed from the solution by filtering the solution reacted for 0 hours. The nickel sludge obtained has high nickel purity and can be sold at a valuable value. Agitation is important for removing nickel deposited on the surface of iron materials by collision between iron materials and exposing a new surface of iron material. In addition, the reaction atmosphere needs to block oxygen to prevent dissolution. It is important to use a reaction accelerator (ferric chloride solution or hydrochloric acid) in this nickel removal step. This is the first chloride
This is because the reaction is insufficient with a solution containing only iron, the nickel removal rate is low when a reaction accelerator is not used, and better activation of the surface of the iron material cannot be achieved.

As a charging method, a method of charging a slurry in which a reaction accelerator and an iron material are mixed in a separate container in advance to a reactor is preferably adopted.

With the ferric chloride solution alone, the removed nickel is redissolved. In particular, when the addition of the iron material is performed at least twice, this charging method is required in the subsequent post-charging. This two-division charging method is particularly preferable because the nickel removal rate is improved as compared with batch charging.

The filtrate obtained through the above steps becomes a ferric chloride liquid by chlorination and can be reused.

[0037]

EXAMPLES The present invention will now be described in more detail with reference to examples.

Example 1 (1) First step Ferric chloride solution (20.3%), ferrous chloride solution (17.5)
%), Copper (10850 ppm), chromium (606 pp)
m) and 1500 g of a salt iron waste liquor containing nickel (15317 ppm) and having a pH ≦ 0, 67 g of iron pieces were charged, and the mixture was heated and stirred at 70 ° C. for 3 hours, and then filtered with a quantitative filter paper 5B.

The contents of copper, chromium and nickel in the filtrate were (4 ppm), (582 ppm) and (1495), respectively.
2 ppm) and pH = 1.4.

In this step, 99% or more of copper could be recovered while suppressing the precipitation of chromium.

(2) Second Step Next, 1522 g of this filtrate was charged with 10 g of ferric chloride solution and 22 g of new iron pieces, and after heating and stirring at 70 ° C. for 3 hours,
It was filtered with quantitative filter paper 5B. The contents of copper, chromium, and nickel in the filtrate are (approximately 0), (34 ppm), (1
4380 ppm) and pH = 2.7.

In this step, most of the chromium in the waste liquid could be recovered.

(3) Third Step Next, to 727 g of this filtrate, 35 g of ferric chloride solution and M-100 iron powder (porous, needle-like crystal iron produced from Hegane's ore) in a separate container were added in advance. Powder, 150 mesh;
Charged with 13 g of Gadelius Co., Ltd.
In a nitrogen atmosphere, the mixture was heated and stirred at 70 ° C. for 14 hours, and after 14 hours, a mixture of 35 g of ferric chloride solution and 13 g of M-100 iron powder was charged again in another container. After reacting for 10 hours, the reaction was terminated, and the mixture was filtered through 5B quantitative filter paper. The contents of copper, chromium and nickel in the filtrate are (0ppm), (approximately 0ppm) and (48ppm), respectively.
And pH = 3.4.

In this step, most of the nickel in the waste liquid could be recovered.

(4) Fourth Step The solution obtained in the third step was chlorinated by a known method to regenerate the ferric chloride solution for etching treatment.

The composition of this liquid is shown in Table 1 below.

[0047]

[Table 1]

When the same operation was carried out in the third step without using the ferric chloride solution, the nickel content in the obtained filtrate was 7478 ppm.

Example 2 The iron powder used in the third step of Example 1 was KIP2.
The operation was carried out in the same manner as in Example 1 except that 25M (100> mesh: manufactured by Kawasaki Steel Co., Ltd.) was used. Regenerated chloride second
The composition of the iron solution is shown in Table 2 below.

[0050]

[Table 2]

In the third step, nickel in the filtrate obtained when the ferric chloride solution was not used was 9778 p.
It was pm.

Example 3 Ferric chloride (19.9%), ferrous chloride (18.1%)
%), Copper (12050 ppm), chromium (1930 pp)
m), salt iron waste liquid containing nickel (13400 ppm) 7
Into 00g, 31g of iron pieces were charged, and after reacting at 70 ° C for 3 hours,
A filtrate from which copper was removed by filtration was obtained, and then 10 g of iron pieces were charged and reacted at 70 ° C. for 3 hours and then filtered to obtain a filtrate from which chromium was further removed.

This filtrate (copper: 0 ppm, chromium: 21 p
pm, nickel; including 13520 ppm) 650 g
Then, 10 g of 35% hydrochloric acid and 11 g of iron powder (M-100) were charged, and the mixture was heated and stirred at 70 ° C. After 24 hours, 10 g of the above 35% hydrochloric acid and iron powder (M-100) 11 in a separate container in advance.
The mixture obtained by mixing g was further charged and the reaction was continued for 24 hours.

After completion of the reaction, nickel in the filtrate obtained by filtering with quantitative filter paper 5B was 64 ppm.

Example 4 The first step and the second step were carried out under the same conditions as in Example 1 to obtain a filtrate from which copper and chromium were removed.

This filtrate (copper: 0 ppm, chromium: 24 p
pm, nickel; including 14550ppm) 650g
70g of 44% ferric chloride solution and iron powder (M-100) 2
4 g was charged and the mixture was heated with stirring at 70 ° C. for 24 hours.

After completion of the reaction, filtration was carried out with a quantitative filter paper 5B, and the amount of nickel in the obtained filtrate was 1164 ppm.

[0058]

According to the method of the present invention, these valuable heavy metals can be separated and recovered from the etching waste liquid of ferric chloride containing copper, chromium and nickel so as to be reused. There is an effect that the iron liquid can be regenerated at low cost.

Further, according to the method of the present invention, since the etching waste liquids used in various fields can be collectively processed, the processing efficiency of the salt iron waste liquid can be improved and the equipment can be shared, and the individual etching waste liquids can be realized. It is extremely useful in realizing industrial implementation as compared with the case of providing equipment for treating

Claims (5)

[Claims] 1. A ferric chloride solution containing ferric chloride in an etching waste liquid containing ferric chloride containing copper, nickel and chromium.
A first step of adding a sufficient amount of iron material necessary for reducing to iron and reducing copper ions to metallic copper, heating and stirring to precipitate copper, and solid-liquid separating the precipitated copper, The iron material is added to the liquid that has passed through the steps, and the mixture is heated and stirred to precipitate chromium in the liquid, and the second step of solid-liquid separating the precipitate, and the iron material is added to the liquid that has passed the second step, and the second chloride Iron solution or hydrochloric acid is added, and the mixture is heated and stirred to precipitate nickel in the solution, and the third step of solid-liquid separation of the precipitate, and the solution obtained after the third step is chlorinated to form ferric chloride solution. A method for treating an etching waste liquid of ferric chloride liquid, comprising: a fourth step of regenerating. 2. The method according to claim 1, wherein the amount of the iron material added to the liquid in the first step is the amount of iron necessary for reducing ferric chloride contained in the etching waste liquid to ferrous chloride, and the etching waste liquid. A method for treating an etching waste liquid of a ferric chloride solution, which is approximately equimolar to the total amount of iron required to reduce the copper ions contained in to copper metal. 3. An iron material preliminarily surface-treated with ferric chloride solution or hydrochloric acid is added to the solution obtained in the second step instead of the third step, and the mixture is heated and stirred to precipitate nickel in the solution. Let
A method for treating an etching waste liquid of ferric chloride liquid, which comprises performing a third step of solid-liquid separating the precipitate. 4. The iron material to be added to the liquid in the third step according to any one of claims 1 to 3, wherein the iron material is added in two steps, an initial stage and an intermediate stage of the entire treatment period of the third step. A method for treating an etching waste liquid of ferric chloride liquid characterized. 5. A method for treating an etching waste liquid of ferric chloride solution, which comprises performing the third step of any one of claims 1 to 4 under an N ₂ gas atmosphere.