JPS6352117B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for regenerating iron liquid that can efficiently regenerate ferric chloride liquid containing heavy metals. [Prior art and its problems] Ferric chloride solution is used as an etching solution for corroding metal plates made of steel, copper, stainless steel, nickel alloy, etc. When this etching solution is used repeatedly, dissolved heavy metals (nickel, chromium, copper, manganese, iron, etc.) accumulate in the solution, and trivalent iron ions are reduced to divalent ones, resulting in divalent chloride. The resulting liquid becomes an iron solution, which reduces the etching ability and must be disposed of as waste, which poses a pollution problem. Therefore, it has been desired to regenerate and reuse such etching waste liquid. Conventionally, as a method for regenerating iron liquid, a so-called one-stage treatment method has been used, in which used iron liquid is sequentially subjected to heat treatment, reaction treatment, discharge treatment, solid-liquid separation treatment, and chlorine gas (Cl ₂ ) injection treatment. There is. However, in the case of the one-stage treatment method, in the case of Ni-containing spent iron solution, 1000 to 500 ppm of Ni remains after treatment. This is thought to be because a large amount of precipitates such as Fe(OH) ₂ are generated as the reaction progresses, which obstructs Ni removal. A large amount of such Ni-containing spent iron solution is generated in factories that etch lead frames for integrated circuits, etc., but since it is difficult to remove the Ni content, it is used after being neutralized. Such neutralization treatment poses problems in terms of pollution and high processing costs. Furthermore,
In addition to Ni, there is also the problem of expensive metals such as Cr and Cu being dumped. In recent years, so-called shadow masks have also been introduced.
Amber wood containing Ni is often used,
In this field as well, the amount of used iron solution containing Ni is increasing, and there is a strong need for the development of an efficient iron solution recycling method. The present invention has been made in view of these points, and provides an iron liquid regeneration method that can efficiently and inexpensively regenerate used iron liquid containing heavy metals such as Ni. It is. [Means for Solving the Problems] The present invention involves heating a strongly acidic ferric chloride solution containing iron and one or more types of heavy metals other than iron for the first time,
After stirring and mixing this with lumpy metallic iron to cause a reaction, this is subjected to solid-liquid separation treatment, and then heated a second time and then stirred and mixed with lumpy metallic iron to react. This iron liquid regeneration method is characterized by subjecting the iron liquid to solid-liquid separation treatment, and then injecting chlorine gas. [Function] According to the method for regenerating iron liquid according to the present invention, the reaction time after the first heating is shortened, the sludge is removed by filtration, and then the remaining liquid is subjected to the second heating and Perform the reaction. After that, the liquid after the reaction is discharged, and after solid-liquid separation, chlorine is injected into it.
As a result, the generation of precipitates such as Fe(OH) ₂ can be suppressed and heavy metals can be removed extremely smoothly. [Examples] Examples of the present invention will be described in detail below. First, a predetermined waste solution consisting of a strongly acidic ferric chloride solution containing iron and one or more heavy metals other than iron is
Heat for the second time and perform the following treatment. The heating temperature is
The range is preferably 60 to 120°C, more preferably 90°C.
~100℃ range. The reason is that below 60°C the reaction is too slow, and above 120°C the reaction proceeds explosively and becomes difficult to control. Next, the heated waste liquid is put into a predetermined reaction container, and stirred and mixed together with lumpy metal iron to cause a heavy metal removal reaction. The waste liquid is kept at a constant appropriate temperature due to the heat of reaction with the lumpy metal iron. This reaction removes heavy metals such as Ni from the waste liquid. Next, the waste liquid after the reaction is filtered to remove sludge and separate solid and liquid. The filtrate thus subjected to the first stage treatment is subjected to the following two stage treatment. In addition, the reaction time in the one-stage treatment is preferably set to be about 60 minutes, although it is preferable that the reaction time be short. Next, a two-stage process is performed as follows. That is,
After heating the filtrate obtained by solid-liquid separation at the same temperature as the first time, it is placed in a predetermined reactor and stirred and mixed with lumpy metallic iron to cause a heavy metal removal reaction. The waste liquid after the reaction is filtered to separate solid and liquid, and a predetermined amount of chlorine (Cl ₂ ) is injected into the filtrate. In this way, the iron solution is regenerated. In addition,
The second reaction time is set to, for example, 30 minutes. Since the iron solution is regenerated in this way, the state of removal of heavy metals, for example, when examining Ni, decreases along the curve of the one-stage treatment shown by the characteristic line in FIG. If the conventional method relies on only one-stage treatment, Ni will decrease along this characteristic line, and from around the point where the pH exceeds 3, a large amount of Fe(OH) ₂ will be generated.
The rate of decrease in Ni decreases rapidly. However, in the example of the present invention, the two-stage treatment is performed approximately 60 minutes after the reaction, so that the reduction of Ni progresses according to the characteristic line in FIG. 2. That is, in the case of one-stage treatment, it decreases to about 5000 ppm in 60 minutes of reaction, and in two-stage treatment, it decreases from this 5000 ppm to 50 ppm or less. In addition,
When the first stage treatment is performed for about 120 minutes to reduce the Ni content to about 1000 ppm and then the second stage treatment is performed, the Ni content decreases from 1000 ppm to 50 ppm or less along the characteristic line in FIG. However, in this case, the time for one-stage processing is longer than the above (approximately 60 minutes), so
The amount of Fe(OH) ₂ generated is large, and when considering the reduction of heavy metals other than Ni, it is difficult to say that it is absolutely preferable. Incidentally, it has been experimentally confirmed that the reduction of other heavy metals such as Ni is as shown in the table below when the reaction time for the one-stage treatment is approximately 60 minutes and the reaction time for the two-stage treatment is approximately 30 minutes. .

[Table] As described above, in the example, heavy metals such as Ni can be efficiently reduced, and since no neutralization treatment or the like is performed, the processing cost can be reduced. [Effects of the Invention] As explained above, according to the iron liquid regeneration method according to the present invention, heavy metals including Ni (excluding iron)
It is possible to efficiently and inexpensively regenerate used iron liquid containing The present invention is extremely superior in that the concentration is as low as that of fresh liquid, resource saving and useful heavy metals can be recovered.

[Brief explanation of the drawing]

FIGS. 1 to 3 are characteristic diagrams showing the relationship between the Ni concentration and the pH of the iron solution and time.

Claims (1)

[Claims] 1. A strongly acidic ferric chloride solution containing iron and at least one type of heavy metal other than iron is heated for the first time, and after stirring and mixing this with lumpy metallic iron, it is reacted with a solid-liquid. Separation treatment is applied, and then, after a second heating, stirring and mixing with lump metal iron causes a reaction, solid-liquid separation treatment is applied to this, and after that, chlorine gas is injected. Characteristic iron liquid regeneration method.