JP3018020B2 - Purification method of iron chloride waste liquid containing chromium, etc. - Google Patents

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 heavy metals such as chromium from chromium or an iron chloride-based waste liquid (for example, an etching solution) containing copper / nickel in accordance with the chromium.

[0002]

2. Description of the Related Art Conventionally, as described in JP-B-61-44814, massive metallic iron is mixed into a strongly acidic ferric chloride waste liquid containing heavy metals other than iron, and the heated state is maintained and stirred. There has been proposed a method for removing heavy metals from iron chloride waste liquid, which removes heavy metals precipitated by the removal.

[0003]

However, in the method according to the above-mentioned prior art, since massive metallic iron is used as a neutralizing material, the neutralization and separation reactivity is low in the case of a non-strongly acidic iron chloride waste liquid. There is a problem that it is bad, and furthermore, after putting in a lump of metallic iron, it is difficult to design a stirrer,
Even if possible, there was a problem that a great deal of cost was required for the stirring device. When the above method is applied to an iron chloride-based waste liquid containing nickel, there has been a problem that nickel separation is poor. Moreover, when chromium is contained in the conventionally known iron chloride acid waste liquid, or when copper or nickel is further contained, there is no means for efficiently removing chromium without contaminating the iron chloride. Carry out iron,
Chromium is converted to hydroxide for disposal. Therefore,
The fact was that the effective ingredients such as chlorine and chromium could not be used. The present invention has been made in view of such circumstances, and the entire apparatus can be manufactured relatively inexpensively, and chromium separation,
It is a further object of the present invention to provide a method for purifying an iron chloride waste liquid containing chromium or the like, which enables highly efficient separation of copper and nickel.

[0004]

According to the present invention, there is provided a semiconductor device comprising:
In the method for purifying an iron chloride waste liquid containing chromium or the like described above, iron powder is mixed into an iron chloride waste liquid containing chromium to adjust the pH to 2.3.
And chromium is precipitated by controlling the reaction temperature to 40 ° C. or more and the iron ion concentration to 220 g / l or less. Further, the method for purifying an iron chloride waste liquid containing chromium and the like according to claim 2 is a step of mixing iron powder into an iron chloride waste liquid containing copper, nickel and chromium to precipitate copper under predetermined conditions, Mixing iron powder into the waste liquid from which copper has been removed in the above step, and precipitating nickel by setting the pH to 2 or less; and pH of the waste liquid from which the nickel has been removed.
Is set to 2.3 to 5, the reaction temperature is controlled to 40 ° C. or more, and the iron ion concentration is controlled to 140 g / l or less to precipitate and separate chromium in the waste liquid.

[0005]

In the method for purifying an iron chloride waste liquid containing chromium and the like according to the first aspect, the pH of the waste liquid is set to 2.3 to 5, the iron ion concentration is set to 220 g / l or less, and the reaction temperature is set to 40 g / l.
By setting the temperature to not less than ° C., the following reaction proceeded, the amount of iron deposits was suppressed, and the precipitation of chromium was performed efficiently. CrCl ₃ (L) + 3H ₂ O (L) → Cr (OH) ₃ (S) + 3HCl (L) (1) 3HCl (L) + 3 / 2Fe (S) → 3 / 2FeCl ₂ (L) + 3 / 2H ₂ ( G) (2) In the method for purifying an iron chloride waste liquid containing chromium or the like according to claim 2, the component of the iron chloride waste liquid such as an etching waste liquid is mainly ferric chloride. During the etching process, metals such as copper, nickel and chromium are dissolved to form ions. Therefore, iron powder (for example, having a particle diameter of 1 m) is added to such an iron chloride waste liquid containing copper, nickel, and chromium.
m, spherical converter refined iron powder containing 90% or more metallic iron)
Is mixed under a specific condition (for example, the oxidation-reduction potential ORP
At −100 to −300 mV, PH 2 or less, temperature 40 ° C. or more, iron ion concentration 260 g / l or less), and copper is precipitated and removed from the acid waste liquid. When recovering nickel from the residual liquid, iron powder is added at a pH of 2 or less, and nickel is precipitated from the difference in ionization tendency at an ORP-450 to -520 mV and an iron ion concentration of 260 g / l. And remove from the acid waste liquor. As described above, chromium is removed from the acid waste liquid from which copper and nickel have been removed. This chromium is recovered by the methods (1) and (2).
Chromium chloride is removed from the acid waste solution by hydrolysis of chromium chloride by PH control according to the reaction formula shown below.

[0006]

EXAMPLES Next, examples embodying a method for purifying an iron chloride waste liquid containing chromium and the like according to the present invention will be described to provide an understanding of the present invention. Here, FIG. 1 is a schematic explanatory view in the case where the method for purifying an iron chloride waste liquid containing copper, nickel and chromium according to one embodiment of the present invention is applied to a waste liquid used for etching stainless steel. As shown in FIG. 1, first, an appropriate amount of copper, nickel,
An etching solution, which is an example of an iron chloride waste solution containing chromium, is put therein, heated to 40 ° C. or more, and further reduced to a pH of 2 or less,
A spherical converter refined iron powder having a particle size of 1 mm or less is charged from the OGP tank 12. As a result, the concentration of iron ions in the waste liquid becomes 26
0 g / l or less, and an oxidation-reduction potential (ORP) of -10
Adjust so as to be 0 to -300 mV. Thereby, copper is precipitated from the following reaction. 2FeCl ₃ + Fe → 3FeCl ₂ (3) CuCl ₂ + Fe → FeCl ₂ + Cu (4) Since copper is precipitated by the above processing, the overflow is collected in the cone tank 13 and flowed to the liquid cyclone 15 by the pump 14, and the particle size is relatively large. Large iron powder is removed and returned to the copper removal tank 11 again.
Apply to 6. As a result, the deposited copper is separated, and the separated liquid is temporarily stored in the cushion tank 17 and then put into the nickel removal tank 18.

In the denickelization tank 18, O
The purified iron powder collected from the converter from the GP tank 19 and, if necessary, ferric chloride are added to the ORP (−450 to −450).
520 mV), PH (2 or less) and iron ion concentration (26
0 g / l or less) to maintain the temperature at 40 ° C. or more,
The following reaction occurs to produce Ni. NiCl ₂ + Fe → FeCl ₂ + Ni (5) In this case, a passive film is formed on the surface of the iron that has been charged, and the progress of the reaction is hindered. Therefore, by adding a small amount of ferric chloride, the formation of a passive film is prevented, and a smooth reaction is promoted. The overflow solution from the denickelization tank 18 is put into a cone tank 20, and iron powder having a large particle size is drawn up by a pump 21 and removed by a liquid cyclone 22. Here, since the deposited nickel adheres to the periphery of the iron powder, it is collected by the liquid cyclone 22 and is again put into the nickel removal tank 18. Therefore, after operating for an appropriate period, the stirring device is stopped and the sediment is removed. From the nickel.

The acid waste liquid from which the nickel content has been removed is once introduced into a dilution tank 23, and diluted with water to adjust the iron ion concentration to about 120 g / l. Thereafter, the diluent in the diluting water tank 23 is pumped up by the pump 24 and put into the dechroming tank 25. The separation of chromium from the iron chloride solution is achieved by hydrolysis of chromium chloride under pH control, and the reaction formula is as described in the above (1) and (2). The complete pH of the reaction varies depending on the Fe ²⁺ concentration of the mother liquor component. The tendency is that the higher the Fe ²⁺ concentration, the lower the PH range. This phenomenon shows that Fe ²⁺ is more stable than Cr ^{3+ at the} same PH.
However, as the concentration increases, the pH shifts to a PH region where the hydrolysis start PH is lower. Therefore, the hydrolysis termination PH of Cr ³⁺ , which is more unstable than Fe ²⁺ , is completed in the low PH region. This is shown in Table 1.

[0009]

[Table 1]

Therefore, an appropriate amount of iron powder is supplied to the dechroming tank 25 from the OGP tank 26, and hydrochloric acid or the like for adjusting pH is supplied. Then, while watching the provided PH meter, the pH is adjusted to 3.5 to 5.0 (preferably 3.8 to 4.0), and the ORP is set to -450 to 52.
0 mV, iron ion concentration 260 g / l or less, temperature 40 ° C
When the reaction time is 60 minutes or more after adjusting as described above, the reaction of the above (1) is promoted, chromium hydroxide precipitates, and the solution is purified. Thereafter, the liquid in the dechroming tank 25 is put into a cone tank 27, pumped up by a pump 28 and passed through a liquid cyclone 29 to separate unreacted iron powder, and a centrifugal dehydrator 30
The resulting hydroxide is separated and the purified liquid is recovered. Table 2 shows the liquids treated according to the above examples.

[0011]

[Table 2]

In the chromium removing step, an Fe ²⁺ concentration of 120
Since the optimum concentration is about 140 g / l, it cannot be recycled for etching as it is. However, it is almost equal to the iron concentration of the pickling waste liquid in the steel industry. Therefore, by using it as a high-grade raw material for a roasting furnace for treating pickling waste liquid,
Fe ²⁺ is regenerated into high-purity iron oxide and Cl ⁻ is regenerated into hydrochloric acid for pickling, so that resources are effectively used.

Next, Fe ²⁺ (69.2 g / l) and Fe ³⁺ (128.7 g /
An example in which another embodiment of the present invention is applied to an iron chloride waste liquid containing 1) and Cr ⁺³ (2.26 g / l) will be described.
First, 4000 ml of these waste liquids are placed in a container and diluted with tap water to make 4312 ml. And metal iron 242
g of OGP containing 257 g, and stirred for 30 minutes. As a result, Fe ²⁺ contained 240.5 g / l and Fe ³⁺ contained 1.0.5 g / l.
It was confirmed that 02 g / l and Cr ³⁺ were 2.30 g / l. This solution was sent to a high-speed reaction tank (200 ml was initially charged as a bed) by a metering pump, and OGP70
0g, adjust ORP to 500mV,
Dilute hydrochloric acid obtained by diluting 500 ml of 35% hydrochloric acid with 131 ml of tap water was injected with the pH adjustment solution to cause a reaction. Table 3 shows the results.

[0014]

[Table 3]

As shown in Table 3, PH for the first hour
Was 1.75 and Cr ³⁺ was 2.151 g / l, but after 3 hours passed after changing PH to 2.00, C
The r ³⁺ was reduced to 1.555 / l, and after the pH was adjusted to 2.4 and 1 hour passed, the Cr ³⁺ was reduced to 0.031 g / l.
And the amount of chromium ions was significantly reduced.

As is clear from the above description, the method for purifying an iron chloride waste liquid containing chromium or the like according to claim 1 or 2 can manufacture the entire apparatus at a relatively low cost, and Thus, it is possible to provide a method for purifying an iron chloride-based waste liquid containing chromium or the like, which enables high-efficiency removal and copper / nickel removal in accordance therewith.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of a method for purifying an iron chloride waste liquid containing chromium and the like according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Waste liquid tank 11 Copper removal tank 12 OGP tank 13 Cone tank 14 Pump 15 Liquid cyclone 16 Centrifuge 17 Cushion tank 18 Nickel removal tank 19 OGP tank 20 Cone tank 21 Pump 22 Liquid cyclone 23 Dilution tank 24 Pump 25 Dechrome tank 26 OGP tank 27 Cone tank 28 Pump 29 Liquid cyclone 30 Centrifugal dehydrator

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hironori Matsuo 1-1, Hibata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka Nippon Steel Corporation Yawata Works (56) References JP-A-53-23898 (JP, A) JP-A-5-125563 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C02F 1/62 C01G 49/10 C23F 1/46

Claims (2)

(57) [Claims] 1. An iron powder is mixed with an iron chloride waste liquid containing chromium to adjust the pH to 2.3 to 5, and the reaction temperature to 40.
A method for purifying an iron chloride-based waste liquid containing chromium or the like, characterized in that chromium is precipitated by controlling the iron ion concentration to 220 g / l or lower at a temperature of not less than 220 ° C. 2. A step of mixing iron powder into an iron chloride waste liquid containing copper, nickel and chromium to precipitate copper under predetermined conditions, and mixing iron powder into the waste liquid from which copper has been removed in said step. Precipitating nickel with a pH of 2 or less;
The pH of the waste liquid from which the nickel has been removed is set to 2.3 to 5,
A method for purifying an iron chloride waste liquid containing chromium or the like, characterized in that chromium in the waste liquid is precipitated and separated by controlling the reaction temperature to 40 ° C. or more and the iron ion concentration to 140 g / l or less.