JPS59226187A - Method and device for cleaning of copper electrolyte - Google Patents

Abstract

PURPOSE:To perform inexpensively and easily washing of an electrolyte and to recover nickel sulfate with high purity by adding a Ca salt to the copper electrolyte dividedly in two stages to neutralize the electrolyte then obtd. a refined aq. nickel sulfate soln. by a specific org. solvent extraction method while adjusting pH. CONSTITUTION:A Ca salt is added to a soln. to be cleaned to adjust the pH of the soln. to 1.5-2.5 in the stage of cleaning an electrolyte in a copper electrolytic refining stage. The precipitate formed in the primary neutralization stage is subjected to a solid-liquid sepn. and about the whole of Sb and Bi and about half of As are removed. The Ca salt is further added to the filtrate thereof to adjust the pH to 6.5-7.5. Cu, Fe and Zn are settled in this secondary neutralization stage and are subjected to a solid-liquid sepn. While the filtrate is adjusted to 2-3pH, Ca is removed by the liquid-liquid extraction involving contact thereof with a kerosene soln. of di-2-ethyl hexyl phosphoric acid or 2-ethyl hexyl phosphoric acid mono-2-ethyl hexyl ester, by which the refined aq. nickel sulfate soln. is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for purifying an electrolyte in a copper electrolytic refining process, and more particularly to a method and apparatus for removing impurities such as Sb, Bj, and As from an electrolyte.

Sb, an impurity in the electrolyte in the copper electrolytic refining process
, Bi, As, etc. from the anode to the VC in the electrolyte.
It is dissolved or suspended in the electrolyte as anode slime.

When the suspended slime adheres to the surface of the cand, it forms a protruding electrodeposition from the point of attachment, causing a short circuit between the electrodes, or the slime and electrolyte are mixed into the electrodeposited copper, causing the cathode This may lead to (or even cause) a decline in the quality of the product.On the other hand,
As the concentration of impurities such as Sb, Bi, and As dissolved in the electrolyte increases, they precipitate on the cathode, causing Sb,
Floating slime of Bi oxide, arsenate, etc. is formed, and the above-mentioned adverse effects occur.

@In order to remove impurities such as 8b, Bi, and As in the electrolyte, a widely practiced method is to electrolytically win CU in the electrolyte using an insoluble anode, during so-called step-out electrolysis. There is a method to extract the copper-free slime that is produced from the system. However, the slime has a high Cu grade and it is economically disadvantageous to discard it as is.
It is normal that Sb, Bi,
Impurities such as As, other than being discarded as slag or exhaust gas in the smelting process, enter the anode again and return to the electrolytic process, and impurities are not completely removed from the thread.

For this reason, in order to completely remove impurities from the system, a method has been proposed in which cations that cause the precipitation of poorly soluble sulfates are added to the electrolytic solution to coprecipitate impurities (Japanese Patent Application Laid-Open No. Publication No. 52-54615: c, a ion, %
-119327 Publication 5BaeSr, Pi) ion)
. However, in these methods, the electrolyte after removing the precipitate is
It has the disadvantage that it becomes saturated with a ions and the like and forms a poorly soluble precipitate in the conduit of the circulation system, so it cannot be put to practical use.

As a result of studying the above-mentioned method for removing residual Ca ions, the present inventors found that the application of organic solvent extraction method was promising, and found that the organic solvent extraction method was optimized along with new processing conditions for the previous neutralization step. By confirming the implementation conditions, the present invention was completed.

That is, the method and apparatus of the present invention are as follows.

(1) In the electrolytic solution purification process in the copper electrolysis 8M process, (b) A calcium salt is further added to the solution obtained by solid-liquid separation of the precipitate generated in the primary neutralization step to adjust the pH of the solution.
A second neutralization step in which the precipitate produced in the second neutralization step is separated into solid and liquid, and the solution obtained is mixed with diethyl while adjusting the pl (2 to 3). A liquid-liquid extraction step of contacting hexyl phosphoric acid or mono-2-ethylhexyl 2-ethylhexylphosphonic acid ester with a kerosene solution to remove metal ions other than nickel ions from the solution to obtain purified nickel sulfate. A copper electrolyte purification method characterized by:

(2) A liquid-liquid mixing tank, a circulation pump that circulates the mixed liquid extracted from the mixing tank, a phase separation box that separates the phases of the mixed liquid sent from the circulation pump, and a phase separation of the phase separation box. At the completion position, a through hole is provided through which only the inferior fluid can be extracted, and a pH electrode installation box is provided to receive the supernatant liquid transferred from the through hole, and the phase separation box and the pH electrode installation box are provided. A copper electrolyte purification device, characterized in that piping is provided so that overflow liquid is returned to the mixing tank.

Next, the present invention will be explained in further detail.

In the primary neutralization step, one or two basic salts of calcium, such as calcium carbonate, calcium hydroxide, and calcium oxide, are slurried with water or an aqueous solution of nickel sulfate, and the slurry is purified. While adding the liquid to the target liquid, observe the change in pH with a pi meter and check if the pH is low (
Continue adding until both are in the range of 1.5 to 2.5.

At this time, if the pH is less than 1.5, the removal of impurities will not be sufficient (
When the value exceeds 2.5, losses due to Cu precipitation begin to occur.

After neutralization, it is filtered and separated into f-liquid and f-slag (gypsum).

Most of (: u, Ni, Fe, Zn and about 0.51/l of Ca in the electrolyte remain in the f solution, which is used for the next secondary neutralization step (
Cu, Ni recovery process).

On the other hand, in the P slag (gypsum), the S present in the 1lEyW solution
b. Contains almost the entire amount of Bi and a small amount of As, and after being washed with water, it is sent to a gypsum factory and removed from the electrolyte to the outside of the system.

According to the processing conditions described above, Cu in the copper electrolyte.

The loss of Ni can be minimized, the impurities St) and Bi in the electrolyte can be almost completely removed, and As can be removed to about half.

Compared to conventional methods, the method itself requires only 141 molecules, and the removal rate is extremely high.

The secondary neutralization process is a process whose purpose is to remove Cu v Fe e Z n from the P liquid that was separated from the t-slag in the primary neutralization process. This is carried out by adding a slurry containing the same basic salt of calcium as in the Japanese process and adjusting the I)H value to 6.5 to 7.5 in the same manner. J) If H is less than 6.5,
The removal of CU and Zn is insufficient (Cu in the nickel sulfate solution obtained at higher pH).

When the ZH content is low (l)H exceeds 785, the loss of Ni also increases. Note that at this time, if Fe is in a divalent state, removal of Fe will be insufficient, so it is preferable to oxidize it to a trivalent state. After pH adjustment, it is filtered and separated into secondary neutralized liquid and steel sludge, and the steel sludge is repeated in the smelting process. This precipitate contains almost no Sb or Bi, and even if the smelting process is repeated, no circulation of impurities occurs. On the other hand, in the secondary neutralized P solution, most of the Ni and Ca still remain in the range of 0.4 to 0.79 -, but when Ca is removed from this solution, it becomes a solution containing only Ni. can do. To remove this residual Ca, a solvent extraction method using di-2-ethylhexyl phosphoric acid or 2-ethylhexylphosphonic acid monoethylhexyl ester using a kerosene ig solution is effective.
It is necessary to perform extraction at a pH of 2.0 to 3.0. The closer the pH is to 3.0', the more complete Ca is removed, but at the same time the amount of Ni extracted also increases, resulting in loss. In addition, to adjust I)H, it is necessary to add an acid or alkali solution while stirring and mixing the aqueous phase and the organic phase and measuring the pH during the extraction operation. A solvent extraction device equipped with a pH measuring device was devised and manufactured and used. FIG. 1 shows a conceptual diagram of the apparatus of the present invention.

As shown in FIG. 1, the apparatus of the present invention includes a mixing tank 1 that stirs and mixes both phases, a circulation pump 2 that circulates the mixed liquid extracted from the lower part of the mixing tank 1, and a mixing tank that is transferred by the pump 2. Phase separation box 3 and phase separation box 3 that receive liquid and separate the phases
1) H electrode installation box 4 for receiving only the phase-separated supernatant liquid (aqueous phase) and measuring pH thereof.

The phase separation box 3 is a container with an elongated structure, and the further the mixed liquid transferred by the circulation pump 2 is away from the receiving port, the more the phase separation nm progresses, and it is completely separated into two layers at the opposite end of the receiving port. A through hole 3a is provided in a part where only the supernatant liquid (aqueous phase) can be extracted, and the supernatant liquid is transferred to the pH electrode installation box 4.
to flow into.

In addition, the supernatant liquid (organic phase) of the phase separation box 3 is returned to the mixing tank l from the solvent overflow outlet 3b, and the liquid received in the pH electrode installation box 4 passes through the supernatant liquid outlet 4b and overflow 4a to the mixing tank l. It is returned to 1. With this device, it is possible to continuously measure the pH of the aqueous phase during mixing and stirring, and according to the measured value, it is possible to add acid or alkali into the mixing tank 1 to adjust the pH to a predetermined value. became.

After the extraction is completed, stirring is stopped and the mixture is allowed to stand still, the phases are separated in the mixing tank 1, and the two phases are separated by operating the three-way cock 5, thereby producing a purified product containing N110~15P/l. A nickel sulfate aqueous solution is submerged and concentrated directly to obtain purified nickel crystals. On the other hand, the organic phase is regenerated by back extraction with hydrochloric acid and repeated in the liquid-liquid extraction process.

According to the present invention, impurities in the electrolyte can be completely removed outside the system by a lff1-1 operation using an inexpensive Ca salt, and it is easy to repeat the process for Cu, which is a M substance. In addition, a method for purifying a copper electrolyte and an apparatus for the same have been established, in which Ni is highly purified.

Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the following examples unless the gist thereof is exceeded.

Example 1 6 parts of calcium carbonate were added to 3 parts of copper electrolyte having the composition shown in Table 1.
001 and water 1.65. ．． A slurry made by adding e was added while stirring, and the I)H of the liquid was adjusted to 1.9. After adjusting PU, it was filtered and separated into P solution and R slag. Table 2 shows the analytical values of the P solution and P slag after this primary neutralization.

Table 1: Analytical values of copper electrolyte (P/l) Table 2: Analytical values of 1st solution and 1st slag after pH adjustment Add a small amount of water to Ca(OH)t2051-
Add the slurry made by adding o o al, and adjust the pH of the liquid.
was adjusted to 7. After adjusting pi-, it was filtered and separated into a secondary neutralized F solution and an F slag containing copper and iron hydroxides.

Furthermore, this secondary neutralized solution P was brought into contact with 20% DZEHPA and kerosene solvent O//A until 2 hours of solution J)H was added.
．． 8, and unnecessary gold ions such as Ca7' and i were removed to obtain a purified nickel sulfate solution. As a result, the primary neutralization P
Table 3 shows the metal ion concentrations of the liquid, the secondary neutralized P liquid, and the aqueous phase after liquid-liquid extraction.

Table 3 Analytical values of neutralized p solution and post-extraction solution Example 2 A slurry of calcium carbonate, nickel sulfate, and water mixed in a weight ratio of 3:1:12 was added to the copper electrolyte shown in Table 4. After adjusting the pH to 2, it was filtered and separated into F solution and P slag to obtain a primary neutralized P solution.

A small amount of H2O2 was added to this primary neutralized P solution to oxidize Fe, and a slurry of calcium hydroxide and water (Ca (
oH) 2: 500 P/! -) and adjust the pH to 6.
After adjusting to
I drained the liquid. The analytical values for both the primary neutralized P solution and the secondary neutralized P solution are shown in Table 4.

Next, add 20 v/v% D2 to the secondary Nakamoto INF solution.
EHP A +80v/v The kerosene solvent is brought into contact with the kerosene solvent, and the liquid p■ is further adjusted to a predetermined p of 2.0 to 3.0.
The organic phase and aqueous phase were separated, and the organic concentration in the extracted solution (aqueous phase) was analyzed. The result is the second
As shown in the figure. The horizontal axis is the pH value, and the vertical axis is the component concentration in the liquid. The dotted line indicates the concentration of the component in the secondary neutralization solution, and the solid line indicates the concentration of the component in the solution after extraction.

Example copper electrolyte (Cu 28.I P/1%Ni 18.2P
/l, As2.93 f-/1. , SbO,4
5fP/1% BiO, 10P/l.

Adding 500ψ/l calcium hydroxide slurry to free sulfuric acid 19By-/1)It, while changing the pH,
The component concentration in the f solution at each pI was determined.

The results are shown in Figure 3.

It can be seen from FIG. 3 that if the pH is less than 1.5, the removal of impurities is not sufficient, and if it exceeds 2.5, precipitation of CO begins to occur. Further, it can be seen that at a pH of 68 degrees, a considerable amount of Cu precipitates, but almost all of Ni remains in the solution.

[Brief explanation of drawings]

Figure 1 (conceptual diagram of one embodiment of the device between al/il/ , (
C1, (Graphic diagram showing the relationship between dlid pH and the concentration after crude Ni solution extraction, Figure 3 shows the pH of impurities in the primary neutralization f solution.
It is a graph diagram showing dependence. In Fig. 1, 1...l mixing tank 2III11, circulation pump 3, phase separation box 3a, bottom liquid passage hole 3b, solvent overflow outlet 4, pH electrode installation box 4a. -・Φ・Overflow (supernatant mixed solvent overflow) 4b・・Φ・Supernatant liquid melting mouth 5・O three-way droplets・・Supernatant liquid (aqueous phase) 7・・Supernatant liquid (Organic phase) Patent applicant Mitsubishi Metals Co., Ltd. Agent Yoshinao Shirakawa

Claims (3)

[Claims] (1) In the electrolytic solution purification process in the copper electrolytic refining process, (a) A primary step in which calcium salt is added to one volume of the solution to be purified to adjust the pH of the solution to 1.5 to 2.5. and (b) further adding calcium salt to the solution obtained by solid-liquid separation of the precipitate generated in the primary neutralization step to adjust the pH of the solution.
A second neutralization step in which the precipitate produced in the twelfth neutralization step is separated into solid and liquid, and the solution obtained is adjusted to I) H2 to 3. A liquid-liquid extraction step in which purified nickel sulfate is obtained by contacting hexyl phosphoric acid or 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester with a kerosene solution to remove metal ions other than nickel ions in the @ liquid. @ Electrolyte purification method characterized by: (2) The calcium salt is one of calcium carbonate, calcium hydroxide, and calcium oxide, or #'i2
The method according to claim 1, wherein the method is a species. (3) A liquid-liquid mixing tank, a circulation pump that circulates the mixed liquid extracted from the mixing tank, and an fc sent from the circulation pump.
A phase separation box for separating the mixed liquid into phases, a hole in the phase separation box from which only the submerged liquid can be extracted at a position where the phase separation is completed, and a pH electrode installed to receive the supernatant liquid transferred from the hole. box, and the phase separation box and the pH
1. A copper electrolyte purification device, characterized in that the overflowing liquid from the electrode installation box is piped to be returned to the mixing tank.