JP3090142B2 - Method for removing lead ions from nickel chloride solution - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for efficiently removing lead ions from a nickel chloride solution containing lead ions.

[0002]

2. Description of the Related Art Various impurities are contained in a raw material of a non-ferrous metal, and whether or not these impurities can be efficiently removed is a criterion for determining the quality of a process. For example, in producing nickel using nickel matte as a raw material, nickel is first dissolved with chlorine, hydrochloric acid or sulfuric acid. Thereafter, impurities in the solution such as lead, iron and copper are sequentially removed, and then a nickel metal is manufactured by electrolyzing the pure nickel solution from which the impurities have been removed.

In order to produce high-purity nickel metal, it is necessary to remove impurities such as lead to a low concentration before electrolysis. Is preferably removed to a sufficiently low concentration before electrolysis. However, in a chloride solution, lead ions form complex ions with chlorine, and PbCl ₃ ⁻ and PbCl ₄ ²⁻
For example, since lead ions are present, it is difficult to remove impurities, and it is particularly difficult to remove lead ions up to a low concentration.

Generally, lead is removed as a metal by a sulfide reaction or a cementation reaction carried out by adding iron or nickel metal. However, in any of the above-mentioned methods, a chloride solution is not sufficient. Further, a method of oxidizing and removing the solution using Cl ₂ gas has also been proposed. In this method, lead ions are oxidized from divalent to tetravalent to remove them as PbO ₂ having low solubility. However, Cl
_Since strong oxidizing agents such as ₂ are used, nickel
BR is also oxidized to produce Ni (OH) ₃ , which leads to excessive use of the oxidizing agent, which is not preferable.

[0005] In recent years, various metal ions have been separated and removed by using solvent extraction or ion exchange resin technology, which is also used for removing lead ions. For example, in the adsorption method using an ion exchange resin, lead ions are removed from a chloride solution using an anion resin. However, the adsorption removal using an ion resin is not practical because the adsorption capacity of the resin is small and the adsorption / desorption operation must be performed frequently.

On the other hand, methods using the solvent extraction technique include:
It has been reported that the reaction is performed using a phosphoric acid-based acidic extractant. However, when lead is removed from a solution containing nickel or cobalt, the extraction of the target metal is minimized and the lead ions are efficiently removed because these metal ions and lead ions are easily extracted. Was difficult to remove. Also, even if only lead can be selectively extracted,
Practical application was difficult for the following reasons.

[0007] That is, the solvent extraction is composed of three main steps of extraction-washing-back extraction, and the extracted lead is back-extracted using a mineral acid or the like to regenerate the organic solvent. In many cases, hydrochloric acid is used for back extraction from the viewpoint of prevention of deterioration of the organic solvent and handling, and a lead chloride solution is obtained as the back extraction liquid. However, the solubility of lead chloride is low, and a hydrochloric acid solution having a concentration of 1 to 3 N used in back extraction has only about 0.9 to 1.6 g / liter of lead at room temperature, so that crystals of lead chloride are easily precipitated. If crystals are deposited in the apparatus or piping, it may cause trouble. In order to operate in a stable state, it is necessary to control the lead concentration of the back extraction liquid so that the solubility of lead chloride is not always exceeded, and as a result, back extraction is performed using a large amount of acid solution. It is necessary.

[0008] In other words, even if the back-extraction solution still has a sufficient back-extraction capacity as the acid concentration, it must be taken out of the back-extraction step so that the crystals of lead chloride do not precipitate, and a hydrochloric acid solution of the same amount as that must be newly added. Must. The extracted back extract is generally subjected to a neutralization treatment, and the back extract having a high acid concentration is disadvantageous in that a large amount of a neutralizing agent is used. As described above, even with an organic solvent capable of extracting lead, there are various problems in a method of removing lead ions using the same, and there have been difficulties in actual operation.

As described above, there is no method capable of efficiently removing lead ions from a nickel chloride solution containing lead ions, and there has been a demand for the development of a feasible removal method.

[0010]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems and efficiently removes lead ions to a low concentration from a nickel chloride solution containing lead ions, and provides an economical and efficient organic solvent. It is an object of the present invention to provide a method for removing lead ions from a nickel chloride solution that can be regenerated.

[0011]

In order to achieve the above object, the present invention provides (a) contacting an organic solvent having a thiophosphinic acid structure at least once with a nickel chloride solution having a pH of 1 to 5 containing lead ions. A first step of extracting and removing lead ions, and (b) bringing the organic solvent from which lead ions have been extracted into contact with an acidic solution adjusted to pH 0.5 to 3.0 at a lower pH than at the time of extraction and removal together with lead. A second step of returning the co-extracted valuable metal to the nickel chloride solution, and (c) back-extracting the lead in the organic solvent as lead sulfate from the organic solvent using a sulfuric acid solution to separate the generated lead sulfate Then, the gist is a method for removing lead ions from a nickel chloride solution, comprising a third step of regenerating the organic solvent.
In this method, the concentration of the sulfuric acid solution used at the time of the back extraction is preferably 0.5 N or more.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The first step in the present invention is based on the fact that lead ions have a high affinity for sulfur compounds, and an organic solvent having a thiophosphinic acid structure has a large affinity for lead ions. It has been found that it has high extractability even from a chloride such as a nickel chloride solution.

The thiophosphinic acid used in the present invention is an organic compound having a structure represented by the following chemical formula 1.

[0014]

Embedded image [Wherein, R is an alkyl group. The lead ions are extracted from the organic solvent according to the following equation (1).

[0015]

[Formula 1] Pb ²⁺ + 2R ₂ PSOH = (R ₂ SO) ₂ −
Pb + 2H ⁺

Therefore, the higher the pH, the better the extraction of lead ions. Although it depends on the concentration of lead ions in the nickel chloride solution and the coexisting ion species, the pH of the aqueous phase, that is, the pH of the nickel chloride solution is adjusted to pH 1 to 5, preferably 2 to 4.
Control. For adjusting the pH, a general neutralizing agent can be used, for example, a neutralizing agent for a solution or a solid such as alkali hydroxide, ammonia, and metal carbonate.

Since the organic solvent can extract not only lead but also iron and zinc, it is possible to extract and remove these impurities in the nickel chloride solution as a raw material solution together with lead. Usually, if the solvent extractant has a high concentration and can be used as it is, it is possible to extract a large amount of impurities in the nickel chloride solution with a small amount of organic solvent, but the viscosity is high, which hinders the extraction operation, so it is usually diluted and used Have been. The dilution ratio is not particularly limited and is determined according to the concentration of the impurity. In general, the concentration of the extractant is preferably used in the range of 1 to 50 vol% (volume percent).

Although the temperature at the time of extraction is not particularly limited, the viscosity of the nickel chloride solution and the extractant decreases as the temperature increases, and the time required for the two-phase separation of the aqueous phase / organic phase after the extraction reaction can be shortened. Therefore, it is desirable to carry out the extraction reaction at a high temperature. However, the operation at 20 to 60 ° C. is desirable because the extractant and the diluent added to reduce the viscosity of the extractant may volatilize or ignite.

Next, the second step in the present invention is to recover valuable metals such as cobalt from the organic solvent from which lead ions have been extracted. Metal ions relatively similar in extraction characteristics to lead, such as cobalt, are co-extracted with an organic solvent during lead extraction, but valuable metals such as cobalt thus co-extracted are mixed with an acidic solution and the organic solvent. Can be returned to the aqueous phase (that is, the nickel chloride solution).

That is, the nickel chloride solution as the raw material solution often contains valuable metals such as cobalt. Since these metal ions are extracted from a nickel chloride solution having a higher pH than that of lead, the metal ions should be washed with an acidic solution at a lower pH than at the time of extraction of the lead ions and while adjusting the pH to 0.5 to 3.0. Can be returned to the aqueous phase (ie, the nickel chloride solution). pH 0.5 ~
The reason for adjusting the pH to 3.0 is that when the pH is less than 0.5, lead also moves from the organic solvent to the aqueous phase.
If the value exceeds 3.0, the cleaning efficiency is reduced and it becomes difficult to completely recover valuable metals such as cobalt.

If a large amount of the acidic solution for washing is used, valuable metals such as cobalt can be efficiently recovered, but post-treatment of the recovered solution becomes a problem. That is, the recovered solution is neutralized or mixed with a nickel chloride solution, which is a raw material solution containing impurities, and is repeatedly processed. Therefore, the smaller the amount, the more advantageous.

The organic solvent / acid solution volume ratio (O / A) in the second step is not particularly limited, but is generally in the range of 10/1 to 1/1 for the reasons described above. It is desirable to control with.

Further, the third step in the present invention is to re-extract the lead in the organic solvent as lead sulfate using a sulfuric acid solution to remove the lead from the organic solvent and regenerate the organic solvent.
As already mentioned, the problem with the conventional back extraction process is that
It is necessary to control so that the solubility of the lead compound is low and the lead concentration in the back extract does not always exceed the solubility,
Therefore, a large amount of acidic solution used for back extraction is required. That is, it is necessary to use a large amount of a back-extraction solution having a sufficient back-extraction ability for the acid concentration and to perform a neutralization treatment.

In the present invention, the organic solvent from which lead has been extracted is brought into contact with a sulfuric acid solution to back-extract and regenerate the organic solvent.
That is, in the back extraction step in the present invention, the lead and sulfuric acid extracted in the organic solvent react with each other to generate lead sulfate, and the solubility of this lead sulfate is extremely small. Can be completely back-extracted, and the generated lead sulfate can be easily removed by filtration. And the organic phase can be well separated. In addition, since lead sulfate is back-extracted by the formation of lead sulfate, most of the sulfuric acid in the back-extraction solution is not used, and lead sulfate is removed. If replenished, it can be used again as the back extraction starting solution. Since the higher the concentration of the sulfuric acid solution used, the higher the lead back extraction rate,
It is desirable to use a sulfuric acid solution having a concentration of 0.5 N or more (about 0.5 or less in terms of pH), preferably 1.0 N or more (about 0 or less in terms of pH).

Further, the lead sulfate produced in the present invention has a good filterability, and the amount of the organic solvent adhering does not matter.
For example, when the extractant is diluted to 20 vol% and used for lead extraction, when the lead sulfate produced by back extraction of sulfuric acid is subjected to suction filtration, the extractant concentration in the lead sulfate is only 1 to 2%. If it is desired to completely recover the extractant attached to the lead sulfate, the concentration of the extractant in the lead sulfate can be reduced to 0.1% or less by washing the lead sulfate with an organic solvent used for diluting the extractant. Can be reduced to

[0026]

Next, embodiments of the present invention will be described. [Example 1] Nickel 1 was used as a raw material nickel chloride solution.
Using a chloride solution containing 63 g / L, 0.041 g / L lead, 2.87 g / L cobalt, and 0.011 g / L zinc, countercurrent extraction was performed in two stages of extraction and two stages of washing. At this time, as an extractant, thiophosphinic acid having an alkyl group of C ₈ H ₁₇ was diluted to 20 vol% with an aromatic organic solvent (trade name: Clinsol G: manufactured by Nippon Oil Co., Ltd.). Used. The volume ratio (O / A) of the organic solvent / aqueous phase at the time of extraction was set to 1, and 100 g / liter of sodium hydroxide solution was used to adjust the pH to 2.5.
Was adjusted. Next, washing of the organic solvent is performed by O / A = 2/1.
And adjusted to pH 1.5 with 3N hydrochloric acid. The test was conducted by extracting this washing solution out of the system without repeating the stock solution. In the actual operation, the process is repeated with the stock solution to recover Co, or the Co is recovered by out-of-system processing.

[0027]

[Table 1]

As can be seen from Table 1, not only lead but also zinc was completely extracted. Also, the amount of co-extraction of cobalt into the organic solvent could be kept extremely low.

[Example 2] Extraction 2 was performed using a chloride solution containing 154 g / L of nickel, 0.034 g / L of lead, 2.54 g / L of cobalt, and 0.011 g / L of zinc as a raw material nickel chloride solution.
Countercurrent extraction of the stage was performed. At this time, an organic solvent obtained by diluting thiophosphinic acid having an alkyl group of C _{8 H17} to 20% by volume was used as in the case of Example 1.
The organic solvent / aqueous phase volume ratio (O / A) at the time of extraction was set at 1/10, and the pH was adjusted to 200 g / liter with sodium hydroxide solution.
It was adjusted to 3.0.

[0030]

[Table 2]

As can be seen from Table 2, as described above, the organic solvent / aqueous phase volume ratio (O / A) is set at 1/10, and lead is extracted even when the amount of the organic solvent used in the aqueous phase is extremely small. The amount of cobalt to be co-extracted can be reduced by limiting the organic solvent used. In Example 2, the extraction rate of cobalt was suppressed to 12.5%, and by using a small amount of the organic solvent, it was easy to collect the co-extracted cobalt in the subsequent step of washing the organic phase with dilute hydrochloric acid. Becomes

Example 3 A thiophosphinic acid having an alkyl group of C _{8 H17} prepared in the same manner as in Example 1
The organic solvent diluted to 0 vol% was extracted with lead at 5.93 g / liter, and back-extracted by shaking with sulfuric acid solutions having different concentrations for 10 minutes. The organic solvent / aqueous phase volume ratio (O / A) at the time of back extraction was set to 1/1.

[0033]

[Table 3]

As can be seen from Table 3, when sulfuric acid having a concentration of 0.5 N or more was used, lead could be efficiently back-extracted and removed. In addition, since the lead to be back-extracted is lead sulfate, the concentration of lead in the back-extraction solution is low. If only sulfuric acid is replenished and added for the amount of lead sulfate generated, it can be used as a starting solution for back-extraction .

Further, even when sulfuric acid solutions having different concentrations as shown in Table 3 were used, the separation of the aqueous phase and the organic phase after back extraction was good, and completely separated into two phases within 2 minutes after the back extraction reaction. .

Example 4 As a raw material nickel chloride solution, a chloride solution containing 154 g / l of nickel, 0.034 g / l of lead, 2.54 g / l of cobalt and 0.011 g / l of zinc was used.
Continuous extraction of the stages was performed. At this time, an organic solvent obtained by diluting thiophosphinic acid having an alkyl group of C _{8 H17} to 20 vol% was used as in Example 1 as an extracting agent. The flow rate was controlled so that the organic solvent / aqueous phase ratio (O / A) after extraction was 1/10, and nickel carbonate powder was added to each stage to adjust the aqueous phase to pH 3.5. Lead obtained by the extraction process,
The organic solvent from which zinc and a part of nickel and cobalt in the raw material nickel chloride solution were extracted was adjusted with 3N hydrochloric acid so that the pH of the aqueous phase became 1.0, and the O / A was adjusted.
= 5/1, continuous washing in two countercurrent stages. The test was conducted by extracting this washing solution out of the system without repeating the stock solution. In the actual operation, the process is repeated with a stock solution to recover Co, or Co is recovered by out-of-system processing. Further, the organic solvent after washing was subjected to one-stage back extraction with a 3N sulfuric acid solution at O / A = 1/1. The aqueous phase and the organic solvent were both filtered to remove the generated lead sulfate. 0.43 g of lead sulfate was recovered by filtration per liter of the organic solvent after washing. Table 4 shows the composition of each liquid in the above series of steps.

[0037]

[Table 4]

As can be seen from Table 4, lead could be efficiently removed from the concentrated nickel chloride solution, and an organic solvent having a low content of various impurities could be regenerated.

[0039]

As described above, according to the present invention, nickel chloride which can efficiently remove lead ions from a nickel chloride solution containing lead ions to a low concentration and can regenerate an economical and efficient organic solvent can be obtained. It is possible to provide a method for removing lead ions from a solution.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C22B 23/06 C22B 13/00

Claims (2)

(57) [Claims] 1. A first step of contacting an organic solvent having a thiophosphinic acid structure at least once with a nickel chloride solution containing lead ions at a pH of 1 to 5 to extract and remove lead ions; An organic solvent from which lead ions have been extracted is brought into contact with an acidic solution adjusted to a pH of 0.5 to 3.0 at a lower pH than at the time of the extraction and removal to return valuable metals co-extracted with lead to the nickel chloride solution. And (c) a third step of back-extracting the lead in the organic solvent as lead sulfate from the organic solvent using a sulfuric acid solution, separating the generated lead sulfate, and regenerating the organic solvent. A method for removing lead ions from a nickel chloride solution, comprising: 2. A method for removing lead ions from the nickel chloride solution of claim 1 Symbol mounting concentration of the sulfuric acid solution used during the back extraction is characterized in that at least 0.5 N.