KR101858873B1 - Solvent extraction method for cobalt recovery - Google Patents

Abstract

The present invention relates to a solvent extraction method, extracting cobalt from an aqueous-phase solution, which is a raw material solution including a cobalt ion, with an organic-phase solution including an extractant to reduce investment costs. According to the present invention, the method comprises: a step of sucking an aqueous-phase solution and an organic-phase solution, which dilutes bis(2,4,4-trimethylphenyl)phosphonic acid extractant in a kerosene dilute solution by a molarity of 0.25 to 0.35, into a mixing and precipitation bath in a volume ratio of organic-phase/aqueous-phase so as to extract cobalt to the organic-phase solution from the aqueous-phase solution, and separating the aqueous-phase solution and the organic-phase solution to recover an organic-phase extraction solution; and a step of sucking the organic-phase extraction solution and a strip solution in the mixing and precipitation bath without a cleaning process to strip the cobalt from the organic-phase extraction solution to the strip solution, and separating the aqueous-phase solution and the organic-phase solution to recover an aqueous-phase strip solution.

Description

SOLVENT EXTRACTION METHOD FOR COBALT RECOVERY FOR COBALT RECOVERY

The present invention relates to a solvent extraction method for recovering cobalt from a raw material solution by a solvent extraction method.

Solvent extraction processes have been used universally in the recovery of cobalt or valuable metals including them from existing industrial by-products and wastes or mixtures thereof.

The solvent extraction process consists of unit processes such as saponification, extraction, scrubbing, and stripping. For this purpose, a multi-stage mixer-settler ) Facilities. In addition, each of the unit processes of the solvent extraction process is generally composed of a continuous multi-stage mixed precipitating facility.

The mixed sedimentation system consists of a mixing zone, a settling zone and a separating zone. The working principle of the mixed sedimentation can be seen from FIG. Fig. 1 is a plan view of the mixed sedimentation enhancer taken from above, a front view seen from the front, and a side view seen from the separation region side.

Referring to FIG. 1, the mixed sedimentation accelerator is configured to separate organic phases and aqueous phases from two neighboring mixed sedimentation-enhancing separation regions by a rotating impeller in the mixing region Suction).

As described above, each of the unit processes of the conventional solvent extraction process is constituted by a continuous multi-stage mixed sedimentation equipment, so that a large number of mixed sedimentation equipment is required.

The present invention provides a technique for reducing the investment cost by minimizing the number of continuous multi-stage mixed precipitating equipment used through optimization of the process in utilizing the solvent extraction process for recovering cobalt metal from industrial byproducts.

The present invention relates to a method for solvent extraction of cobalt from an aqueous solution which is a raw material solution containing cobalt ions by using an organic phase solution containing an extractant, wherein a kerosene diluent is a bis (2,4,4-trimethylphenyl) phosphonic acid extractant Was diluted to a concentration of 0.25 to 0.35 mol, and the aqueous phase solution was sucked into the mixed precipitate at a volume ratio of 2 to 5 of the organic phase / water phase to extract cobalt from the aqueous phase solution into the organic phase solution. The aqueous phase solution and the organic phase solution were separated, Removing the organic phase solution from the organic phase solution, removing the organic phase solution from the organic phase solution, removing the organic phase solution from the organic phase solution, And recovering the cobalt by solvent extraction.

The organic phase solution preferably further contains sodium hydroxide in a concentration of 0.6 to 1.0 mol.

The removal liquid may be sulfuric acid at a concentration of 0.2 to 0.35%.

The removing solution may be added to skin of 100 parts of the organic phase extract solution to 50 to 500 parts of skin.

According to the present invention, it is possible to omit the cleaning process, which is one of the unit processes of the solvent extraction process, and to reduce the cost of equipment investment for recovering cobalt.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view, a front view, and a side view of a conventional mixed sedimentation enhancer viewed from the side of the separation region; FIG.

In the present invention, a process of selectively extracting cobalt from a solution containing cobalt (Co), nickel (Ni), calcium (Ca), sodium (Na), etc. and not extracting nickel, calcium, By simplifying the solvent extraction process, the cleaning process of the solvent extraction process is excluded.

The solvent extraction process according to the present invention is performed by a generally applicable process, except that it does not include a cleaning process, and includes saponification, extraction and stripping.

The solvent extraction process is generally a process of mixing a raw material solution containing a metal and an organic phase containing an extraction agent, extracting the desired metal from the raw solution into an organic phase, and recovering the metal.

For example, the raw material solution may contain components such as nickel, calcium, and sodium in addition to cobalt as a target metal. In the extraction process, which is a unit process of the solvent extraction process, the target metal present in the water phase is extracted into an organic phase At this time, a trace element is extracted together with the target metal, which acts as an impurity.

Generally, in order to remove elements other than the target metal, a cleaning process is continuously applied after the extraction process to remove trace elements other than the target metal extracted in the organic phase, and then back-extracted with water . In this cleaning process, weak acid or weak base solution is used for cleaning.

However, such a cleaning process increases the cost of equipment investment by causing enlargement and complication of facilities. Accordingly, the present invention provides a method for removing the cleaning process. In order to omit such a washing step, it is preferable to increase the selectivity in the extraction step.

The solvent extractant as described above is used as an organic phase, mixed with a water-insoluble solvent containing a metal such as cobalt, nickel, sodium and calcium, and mixed with the mixed sedimentation mixture. The mixture is then separated into an organic phase and an aqueous phase And separated into organic phase and water phase in the separation region.

In the present invention, the solvent extractant may be suitably used in the present invention as long as it is generally used in a solvent extraction process. However, the present invention is for extracting cobalt metal in a solution, and a solvent extractant for cobalt extraction can be used.

As a solvent extractant for cobalt extraction, a commonly used solvent extractant may be used. In the present invention, bis (2,4,4-trimethylphenyl) phosphonic acid (bis (2, 4,4-trimethylpentyl) phosphinic acid may be used.

[Structural formula 1]

As shown in Fig. 2, such a solvent extractant is present in the form of a dimer in the form of a compound having the molecular structure of the structural formula (1).

When the metal ion of cobalt is extracted from the water-soluble solvent, the two molecules of the dimer participate in the bonding reaction with a metal ion such as cobalt. That is, the solvent extractant selectively reacts with cobalt ions from the water-phosphorous solvent to extract metal ions such as cobalt as an organic phase.

The cobalt ion extraction reaction of the solvent extractant is an equilibrium reaction, and can be represented by the following reaction formula (1).

[Reaction Scheme 1]

M ²⁺ + 2 (HA) ₂ MA _2? (AH) ₂ + 2H ⁺

In the above reaction scheme 1, M represents a metal ion to be extracted, that is, Co ion, and A represents a solvent extractant.

As can be seen from the above reaction scheme 1, when metal ions are extracted with a solvent extracting agent, H ⁺ ions are generated and exist in the water phase, so that the pH of the water phase is lowered. The pH change of the water phase influences the extraction rate of metal ions.

Therefore, in order to reduce the change of the extraction ratio according to the pH change of the aqueous phase during the extraction process by the extractant, it is preferable that the extraction agent is subjected to a saponification process and then mixed with the aqueous phase.

The saponification of the extractant may be accomplished by reacting the solvent extractant with a dilute sodium hydroxide (NaOH) solution to replace a portion of the terminal hydrogen (H ⁺ ) of the solvent extractant with Na ⁺ of sodium hydroxide. Thus, by decreasing the amount of H.sup. ⁺ Ions generated during metal ion extraction, the pH drop width can be reduced.

At this time, sodium hydroxide is preferably used in a concentration range of 0.6 to 1.0 mol, more preferably 0.7 to 0.9 mol, most preferably 0.8 mol, for the saponification. When sodium hydroxide is used at a concentration of 0.6 mol or less, the degree of saponification is low and the pH of the aqueous phase may be lowered during the extraction process, which may result in a decrease in the extraction rate. On the other hand, when sodium hydroxide is used in a concentration exceeding 1.0 molar concentration, undesired third phases may occur in addition to the organic phase and the water phase, thereby hindering the operation of the process.

In the present invention, the organic phase comprises an extractant, which is used after being saponified as described above or diluted without saponification. For the dilution, kerosene may be used as a diluent. Such kerosene is not particularly limited and may be suitably used in the present invention as long as it is generally used in a solvent extraction process. For example, Escaid 110 manufactured by Exxon Mobil Chemical Co., Ltd. and the like.

In the present invention, the organic phase diluted with the diluent is preferably diluted so that the concentration of the extracting agent is 0.25 to 0.35 mol, and most preferably, the organic phase in the organic phase is 0.3 molar. If the concentration of the extractant is less than 0.25 molar, the extraction of the desired metal is less. On the other hand, when the concentration exceeds 0.35 mol, the extraction selectivity of the target metal, cobalt ion, is lowered, so that the extraction rate with respect to other metal ions is increased. Therefore, a cleaning process for recovering the target metal must be performed. Therefore, the inclusion of the extractant at the concentration in the above range can increase the selective extraction ratio of the desired cobalt, and the subsequent cleaning step can be omitted.

The organic phase containing the above-mentioned extractant is mixed with the water phase as a raw material solution by being sucked into a mixed region of mixed sedimentation, and then the target metal in the aqueous phase is converted into an organic phase The extraction reaction is carried out. The mixed sedimentation accelerator of the present invention is not particularly limited and is commonly used, and can be suitably used in the present invention as long as it is as shown in Fig.

In order to increase the efficiency of the extraction reaction in the mixed sedimentation enhancement, it is preferable that the organic phase and the water phase have 2 to 5 in the volume ratio (organic phase / water phase). More preferably 4 to 5, and most preferably 4. If the volume ratio of the organic phase and the water phase is less than 2, the extraction rate of the target metal is low, and the incorporation rate of the impurity metal becomes relatively high, thereby increasing the necessity of performing the subsequent cleaning process. On the other hand, if it exceeds 5, an additional synergistic effect for selective extraction of the target metal is not obtained, and the amount of the extractant used increases, which is uneconomical.

After the organic phase and water phase are separated and recovered from the solvent extraction step, a stripping process is performed to obtain a desired metal from the organic phase. The stripping step is a step of back-extracting the target metal from the organic phase in which the target metal is present, to the water phase.

In order to back-extract the target metal, a strong acid or strong base solution may be used as a deblocking liquid in the organic phase containing the target metal. Such a stripping liquid is not particularly limited as it can be suitably used in the present invention as long as it is generally used for stripping cobalt in a solvent extraction process. Examples thereof include sulfuric acid, NaOH, and NH ₄ OH.

At this time, when sulfuric acid is used, the sulfuric acid may be diluted to a concentration of 0.2 to 0.35%, which can be removed from the organic phase extract at a high ratio of cobalt.

The removing solution may be added to the skin of the organic phase extract in an amount of 50 to 500 parts per 100 parts of the skin. If the amount of the removing solution is too small, the removal of cobalt may not be performed smoothly. Even if a large amount of devolatilization liquid is used, there is a limit to the removal of Sc, and a waste droplet removal amount may be unnecessarily generated. Therefore, the devolatilization liquid can be used in the above-mentioned range.

When extracting cobalt from a solution containing a metal such as cobalt, nickel, calcium or sodium, the solvent extraction process according to the present invention as described above can increase the selective extraction rate of cobalt, The process can be simplified.

Example

Hereinafter, the present invention will be described in more detail with reference to examples. The following examples are illustrative of the present invention, but the present invention is not limited thereto.

Example  One

A saponification process was performed by mixing Escaid 110 (manufactured by ExxonMobil) as a diluent with 0.8 molar concentration of sodium hydroxide as a saponifying agent and Cyanex 272 as an extracting agent in a concentration range of 0.2 to 0.5 molar ratio to prepare an organic phase solution.

The solvent was extracted by sucking the prepared organic phase solution into a mixing zone of a solvent extraction tank at a volume ratio of 1: 1 with a raw material solution containing 1500 ppm of cobalt and 390 ppm of nickel.

The organic phase and water phase separated and discharged through the separation region of the solvent extraction tank were respectively recovered, and the contents of cobalt and nickel contained in the organic phase and water phase were respectively analyzed, and the results are shown in Table 1.

Experiment
No. Extractant concentration division Concentration (ppm) Extraction rate (%) Co Ni Co Ni One Extraction 1st 0.2 molar concentration Organic phase <1 <1 0.1 0.3 Awards 1500 390 2 Extraction second 0.3 molar concentration Organic phase 620 10 41.3 2.6 Awards 880 380 3 Extraction third 0.4 molar concentration Organic phase 1500 386 100 98.97 Awards <1 4.3 4 Extraction fourth 0.5 molar concentration Organic phase 1500 388 100 99.49 Awards <1 1.7

As can be seen from the above Table 1, in the case where the concentration of the extracting agent was 0.2 molar (Experiment 1), extraction was scarcely occurred.

On the other hand, when the concentration of the extractant was 0.3 mole (Experiment 2), the extraction rate of cobalt was 41%, but nickel was trace extracted, and the selectivity to cobalt was very high.

On the other hand, when the extraction agent was 0.4 molar concentration (Experiment 3) and 0.5 molar concentration (Experiment 4), almost 100% of cobalt was extracted, but nickel was largely extracted and little selectivity to cobalt was shown. As a result, it can be seen that a cleaning process is necessarily required after the extraction process.

From these results, it was found that the extraction rate of nickel, which is an impurity, is almost the same as that of cyanite, .

Example  2

The saponification process was carried out by mixing Escaid 110 (manufactured by ExxonMobil) as a diluent with 0.8 molar concentration of sodium hydroxide as a saponifying agent and 0.3 molar concentration of Cyanex 272 as an extracting agent to prepare an organic phase solution.

The organic phase solution thus prepared was subjected to a solvent extraction process by sucking the aqueous phase raw material solution containing 1600 ppm of cobalt and 430 ppm of nickel into the mixing region of the solvent extraction tank. At this time, the organic phase and water phase were inhaled under the conditions shown in Table 2 below.

The organic phase and water phase separated and discharged through the separation zone of the solvent extraction tank were respectively recovered, and the contents of cobalt and nickel contained in the organic phase and water phase were respectively analyzed, and the results are shown in Table 2.

Experiment No. Mixing volume ratio
(Organic phase / water phase) division Concentration (ppm) Extraction rate (%) Co Ni Co Ni 5 One Organic phase 674 24 42.1 5.6 Awards 926 406 6 2 Organic phase 989 7 61.8 1.6 Awards 611 423 7 4 Organic phase 1417 6 88.6 1.4 Awards 183 424

As can be seen from the above Table 2, when the volume ratio of the organic phase and the water phase is 1 (Experiment 5), the extraction rate of cobalt is low and the extraction rate of nickel is high. On the other hand, when the volume ratio is 2 (Experiment 6) and 4 (Experiment 7), the extraction rate of cobalt is relatively high while the extraction rate of nickel is low. As a result, cobalt can be extracted with high purity, It can be omitted.

Example  3

The saponification process was performed by mixing Escaid 110 (manufactured by ExxonMobil) as a diluent with 0.8 molar concentration of sodium hydroxide as a saponifying agent and 0.3 molar ratio of Cyanex 272 as an extracting agent to prepare an organic phase solution.

The organic phase solution thus prepared was sucked into a mixed region of a solvent extraction bath at a volume ratio of 4: 1 with a raw material solution containing 1706 ppm of cobalt and 448 ppm of nickel to perform a solvent extraction process.

The organic phase and water phase separated and discharged through the separation region of the solvent extraction tank were respectively recovered and the contents of cobalt and nickel remaining in the water phase were analyzed respectively. The cobalt content was 183 ppm and the nickel content was 424 ppm.

The organic phase (cobalt: 1523 ppm, nickel: 24 ppm) obtained from the separation zone of the solvent extraction tank was directly subjected to a stripping process without a washing process to back-extract cobalt.

Sulfuric acid (2% solution) was used as the stripping solution in the stripping step, and the concentrations were diluted to 0.15% and 0.3% as shown in Table 3. [

At this time, the organic phase and water phase of the stripping process were fixed at a volume ratio of 1: 1.

Table 3 shows the concentrations of cobalt and nickel contained in the removal liquid thus obtained and the reverse extraction ratio.

Experiment No. Removal amount
(Sulfuric acid dilution concentration) Water concentration (ppm) Reverse extraction ratio (%) Co Ni Co Ni 8 0.15% diluent 1009 <10 66 42 9 0.3% diluent 1521 <10 100 42

As can be seen from Table 3, according to the method of the present invention, cobalt can be extracted at a high purity even without a washing step. Furthermore, in the removal process,

As described above, the washing process in the unit process of the solvent extraction process was omitted, and the continuous multi-stage mixed sedimentation was operated based on the selected conditions of the saponification process, the extraction process and the stripping process, and the cobalt content recovered through the stripping process The results of analysis of the solution are shown in FIG.

Based on the above-described embodiments, the present invention can reduce the investment cost by applying the solvent extraction process using the continuous multi-stage mixed sedimentation process, which comprises the saponification process, the extraction process, and the stripping process.

Claims (4)

1. A method for extracting cobalt from an aqueous solution which is a raw material solution containing cobalt ions by using an organic phase solution containing an extractant,
The organic phase solution in which the bis (2,4,4-trimethylphenyl) phosphonic acid extractant is diluted to a concentration of 0.25 to 0.35 mol in the kerosene diluent and the aqueous solution are sucked into the mixed precipitate at a ratio of 2 to 5 of the organic phase / water phase to prepare an aqueous solution Extracting cobalt from the organic phase solution, separating the aqueous phase solution and the organic phase solution, and recovering the organic phase extraction solution;
Withdrawing the organic phase extracting solution and the removing liquid from the organic phase extracting solution by sucking the organic phase extracting solution and the elimination liquid through a washing step, separating the aqueous solution and the organic phase solution, recovering the water-
&Lt; RTI ID = 0.0 &gt; cobalt &lt; / RTI &gt;
The method of claim 1, wherein the organic phase solution further comprises sodium hydroxide at a concentration of 0.6 to 1.0 mole.
The method according to claim 1, wherein the removing solution is recovered from cobalt by solvent extraction with a concentration of 0.2 to 0.35% sulfuric acid.
The method of recovering cobalt according to claim 1, wherein the removing solution is introduced into skin of 100 parts of the skin of the organic phase extraction solution by 50 to 500 parts of the skin.

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