JP6891757B2 - Solvent extraction equipment and solvent extraction method - Google Patents

Description

The present invention relates to a solvent extraction facility and a solvent extraction method. More specifically, the present invention relates to a solvent extraction facility capable of suppressing an increase in deterioration products of an amine-based extractant contained in an organic solvent, and a solvent extraction method.

In the hydrometallurgy process of recovering nickel and cobalt from sulfide, the raw material nickel matte and nickel-cobalt mixed sulfide are leached with chlorine, and impurities are removed from the obtained leachate. Recover electric nickel and electric cobalt at. This hydrometallurgy process includes a solvent extraction step in which nickel and cobalt contained in the leachate are separated by solvent extraction to obtain a nickel chloride aqueous solution and a cobalt chloride aqueous solution.

For solvent extraction that separates nickel and cobalt, an amine-based extractant such as TNOA (trinormal octylamine) is preferably used as the organic extractant. However, it is known that amine compounds are hydrolyzed under acidic conditions and are oxidized to be decomposed into hydroxylamine and the like. Therefore, when the organic solvent is used repeatedly, there is a problem that a deteriorated product that does not function as an organic extractant is generated and the extraction efficiency is lowered.

In Patent Document 1, when metal ions are extracted from a nickel chloride aqueous solution using an organic solvent containing a tertiary amine compound, sodium thiosulfate is added to the nickel chloride aqueous solution to increase the oxidation-reduction potential to 500 mV (Ag / AgCl electrode). Criteria) The following adjustments are disclosed. As a result, deterioration of the tertiary amine compound can be suppressed.

Japanese Unexamined Patent Publication No. 2015-209582

When sodium thiosulfate is added to an aqueous nickel chloride solution, sulfate roots (SO ₄ ^2- ion) are generated as shown in Chemical Formula 1 below.
(Chemical formula 1)
Na ₂ S ₂ O ₃ + 4Cl ₂ + 5H ₂ O → 2 NaCl + 2H ₂ SO ₄ + 6HCl

When the number of sulfate roots increases, the electrolytic voltage in the electrolytic process increases, so that the power cost increases. In addition, the amount of oxygen generated from the anode increases and the chlorine recovery rate decreases. Therefore, it is preferable to suppress the increase of sulfate roots as much as possible. Further, in the electrolysis step, when the electrolysis voltage is already high due to an increase in impurities or an increase in contact resistance, it is difficult to further increase the number of sulfate roots. In such a case, the required amount of sodium thiosulfate cannot be added to the nickel chloride aqueous solution, and the oxidation-reduction potential of the nickel chloride aqueous solution cannot be adjusted to 500 mV (Ag / AgCl electrode standard) or less. As a result, the deterioration products of the amine-based extractant increase.

In view of the above circumstances, it is an object of the present invention to provide a solvent extraction facility capable of suppressing an increase in deterioration products of an amine-based extractant contained in an organic solvent, and a solvent extraction method.

Solvent extraction facilities of the first invention, by recycling the organic solvent containing TNOA as an amine-based extractant, cobalt from nickel chloride aqueous solution is extracted DeHajimeeki a solvent extraction equipment for solvent extraction, the organic solvent The amine-based extraction is performed by cooling the circulation flow path that circulates the water, the extraction flow path that branches from the circulation flow path and extracts a part of the organic solvent, and the organic solvent supplied from the extraction flow path. A cooling device for solidifying DNOA, which is a deterioration product of an agent, a solid-liquid separation device for removing the deterioration product from the organic solvent supplied from the cooling device, and the solid-liquid separation device discharged from the solid-liquid separation device. A return flow path for returning the organic solvent to the circulation flow path, an organic solvent supply device for supplying the new amine-based extractant to the circulation flow path so as to make up for the shortage due to the removal of the deterioration product, and an organic solvent supply device. The extraction start liquid is a liquid after the iron removal step in the wet smelting process for recovering nickel and cobalt from the sulfide .
The solvent extraction equipment of the second invention is characterized in that, in the first invention, the cooling device is a tank that cools the organic solvent by natural heat dissipation by storing the organic solvent for a predetermined time.
The solvent extraction equipment of the third invention is characterized in that, in the first invention, the cooling device is a device that cools the organic solvent by forced heat dissipation.
The solvent extraction equipment of the fourth invention is characterized in that, in the first, second or third invention, the solid-liquid separation apparatus solid-liquid separates a mixture of the organic solvent and water.
The solvent extraction equipment of the fifth invention is characterized in that, in the fourth invention, the solid-liquid separation device separates the mixed liquid into solid and liquid in multiple stages.
The solvent extraction equipment of the sixth invention is characterized in that, in the first, second, third, fourth or fifth invention, the solid-liquid separation device is a filtration device.
In the solvent extraction equipment of the seventh invention, in the first, second, third, fourth, fifth or sixth invention, the circulation flow path passes through an extraction stage, a reverse extraction stage and an activation step in this order. The extraction flow path is characterized in that it is connected between the reverse extraction stage of the circulation flow path and the activation step.
In the first, second, third, fourth, fifth, sixth or seventh invention, the solvent extraction facility of the eighth invention adds a reducing agent to the extraction starting solution to oxidize the extraction starting solution. It is characterized by comprising a reducing agent adding device for adjusting the reduction potential to 500 to 550 mV (based on Ag / AgCl electrode).
The solvent extraction method of the ninth invention, by recycling the organic solvent containing TNOA as an amine-based extractant, cobalt from nickel chloride aqueous solution is extracted DeHajimeeki a solvent extraction method of solvent extraction, the organic solvent By extracting a part of the organic solvent from the circulation flow path that circulates the above and cooling the extracted organic solvent, DNOA, which is a deterioration product of the amine-based extractant, is solidified, and the organic solvent after cooling is solidified. By solid-liquid separation, the deterioration product is removed from the organic solvent, and the organic solvent after solid-liquid separation is returned to the circulation flow path to make up for the shortage due to the removal of the deterioration product. The new amine-based extractant is supplied to the circulation flow path, and the extraction starting liquid is a liquid after the iron removal step in the wet smelting process for recovering nickel and cobalt from the sulfide. ..
The solvent extraction method of the tenth invention is characterized in that, in the ninth invention, the cooling of the organic solvent is performed by storing the organic solvent in a tank for a predetermined time and naturally dissipating the organic solvent. ..
The solvent extraction method of the eleventh invention is characterized in that, in the ninth invention, the cooling of the organic solvent is performed by forcibly dissipating heat from the organic solvent.
The solvent extraction method of the twelfth invention is characterized in that, in the ninth, tenth or eleventh invention, the solid-liquid separation of the organic solvent is performed by a filtration device.
In the ninth, tenth or eleventh invention, the solvent extraction method of the thirteenth invention is to remove the deterioration product from the mixed liquid by solid-liquid separating the mixed liquid of the organic solvent and water. It is a feature.
In the thirteenth invention, the solvent extraction method of the fourteenth invention is characterized in that the mixed liquid is solid-liquid separated in multiple steps.
In the solvent extraction method of the fifteenth invention, in the ninth, tenth, eleventh, twelfth, thirteenth or fourteenth invention, the circulation flow path passes through an extraction step, a back extraction step and an activation step in this order. It is characterized in that a part of the organic solvent is extracted from between the back extraction step and the activation step of the circulation flow path.
In the solvent extraction method of the 16th invention, in the 9th, 10th, 11th, 12th, 13th, 14th or 15th inventions, a reducing agent is added to the extraction starting liquid to oxidize the extraction starting liquid. It is characterized in that the reduction potential is adjusted to 500 to 550 mV (based on Ag / AgCl electrode).

According to the first invention, since the deterioration product solidified by cooling can be removed by solid-liquid separation, it is possible to suppress an increase in the deterioration product contained in the organic solvent circulating in the solvent extraction facility.
According to the second invention, since the organic solvent is cooled by a simple device, equipment cost and operation cost can be suppressed.
According to the third invention, since the organic solvent is cooled by forced heat dissipation, the organic solvent can be cooled to a desired temperature without being affected by the outside air temperature, and the deteriorated product can be surely solidified.
According to the fourth invention, by adding water to the organic solvent, a solid substance composed of impurities contained in the organic solvent is dissolved in water. Since the amount of solid matter removed can be reduced, the time required for solid-liquid separation can be shortened.
According to the fifth invention, the removal rate of deterioration products can be improved by solid-liquid separation of the mixed solution in multiple steps.
According to the sixth invention, since the organic solvent is solid-liquid separated by a simple device, the equipment cost can be suppressed.
According to the seventh invention, since the content of the target substance is small in the organic solvent after passing through the back extraction stage, the loss of the target substance due to the target substance being incorporated into the solidified degrading substance can be reduced.
According to the eighth invention, by adjusting the redox potential of the extraction starting solution to 500 to 550 mV (based on the Ag / AgCl electrode), the amount of deteriorated products generated can be reduced while suppressing the amount of the reducing agent added.
According to the ninth invention, since the deterioration product solidified by cooling can be removed by solid-liquid separation, it is possible to suppress an increase in the deterioration product contained in the organic solvent circulating in the solvent extraction facility.
According to the tenth invention, since the organic solvent is cooled by a simple device, equipment cost and operation cost can be suppressed.
According to the eleventh invention, since the organic solvent is cooled by forced heat dissipation, the organic solvent can be cooled to a desired temperature without being affected by the outside air temperature, and the deteriorated product can be surely solidified.
According to the twelfth invention, since the organic solvent is solid-liquid separated by a simple device, the equipment cost can be suppressed.
According to the thirteenth invention, by adding water to the organic solvent, a solid substance composed of impurities contained in the organic solvent is dissolved in water. Since the amount of solid matter removed can be reduced, the time required for solid-liquid separation can be shortened.
According to the fourteenth invention, the removal rate of deterioration products can be improved by solid-liquid separation of the mixed solution in multiple steps.
According to the fifteenth invention, since the organic solvent after passing through the back extraction stage has a small content of the target substance, the loss of the target substance due to the target substance being incorporated into the solidified degrading substance can be reduced.
According to the sixteenth invention, by adjusting the redox potential of the extraction starting solution to 500 to 550 mV (based on the Ag / AgCl electrode), the amount of deteriorated products generated can be reduced while suppressing the amount of the reducing agent added.

It is a detailed process diagram of the solvent extraction process. It is explanatory drawing of the part corresponding to the deterioration product removal process in the solvent extraction equipment. It is the whole process diagram of the wet smelting process. It is a graph which shows the measurement result of the DNOA concentration in an Example.

Next, an embodiment of the present invention will be described with reference to the drawings.
[First Embodiment]
The solvent extraction equipment and the solvent extraction method according to the first embodiment of the present invention are suitably applied to the solvent extraction step of the wet smelting process for recovering nickel and cobalt. The solvent extraction equipment and the solvent extraction method of the present embodiment may be any step as long as it is a step of extracting the target substance from the extraction starting liquid in a strongly oxidizing atmosphere by circulating an organic solvent containing an amine-based extractant. It can also be applied to the process of the process. Hereinafter, a case where it is applied to the solvent extraction step of the hydrometallurgy process will be described as an example.

(Hydrometallurgy process)
First, the hydrometallurgy process will be described with reference to FIG.
In the hydrometallurgy process, two types of nickel sulfide as a raw material, nickel matte and nickel-cobalt mixed sulfide (MS: mixed sulfide), are used.

Nickel mats are obtained by pyrometallurgy. Specifically, the nickel mat is obtained by melting iron-sulfur nickel ore.

The nickel-cobalt mixed sulfide is obtained by hydrometallurgy. Specifically, nickel oxide ore such as low-grade laterite ore is leached with high pressure acid (HPAL) to remove impurities such as iron from the leachate, and then hydrogen sulfide gas is blown into the leachate to carry out a sulfurization reaction. To obtain a nickel-cobalt mixed sulfide.

First, a slurry composed of a nickel-cobalt mixed sulfide and a cementation residue described later is supplied to a chlorine leaching step. In the chlorine leaching step, substantially all the metals contained in the solid matter in the slurry are leached into the liquid by the oxidizing power of the chlorine gas blown into the leaching tank. The slurry discharged from the chlorine leaching step is solid-liquid separated into a leachate and a leachate residue.

The nickel mat is pulverized in the pulverization step and then repulped to form a mat slurry, which is supplied to the cementation step. The leachate obtained in the chlorine leaching step is also supplied to the cementation step. The leachate contains the target metals nickel and cobalt, as well as impurities such as copper, iron, lead and manganese.

The leachate contains divalent copper chloro complex ions. The main components of the nickel mat are trinickel disulfide (Ni ₃ S ₂ ) and metallic nickel (Ni ⁰ ). In the cementation step, the leachate and the nickel mat are brought into contact with each other to carry out a substitution reaction between copper and nickel. As a result, nickel in the nickel mat is replaced and leached by the liquid, and copper ions in the leachate are precipitated in the form of _{copper sulfide (Cu 2} S) or metallic copper (Cu ^0). The cementation residue obtained by solid-liquid separation is supplied to the chlorine leaching step.

The cementation final solution obtained from the cementation step is supplied to the iron removal step. In the iron removal step, impurities such as iron and arsenic contained in the cementation final solution are removed. The liquid obtained from the iron removal step is supplied to the solvent extraction step as an extraction starting liquid. In the solvent extraction step, the cobalt contained in the extraction starting solution is separated by solvent extraction to obtain a nickel chloride aqueous solution and a cobalt chloride aqueous solution. The details of the solvent extraction step will be described later.

Impurities are further removed from the nickel chloride aqueous solution through a liquid purification step to obtain a high-purity nickel chloride aqueous solution. The high-purity nickel chloride aqueous solution is supplied to the nickel electrolysis process as an electrolytic feed solution. In the nickel electrolysis process, electrolytic nickel is produced by electrowinning.

Impurities are further removed from the cobalt chloride aqueous solution through a liquid purification step to obtain a high-purity cobalt chloride aqueous solution. The high-purity cobalt chloride aqueous solution is supplied to the cobalt electrolysis step as an electrolytic feed solution. In the cobalt electrolysis process, electrowinning produces electric cobalt.

(Solvent extraction step)
FIG. 1 shows the details of the solvent extraction step. In FIG. 1, the broken line means the flow of the organic phase, and the solid line means the flow of the aqueous phase.
In the solvent extraction step, the post-treatment liquid (nickel chloride aqueous solution) of the iron removal step is supplied as the extraction starting liquid. The extraction starting liquid is supplied to the extraction stage. In the extraction stage, cobalt contained in the aqueous phase is extracted into the organic phase. The aqueous phase after extraction is sent to a subsequent process as a nickel chloride aqueous solution. The organic phase of the extraction stage is sent to the washing stage, and after removing a trace amount of nickel chloride contained in the organic phase with an aqueous cobalt chloride solution, it is sent to the back extraction stage. In the back extraction stage, cobalt contained in the organic phase is back-extracted into the aqueous phase using an acidic aqueous solution such as dilute hydrochloric acid to produce a cobalt chloride aqueous solution. The produced cobalt chloride aqueous solution is sent to a subsequent process.

In the extraction stage, impurities such as zinc, iron, and copper are extracted into the organic phase as well as cobalt. Cobalt is back-extracted into the aqueous phase in the back-extraction stage, but impurities remain in the organic phase without back-extraction. When the impurity concentration of the organic solvent increases, there arises a problem that the amount of cobalt extracted in the extraction stage decreases and impurities are eluted in the nickel chloride aqueous solution or the cobalt chloride aqueous solution. Therefore, the organic solvent after the back extraction is sent to the dezincification step to remove impurities such as zinc, iron and copper.

In the dezincification step, a part of the organic solvent after back extraction is extracted, and a neutralizing agent is added thereto to neutralize the organic solvent, whereby impurities in the organic solvent are used as neutralized starch. Next, the liquid discharged from the neutralization step is separated into a heavy liquid (aqueous phase containing neutralized starch) and a light liquid (organic phase not containing neutralized starch) by a decanter. The light liquid is sent to the activation step as an organic solvent from which impurities have been removed. The organic solvent is repeated in the extraction stage after the acidic aqueous solution is added in the activation step.

For solvent extraction that separates nickel and cobalt, an amine-based extractant is preferably used as the organic extractant. Among them, the tertiary amine extractant has the ability to extract metal chloro complex ions by adding hydrochloric acid and activating it, and has excellent selectivity between nickel and cobalt. TNOA (trinormal octylamine) can be mentioned as a tertiary amine extractant.

On the other hand, the post-treatment liquid in the iron removal step, which is the extraction starting liquid, has an oxidation-reduction potential of 900 mV (Ag / AgCl electrode standard, the same applies hereinafter) or more, and has a strongly oxidizing atmosphere. Therefore, when the organic solvent is used repeatedly, the amine-based extractant contained in the organic solvent is decomposed to generate a deteriorated product that does not function as the organic extractant. For example, when TNOA is used as the organic extractant, DNOA (dinormal octylamine), which is a deterioration product, is generated.

(Deterioration product removal process)
The present embodiment is characterized in that a part of the organic solvent is extracted from the circulation flow path 10 for circulating the organic solvent, and the generated deterioration product is removed. Hereinafter, this step is referred to as a deterioration product removing step.

FIG. 2 shows a portion of the solvent extraction equipment 1 that executes the solvent extraction step, which corresponds to the deterioration product removing step.
The circulation flow path 10 branches in the middle. The flow path branched from the circulation flow path 10 is referred to as a sampling flow path 11. A part of the organic solvent flowing through the circulation flow path 10 is extracted by the extraction flow path 11 and supplied to the tank 20.

A predetermined amount of organic solvent is stored in the tank 20 for a predetermined time. The liquid temperature of the organic solvent flowing through the circulation flow path 10 is 50 to 60 ° C., and by storing this in the tank 20 for a predetermined time, the organic solvent is cooled to room temperature (20 to 30 ° C.) by natural heat dissipation. Then, the deterioration product contained in the organic solvent solidifies in a floc shape. After cooling the organic solvent, the organic solvent in the tank 20 is supplied to the solid-liquid separation device 30. In addition, in this specification, "natural heat dissipation" means that heat is dissipated by the temperature difference from the outside air temperature.

The storage time of the organic solvent may be set to a time during which the organic solvent can be cooled to a temperature at which the deterioration product solidifies. For example, the storage time is 6-18 hours. Further, since the tank 20 performs batch processing, the valve 12 provided in the sampling flow path 11 is opened and closed according to the processing cycle of the tank 20.

The tank 20 corresponds to the "cooling device" described in the claims. Since the organic solvent is cooled by a simple device such as the tank 20, equipment costs and operating costs can be suppressed.

The solid-liquid separation device 30 removes deterioration products from the organic solvent by solid-liquid separation of the organic solvent supplied from the tank 20. The solid-liquid separator 30 is not particularly limited as long as it can separate floc-like deterioration products, but is not particularly limited, but is a filtration device using filter paper, filter cloth, cartridge filter, etc., a centrifuge such as a screw decanter, and a gravity separator such as a thickener. Can be used. Above all, although the filtration device is a simple device, the organic solvent can be separated into solid and liquid, so that the equipment cost can be suppressed.

The organic solvent discharged from the solid-liquid separation device 30 is returned to the circulation flow path 10 through the return flow path 13.

As shown in FIG. 1, the circulation flow path 10 passes through the extraction step, the washing step, the back extraction step, the dezincification step, and the activation step in this order, and the organic solvent is circulated in this order. The organic solvent discharged from the activation step is supplied to the extraction stage.

The position where the organic solvent is extracted in the deterioration product removing step, that is, the connection position of the extraction flow path 11, is not particularly limited. This is because the organic solvent circulating in the circulation flow path 10 contains the deterioration product at any position, and the deterioration product can be removed by extracting the organic solvent at any position.

However, it is preferable that the sampling flow path 11 is connected between the back extraction stage and the activation step in the circulation flow path 10. The organic solvent between the extraction stage and the back extraction stage contains cobalt, which is the target substance. On the other hand, the organic solvent after the back extraction stage has a low cobalt content. Therefore, when the organic solvent is cooled to solidify the deterioration product, cobalt is less likely to be incorporated into the solidified degrading substance. Therefore, the loss of cobalt can be reduced.

By removing the deterioration product in the deterioration product removing step, the amount of organic solvent held in the solvent extraction equipment 1 is reduced. Therefore, a new organic extractant is supplied to the circulation flow path 10 so as to make up for the shortage due to the removal of the deterioration product. The configuration of the organic solvent supply device for supplying the new organic extractant is not particularly limited, but for example, the configuration includes a tank for storing the new organic extractant and a pump for feeding the organic extractant in the tank. Conceivable.

The supply position of the new organic extractant is not particularly limited, but the extraction stage is preferable. This is because it is a position where the extraction function of the organic solvent is exhibited.

As described above, since the deterioration product solidified by cooling can be removed by solid-liquid separation, it is possible to suppress an increase in the deterioration product contained in the organic solvent circulating in the solvent extraction equipment 1. Further, by supplying a new organic extractant, the amount of the organic solvent held in the solvent extraction equipment 1 can be maintained, and the ratio of deteriorated products in the organic extractant can be reduced. Therefore, the extraction efficiency of the solvent extraction step can be maintained.

By the way, if a reducing agent is added to the extraction starting liquid to lower the redox potential of the extraction starting liquid, the increase of deterioration products contained in the organic solvent can be further suppressed. The configuration of the reducing agent adding device for adding the reducing agent is not particularly limited, but for example, a configuration including a tank for storing the reducing agent and a pump for feeding the reducing agent in the tank can be considered.

The reducing agent is not particularly limited, and sodium thiosulfate, sodium sulfite, sodium hydrogen sulfite and the like can be used. Of these, sodium thiosulfate, which is generally used as a dehalogenating agent and produces less sulfate roots, is preferably used.

Further, it is preferable to adjust the redox potential of the extraction starting liquid to 500 to 550 mV. As disclosed in Patent Document 1, in order to adjust the redox potential of the extraction starting solution to 500 mV or less, it is necessary to add 60 mg or more of sodium thiosulfate per 1 L of the extraction starting solution. However, in order to adjust the redox potential of the extraction starting solution to 525 mV, the amount of sodium thiosulfate added per 1 L of the extraction starting solution may be 40 mg, and in order to adjust the redox potential of the extraction starting solution to 550 mV. The amount of sodium thiosulfate added per 1 L of the extraction starting solution may be 20 mg. As described above, when the redox potential of the extraction starting liquid is adjusted to 500 to 550 mV, the amount of sodium thiosulfate added can be reduced to a maximum of 1/3 as compared with the case where the oxidation-reduction potential is adjusted to 500 mV or less.

Therefore, by adjusting the redox potential of the extraction starting liquid to 500 to 550 mV, it is possible to reduce the amount of deteriorated products generated while suppressing the amount of the reducing agent added. By suppressing the amount of the reducing agent added, the increase in sulfate roots can be suppressed. As a result, it is possible to suppress an increase in electric power cost in the electrolysis process in the subsequent process, and maintain the chlorine recovery rate.

When sodium thiosulfate is used as the reducing agent, it is preferably an aqueous solution having a concentration of 50 to 125 g / L. By making it an aqueous solution, it can be efficiently mixed with the extraction starting liquid. Further, when the concentration is 50 g / L or more, an increase in the amount of water during the hydrometallurgy process can be suppressed, the concentration of the valuable metal does not decrease, and the operation efficiency is improved. Further, when the concentration is 125 g / L or less, there is no possibility that sodium thiosulfate is precipitated to block the pipe.

The solvent for dissolving sodium thiosulfate may be pure water or industrial water. It is preferable to dissolve sodium thiosulfate in the nickel chloride aqueous solution obtained from the extraction stage. Then, the increase in the amount of water during the hydrometallurgy process can be suppressed.

[Second Embodiment]
The inventor of the present application has obtained the finding that the solid phase state of pure DNOA changes around 20 ° C. Further, the solid phase state of the organic solvent in which TNOA (organic extractant) is 27 to 28% by volume, DNOA is less than 1% by volume, and the rest is aromatic hydrocarbon (diluent) changes at around 25 ° C. I got the knowledge. That is, when the organic solvent is cooled to 25 ° C. or lower, the gel-like DNOA becomes floc-like. Therefore, if the organic solvent is cooled by natural heat dissipation as in the first embodiment, when the outside air temperature exceeds 25 ° C., DNOA becomes a gel and cannot be sufficiently removed by solid-liquid separation.

Therefore, in the present embodiment, instead of cooling the organic solvent by natural heat dissipation in the first embodiment, the organic solvent is cooled by forced heat dissipation. The device for cooling the organic solvent by forced heat dissipation is not particularly limited, but a configuration in which cold air obtained from the vortex tube is blown into the organic solvent stored in the tank 20 may be used, or a water cooling jacket may be provided around the tank 20. But it may be. In addition, in this specification, "forced heat dissipation" means heat dissipation by direct or indirect contact with a refrigerant.

If the organic solvent is cooled by forced heat dissipation, the organic solvent can be cooled to a desired temperature (for example, 25 ° C. or lower) without being affected by the outside air temperature. Since the deterioration product (DNOA) can be made into a floc shape, it can be sufficiently removed by solid-liquid separation.

[Third Embodiment]
After adding water to the organic solvent, the mixed solution may be solid-liquid separated to remove the deterioration product. The water added to the organic solvent is not particularly limited, but from the viewpoint of water balance in the hydrometallurgical process, it is preferable to use the electrolytic waste liquid (anolite) obtained from the electrolytic step (see FIG. 3).

Water may be added to the organic solvent at a stage prior to solid-liquid separation. For example, water may be supplied to the tank 20. In this case, water may be supplied after the organic solvent is supplied to the tank 20, or the organic solvent may be supplied after the water is supplied to the tank 20. Further, the organic solvent and water may be supplied to the tank 20 at the same time.

Water is preferably at a low temperature (eg, 25 ° C. or lower). The timing of supplying the low-temperature water to the tank 20 may be before, after, or during the cooling of the organic solvent. The timing of supplying hot water (for example, exceeding 25 ° C.) to the tank 20 is preferably before cooling of the organic solvent.

The solid-liquid separation device 30 separates the mixed liquid of the organic solvent and water discharged from the tank 20 into solid-liquid. This removes the degradation products from the mixture. By adding water to the organic solvent, the time required for solid-liquid separation can be shortened. The reason is presumed to be as follows.

The organic solvent contains impurities such as zinc, iron and copper. In particular, when the organic solvent is extracted between the back extraction step and the dezincification step, the organic solvent contains a relatively large amount of impurities. When this organic solvent is cooled, the deterioration product solidifies in a floc shape, and some of the impurities contained in the organic solvent become a gel-like solid.

When an organic solvent containing solids composed of impurities is separated into solids and liquids as it is, it takes a long time for solids and liquids to be separated because the amount of solids is relatively large. For example, when a filtration device is used as the solid-liquid separation device 30, solid matter composed of impurities causes clogging, and filtration takes time.

On the other hand, when water is added to the organic solvent, a solid substance composed of impurities contained in the organic solvent dissolves in water. That is, the amount of solid matter consisting of impurities that interferes with solid-liquid separation can be reduced, leaving the deterioration product to be removed. Therefore, the time required for solid-liquid separation can be shortened.

The amount of water added is preferably 33% by volume or more of the organic solvent. When the amount of water added is 33% by volume of the organic solvent, the time required for solid-liquid separation can be reduced by half. Therefore, the solid-liquid separation treatment can be performed twice as many times within the same treatment time as in the case where water is not added. The amount of water added is preferably 67% by volume or less of the organic solvent. By doing so, the volume of the mixed liquid does not increase too much, and the load on the solid-liquid separation device 30 can be reduced.

Further, the mixed solution of the organic solvent and water may be solid-liquid separated in multiple steps. For example, a plurality of solid-liquid separation devices 30 may be arranged in series to process the mixed liquids in order. The filtrate may be repeatedly charged into one solid-liquid separator 30. By adding water to the organic solvent, the time required for solid-liquid separation can be shortened, and it becomes easy to secure the time for performing solid-liquid separation in multiple stages. By solid-liquid separation of the mixed solution in multiple stages, it is possible to reduce the loss of deterioration products. That is, the removal rate of the deteriorated product can be improved. As a result, the increase of deterioration products contained in the organic solvent can be further suppressed.

Next, an embodiment will be described.
The hydrometallurgy process shown in FIG. 3 was operated. In the solvent extraction step shown in FIG. 1, a nickel chloride aqueous solution containing cobalt was used as an extraction starting solution, and a nickel chloride aqueous solution and a cobalt chloride aqueous solution were obtained by solvent extraction. In the solvent extraction step, an AC multi-stage mixer settler consisting of three extraction stages, three cleaning stages, and three back extraction stages was used.

The flow rate of the extraction starting liquid supplied to the extraction stage is 2,000 m ³ / day, and the redox potential is 1,050 mV. The Ni concentration of the extraction starting solution is 160 to 300 g / L, the Co concentration is 6 to 13 g / L, the Cu concentration is 0.01 to 0.05 g / L, and the Zn concentration is 0.01 to 0.03 g / L. The Fe concentration is 6 to 20 mg / L. The organic solvent used in the solvent extraction step contains 28% by volume of TNOA as an organic extractant and 72% by volume of an aromatic hydrocarbon (Maruzen Petrochemical Co., Ltd .: trade name Swazole 1800) as a diluent. The flow rate of the organic solvent supplied to the extraction stage is 2,200 m ³ / day. The organic solvent held in the solvent extraction equipment is 200 m ³ . Therefore, the organic solvent circulates in the solvent extraction facility about 11 times a day.

(Example 1)
An aqueous sodium thiosulfate solution having a concentration of 125 g / L was added to the extraction starting solution with a metering pump. Here, the addition amount was set to 30 kg / day. As a result, the redox potential of the extraction starting solution could be adjusted to 550 mV.

Using the equipment shown in FIG. 2, the organic solvent was extracted immediately after the back extraction stage to remove the deteriorated product. Degradation products were removed once a day. The amount of organic solvent extracted was 1 m ³ / time. The extracted organic solvent was stored in a tank and left for 16 hours. As a result, the liquid temperature of the organic solvent, which was 58 ° C., was lowered to 25 ° C., and a floc-like solid substance was produced. In addition, the organic solvent after cooling was filtered to remove deterioration products. Filtration was performed by forced filtration using a pump using a filter cloth. It took 2 hours to filter 1 m ^{3 of the organic solvent.} The amount of deterioration products removed was measured by a gas chromatograph mass spectrometer (model number: QP-2010 manufactured by Shimadzu Corporation, the same applies hereinafter).

The organic solvent after removing the degradation products was put back just before the dezincification step. In addition, a new TNOA was supplied to the extraction stage by a metering pump so as to make up for the shortage due to the removal of the deterioration product. When the solid content removed by filtration was analyzed by a gas chromatograph mass spectrometer, 50% by volume of the solid content was DNOA and the remaining 50% by volume was TNOA. It is considered that this is because TNOA is taken up when DNOA solidifies.

Thirty days after the start of operation, the organic solvent discharged from the back extraction stage was sampled, and the DNOA concentration was measured with a gas chromatograph mass spectrometer. As a result, the DNOA concentration was 0.065% by volume.

(Example 2)
After Example 1, the cold air (20 ° C.) obtained from the vortex tube was guided by a vinyl tube and blown into the organic solvent in the tank. As a result, the temperature of the organic solvent supplied to the solid-liquid separator can always be maintained at 25 ° C. or lower. The other conditions are the same as in Example 1.

Thirty days after the start of blowing cold air, the organic solvent discharged from the back extraction stage was sampled, and the DNOA concentration was measured with a gas chromatograph mass spectrometer. As a result, the DNOA concentration was 0.065% by volume. That is, there was no change in the DNOA concentration for 30 days from the start of blowing cold air. This means that substantially all of the degradation products generated during the 30-day operation could be removed.

(Example 3)
After Example 2, water was added to the tank for storing the organic solvent. As water, an electrolytic waste liquid (anolite) obtained from the electrolytic process was used. The amount of water added was ^{350 L with respect to 1 m 3} of the organic solvent (corresponding to 35% by volume). The liquid temperature of anorite is 58 ° C. This anorite was added prior to cooling with cold air.

The cooled mixture was filtered to remove degradation products. Filtration was performed by forced filtration using a pump using a filter cloth. Here, the filtration operation was performed twice. It took 1 hour to filter the mixture once. That is, the time required for solid-liquid separation could be reduced by half as compared with Example 1. The other conditions are the same as in Example 2.

Thirty days after the start of water addition, the organic solvent discharged from the back extraction stage was sampled, and the DNOA concentration was measured with a gas chromatograph mass spectrometer. As a result, the DNOA concentration was 0.058% by volume. That is, the DNOA concentration was slightly lower than that of Example 2. This means that more degradation products could be removed than the degradation products generated during the 30 days of operation.

(Comparative Example 1)
An aqueous sodium thiosulfate solution having a concentration of 125 g / L was added to the extraction starting solution with a metering pump. Here, the addition amount was set to 30 kg / day. As a result, the redox potential of the extraction starting solution could be adjusted to 550 mV. No degradation products were removed. The other conditions are the same as in Example 1.

Thirty days after the start of the operation, the organic solvent discharged from the back extraction stage was sampled, and the DNOA concentration was measured by the same method as in Example 1. As a result, the DNOA concentration was 0.13% by volume.

(Comparative Example 2)
No sodium thiosulfate aqueous solution was added to the extraction starting solution. No degradation products were removed. The other conditions are the same as in Example 1.

Thirty days after the start of the operation, the organic solvent discharged from the back extraction stage was sampled, and the DNOA concentration was measured by the same method as in Example 1. As a result, the DNOA concentration was 0.26% by volume.

The measurement results of the DNOA concentration in Examples 1 to 3 and Comparative Examples 1 and 2 are summarized in the graph of FIG. When no treatment is performed on the deteriorated product (Comparative Example 2), the DNOA concentration 30 days after the start of operation is 0.26% by volume. When an aqueous sodium thiosulfate solution is added to the extraction starting solution (Comparative Example 1), the DNOA concentration 30 days after the start of operation becomes 0.13% by volume, which is halved. Further, when the deterioration product is also removed (Example 1), the DNOA concentration 30 days after the start of operation becomes 0.065% by volume, which is further halved. As described above, it was confirmed that the combination of the addition of sodium thiosulfate and the removal of the deterioration product can reduce the increase in DNOA concentration to 1/4 as compared with the case where nothing is done.

Further, by cooling the organic solvent by forced heat dissipation (Example 2), the same amount of deterioration products as the generated amount could be removed, and the increase in DNOA concentration could be stopped. Furthermore, by performing the filtration operation twice (Example 3), more deterioration products than the generated amount could be removed, and the DNOA concentration could be reduced.

1 Solvent extraction equipment 10 Circulation flow path 11 Extraction flow path 12 Valve 13 Return flow path 20 Tank 30 Solid-liquid separator

Claims (16)

By recycling the organic solvent containing TNOA as an amine-based extractant, cobalt from nickel chloride aqueous solution is extracted DeHajimeeki a solvent extraction equipment for solvent extraction,
A circulation channel for circulating the organic solvent and
A sampling flow path that branches from the circulation flow path and extracts a part of the organic solvent, and a sampling flow path.
A cooling device that solidifies DNOA, which is a deterioration product of the amine-based extractant, by cooling the organic solvent supplied from the extraction flow path.
A solid-liquid separation device for removing the deterioration product from the organic solvent supplied from the cooling device, and a solid-liquid separation device.
A return flow path for returning the organic solvent discharged from the solid-liquid separation device to the circulation flow path, and a return flow path.
An organic solvent supply device for supplying a new amine-based extractant to the circulation channel is provided so as to make up for the shortage due to the removal of the deterioration product .
A solvent extraction facility characterized in that the extraction starting liquid is a liquid after treatment of an iron removal step in a hydrometallurgical process for recovering nickel and cobalt from sulfide. The solvent extraction equipment according to claim 1, wherein the cooling device is a tank that cools the organic solvent by natural heat dissipation by storing the organic solvent for a predetermined time. The solvent extraction equipment according to claim 1, wherein the cooling device is a device that cools the organic solvent by forced heat dissipation. The solvent extraction equipment according to claim 1, 2 or 3, wherein the solid-liquid separation apparatus solid-liquid separates a mixture of the organic solvent and water. The solvent extraction equipment according to claim 4, wherein the solid-liquid separation device separates the mixed liquid into solid and liquid in a multi-step manner. The solvent extraction equipment according to claim 1, 2, 3, 4 or 5, wherein the solid-liquid separation device is a filtration device. The circulation flow path passes through an extraction stage, a reverse extraction stage, and an activation step in this order.
The solvent extraction according to claim 1, 2, 3, 4, 5 or 6, wherein the extraction flow path is connected between the reverse extraction step of the circulation flow path and the activation step. Facility. Claims 1 and 2 include a reducing agent adding device for adding a reducing agent to the extraction starting solution to adjust the oxidation-reduction potential of the extraction starting solution to 500 to 550 mV (Ag / AgCl electrode reference). 3, 4, 5, 6 or 7 solvent extraction equipment. By recycling the organic solvent containing TNOA as an amine-based extractant, cobalt from nickel chloride aqueous solution is extracted DeHajimeeki a solvent extraction method of solvent extraction,
A part of the organic solvent is extracted from the circulation channel for circulating the organic solvent.
By cooling the extracted organic solvent, DNOA, which is a deterioration product of the amine-based extractant, is solidified.
By solid-liquid separation of the organic solvent after cooling, the deterioration product is removed from the organic solvent.
The organic solvent after solid-liquid separation is returned to the circulation flow path,
A new amine-based extractant is supplied to the circulation channel so as to make up for the shortage due to the removal of the deterioration product.
A solvent extraction method, wherein the extraction starting liquid is a liquid after treatment of an iron removal step in a hydrometallurgical process for recovering nickel and cobalt from sulfide. The solvent extraction method according to claim 9, wherein the solvent is cooled by storing the organic solvent in a tank for a predetermined time to naturally dissipate heat from the organic solvent. The solvent extraction method according to claim 9, wherein the organic solvent is cooled by forcibly dissipating heat from the organic solvent. The solvent extraction method according to claim 9, 10 or 11, wherein the solid-liquid separation of the organic solvent is performed by a filtration device. The solvent extraction method according to claim 9, 10 or 11, wherein the deterioration product is removed from the mixture by solid-liquid separation of the mixture of the organic solvent and water. The solvent extraction method according to claim 13, wherein the mixed solution is solid-liquid separated in multiple steps. The circulation flow path passes through an extraction stage, a reverse extraction stage, and an activation step in this order.
The solvent extraction method according to claim 9, 10, 11, 12, 13 or 14, wherein a part of the organic solvent is extracted from between the reverse extraction step of the circulation flow path and the activation step. .. Claims 9, 10, 11, 12, and 13 are characterized in that a reducing agent is added to the extraction starting liquid to adjust the redox potential of the extraction starting liquid to 500 to 550 mV (Ag / AgCl electrode reference). , 14 or 15. The solvent extraction method.

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