JP5561201B2 - Method for producing electric cobalt or electric nickel - Google Patents

Description

  The present invention relates to a method for producing electrocobalt or electronickel excellent in acid solubility.

  Cobalt is used as an electrode material for lithium-ion batteries used in mobile phones and laptop computers, special steel materials used in aircraft and plants, magnetic materials, and catalysts used in petroleum refining. .

  The following methods are widely used as a method for purifying cobalt. First, minerals containing cobalt are selected to obtain concentrate. Next, using sulfuric acid or hydrochloric acid, cobalt contained in the concentrate is leached into a sulfuric acid or hydrochloric acid solution, and then impurities such as nickel, iron, and zinc are separated and removed from the leachate by a method such as solvent extraction. A pure cobalt solution is obtained. Then, this sulfuric acid acidic or hydrochloric acid acidic pure solution is used as an electrolytic solution, and cobalt is electrolyzed to obtain electric cobalt.

  Among these, electrolysis using an acidic solution of hydrochloric acid has the advantage that the battery cost during electrolysis is lower than electrolysis using an acidic solution of sulfuric acid. The electrodeposited structure of electrocobalt is very dense and hard. Such characteristics do not affect the characteristics when used as an additive element or magnetic material of a heat-resistant alloy, which is special steel, for example. That is, in the above application, since the electric cobalt is melted at a melting point or higher, the electrodeposited structure of the electric cobalt is eliminated along with the melting and becomes a uniform melt.

  When producing cobalt chemical products such as cobalt sulfate and cobalt chloride using electrocobalt, the characteristic of electrodeposited structure being very dense and hard is that dissolution rate of electrocobalt in acid, that is, acid solubility is good or bad. Can affect product productivity as a result. However, once it is melted by heating it to the melting point or higher as described above, it is then gradually cooled to obtain a metal with a uniform and coarse structure. It becomes.

  In the manufacturing process of cobalt chemical products, electrolytic cobalt is put in a reaction tank filled with an acid such as sulfuric acid or hydrochloric acid, and is oxidized and chemically dissolved while blowing air while maintaining a temperature of 60 to 90 ° C. To obtain a cobalt sulfate solution and a cobalt chloride solution. Next, these solutions are concentrated to crystallize cobalt sulfate or cobalt chloride crystals, or neutralize by adding an alkali such as sodium hydroxide to these solutions to produce cobalt hydroxide precipitates. By doing so, the target cobalt chemical product is manufactured. In this step, if the acid solubility of electrocobalt is low, it takes a long time to dissolve in order to obtain a predetermined amount of solution, and it is necessary to increase the amount of air blown to increase the oxidizing power, As a result, it leads to an increase in facility scale and time and effort for process management.

  As a method for obtaining a metal having excellent acid solubility, there have been several reports regarding nickel having chemical properties similar to cobalt. For example, Patent Document 1 discloses a sulfur-containing electrolytic nickel using a nickel matte or crude nickel anode and a metal nickel plate cathode, and using a sulfate-chloride mixture containing a sulfur-containing compound or a single chloride electrolytic bath. In this manufacturing method, a method is disclosed in which tetrathionate is used as a sulfur-containing compound to be added, and nickel is electrodeposited in a highly soluble form by applying a reverse current for a short time prior to electrolysis. Yes. Patent Document 2 discloses a method for obtaining powder electrodeposition having a large surface area by electrolyzing a nickel sulfate solution.

  However, in the method disclosed in Patent Document 1, there is a problem that an undissolved residue mainly containing sulfur is generated after electrolytic nickel is dissolved because sulfur is contained in electrolytic nickel. Therefore, it takes time for the post-treatment after dissolution, or undissolved residues such as fine sulfur contained in the liquid float in the liquid, which may be involved in producing chemical products and cause impurities. There was concern. Moreover, according to the electric nickel obtained by the method disclosed in Patent Document 2, since the specific surface area is large, the solubility in an acid solution is improved. However, in the form of powder, the electrolytic solution is easily caught in the gap. . When the electrolytic solution is involved, impurities in the electrolytic solution and components of the electrolytic solution itself may be contained in the product when the electrolytic nickel is processed into a product.

Japanese Patent Publication No. 3-59145 Japanese Patent No. 3381793

  The present invention has been made in view of the above problems, and is excellent in acid solubility, hardly causes an undissolved residue at the time of acid dissolution, has a smooth surface, and high-purity electrocobalt, and a method for producing the same, and It aims at providing the manufacturing method of electro nickel.

  In order to solve the above-mentioned problems, the present inventors have conducted extensive research and confirmed that there is a certain tendency between the acid solubility of electric cobalt and the concentration of hydrogen contained in electric cobalt. did. And when the present inventors have further researched, the concentration of hydrogen contained in the electric cobalt can be controlled by energizing a specific method when depositing cobalt by electrolytic purification or electrowinning. As a result, the present invention has been completed.

  Specifically, the present invention provides the following.

  (1) A method of producing electrolytic cobalt or electrolytic nickel by electrolytic collection or electrolytic purification using an electrolytic solution comprising an acidic solution containing cobalt or nickel, and in the electrolytic collection or electrolytic purification, On the other hand, a method for producing electric cobalt or electric nickel, characterized by performing intermittent energization that repeats power outage and energization.

  (2) The method for producing electric cobalt or electric nickel according to (1), wherein in the intermittent energization, the repeated power failure time is 30 to 60 seconds.

  (3) The method for producing electric cobalt or electric nickel according to (1) or (2), wherein the pH of the electrolytic solution is 1.0 to 3.5.

  (4) The electric cobalt characterized by having a hydrogen concentration of 20 ppm or more and a sulfur concentration of 1 ppm or less.

According to the electrocobalt of the present invention, it is excellent in acid solubility and contains almost no sulfur as an impurity, so that a high-quality product can be efficiently produced.
Further, according to the method for producing electrocobalt or electronickel of the present invention, it is excellent in acid solubility, hardly causes undissolved residue during acid dissolution, has a smooth surface, and has high purity electrocobalt or electronickel. Can be obtained.

It is a figure which shows the relationship between the dissolution rate ratio of electric cobalt, and the hydrogen concentration (ppm) in this electric cobalt. It is a figure which shows the relationship between the hydrogen concentration (ppm) in electric cobalt, and the power failure time (minute) repeated by intermittent electricity supply. It is a figure which shows the relationship between the dissolution rate ratio of electric cobalt, and the power failure time (minute) repeated by intermittent electricity supply. It is a figure which shows the relationship between the dissolution rate ratio of electric cobalt, and the hydrogen concentration (ppm) in electric cobalt. It is a figure which shows the relationship between the current efficiency (%) at the time of electrowinning, and the hydrogen concentration (ppm) in electric cobalt. It is a figure which shows the relationship between the current efficiency (%) at the time of electrowinning, and the dissolution rate ratio of electric cobalt.

  Hereinafter, specific embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and may be implemented with appropriate modifications within the scope of the object of the present invention. be able to.

  The electric cobalt of the present invention is characterized in that the hydrogen concentration is 20 ppm or more and the sulfur concentration is 1 ppm or less. The present invention is significant in that it has been found for the first time that there is a certain tendency between the concentration of hydrogen in electrolytic cobalt and the solubility of the electrolytic cobalt in acid. According to the electrocobalt of the present invention, since it exhibits excellent solubility in acids, a cobalt-containing product can be produced efficiently. In the present specification, the electric cobalt or the like means cobalt metal or the like obtained by electrolytic collection or electrolytic purification.

  The electric cobalt of the present invention preferably has a hydrogen concentration of 40 ppm or more, more preferably 60 ppm or more. As the hydrogen concentration in the electrocobalt increases, the acid solubility is relatively improved. When the hydrogen concentration is 20 ppm or more, the solubility of electrocobalt in an acid is remarkably improved. When the hydrogen concentration is 40 ppm or more, it is more easily dissolved, and when it is 60 ppm or more, the dissolution rate is double that of the conventional one. The upper limit is not particularly limited. However, even if it exceeds 60 ppm, the solubility is hardly improved and is maintained as it is.

  Although the mechanism by which dissolution of electrocobalt in an acid is promoted when the hydrogen concentration in electrocobalt is increased is not clear, in the acid solution, the hydrogen atom contained in electrocobalt and the cobalt atom are adjacent to each other. Thus, it is presumed that a battery reaction occurs, hydrogen having a small ionization tendency acts as a cathode, and cobalt having a large ionization tendency acts as an anode and is eluted in an acid solution. In addition, since the hydrogen gas after elution of electrocobalt escapes to the gas phase as bubbles, it is considered that there is no possibility that the product is contaminated by generating an undissolved residue as in the conventional case.

  The electrocobalt of the present invention preferably has a sulfur concentration of 0.5 ppm or less, more preferably 0.1 ppm or less. According to the electrocobalt of the present invention, since it hardly contains sulfur that causes undissolved residue during acid dissolution, it takes time for post-treatment after acid dissolution, or the contained fine sulfur content is not dissolved. There is no concern of becoming a residue, floating in the liquid, and being involved in the production of a chemical product to cause contamination of impurities.

  Since the electrocobalt of the present invention exhibits good solubility in acid, for example, even when it is used for the production of cobalt chemical products such as cobalt sulfate and cobalt chloride, a predetermined amount of solution is used as in the prior art. Therefore, it is not necessary to increase the oxidizing power, such as increasing the amount of air blown, and the need to expand the equipment scale and process management.

  The method for producing electrocobalt according to the present invention is not particularly limited. Electrolytic extraction or electrolytic purification is performed by intermittently energizing and repeating power failure and energization with respect to an electrolytic solution composed of an acidic solution containing cobalt. It is preferable to manufacture by. This method is an energization method in which energization and power failure are repeated, unlike an energization method generally performed when cobalt is produced by electrolysis, that is, a method of continuous energization. In this specification, continuous energization that is generally performed is referred to as unidirectional energization, whereas energization that repeats power outage and energization is referred to as intermittent energization.

  As a method of obtaining electric cobalt having a high hydrogen concentration, for example, in one-way electrolysis, a method of mechanically entraining hydrogen gas in cobalt by blowing hydrogen gas into the electrolyte may be considered. Even if a large amount of gas is blown, the efficiency with which hydrogen gas is entrained in cobalt is extremely low, which is not practical. In addition, blowing hydrogen gas into the electrolytic cell may cause ignition due to a short circuit of the electrode, which is problematic in terms of safety. Furthermore, in the case of large bubbles generated by blowing hydrogen gas, the surface of the electrodeposit becomes rough, and there is a high possibility that the electrolytic solution is simultaneously involved in cobalt. Since the electrolytic solution contains impurities such as zinc and copper, and sulfur and chlorine, which are components of the electrolytic solution itself, the inclusion of these in the electric cobalt leads to a decrease in product quality, which is not preferable. .

  When the present inventors produce electrolytic cobalt by electrowinning or electrolytic refining, the electrolytic solution consisting of an acidic solution containing cobalt is subjected to intermittent energization that repeats power outage and energization. It was found that hydrogen can be efficiently contained in It is known that the initial hydrogen generated by electrolysis is extremely active finely and chemically. When energization and power outage are repeated, initial active hydrogen is frequently generated, and this is considered to diffuse into the electrodeposited cobalt.

  In the production method of the present invention, an acidic solution containing cobalt is used as the electrolytic solution. The acidic solution containing cobalt used as the electrolytic solution may be a hydrochloric acid bath or a sulfuric acid bath, and is not particularly limited. The pH of the acidic solution is preferably in the range of 1.0 to 3.5, more preferably in the range of 1.2 to 3.0. If the pH of the electrolytic solution is within the above range, electrocobalt with higher acid solubility can be obtained. When the pH of the electrolyte is less than 1.0, the electrodeposited electrocobalt is immediately redissolved or excessive hydrogen is generated, resulting in a significant reduction in cathode current efficiency to about 50%. Could have a significant impact on productivity. In addition, when the pH of the electrolytic solution exceeds 3.5, the pH further rises locally on the cathode surface during electrolysis, and cobalt ions form a heterogeneous mixture of metal and hydroxide, resulting in pure electricity. Cobalt may not be obtained.

  The method for adjusting the pH of the electrolytic solution is not particularly limited. For example, while measuring the pH of the electrolytic solution using a commercially available pH meter, the recycled acid is added to the free acid in the electrolytic solution. The pH may be neutralized to raise the pH, or an acid such as hydrochloric acid may be added to lower the pH.

  In the production method of the present invention, the preferable cobalt concentration of the electrolytic solution varies depending on the pH and the repetition period of power failure and energization described later, and thus cannot be specified unconditionally. For example, when both the pH and the cobalt concentration are low, hydrogen is excessively generated, which is not preferable because the current efficiency of the cathode decreases. On the other hand, when both the pH and the cobalt concentration are high, the amount of hydrogen generated Is decreased, and as a result, the solubility is lowered, which is not preferable. As a preferred example, if the pH of the electrolyte is in the range of 1 to 1.5, the cobalt concentration is about 50 g / l.

  In the manufacturing method of this invention, intermittent electricity supply which repeats a power failure and electricity supply as one cycle with respect to the electrolyte solution which consists of an acidic solution containing cobalt is performed. In this intermittent energization, the repeated power failure time is preferably in the range of 30 to 60 seconds per cycle, or preferably in the range of 6 to 12 minutes, more preferably in the range of 30 to 60 seconds. preferable. If the repeated power failure time is within the above range, it is possible to obtain electric cobalt having better solubility in acid than electric cobalt obtained by conventional one-way electrolysis.

  The reason why the electric cobalt having good solubility in acid can be obtained by setting the repeated power failure time within the above range is not clear, but can be estimated as follows, for example. During the electrolysis of cobalt, some hydrogen is generated on the cathode from the deposition potential. On the surface of the cathode, the electrolyte in the electrolytic cell flows as an upward flow due to the reaction of the electrolytic solution through the electrolytic cell, the magnetic field accompanying the energization, and the reaction at the electrode. Since this upward flow occurs with energization, it disappears when a power failure occurs. As mentioned above, the initial hydrogen generated by electrolysis is finely and chemically extremely active, and therefore tends to diffuse into cobalt at the same time as the generation. As a result, the hydrogen atom and the cobalt atom are adjacent to each other. It is thought that an alloy that easily causes a battery reaction is formed. On the other hand, in the conventional general one-way energization, the generated hydrogen is transported to the liquid surface by the upward flow, so it is considered difficult to diffuse into cobalt.

  In addition, when energization is performed by shortening the length of one cycle and repeating a power failure for a short time, active hydrogen is generated one after another on the cathode, so that the amount of diffusion into the electrodeposited cobalt increases. It is considered that the hydrogen concentration is increased and the acid solubility is improved. On the other hand, even if the amount of electricity to be energized is the same, if the energization is repeated for a long period of time and the power of the cycle is extended for a long time, the upward flow on the cathode surface stops due to the long-time power outage. The hydrogen deposited and deposited on the cathode surface is less likely to be transported to the liquid surface and the deposition time becomes longer, so that it is likely to enter the cobalt and diffuse. For this reason, it is presumed that an electric cobalt having a high hydrogen concentration and good acid solubility can be obtained when the power failure time is short and long.

In the production method of the present invention, the current density used for electrolysis is not particularly defined, but is preferably in a range where the electrodeposition surface is smooth. The range of the current density at which the electrodeposition surface becomes smooth cannot be determined unconditionally because of the influence of other electrolysis conditions, but is generally in the range of 200 to 1500 A / m ² . If the current density is too high, it is not preferable because it exceeds the limit current density on the cathode surface, generation of hydrogen is excessively prioritized, and the power cost is remarkably increased. On the other hand, if the current density is too low, productivity is lowered, which is not preferable.

  If the surface of the electrodeposition is not smooth, impurities and electrolytes can easily be entrained during electrolysis, resulting in low-purity electrocobalt, long dendrites on the electrodeposition surface, and short-circuiting. It is not preferable. In addition, if the surface of the electrocobalt finally obtained is not smooth, handling properties when processing into a product are lowered, which is also not preferable. The surface roughness of the finally obtained electrocobalt preferably has a maximum height (Rmax) of 30 μm or less measured by a method based on JIS B0601 (2001) using a contact surface roughness meter.

  In the production method of the present invention, the current efficiency of the cathode is preferably in the range of 70 to 95%. Here, the current efficiency means the ratio of the current used for the target electrode reaction out of the passed current, and in general, the actual electrodeposition amount with respect to the theoretical electrodeposition amount calculated from the energized electricity amount. The percentage is expressed as a percentage. If the current efficiency of the cathode is within the above range, electric cobalt having a hydrogen concentration of 20 ppm or more can be obtained. On the other hand, when the cathode current efficiency exceeds 95%, the hydrogen concentration in the electric cobalt is less than 20 ppm. From this, it is considered that the acid solubility of the obtained electric cobalt can be judged by measuring the current efficiency when producing the electric cobalt. According to this method, even if the hydrogen concentration in the finally obtained electric cobalt is not measured, it is possible to easily determine whether the acid solubility of the electric cobalt is good or not simply by measuring the current efficiency during production. be able to. In addition, when the cathode current efficiency is low, it is expected that electrocobalt with a high hydrogen concentration can be obtained, but at the same time, the productivity may be remarkably lowered, so 70% or more is desirable.

  In the present specification, although cobalt was described in detail, the production method of the present invention can be easily applied to nickel having chemical properties similar to cobalt.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention does not receive a restriction | limiting at all in these description.

[Evaluation of acid solubility]
The acid solubility was judged by using the dissolution rate per unit area of electrolytic cobalt as an index. The dissolution rate per unit area of electrocobalt that has been produced industrially in the past was used as the evaluation standard (1 time).

(1) Manufacture of evaluation standard products A 8 mm thick cobalt plate is cut into a size of 60 mm long × 60 mm wide, and other portions are plated so that the electrode area is 20 cm ² only on one side (40 mm long × 50 mm wide). The material masked with the masking tape for use was used as the anode. Moreover, a 0.5 mm thick titanium plate is cut into a size of 60 mm long × 60 mm wide, and the other area is covered with a masking tape for plating so that the electrode area is 20 cm ² only on one side (40 mm long × 50 mm wide). The masked one was used as the cathode. The electrolytic solution was prepared by dissolving cobalt chloride as a reagent in pure water and adjusting the cobalt concentration in the solution to 55 g / L, and then adjusting the pH to 1.2 using hydrochloric acid. A thing was used. Next, the anode and the cathode were placed in a vinyl chloride container (electrolyzer) having a capacity of 2 liters, respectively, and arranged such that the distance between the electrode plates facing each other was 60 mm. Then, 1.8 liters of the electrolytic solution heated to 50 ° C. is put in this electrolytic cell, and the rotation speed (10 to 20 rotations) is set so as not to stop naturally using a stirrer and a stirrer while maintaining the temperature. (Min / min). A current of 0.54 A was applied for 48 hours so that the cathode current density was 270 A / m ² . After energization for 48 hours, the energization was stopped, the cathode was pulled up, and the cobalt electrodeposited on the surface of the titanium plate was impacted with a hammer and peeled off from the titanium plate. The peeled cobalt was washed with pure water, then further washed with alcohol, and dried with cold air from a dryer to obtain electric cobalt as an evaluation standard product.

(2) Preparation of Sample for Dissolution Rate Measurement Electrocobalt was cut using a cutting machine so that the area was in the range of 1.0 to 3.0 cm ² . Next, the cut electrocobalt was placed in the bottom of a plastic holder so that the surface in contact with the cathode was a polished surface, and filled with a room temperature curing type epoxy resin. After allowing to stand for 24 hours for consolidation, the mold was removed to obtain a consolidated sample. The obtained consolidated sample is set in an automatic polishing machine (product name: Ecomet, manufactured by Buehler), and is rotated with a slurry of water and alumina using a water-resistant abrasive paper having a roughness of 320. Wet polished. The consolidated sample polished with the # 320 abrasive paper was then wet-polished with an automatic polishing machine replaced with a # 1000 abrasive paper until no scratches were visible. Further, after polishing with an automatic polishing machine replaced with polishing paper having a roughness of No. 2400 until scratches could not be visually confirmed, the size of the portion exposed by polishing was measured, and the surface area was calculated. The ground sample after polishing was thoroughly washed with pure water, further washed with ethanol and degreased, and then dried with cold air from a dryer, and this was used as a sample for dissolution rate measurement.

(3) Measurement of dissolution rate For the measurement of the dissolution rate, 200 ml of 22 mass% sulfuric acid was used. The concentration of the sulfuric acid is set in consideration of the cobalt sulfate not reaching the saturation concentration even when the electric cobalt is completely dissolved. The sample for dissolution rate measurement was put into the sulfuric acid heated to 90 ° C. and immersed for 3 hours while stirring with a stirrer and a stirrer while maintaining the temperature. Then, the sample was taken out and the surface was washed with pure water. Next, the cleaning solution and the solution after the sample was taken out were collected, the total amount was measured, and the electric cobalt concentration in these solutions was measured by an inductively coupled plasma emission spectroscopy (ICP-AES) method. And the dissolution rate of the electric cobalt per unit area was computed from the quantity of the electric cobalt eluted from the said sample.

(4) Measurement of hydrogen concentration The hydrogen concentration in the electric cobalt was measured using a hydrogen analyzer (EMGA-921) manufactured by Horiba, Ltd. In addition, the remaining part of the electrocobalt cut | disconnected by said (2) was used for the sample for a hydrogen concentration measurement.

(5) Measurement of sulfur concentration The sulfur concentration in electrocobalt was measured by glow discharge mass spectrometry (GD-MS). In addition, the remaining part of the electrocobalt cut | disconnected by said (2) was used for the sample for sulfur concentration measurement.

<Test Example 1>
The relationship between the acid solubility of electrocobalt and the hydrogen concentration in the electrocobalt was examined.

In the test, five types of electric cobalt produced by changing electrolysis conditions such as current density, cobalt concentration of the electrolytic solution, and energization method, and electric cobalt commercially available for plating anodes were used. After measuring the dissolution rate by the above method, these electrocobalts were produced by electrolytic extraction (hydrogen concentration: 3 ppm) industrially by the conventional method described in the above (1), that is, by conducting unidirectional energization. ) Was used as an evaluation standard product, and a dissolution rate ratio was calculated when the dissolution rate (90 g / m ² / hr) of the evaluation standard product with respect to sulfuric acid was 1, and the quality of the acid solubility was determined based on this value. Further, the hydrogen concentration in the electric cobalt was also measured by the above method. FIG. 1 shows the relationship between the dissolution rate ratio of electrocobalt to acid based on conventional electrocobalt and the hydrogen concentration (ppm) in electrocobalt.

  As shown in FIG. 1, the acid solubility of electric cobalt improved as the hydrogen concentration in the electric cobalt increased. In particular, when the hydrogen concentration exceeded 20 ppm, the solubility was remarkably improved, and when it exceeded 40 ppm, it was more easily dissolved, and at around 60 ppm, the solubility was more than twice that of conventional electric cobalt. And when hydrogen concentration exceeded 60 ppm, even if hydrogen concentration was high after that, the change was not recognized by solubility. In addition, the hydrogen concentration in commercially available electric cobalt was 5 ppm, and the acid solubility was comparable to the electric cobalt produced by electrowinning according to the conventional method described in (1) above.

  From this, there is a certain tendency between the acid solubility of the electric cobalt and the hydrogen concentration in the electric cobalt. By increasing the hydrogen concentration in the electric cobalt, the acid solubility of the electric cobalt is increased. It became clear that it could be improved.

<Test Example 2>
Using electric cobalt produced by electrolytic extraction industrially by the conventional method of conducting unidirectional energization, and electric cobalt obtained by the method of electrolytic collection produced by intermittent energization that repeats power outage and energization, The effect of intermittent energization on the hydrogen concentration in electrolytic cobalt was investigated.

The electrolytic solution was adjusted so that the cobalt concentration in the solution was 55 g / L using cobalt chloride as a reagent, and then adjusted to a pH of 1.2 using hydrochloric acid. Next, an anode and a cathode prepared in the same manner as in the production of the evaluation standard product in (1) above were put in a vinyl chloride container (electrolyzer) having a capacity of 1.5 liters and faced each other. The electrodes were arranged so that the distance between the anode and the cathode was 60 mm, and during energization, wiring was performed so as to automatically repeat the power outage and energization for a predetermined time via a timer. The ratio of the energization time to the total electrolysis time was adjusted to be 80 to 90%. Then, 1 liter of the above electrolytic solution heated to 50 ° C. is put into this electrolytic cell, and the number of revolutions (10 to 20 revolutions / minute) that does not stop spontaneously using a stirrer and a stirrer while maintaining the temperature. ), A current of 0.54 A was applied for 48 hours so that the current density of the cathode was 270 A / m ² . During the electrolysis, the amount of liquid was observed, and when it decreased due to evaporation, pure water was replenished each time to maintain a constant amount of liquid.

  After energization for 48 hours, the energization was stopped, the cathode was pulled up, and the cobalt electrodeposited on the surface of the titanium plate was impacted with a hammer and peeled off from the titanium plate. The peeled cobalt was washed with pure water, further washed with alcohol, and dried with cold air from a dryer to obtain electric cobalt. The hydrogen concentration in the electric cobalt thus obtained was measured by the above method. FIG. 2 shows the relationship between the hydrogen concentration (ppm) in the electric cobalt and the power failure time (minutes) repeated by intermittent energization. In addition, the hydrogen concentration in the electrocobalt produced by electrolytically collecting and manufacturing industrially by a conventional method using unidirectional energization used as a comparative control was 3 ppm.

  As shown in FIG. 2, the hydrogen concentration in the electrical cobalt obtained by intermittent energization that repeats power outage and energization is compared with the hydrogen concentration in the electrical cobalt obtained by the conventional method in which unidirectional energization is performed. It was expensive. Further, the hydrogen concentration in the electric cobalt varies depending on the length of the power failure time, that is, the repetition cycle between the energization and the power failure, and in particular, the power failure time is around 0.5 to 1 minute, more than 6 minutes and 10 to 10 minutes. By setting the time around 12 minutes, electrocobalt with a high hydrogen concentration was obtained.

  From this, it has been clarified that electric cobalt having a high hydrogen concentration can be obtained by intermittently energizing an electrolytic solution composed of an acidic solution containing cobalt by repeating power interruption and energization. It has also been clarified that electric cobalt having a higher hydrogen concentration can be obtained by adjusting the length of the cycle of energization and power failure.

<Test Example 3>
Electrocobalt manufactured by electrolytic extraction industrially by the conventional method of conducting unidirectional energization, and manufactured by electrolytic extraction by performing intermittent energization that repeats power outage and energization for an electrolytic solution consisting of an acidic solution containing cobalt The effect of intermittent energization on the acid solubility of electrocobalt was investigated using electrocobalt.

The electrolytic solution was adjusted so that the cobalt concentration in the solution was 55 g / L using cobalt chloride as a reagent, and then adjusted to a pH of 1.2 using hydrochloric acid. Next, an anode and a cathode prepared in the same manner as in the production of the evaluation standard product in (1) above were put in a vinyl chloride container (electrolyzer) having a capacity of 1.5 liters and faced each other. The electrodes were arranged so that the distance between the anode and the cathode was 60 mm, and during energization, wiring was performed so as to automatically repeat the power outage and energization for a predetermined time via a timer. The ratio of the energization time to the total electrolysis time was adjusted to be 80 to 90%. Then, 1 liter of the electrolysis starting solution heated to 50 ° C. is put in this electrolytic cell, and the rotation speed (10 to 20 rotations / degree) that does not stop spontaneously using a stirrer and a stirrer while maintaining the temperature. The current of 0.54 A was applied for 48 hours so that the cathode current density was 270 A / m ² . During the electrolysis, the amount of liquid was observed, and when it decreased due to evaporation, pure water was replenished each time to maintain a constant amount of liquid.

After energization for 48 hours, the energization was stopped, the cathode was pulled up, and the cobalt electrodeposited on the surface of the titanium plate was impacted with a hammer and peeled off from the titanium plate. The peeled cobalt was washed with pure water, further washed with alcohol, and dried with cold air from a dryer to obtain electric cobalt. The electrolytic cobalt thus obtained was measured for dissolution rate by the above method, and the electrolytic cobalt produced by electrolytic extraction industrially by conducting the unidirectional energization described in (1) above was used as an evaluation standard product. The dissolution rate ratio when the dissolution rate (90 g / m ² / hr) in sulfuric acid of the evaluation standard product was 1 was calculated, and the quality of acid solubility was judged based on the calculated value. FIG. 3 shows the relationship between the dissolution rate ratio of electric cobalt to acid based on conventional electric cobalt and the power failure time (minutes) repeated by intermittent energization.

  As shown in FIG. 3, the electric cobalt obtained by performing intermittent energization that repeats power outage and energization is more soluble in acid than conventional electric cobalt obtained by performing unidirectional energization. It was excellent. In addition, when the power failure time was as short as about 0.5 minutes, electrocobalt having very high solubility was obtained, and when the power failure time was about 3 minutes, the solubility tended to decrease. And when power failure time became long to about 10 minutes, highly soluble electrocobalt came to be obtained again.

  From this, it has been clarified that an electrolytic cobalt excellent in acid solubility can be obtained by performing intermittent energization that repeats power failure and energization on an electrolytic solution made of an acidic solution containing cobalt. It has also been clarified that by setting the power outage time to a specific short time or a specific long time, it is possible to obtain electrocobalt exhibiting better acid solubility.

<Test Example 4>
Electrocobalt manufactured by electrolytic extraction industrially by the conventional method of conducting unidirectional energization, and manufactured by electrolytic extraction by performing intermittent energization that repeats power outage and energization for an electrolytic solution consisting of an acidic solution containing cobalt The effect of the current efficiency during electrolysis on the hydrogen concentration in electrocobalt and the acid solubility of electrocobalt was examined using the electrocobalt. Moreover, the smoothness of the surface was evaluated about the obtained electric cobalt.

The electrolytic solution was adjusted so that the cobalt concentration in the solution was 55 g / L using cobalt chloride as a reagent, and then adjusted to a pH of 1.2 using hydrochloric acid. Next, an anode and a cathode prepared in the same manner as in the production of the evaluation standard product in (1) above were put in a vinyl chloride container (electrolyzer) having a capacity of 1.5 liters and faced each other. The electrodes were arranged so that the distance between the anode and the cathode was 60 mm, and during energization, wiring was performed so as to automatically repeat the power outage and energization for a predetermined time via a timer. In addition, the ratio of the energization time to the total electrolysis time was adjusted to be 85 to 100%. Then, 1 liter of the electrolysis starting solution heated to 50 ° C. is put in this electrolytic cell, and the rotation speed (10 to 20 rotations / degree) that does not stop spontaneously using a stirrer and a stirrer while maintaining the temperature. The current of 0.54 A was applied for 48 hours so that the cathode current density was 270 A / m ² . During the electrolysis, the amount of liquid was observed, and when it decreased due to evaporation, pure water was replenished each time to maintain a constant amount of liquid.

After energization for 48 hours, the energization was stopped, the cathode was pulled up, and the cobalt electrodeposited on the surface of the titanium plate was impacted with a hammer and peeled off from the titanium plate. The peeled cobalt was washed with pure water, further washed with alcohol, and dried with cold air from a dryer to obtain electric cobalt. The hydrogen concentration in the electrocobalt thus obtained was measured by the above method. Moreover, the dissolution rate of electric cobalt is measured by the above method, and the electric cobalt produced by industrially electrolytically collecting by performing the unidirectional energization described in the above (1) is used as the evaluation reference product. The dissolution rate ratio when the dissolution rate of sulfuric acid in sulfuric acid (90 g / m ² / hr) was 1 was calculated. Furthermore, the smoothness of the obtained electric cobalt surface was evaluated. In addition, it was evaluated by the following method whether it was smooth. First, when a particle having a diameter of 2 mm or more was visually observed on the surface, it was evaluated as x, and for a particle having a diameter of 2 mm or more not recognized, a contact type surface roughness meter was installed in the measuring device. A sample having a maximum height (Rmax) measured in accordance with JIS B0601 (2001) of 30 μm or less was evaluated as “◯”, and a sample having a maximum height exceeding 30 μm was evaluated as “Δ”.

  FIG. 4 shows the relationship between the dissolution rate ratio of electrocobalt to acid based on conventional electrocobalt and the hydrogen concentration (ppm) in electrocobalt. FIG. 4 shows the current efficiency during electrolysis and the hydrogen concentration in electrocobalt. Fig. 5 shows the relationship with (ppm), Fig. 6 shows the relationship between the current efficiency during electrolysis and the dissolution rate ratio of electric cobalt to acid based on conventional electric cobalt, and the evaluation of the smoothness of the surface of electric cobalt. The results are shown in Table 1.

  As shown in FIG. 4, the acid solubility of electric cobalt improved as the hydrogen concentration in the electric cobalt increased. As shown in FIGS. 5 and 6, a certain relationship was recognized between the current efficiency, the hydrogen concentration in the electric cobalt, and the acid solubility of the electric cobalt. From this, it is considered that the acid solubility of the obtained electric cobalt can be judged by measuring the current efficiency when producing the electric cobalt.

  Moreover, as shown in Table 1, according to the manufacturing method of this invention, it was confirmed that the electric cobalt with the smooth surface is obtained.

<Reference Test Example 1>
The effect of the pH of the electrolytic solution on the acid solubility of electrocobalt was examined.

  As the electrolytic cell, the anode, and the cathode, those prepared by the same method as the production of the evaluation standard product of (1) above were used. In addition, the electrolytic solution was adjusted so that the cobalt concentration in the solution became 55 g / L using the reagent cobalt chloride, and then the pH was adjusted to 0.5, 1.2, 2.0, using hydrochloric acid. What was adjusted so that it might be set to 3.0 or 3.8 was used.

Each of the anode and the cathode was placed in a 1.5 liter vinyl chloride container (electrolyzer), and the electrodes were arranged so that the distance between the anode and cathode facing each other was 60 mm. Then, 1 liter of the above electrolytic solution heated to 50 ° C. is put into this electrolytic cell, and the number of revolutions (10 to 20 revolutions / minute) that does not stop spontaneously using a stirrer and a stirrer while maintaining the temperature. ). A current of 0.54 A was applied in one direction for 48 hours so that the cathode current density was 270 A / m ² .

After energization for 48 hours, the energization was stopped, the cathode was pulled up, and the cobalt electrodeposited on the surface of the titanium plate was impacted with a hammer and peeled off from the titanium plate. The peeled cobalt was washed with pure water, further washed with alcohol, and dried with cold air from a dryer to obtain electric cobalt. The electrolytic cobalt thus obtained was measured for the dissolution rate by the above-mentioned method, and the dissolution rate of sulfuric acid in sulfuric acid for the electrical cobalt (hydrogen concentration: 3 ppm) produced by industrial electrolytic extraction by the conventional method in which unidirectional energization is performed ( The dissolution rate ratio when 90 g / m ² / hr) was set to 1 was calculated, and the acid solubility was judged based on the calculated value. The results are shown in Table 2.

  When electrolytic collection was performed using an electrolyte solution having a pH of 0.5, generation of hydrogen was prioritized over electrodeposition, and almost no electrodeposits could be obtained. Moreover, when electrolytic extraction was performed using an electrolyte solution having a pH of 3.8, hydroxide began to be generated, and the dissolution rate ratio and cathode current efficiency were reduced. On the other hand, in the electrolytic solutions of pH 2.0 and 3.0, electrocobalt with good acid solubility was obtained. The electrolyte solution with pH 1.2 did not change the acid solubility, but the hydrogen concentration increased. These results are for the case of unidirectional energization, but it is considered that the present invention can be applied without problems even in intermittent energization. Therefore, it is presumed that by using an electrolytic solution having a pH of about 1.2 to 3.0 in intermittent energization, it is possible to produce electrocobalt with good acid solubility.

<Reference Test Example 2>
The effect of the presence or absence of additives in the electrolytic solution on the acid solubility and electric cobalt was investigated.

  As the electrolytic cell, the anode, and the cathode, those prepared by the same method as the production of the evaluation standard product of (1) above were used. In addition, the electrolytic solution was adjusted so that the cobalt concentration in the solution was 55 g / L using the reagent cobalt chloride, and further adjusted to a pH of 1.2 using hydrochloric acid. A solution to which an appropriate amount of sodium thiosulfate was added was used.

Then, each of the anode and the cathode was put into a container (electrolysis cell) made of vinyl chloride having a capacity of 2 liters, and arranged so that the distance between the electrode plates facing each other was 60 mm. Then, 1 liter of the above electrolytic solution heated to 50 ° C. is put into this electrolytic cell, and the number of revolutions (10 to 20 revolutions / minute) that does not stop spontaneously using a stirrer and a stirrer while maintaining the temperature. ). A current of 0.54 A was applied for 1 hour so that the current density of the cathode was 270 A / m ² .

After energization for 1 hour, the energization was stopped, the cathode was pulled up, and cobalt electrodeposited on the surface of the titanium plate was impacted with a hammer and peeled off from the titanium plate. The peeled cobalt was washed with pure water, further washed with alcohol, and dried with cold air from a dryer to obtain electric cobalt C. Electrocobalt C thus obtained was measured for dissolution rate by the above method, and dissolved in sulfuric acid by electrocobalt B (hydrogen concentration: 3 ppm) produced by industrial electrowinning by a conventional method in which unidirectional energization was performed. The dissolution rate ratio when the rate (90 g / m ² / hr) was 1 was calculated, and the quality of acid solubility was judged from the value. Further, the hydrogen concentration and sulfur concentration were measured by the above methods. Furthermore, the smoothness of the obtained electric cobalt surface was evaluated. In addition, it was evaluated by the following method whether it was smooth. First, when a particle having a diameter of 2 mm or more was visually observed on the surface, it was evaluated as x, and for a particle having a diameter of 2 mm or more not recognized, a contact type surface roughness meter was installed in the measuring device. A sample having a maximum height (Rmax) measured in accordance with JIS B0601 (2001) of 30 μm or less was evaluated as “◯”, and a sample having a maximum height exceeding 30 μm was evaluated as “Δ”. The results are shown in Table 3.

For comparison, Table 3 also shows the results of the electric cobalt A (power failure time: 0.5 minutes) obtained by performing intermittent energization in which the power failure and the energization are repeated in Test Example 2. The dissolution rate of electrocobalt C in which sodium thiosulfate was added to the electrolytic solution was 1.7 times (157 g / m ² / hr) of electrocobalt B that was not added. However, since the sulfur concentration is as high as 160 ppm and a dissolution residue containing sulfur as a main component is generated after dissolution in sulfuric acid, it takes time for post-treatment. On the other hand, electrocobalt A obtained by performing intermittent energization that repeats power outage and energization using an electrolyte solution that does not contain sodium thiosulfate has a smooth surface and is also sodium thiosulfate. It shows a dissolution rate 1.5 times (135 g / m ² / hr) of electric cobalt B obtained by conducting unidirectional energization using an electrolyte solution containing no oxygen, and the sulfur concentration as an impurity is also 0. The purity was very high, less than 1 ppm.

Claims (4)

A method of producing electrolytic cobalt or electrolytic nickel by electrolytic collection or electrolytic purification using an electrolytic solution comprising an acidic solution containing cobalt or nickel,
In the electrowinning or electrolytic refining, the ratio of the energization time to the total electrolysis time is set to 80 to 90%, and the electrolytic solution is subjected to intermittent energization that repeats power failure and energization. Nickel manufacturing method.   The method for producing electric cobalt or electric nickel according to claim 1, wherein in the intermittent energization, the repeated power failure time is 30 to 60 seconds.   The method for producing electric cobalt or electric nickel according to claim 1 or 2, wherein the pH of the electrolytic solution is 1.0 to 3.5. An electric cobalt having a hydrogen concentration of 20 ppm or more and a sulfur concentration of 1 ppm or less.

Images