JP5716614B2 - Metal sulfide precipitation method - Google Patents

Description

  The present invention relates to a method for metal sulfide precipitation. More specifically, the present invention relates to a metal sulfide precipitation method in which a sulfurizing agent is added to an acidic treatment liquid containing a target metal to precipitate the target metal as a sulfide.

Used nickel metal hydride batteries, lithium ion batteries, etc., and valuable metals such as nickel and cobalt from defective products (hereinafter collectively referred to as waste batteries) produced in the manufacturing process of the positive electrode materials and the like constituting these batteries As a method for recovery, a method using a wet process is known (for example, Patent Document 1).
In the wet processing method, for example, valuable metals contained in the waste battery are leached into an acidic aqueous solution and separated from the leaching residue, and valuable metals are recovered from the obtained treatment liquid by a sulfide precipitation method, a solvent extraction method, or the like. Is done. Here, since the treatment liquid in which the valuable metal is leached also contains impurities such as manganese and aluminum, the valuable metal and the impurity can be selectively separated by a sulfide precipitation method or a solvent extraction method. Done. In particular, the separation by the sulfide precipitation method is frequently used because it has a fast reaction and is easy to selectively separate valuable metals.

For example, when a sodium hydrogen sulfide aqueous solution (NaHS) is dropped as a sulfiding agent into a treatment solution in which nickel or cobalt is leached in a sulfuric acid aqueous solution, nickel is sulfided and precipitated as nickel sulfide (NiS) by the following reaction. Is sulfided and precipitates as cobalt sulfide (CoS).
(Chemical formula 1)
NiSO ₄ + NaHS → NiS + NaHSO ₄
(Chemical formula 2)
CoSO ₄ + NaHS → CoS + NaHSO ₄

Here, since sodium hydrogen sulfate (NaHSO ₄ ) is acidic, the pH of the treatment liquid is lowered. When the treatment liquid is below a specific pH, nickel sulfide re-dissolves and the sulfurization reaction does not proceed. Therefore, an alkaline aqueous solution is also added dropwise to adjust the pH of the treatment liquid. For example, when a sodium hydroxide aqueous solution (NaOH) is dropped as an alkaline aqueous solution, the following reaction occurs, and the pH can be maintained.
(Chemical formula 3)
NaHSO ₄ + NaOH → Na ₂ SO ₄ + H ₂ O

When nickel in the treatment liquid is precipitated as nickel sulfide, hydrogen sulfide (H ₂ S) is generated by the following reaction.
(Chemical formula 4)
H ₂ SO ₄ + NaHS → H ₂ S + NaHSO ₄

Conventionally, when dropping a sulfiding agent and an alkaline aqueous solution into the treatment liquid, a pipe for dropping the sulfiding agent and a pipe for dropping the alkaline aqueous solution are separately provided in the reaction tank in which the treatment liquid is placed, and the sulfiding agent and the alkaline solution are separately provided. It was dripped separately, without mixing with aqueous solution.
The inventor of the present application, when the sulfiding agent and the alkaline aqueous solution are separately dropped into the treatment liquid as in the conventional case, even when the target metal remains in the treatment liquid, the reaction of Chemical Formula 4 occurs and hydrogen sulfide is generated. I found out that

Since hydrogen sulfide gas is a toxic substance, careful attention is required to prevent leakage, etc., and there is a problem that equipment costs and management costs for collection and abatement equipment to prevent it from being released into the environment increase. I found it.
Moreover, since the dripping sulfiding agent and the alkaline aqueous solution are used in addition to the generation of the sulfide of the target metal, the use amount is increased and the problem of increased cost is found.

JP 2010-277868 A

  An object of this invention is to provide the metal sulfide precipitation method which can suppress generation | occurrence | production of hydrogen sulfide gas in view of the said situation.

Sulfide coagulation method of a metal of the first invention, by adding a sulfurizing agent and an alkaline aqueous solution composed of sodium hydrosulfide aqueous solution (NaHS) in the treatment liquid of sulfuric acid or hydrochloric acid containing the target metal, while maintaining the pH the A metal sulfide precipitation method for precipitating a target metal as a sulfide, wherein the sulfide is mixed with the alkaline aqueous solution, and the mixture is added to the treatment liquid.
According to a metal sulfide precipitation method of the second invention, in the first invention, the amount of hydrogen sulfide gas generated by adding the mixed solution to the treatment solution is measured per unit time, and the amount per unit time is measured. The process is terminated when the generation amount exceeds a threshold value.
The metal sulfide precipitation method of the third invention is characterized in that, in the first or second invention, the treatment liquid is obtained by leaching a valuable metal contained in a waste battery in an acidic aqueous solution.
The metal sulfide precipitation method of the fourth invention is characterized in that, in the first or second invention, the treatment liquid is obtained by leaching a target metal contained in an ore in an acidic aqueous solution .
A metal sulfide precipitation apparatus according to a fifth aspect of the present invention includes a reaction tank in which a sulfuric acid or hydrochloric acid treatment solution containing a target metal is placed, a sulfiding agent pipe through which a sulfiding agent made of a sodium hydrogen sulfide aqueous solution (NaHS) flows. The alkali pipe through which the alkaline aqueous solution flows, the sulfiding agent pipe and the alkaline pipe are connected, the sulfiding agent and the alkaline aqueous solution are mixed, and the mixed solution is dropped into the reaction vessel And a pipe.

According to the first invention, since the generation of hydrogen sulfide gas is suppressed in the state where the target metal remains in the processing liquid, the processing load of the toxic hydrogen sulfide gas can be reduced. Further, no excessive hydrogen sulfide gas is generated, and the sulfiding agent and the alkaline solution are efficiently used for the production of sulfides. Therefore, the amount of the sulfiding agent and the alkaline solution used can be reduced, and the cost can be reduced.
According to the second invention, since the concentration of the hydrogen sulfide gas becomes high at the end point of the sulfidation reaction of the target metal, the treatment is terminated when the concentration of the hydrogen sulfide gas exceeds the threshold value. The amount can be suppressed, and the processing load of toxic hydrogen sulfide gas can be reduced. Further, by terminating the treatment, the sulfiding agent and the alkaline solution can be suppressed to the amount necessary for sulfiding the target metal, and the cost can be reduced.
According to the third aspect of the present invention, valuable metals contained in the waste battery can be separated from impurities, so that high-purity valuable metals can be recovered.
According to the fourth invention, since the target metal contained in the ore can be separated from the impurities, the target metal with high purity can be collected .
According to the fifth invention, since generation of hydrogen sulfide gas is suppressed in a state where the target metal remains in the processing liquid, excess hydrogen sulfide gas is not generated, and the sulfiding agent and the alkaline solution are efficiently sulfided. Used to produce products. Therefore, the amount of the sulfiding agent or alkaline solution used can be reduced and the cost can be reduced.

It is explanatory drawing of the sulfide precipitation apparatus which concerns on one Embodiment of this invention. It is a graph of pH of a processing liquid and hydrogen sulfide gas concentration in an example. It is a graph of ORP of a processing liquid and hydrogen sulfide gas concentration in an example. It is a graph of pH of a processing liquid and hydrogen sulfide gas concentration in a comparative example. It is a graph of ORP of a processing liquid and hydrogen sulfide gas concentration in a comparative example.

Next, an embodiment of the present invention will be described with reference to the drawings.
First, based on FIG. 1, the sulfide precipitation apparatus 1 which concerns on one Embodiment of this invention is demonstrated.
In FIG. 1, the code | symbol 10 is a reaction tank and the code | symbol 11 is a stirrer. An acidic treatment liquid containing a target metal is placed in the reaction tank 10, and the treatment liquid placed in the reaction tank 10 is stirred by a stirrer 11. The reaction tank 10 is, for example, a tank made of FRP, but may be a tank made of a material that is not corroded by the treatment liquid, such as vinyl chloride, polypropylene, or rubber-lined iron. The stirring blades of the stirrer 11 are made of, for example, Teflon (registered trademark), but may be made of other materials.

  Reference numeral 21 denotes a sulfiding agent pipe through which a sulfiding agent flows, reference numeral 22 denotes an alkali pipe through which an alkaline aqueous solution flows, reference numeral 23 denotes a mixing pipe, and reference numeral 24 denotes a washing water pipe through which washing water flows. Both the sulfiding agent pipe 21 and the alkali pipe 22 are connected to the mixing pipe 23, and the sulfiding agent and the alkaline aqueous solution are mixed in the mixing pipe 23. The mixing pipe 23 is connected to the reaction tank 10 so that a mixed liquid in which a sulfiding agent and an alkaline aqueous solution are mixed can be dropped into the reaction tank 10. In addition, a washing water pipe 24 is also connected to the mixing pipe 23, and the mixing pipe 23 and the reaction tank 10 can be washed by flowing washing water from the washing water pipe 24.

  A flow rate adjusting valve is attached to each of the sulfiding agent pipe 21, the alkali pipe 22 and the washing water pipe 24 so that the flow rates of the sulfiding agent, the alkaline aqueous solution and the washing water can be adjusted. Therefore, the ratio of the sulfiding agent and the alkaline aqueous solution in the mixed solution dropped into the reaction vessel 10 can be adjusted. Further, the supply / stop of the mixed solution and the washing water to the reaction tank 10 can be controlled.

  The mixing order of the sulfiding agent and the alkaline aqueous solution may be such that the sulfiding agent may be added to the flow of the alkaline aqueous solution, the alkaline aqueous solution may be added to the flow of the sulfiding agent, or the sulfiding agent and the alkaline aqueous solution. May be mixed at the same time. That is, the arrangement of the sulfiding agent pipe 21 and the alkali pipe 22 may be an arrangement in which the alkali pipe 22 is connected to the upstream side of the mixing pipe 23 and the sulfiding agent pipe 21 is connected to the downstream side (FIG. 1). (Refer to the above), the reverse arrangement may be used. Moreover, it is good also as a structure which connects the piping 21 for sulfurizing agents, the piping 22 for alkalis, and the mixing piping 23 with a Y-shaped pipe | tube etc. FIG.

As the sulfiding agent, it is preferable to use a liquid sulfiding agent such as a sodium hydrogen sulfide aqueous solution (NaHS), a sodium sulfide aqueous solution (Na ₂ S), or a mixture thereof. This is because in the case of using a gaseous sulfiding agent such as hydrogen sulfide gas, there is a facility cost and a management cost for collecting and removing devices for preventing the toxic hydrogen sulfide gas from being released into the environment. Further, as the alkaline aqueous solution, for example, a sodium hydroxide aqueous solution (NaOH) is used, but other alkaline aqueous solutions may be used. Here, when a sodium sulfide aqueous solution is used as the sulfiding agent, sodium sulfide in the mixed solution has low solubility, so that crystals may be formed and the pipe may be blocked. It is preferable to wash the inside of the mixing pipe 23 by flowing washing water from the inside.

  Furthermore, the sulfiding agent pipe 21 and the alkali pipe 22 are, for example, pipes made of Teflon (registered trademark), but pipes of other materials may be used. The mixing pipe 23 and the washing water pipe 24 are, for example, pipes made of vinyl chloride, but pipes made of other materials may be used.

An acid pipe 25 is connected to the reaction tank 10 so that an acidic aqueous solution can be dropped into the reaction tank 10. A flow rate adjustment valve is attached to the acid pipe 25 so that the flow rate of the acidic aqueous solution can be adjusted, and supply / stop to the reaction tank 10 can be controlled.
For example, sulfuric acid (H ₂ SO ₄ ) is used as the acidic aqueous solution, but other acidic aqueous solutions may be used. The acid pipe 25 is made of, for example, vinyl chloride, but may be pipe made of other materials as long as it is acid resistant.

  The reaction tank 10 is provided with a hydrogen sulfide gas concentration meter 31, a pH meter 32, and an ORP meter 33, and the hydrogen sulfide gas concentration meter 31 can measure the concentration of hydrogen sulfide gas in the gas phase portion above the reaction vessel 10. The pH of the treatment liquid in the reaction tank 10 can be measured by the pH meter 32, and the ORP (oxidation reduction potential) of the treatment liquid in the reaction tank 10 can be measured by the ORP meter 33.

Next, a sulfide precipitation method using the sulfide precipitation apparatus 1 will be described.
First, the processing liquid is caused to flow into the reaction vessel 10. The treatment liquid is, for example, an acidic aqueous solution in which valuable metals contained in a waste battery are leached. More specifically, defective nickel-metal hydride batteries, lithium ion batteries, etc., and defective products (hereinafter collectively referred to as waste batteries) produced in the manufacturing process of the positive electrode materials constituting these batteries are roasted. Then reduced sulfuric acid is added to the reduced roasted product and stirred, and the valuable metal such as nickel and cobalt contained in the waste battery is leached and separated from the leaching residue. To do. In addition to reductive roasting, a reducing agent such as sodium sulfite and sulfuric acid are added to the liquid in which the waste battery that has been crushed is added, and the mixture is stirred to leach out valuable metals contained in the waste battery. Good. Further, the treatment liquid may be an acidic solution in which a target metal contained in the ore is leached. For example, a treatment liquid is obtained by leaching nickel oxide ore or copper sulfide mineral with sulfuric acid or hydrochloric acid.

  In the following, an example is described in which a sulfuric acid aqueous solution in which nickel and cobalt contained in a waste battery are leached is used as a treatment liquid, and the nickel and cobalt are precipitated as sulfides. The target metal can be precipitated as a sulfide. The sulfuric acid aqueous solution in which nickel and cobalt contained in the waste battery are leached also contains impurities such as manganese and aluminum.

  Next, while stirring the treatment liquid with the stirrer 11, an aqueous sodium hydroxide solution is supplied as an alkaline aqueous solution from the alkali pipe 22 and dropped into the reaction vessel 10 to adjust the pH of the treatment liquid. Here, the treatment liquid is adjusted to a pH suitable for precipitating the target metal as a sulfide and separating impurities. Therefore, the pH is adjusted to an optimum value depending on the type of the target metal and impurities contained in the treatment liquid. For example, when nickel and cobalt are precipitated by sulfidation, the treatment solution is adjusted to pH 3.

After the pH of the treatment liquid is adjusted, the supply of the sodium hydrogen sulfide aqueous solution as the sulfiding agent is started from the sulfiding agent pipe 21 while stirring the treatment liquid with the stirrer 11. Then, the sodium hydrogen sulfide aqueous solution and the sodium hydroxide aqueous solution supplied from the alkali pipe 22 are mixed by the mixing pipe 23, and the mixed liquid is dropped into the treatment liquid inside the reaction tank 10.
Then, by the following reaction, nickel is sulfided and precipitated as nickel sulfide, and cobalt is sulfided and precipitated as cobalt sulfide.
(Chemical formula 1)
NiSO ₄ + NaHS → NiS + NaHSO ₄
(Chemical formula 2)
CoSO ₄ + NaHS → CoS + NaHSO ₄
(Chemical formula 3)
NaHSO ₄ + NaOH → Na ₂ SO ₄ + H ₂ O

  During the sulfidation reaction, it is necessary to control so that the treatment liquid is maintained at around pH 3. This control is performed, for example, by adjusting the mixing ratio of the aqueous sodium hydrogen sulfide solution and the aqueous sodium hydroxide solution so that the aqueous sodium hydroxide solution is slightly excessive, and the pH of the treatment liquid gradually increases as the mixed liquid is dropped. When the value measured by the total 32 reaches pH 3, a small amount of sulfuric acid is dropped from the acid pipe 25 to slightly lower the pH of the treatment liquid. When the dropping of the mixed solution is continued, the treatment solution reaches pH 3 again, so that sulfuric acid is dropped again. Thus, the treatment liquid is maintained at around pH 3 by intermittently dropping sulfuric acid. The reason for controlling by such a method is that, at the end of the sulfidation reaction, the pH of the treatment liquid rises rapidly due to the reaction of the following chemical formula 4, so that the control is mainly performed by dropping sulfuric acid to lower the pH of the treatment liquid. This is because it is easy to cope with a rapid increase in pH of the treatment liquid at the end point of the sulfurization reaction.

As described above, when sodium hydrogen sulfide aqueous solution and sodium hydroxide aqueous solution are dropped separately into the treatment liquid as in the past, the following reaction occurs even when nickel and cobalt remain in the treatment liquid. Hydrogen sulfide is generated.
(Chemical formula 4)
H ₂ SO ₄ + NaHS → H ₂ S + NaHSO ₄

However, the inventor of the present application drops hydrogen sulfide gas in a state in which nickel and cobalt remain in the treatment liquid by dropping a mixed liquid of a sodium hydrogen sulfide aqueous solution and a sodium hydroxide aqueous solution into the treatment liquid. It was found to be suppressed.
Therefore, by applying the present invention, generation of hydrogen sulfide gas is suppressed, so that the processing load of toxic hydrogen sulfide gas can be reduced. Further, no excessive hydrogen sulfide gas is generated, and the sulfiding agent and the alkaline solution are efficiently used for the production of sulfides. Therefore, the amount of the sulfiding agent and the alkaline solution used can be reduced, and the cost can be reduced.

The mechanism by which the generation of hydrogen sulfide gas is suppressed is considered as follows.
That is, when the sodium hydrogen sulfide aqueous solution and the sodium hydroxide aqueous solution are dropped separately, the concentration of the sodium hydrogen sulfide aqueous solution locally increases in the portion of the treatment liquid where the sodium hydrogen sulfide aqueous solution is dropped. The concentration of nickel and cobalt locally decreases due to the sulfurization reaction. Therefore, it is considered that the reaction of Chemical Formula 4 also occurs and hydrogen sulfide is generated. Similarly, with respect to an aqueous sodium hydroxide solution, it is considered that not only the reaction of Chemical Formula 3 but also the following reaction occurs with manganese as an impurity.
(Chemical formula 5)
MnSO ₄ + 2NaOH → Mn (OH) ₂ + Na ₂ SO ₄

  On the other hand, if a sodium hydrogen sulfide aqueous solution and a sodium hydroxide aqueous solution are mixed and added dropwise, it is possible to suppress the reactions of Chemical Formula 4 and Chemical Formula 5 and to efficiently advance the reactions of Chemical Formula 1, Chemical Formula 2 and Chemical Formula 3 As a result, it is considered that generation of hydrogen sulfide gas is suppressed.

Next, when nickel and cobalt in the treatment liquid are completely precipitated as sulfides, hydrogen sulfide gas is generated by the reaction of the above chemical formula 4.
Therefore, the concentration of hydrogen sulfide gas generated by the hydrogen sulfide gas concentration meter 31 is measured, and when the concentration exceeds a predetermined threshold value, it is determined that the end point of the sulfurization reaction. By measuring the concentration of hydrogen sulfide gas, the amount of hydrogen sulfide gas generated per unit time can be measured, and since it is detected that the reaction of Chemical Formula 4 has started, the end point of the sulfurization reaction can be determined. is there.
If it is determined that the end point of the sulfurization reaction, the sulfurization process is terminated. Specifically, the supply of the sodium hydrogen sulfide aqueous solution and the sodium hydroxide aqueous solution to the reaction tank 10 is stopped, and the treatment liquid in the reaction tank 10 is discharged.

By applying the present invention, generation of hydrogen sulfide gas is suppressed in a state where nickel and cobalt remain in the processing liquid, and hydrogen sulfide gas is generated when nickel and cobalt are precipitated as sulfides. That is, since the concentration of the hydrogen sulfide gas rapidly increases at the end point of the sulfurization reaction, the end point of the sulfurization reaction can be easily determined by measuring the concentration of the hydrogen sulfide gas.
Moreover, by terminating the treatment at the end point of the sulfurization reaction, the amount of generated hydrogen sulfide gas can be suppressed, and the treatment load of toxic hydrogen sulfide gas can be reduced. Furthermore, by terminating the treatment at the end point of the sulfidation reaction, the sulfiding agent and the alkaline solution can be suppressed to only the amount necessary for sulfiding the target metal, and the cost can be reduced.

  Finally, the treatment liquid discharged from the reaction tank 10 is solid-liquid separated with a filter press or the like to separate the sulfide and the liquid after sulfidation. Valuable metals such as nickel and cobalt are precipitated as sulfides, and impurities such as manganese and aluminum are dissolved in the liquid after sulfidation, so that valuable metals and impurities can be separated by solid-liquid separation, and high purity from waste batteries. Valuable metals can be recovered. In addition, when the acidic solution in which the target metal contained in the ore is leached is used as the treatment liquid, the target metal contained in the ore can be separated from the impurities, so that the high-purity target metal can be collected.

  In the step of adjusting the pH by dropping an alkaline aqueous solution before dropping the mixed solution into the treatment solution, an alkali salt is generated by the reaction of Chemical Formula 5 among the above steps. This alkali salt is redissolved immediately when the pH of the treatment liquid is low, but does not immediately re-dissolve when the pH of the treatment liquid rises, and remains in the treatment liquid as a solid for a predetermined time. If the mixed solution starts dripping immediately after the pH adjustment, an insoluble sulfide is generated around the alkali salt that remains as a solid, so that the alkali salt cannot be redissolved. If it does so, an impurity metal will mix in sulfide. In order to prevent this, it is only necessary to provide time for the alkali salt to redissolve before the start of dropping of the mixed solution. That is, after the pH of the treatment liquid is adjusted, the supply of the alkaline aqueous solution is once stopped, and after waiting for the re-dissolution time, the dropping of the mixed liquid may be started. The alkali salt re-dissolution time is selected based on the type and amount of impurities contained in the treatment liquid. By doing in this way, the purity of the obtained sulfide can be increased.

  Further, in the above sulfidation process, if the sulfide slurry concentration is high, some amount of impurity metal is co-precipitated. In order to prevent this, the concentration of the sulfide slurry may be lowered by diluting the treatment liquid flowing into the reaction vessel 10 in advance. The degree of dilution of the processing liquid is selected based on the type and amount of impurities contained in the processing liquid. By doing in this way, a coprecipitation effect can be made small and the purity of the sulfide obtained can be raised.

Next, examples will be described.
In the following examples and comparative examples, a sulfuric acid aqueous solution in which nickel and cobalt contained in a waste battery were leached was used as a treatment liquid. Specifically, a used nickel metal hydride battery is roasted to obtain a reduced roasted product, and sulfuric acid is added to this reduced roasted product (55 kg) so that the pH is 1, and diluted to a slurry concentration of 110 g / L. The mixture was heated to 80 ° C. and stirred for 6 hours to leach out nickel and cobalt contained in the nickel metal hydride battery. Next, sodium sulfate was added to separate rare earth elements and the like in the form of a sulfate double salt to obtain a treatment liquid. The treatment liquid contained impurities such as manganese and aluminum in addition to valuable metals such as nickel and cobalt.

(Example)
First, the treatment liquid was caused to flow into the reaction tank 10 of the sulfide precipitation apparatus 1 described above. Here, the reaction vessel 10 has a cylindrical shape with a diameter of 1 m and a height of 1.3 m and a capacity of 750 liters.
Next, an aqueous sodium hydroxide solution was supplied from the alkali pipe 22 and dropped into the reaction vessel 10 to adjust the treatment solution to pH3.

Next, a sodium hydrogen sulfide aqueous solution having a concentration of 25% is supplied from the sulfurating agent pipe 21 as a sulfiding agent, a sodium hydroxide aqueous solution having a concentration of 25% is supplied as an alkaline aqueous solution from the alkali pipe 22, and hydrogen sulfide is supplied from the mixing pipe 23. A sodium aqueous solution and a sodium hydroxide aqueous solution were mixed, and the mixed solution was dropped into a treatment solution inside the reaction vessel 10. Here, the respective flow rates were adjusted so that the mixing ratio of the aqueous sodium hydrogen sulfide solution and the aqueous sodium hydroxide solution was approximately equimolar.
At the same time, the processing liquid was stirred at a rotation speed of the stirring blade of the stirrer 11 at 200 rpm.

  During the sulfidation reaction, the mixing ratio of the sodium hydrogen sulfide aqueous solution and the sodium hydroxide aqueous solution is set so that the sodium hydroxide aqueous solution is slightly excessive, and the pH of the treatment liquid gradually increases as the mixture is dropped. When the value measured by the pH meter 32 reached pH 3, a small amount of sulfuric acid was dropped from the acid pipe 25 to slightly lower the pH of the treatment solution.

  As a result of monitoring the concentration of hydrogen sulfide gas, the pH of the treatment liquid, and the ORP in the gas phase portion of the upper part of the reaction tank 10 with the hydrogen sulfide gas concentration meter 31, the pH meter 32, and the ORP meter 33, the graphs shown in FIG. 2 and FIG. was gotten. The pH meter 32 and the ORP meter 33 were installed in the reaction tank 10 after the reaction tank 10 was filled with the treatment solution, and removed from the reaction tank 10 after completion of the sulfurization reaction in order to prevent the electrodes from drying. In other cases, that is, before the treatment liquid was filled in the reaction vessel 10 and after the sulfurization reaction was completed, the pH meter 32 and the ORP meter 33 were immersed in water for preventing drying. For this reason, the measured values of the pH meter 32 and the ORP meter 33 before and after the sulfurization reaction are not measured values of the treatment liquid but measured values of water for preventing drying. 2 and 3, the pH meter 32 and the ORP meter 33 are installed in the reaction tank 10 in the region described as “pH meter installation” or “ORP meter installation”.

  As shown in FIG. 2, the hydrogen sulfide gas concentration during the sulfidation reaction was less than 1 ppm, and it was confirmed that the generation of hydrogen sulfide gas was suppressed. Further, the hydrogen sulfide gas concentration suddenly increased from about 110 minutes after the start of dropping of the mixed solution.

  By the way, the end point of the sulfurization reaction can be judged by the frequency of sulfuric acid dropping. More specifically, as shown in FIG. 2, the pH of the treatment liquid during the sulfidation reaction changes in a sawtooth shape. This is because the pH of the treatment liquid gradually increases as the mixed solution is dropped, and the pH of the treatment liquid decreases when sulfuric acid is dropped. That is, the frequency of sulfuric acid dripping can be found from the sawtooth-like pH fluctuation cycle. When the end point of the sulfidation reaction is approached, the pH of the treatment liquid is likely to increase due to the dropping of the mixed liquid, so that the dropping frequency of sulfuric acid that lowers the pH of the treatment liquid increases. Therefore, when the frequency of sulfuric acid dripping exceeds a predetermined frequency, the end point of the sulfurization reaction can be determined.

  From FIG. 2, the frequency of sulfuric acid dripping is high when the hydrogen sulfide gas concentration is rapidly increasing. That is, it can be seen that hydrogen sulfide gas is generated at the end of the sulfurization reaction. Thus, in this example, it was confirmed that the generation of hydrogen sulfide gas was suppressed during the sulfidation reaction, and hydrogen sulfide gas was generated when the sulfidation reaction reached the end point.

  As shown in FIG. 3, the ORP gradually decreased as the mixed solution was dropped, and decreased rapidly when the ORP reached around -300 mV (Ag / AgCl electrode). This is because when nickel and cobalt in the treatment liquid are completely precipitated as sulfides, hydrogen sulfide gas is generated by the reaction of Chemical Formula 4, and this hydrogen sulfide gas reduces the treatment liquid. For this reason, it is possible to determine when the sulfurization reaction reaches the end point from the time when hydrogen sulfide gas is generated and the ORP rapidly decreases.

  After completion of the sulfidation reaction, the treatment liquid discharged from the reaction vessel 10 was subjected to solid-liquid separation with a filter press to separate sulfide and post-sulfurization liquid. Here, the end point of the sulfurization reaction was judged from the time when the treatment liquid exceeded pH3. More specifically, the end point of the sulfurization reaction was determined when the pH of the treatment solution rapidly increased due to the effect of Chemical Formula 4 and when the pH did not drop sufficiently even when sulfuric acid was added dropwise.

  When the obtained sulfide was analyzed with an ICP emission spectrometer, the manganese quality was found to be sufficiently low at 0.14%. Further, when the recovery rate of nickel and cobalt was calculated from the amount of the treatment solution and sulfide before the sulfidation reaction and the manganese quality, it was confirmed that the recovery rate was 99% or more and was sufficiently recovered.

(Comparative example)
The treatment was performed in the same manner as in the example except that a sodium hydrogen sulfide aqueous solution as a sulfiding agent and a sodium hydroxide aqueous solution as an alkaline aqueous solution were separately dropped into the treatment liquid.
As a result of monitoring the concentration of hydrogen sulfide gas, the pH of the treatment liquid, and the ORP in the gas phase portion of the upper part of the reaction tank 10 with the hydrogen sulfide gas concentration meter 31, the pH meter 32, and the ORP meter 33, the graphs shown in FIG. 4 and FIG. was gotten. 4 and 5, the pH meter 32 and the ORP meter 33 are installed in the reaction tank 10 in the region described as “pH meter installation” or “ORP meter installation”.

As shown in FIGS. 4 and 5, the change in ORP, the change in pH, and the frequency of sulfuric acid supply were not significantly different from those in the Examples.
Further, the manganese quality of the obtained sulfide was 0.12%, and the recovery rate of nickel and cobalt was 99% or more, which was not significantly different from the examples.

However, the hydrogen sulfide gas concentration rapidly increased after the start of dropping of the aqueous sodium hydrogen sulfide solution, and it was confirmed that it was 200 to 400 ppm even during the sulfurization reaction.
From the above, it was confirmed that by applying the present invention, the generation of hydrogen sulfide gas can be suppressed, the processing load of toxic hydrogen sulfide gas can be reduced, and the amount of sulfiding agent and alkaline solution used can be reduced.

DESCRIPTION OF SYMBOLS 1 Sulfide precipitation apparatus 10 Reaction tank 11 Stirrer 21 Pipe for sulfide agent 22 Pipe for alkali 23 Mixing pipe 24 Pipe for washing water 25 Pipe for acid 31 Hydrogen sulfide gas concentration meter 32 pH meter 33 ORP meter

Claims (5)

It was added and sulfurizing agent and an alkaline aqueous solution composed of sodium hydrosulfide aqueous treating solution of sulfuric acid or hydrochloric acid (NaHS) containing the desired metal, metal sulfides precipitating the said purpose metal as a sulfide while maintaining pH A precipitation method,
Mixing the sulfiding agent and the alkaline aqueous solution,
A metal sulfide precipitation method comprising adding the mixed solution to the treatment solution. Measure the amount of hydrogen sulfide gas generated per unit time generated by adding the mixed solution to the treatment solution,
2. The metal sulfide precipitation method according to claim 1, wherein the treatment is terminated when the generation amount per unit time exceeds a threshold value. 3. The metal sulfide precipitation method according to claim 1, wherein the treatment liquid is obtained by leaching a valuable metal contained in a waste battery in an acidic aqueous solution. 3. The metal sulfide precipitation method according to claim 1, wherein the treatment liquid is obtained by leaching a target metal contained in an ore into an acidic aqueous solution. A reaction vessel in which a sulfuric acid-acid or hydrochloric acid-acid treatment liquid containing the target metal is placed;
A pipe for sulfiding agent through which a sulfiding agent composed of a sodium hydrogen sulfide aqueous solution (NaHS) flows
An alkali pipe through which an alkaline aqueous solution flows;
A metal comprising: a pipe for connecting the sulfiding agent pipe and the alkali pipe, mixing the sulfiding agent and the alkaline aqueous solution, and dropping the mixed liquid into the reaction vessel. Sulfide precipitation equipment.

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