JP5929664B2 - Metal acid leaching apparatus and acid leaching method - Google Patents

Description

  The present invention relates to a metal acid leaching apparatus and an acid leaching method. More specifically, the present invention relates to an acid leaching apparatus and an acid leaching method for recovering valuable metals by acid leaching from used nickel-metal hydride batteries or lithium ion batteries.

  Nickel, cobalt, etc. from defective products (hereinafter collectively referred to as “waste batteries”) produced in the manufacturing process of used nickel metal hydride batteries, lithium ion batteries, etc., and positive electrode materials constituting these batteries. As a method for recovering valuable metals, a method by wet processing is known (for example, Patent Document 1).

  In general, in the wet processing method, a waste battery is disassembled or crushed as a pretreatment and processed into a shape and size in which valuable metals contained in a member such as a positive electrode material are easily dissolved, and then the battery treatment product is leached (sulfuric acid). By leaching valuable metals by acid immersing in acidic aqueous solutions (such as acid and hydrochloric acid) and separating them from the leaching residue by a method such as sulfide precipitation, solvent extraction, neutralization, and electrowinning. Collection of valuable metals is performed.

  However, simply immersing the battery-treated product in the leachate creates a concentration gradient in the leachate, causes bubbles of hydrogen gas generated by the leaching reaction, and nonmetal components such as separators contained in the waste battery are metal parts. There is a problem that the leaching efficiency becomes low. If the leaching efficiency is low, it is not economical because the facility scale needs to be increased in order to recover the target amount of valuable metals.

  On the other hand, it is considered that the leaching efficiency is improved by stirring the leaching solution. However, in the case of treating a battery-treated product, the metal piece damages the inner wall of the leaching tank and the stirrer, and the corrosion rate increases, so there is a problem that the life of the apparatus is shortened.

  On the other hand, column leaching is known as a method for suppressing the occurrence of a concentration gradient of the leaching solution (for example, Patent Document 2). Column leaching is a method of leaching a target metal while filling the column with a substance containing the target metal and circulating a leachate through the column. In the case of column leaching, the generation of a concentration gradient can be suppressed by the flow of the leaching solution, and the generation of hydrogen gas bubbles can be suppressed, so that the leaching efficiency is increased.

  However, the conventional column leaching has a problem that the progress of the leaching reaction is unknown. For example, there is a possibility that the process may be continued even though the leaching reaction has ended, or the process may be stopped even though the leaching reaction has not ended. If the circulation of the leachate is stopped before the leaching reaction is completed, the leaching reaction may proceed due to the leachate remaining in the column, and the generated hydrogen gas may partially accumulate, resulting in a concentration higher than the explosion limit. There is danger. Moreover, if the end point of the leaching reaction is not known, it is difficult to formulate an operation plan for the leaching process and a raw material processing plan.

JP 2010-277868 A JP 2011-154811 A

  In view of the above circumstances, an object of the present invention is to provide a metal acid leaching apparatus and an acid leaching method capable of confirming the progress of the leaching reaction.

A metal acid leaching apparatus according to a first aspect of the present invention is an acid leaching apparatus for acid leaching a target metal from a waste battery or a battery-treated product as a raw material, and a column into which the raw material is charged and an acidic aqueous solution as a leaching solution. And a leachate circulating means for circulating in the column, a hydrogen concentration meter for measuring the concentration of hydrogen gas generated in the column, and / or a redox potentiometer for measuring the redox potential of the leachate. To do.
The metal acid leaching device according to a second aspect of the present invention is characterized in that, in the first aspect, the leachate circulating means includes a heating tank capable of heating the leachate.
The metal acid leaching apparatus according to a third aspect of the present invention is characterized in that, in the first or second aspect, the leachate circulation means includes a storage tank for storing the leachate.
A metal acid leaching device according to a fourth aspect of the present invention is characterized in that, in the first, second or third aspect of the invention, the column is provided with a discharge means capable of discharging the leachate in the column.
The metal acid leaching device according to a fifth aspect of the present invention is the first, second, third or fourth aspect of the invention, wherein the column is provided with an overflow port for overflowing the leachate in the column, A filter device that prevents the outflow of the raw material is attached, and the filter device includes a filter material that protrudes around the overflow port and a closing member that closes the upper surface of the filter material. And
Acid leaching method of a metal of the sixth invention, a column waste battery or battery treated is turned on, by circulating the acidic aqueous solution as a leachate, a method for acid leaching the purpose metal, generated from the column The concentration of the hydrogen gas measured is measured, and the process is terminated when the concentration of the hydrogen gas falls below a threshold value.
Acid leaching method of the metal of the seventh invention, a column waste battery or battery treated is turned on, by circulating the acidic aqueous solution as a leachate, a method for acid leaching the purpose metal, generated from the column The concentration of the hydrogen gas measured is measured, and the leaching conditions are controlled so that the concentration of the hydrogen gas becomes a predetermined target value.
Acid leaching method of a metal of the eighth invention, a column waste battery or battery treated is turned on, by circulating the acidic aqueous solution as a leachate, a method for acid leaching the purpose metal, oxidation of the leachate The reduction potential is measured, and the process is terminated when the oxidation-reduction potential exceeds a threshold value or when it does not change over time.

According to the first invention, since the hydrogen concentration meter and / or the oxidation-reduction potential meter are provided, the progress of the leaching reaction can be confirmed from the hydrogen gas concentration and the oxidation-reduction potential. In addition, the end point of the leaching reaction is known, and an efficient operation cycle is possible.
According to the second invention, the leaching efficiency can be improved by heating the leachate in the heating tank. In addition, since a heating tank is provided separately from the column, even if the leaching reaction progresses rapidly, if the circulation of the leachate is stopped, the heated leachate can be stopped from flowing into the column, thereby suppressing the leaching reaction. Can be safe.
According to the third aspect of the invention, since the storage tank is provided, the amount of the leaching liquid that circulates can be increased and the operation can be performed efficiently.
According to the fourth aspect of the invention, since the column is provided with the discharging means, even when the leaching reaction proceeds rapidly, the leaching reaction can be stopped by discharging the leaching solution, which is safe.
According to the fifth aspect, since the filter device is attached to the overflow port, it is possible to prevent the raw material in the column from flowing out due to the flow of the leachate. Moreover, since the upper surface of the filter material of the filter device is closed by the closing member, it is possible to prevent the raw material from being discharged from the overflow port when the raw material is put into the column. Therefore, it is possible to prevent the leaching reaction from occurring outside the column and the apparatus from being damaged.
According to the sixth aspect of the invention, since the process is terminated when the hydrogen gas concentration falls below the threshold value, the process can be terminated at the end point of the leaching reaction, and an efficient operation cycle is possible.
According to the seventh aspect, since the leaching conditions are controlled so that the hydrogen gas concentration becomes a predetermined target value, it is possible to prevent the hydrogen gas concentration from reaching the explosion limit while maintaining the leaching efficiency, and it is safe.
According to the eighth invention, the process is terminated when the oxidation-reduction potential exceeds the threshold value or when it does not change over time. Therefore, the process can be terminated at the end point of the leaching reaction, and an efficient operation cycle is possible. Become.

It is explanatory drawing of the acid leaching apparatus which concerns on one Embodiment of this invention. (A) is a longitudinal cross-sectional view of the column of the acid leaching device, and (b) is a cross-sectional view taken along the line bb in FIG. (A) is a graph which shows the time change of the hydrogen gas concentration and oxidation-reduction potential in Example 1, (b) is a graph which shows the time change of the hydrogen gas concentration and oxidation-reduction potential in Example 2.

Next, an embodiment of the present invention will be described with reference to the drawings.
(Acid leaching device)
As shown in FIG. 1, the acid leaching apparatus A according to an embodiment of the present invention includes a column 1. The column 1 is for performing so-called column leaching, in which a raw material containing a target metal is introduced and a leachate is circulated to leached the target metal.

  A raw material inlet 11 is provided at the top of the column 1, and the raw material can be introduced into the column 1 from the raw material inlet 11. The raw material charged into the column 1 is not particularly limited as long as it is a substance containing a target metal for acid leaching. For example, used nickel-metal hydride batteries and lithium ion batteries, and positive electrode materials constituting these batteries Inferior goods (hereinafter collectively referred to as “waste battery”) generated in the manufacturing process such as the above, and battery processed products obtained by disassembling or crushing waste batteries are used. When a nickel metal hydride battery or a lithium ion battery is used as a raw material, the target metal for acid leaching is nickel or cobalt.

  Inside the column 1, a support plate 12 is provided across the cross section near the bottom. The raw material put into the column 1 is supported by the support plate 12. The structure of the support plate 12 is not particularly limited as long as it can support the raw material and allow the leachate to pass therethrough. For example, the support plate 12 is configured by laminating a filter cloth on a punching plate. In this way, by placing the raw material on the support plate 12, it is possible to prevent the leachate from contacting the raw material uniformly and leaving a part of the raw material unreacted.

  The acid leaching device A includes a storage tank 2 and a heating tank 3. Water and sulfuric acid can be supplied to the storage tank 2, and the mixed liquid thereof can be stored as a leachate. The leachate may be an acidic aqueous solution, and may be other mineral acids such as hydrochloric acid in addition to sulfuric acid.

  One end of a pipe 41 in which the pump 4 is interposed is connected to the bottom of the storage tank 2, and the other end of the pipe 41 is connected to an intermediate part of the pipe 42. The pipe 42 connects the bottom of the column 1 and the upper part of the storage tank 2. Valves V1 and V2 are provided at the connection portion between the pipe 41 and the pipe 42, and the state in which the bottom of the column 1 is connected to the bottom of the storage tank 2 (the valve V1 is opened and the valve V2 is closed) It is possible to selectively switch between the state in which the bottom is connected to the upper part of the storage tank 2 (the valve V1 is closed and the valve V2 is opened). When the bottom of the column 1 and the bottom of the storage tank 2 are connected, the leachate in the storage tank 2 can be supplied to the bottom of the column 1 by driving the pump 4.

  An overflow port 13 is provided at the top of the column 1. The leachate supplied to the bottom of the column 1 comes into contact with the raw material while rising in the column 1, overflows from the overflow port 13, and is discharged from the column 1. One end of an overflow pipe 43 is connected to the overflow port 13, and the other end of the overflow pipe 43 is connected to the bottom of the heating tank 3. Therefore, the leachate overflowed from the column 1 is supplied to the bottom of the heating tank 3.

  The heating tank 3 is provided with heating means 31 such as a heater so that the leachate can be heated. An overflow port is provided in the upper part of the heating tank 3, and the overflow port is connected to the upper part of the storage tank 2 by a pipe 44. Therefore, the leachate heated in the heating tank 3 is supplied to the storage tank 2. Heating the leachate in the heating tank 3 can improve the leaching efficiency.

As described above, the leachate stored in the storage tank 2 is supplied to the bottom of the column 1 by driving the pump 4, and ascends in the column 1 while contacting the raw material. The leachate overflowed from the overflow port 13 is heated in the heating tank 3 and returns to the storage tank 2 again. Thus, the leachate can be circulated through the column 1 by driving the pump 4.
In addition, the storage tank 2, the heating tank 3, the pump 4, and the pipes 41 to 44 correspond to the leachate circulation means described in the claims.

Further, if the valves V1 and V2 at the connection portion between the pipe 41 and the pipe 42 are switched so that the bottom of the column 1 is connected to the upper part of the storage tank 2, the difference between the column 1 and the storage tank 2 causes the column 1 All the leachate inside can be discharged into the storage tank 2.
The pipe 42 corresponds to the discharge means described in the claims.

  Further, a pipe 45 is branched downstream from the pump 4 of the pipe 41. Through the pipe 45, the leachate in the storage tank 2 can be discharged from the acid leaching device A. For example, the leaching solution after the leaching reaction is completed (hereinafter referred to as “liquid after leaching”) can be discharged and supplied to a subsequent process.

In the column 1, the raw material and the leachate come into contact with each other to cause a leaching reaction, thereby generating hydrogen gas. For example, when sulfuric acid as a leachate comes into contact with a raw material containing nickel, the following reaction of Chemical Formula 1 occurs and hydrogen gas is generated.
(Chemical formula 1)
Ni + H ₂ SO ₄ → NiSO ₄ + H ₂ ↑

In order to exhaust the hydrogen gas generated by the leaching reaction, an exhaust pipe 51 leading to an exhaust treatment device such as a scrubber is connected to the upper part of the column 1. The inside of the column 1 is maintained at a negative pressure by the suction of the exhaust treatment device, and the generated hydrogen gas is exhausted.
Note that an air port 14 is provided in the upper part of the column 1 so that air flows in when the inside of the column 1 becomes a negative pressure. Therefore, the generated hydrogen gas is diluted with the air flowing in from the air port 14, and is led to the exhaust treatment device in a state where the hydrogen gas concentration is lowered. In this way, by flowing air, it is safe because the hydrogen gas concentration can be prevented from reaching the explosion limit.

  One end of the exhaust pipe 52 is connected to the upper portion of the storage tank 2, and the other end of the exhaust pipe 52 is connected to the exhaust pipe 51. Therefore, the gas in the storage tank 2 is exhausted to the exhaust treatment device. This is because when hydrogen gas is generated in the storage tank 2 such as when the raw material flows into the storage tank 2 for some reason, the hydrogen gas is exhausted.

  The exhaust pipe 51 is provided with a condenser 5, which is configured to liquefy the water vapor evaporated in the column 1 or the storage tank 2 and return it to the column 1. Therefore, the water balance of the acid leaching device A can be maintained. A demister may be used instead of the condenser.

  The exhaust pipe 51 is provided with a hydrogen concentration meter 6 so that the concentration of hydrogen gas generated in the column 1 can be measured. The hydrogen concentration meter 6 only needs to be able to measure the concentration of hydrogen gas generated in the column 1, and may be provided in the gas phase portion of the column 1 instead of the exhaust pipe 51.

  The overflow pipe 43 is provided with an oxidation-reduction potentiometer 7 so that the oxidation-reduction potential of the leachate overflowed from the column 1 can be measured.

  Furthermore, the heating tank 3 is provided with a thermometer 8 so that the temperature of the leachate can be measured.

  The storage tank 2 and the heating tank 3 may be separate tanks as in the present embodiment, or may be a single tank. That is, the heating tank 31 may be provided in the storage tank 2. However, if the storage tank 2 and the heating tank 3 are separate tanks, for example, while the storage tank 2 secures the amount of leachate stored, the heating tank 3 is used as a thin tank and the heat transfer area of the heater This is preferable because the leaching solution can be efficiently heated.

  Further, the storage tank 2 is not limited to one tank, and a plurality of tanks may be provided, or one tank may not be provided. However, it is preferable to provide the storage tank 2 because the amount of the leaching liquid that circulates can be increased and the operation can be efficiently performed. Further, if a plurality of storage tanks 2 are provided, it is possible to discharge the liquid after leaching and supply new leaching liquid at the same time, and continuous operation becomes possible.

  Furthermore, the column 1 and the heating tank 3 may be separate tanks as in the present embodiment, or may be a single tank. In other words, the heating means 31 may be provided in the column 1. However, it is preferable to use the column 1 and the heating tank 3 as separate tanks since the leaching reaction can be immediately suppressed when the leaching reaction proceeds rapidly in the column 1. Details of this will be described later.

(Filter device)
By the way, when acid-leaching a battery-processed material, there is a possibility that a member having a low specific gravity, such as a separator included in a waste battery, or a plate-like member is mixed in the raw material. As described above, when members that easily float in the leachate are mixed in the raw material, if the flow rate of the leachate in the column 1 is high, they may rise in the column 1 and float and flow out of the overflow port 13. If it does so, there exists a possibility that leaching reaction may occur in unexpected places, such as the heating tank 3 and the storage tank 2, and hydrogen gas may be generated, or a raw material may be caught in the pump 4 etc., and an apparatus may be damaged.

  In order to prevent this, a filter for preventing the raw material from flowing out may be attached to the overflow port 13. However, when the raw material is a battery-treated product, the inventor of the present application says that if the cross section of the overflow port 13 is simply plugged with the filter material, the floated raw material adheres to the filter material and closes the overflow port 13. We have knowledge. This is considered to be because the flow rate of the leachate passing through the filter material is fast because the area of the filter material is small, and the raw material is pressed against the filter material by the flow of the leachate.

Hereinafter, the filter device 15 in the present embodiment will be described with reference to FIG.
The filter device 15 includes a C-shaped top plate 15a provided along the side wall of the column 1, a side filter 15b that hangs down along the edge of the top plate 15a, a lower edge of the side filter 15b, and a column. 1 and a bottom filter 15c provided horizontally between the side walls. The overflow port 13 is provided on the side wall of the column 1 between the top plate 15a and the bottom filter 15c. Therefore, the side filter 15b and the bottom filter 15c are provided to protrude around the overflow port 13, and the top plate 15a closes the upper surfaces of the filters 15b and 15c.
The top plate 15a corresponds to the closing member described in the claims, and the side filter 15b and the bottom filter 15c correspond to the filter material described in the claims.

  The leachate rising in the column 1 passes through the side filter 15b or the bottom filter 15c and is then discharged from the overflow port 13. Therefore, it is possible to prevent the raw material in the column 1 from flowing out due to the flow of the leachate, and to prevent the leaching reaction from occurring outside the column 1 or damage to the apparatus.

  Further, since the top plate 15a is C-shaped in plan view, the filter device 15 does not exist below the raw material charging port 11 (see FIG. 2B). Therefore, the filter device 15 does not get in the way when the raw material is charged from the raw material inlet 11.

  In addition, since the top surface of the filter device 15 is closed by the top plate 15 a, even when the charged raw material falls down to the filter device 15 when the raw material is charged into the column 1, they are still inside the filter device 15. Never fall into. Therefore, it is possible to prevent the raw material from being discharged from the overflow port 13.

  Since the top plate 15 a is C-shaped in plan view, the areas of the filters 15 b and 15 c provided on the top plate 15 a are wider than the cross-sectional area of the overflow port 13. Therefore, the flow rate of the leachate passing through the filters 15b and 15c is slowed, and it is difficult for the floated raw material to reach the filter, and the overflow port 13 can be prevented from being blocked. The areas of the filters 15b and 15c are determined by the properties of the raw materials, the amount of the feed, the flow rate of the leachate, the shape of the column tank, etc., but are preferably about 5 to 15 times the cross-sectional area of the overflow port 13.

  The openings of the filters 15b and 15c are preferably 1 mm to 10 mm. When waste batteries are crushed for industrial treatment, many of them have a size of about 10 mm. Therefore, if the opening is 10 mm or less, outflow of raw materials can be prevented. On the other hand, if the mesh opening is too fine, the raw material will easily adhere and the overflow port 13 will be easily blocked.

  If the areas and openings of the filters 15b and 15c are as described above, even if a member such as a separator included in the waste battery is lifted, the filter 15b and 15c are not firmly attached to the surfaces of the filters 15b and 15c. Moreover, the raw material adhering to the filters 15b and 15c can be peeled off and settled again by the flow of the leachate and the shaking of the filters 15b and 15c.

  The material of the filters 15b and 15c is not particularly limited as long as it has chemical resistance against the leachate, but a hard net made of, for example, polypropylene can be used.

The filter device 15 may have another structure as long as the filter device 15 includes a filter material provided to protrude around the overflow port 13 and a closing member that closes the upper surface of the filter material.
For example, it is good also as a structure which provides an inclination in the top plate 15a and drops the raw material which fell down. Even if the closing member is not a plate material such as the top plate 15a, it may be formed of a material having holes, such as a filter material, as long as the opening does not pass the raw material.

  The shape of the filter device 15 is not limited to a C-shape in plan view, and other shapes may be used as long as the areas of the filters 15b and 15c can be increased. For example, a shape like Dejima connected to the overflow port 13 may be used.

  Further, a plurality of overflow ports 13 of the column 1 may be provided, or the cross-sectional area thereof may be widened by providing the overflow ports 13 over a predetermined range in the circumferential direction of the side wall of the column 1.

(Acid leaching method)
Next, an acid leaching method using the acid leaching apparatus A will be described.
First, water is supplied to the storage tank 2, and the column 1, the storage tank 2, and the heating tank 3 are filled with water so that the liquid can be circulated. The amount of water at this time is determined in advance based on the amount of leachate and the acid concentration necessary for leaching the target metal from the raw material to be added.
Next, the raw material is charged into the column 1.
Note that water may be added after the raw material is charged into the column 1.

  Next, heating is started in the heating tank 3 while circulating the liquid. In consideration of the balance between the leaching efficiency and the heat resistance and corrosion resistance of the apparatus, the heating is controlled so that a target temperature is determined in advance and maintained at the target temperature.

  Next, supply of sulfuric acid to the storage tank 2 is started. Then, sulfuric acid as a leaching solution circulates in the column 1 into which the raw material is charged, and acid leaching of the target metal is performed.

During the leaching process, the concentration of hydrogen gas generated in the column 1 is measured by the hydrogen concentration meter 6 and the leaching conditions are controlled so that the hydrogen gas concentration becomes a predetermined target value.
Here, the target value of the hydrogen gas concentration is determined in advance in consideration of the balance between the leaching efficiency and the explosion limit of the hydrogen gas concentration. For example, the target value of the hydrogen gas concentration is set to 0.5%. If the target value is set to 0.5%, the hydrogen gas concentration will not reach the explosion limit of 4.1%, even if there is a time delay in the leaching reaction relative to the control of the leaching conditions, and it is safe. Further, the target value of the hydrogen gas concentration may be determined as a predetermined range, for example, 0.1% or more and less than 4.1%. If the hydrogen gas concentration is less than 0.1%, the leaching efficiency is deteriorated. If the hydrogen gas concentration is 4.1% or more, the explosion limit is reached, which is dangerous. In this way, if the leaching conditions are controlled so that the hydrogen gas concentration becomes the target value, it is possible to prevent the hydrogen gas concentration from reaching the explosion limit while maintaining the leaching efficiency.

  The leaching conditions are controlled by increasing / decreasing the circulation rate of the leaching solution, the temperature of the leaching solution, the supply amount of sulfuric acid, the input amount of raw materials, and the like. Increasing the circulation rate of the leachate, increasing the temperature of the leachate, increasing the supply amount of sulfuric acid, and increasing the input amount of raw materials will promote the leaching reaction, improve the leaching efficiency, and increase the hydrogen gas concentration. . Conversely, if the circulation rate of the leachate is reduced, the temperature of the leachate is lowered, the supply amount of sulfuric acid is reduced, and the input amount of raw material is reduced, the leaching reaction is suppressed, the leaching efficiency is lowered, and the hydrogen gas concentration Becomes lower. The control of the leaching conditions may be performed by increasing / decreasing all of the circulating flow rate of the leachate, the temperature of the leachate, the supply amount of sulfuric acid, and the input amount of the raw material, or may be performed by increasing / decreasing a part thereof.

  For example, when the hydrogen gas concentration is increasing, the leaching condition is controlled so as to suppress the increase in the hydrogen gas concentration by reducing the supply amount of sulfuric acid before deviating from the target value. However, since the leaching reaction has a time delay, the hydrogen gas concentration may approach the explosion limit of 4.1% even if the sulfuric acid supply is stopped. In such a case, the leaching reaction is further suppressed by stopping the circulation of the leachate and stopping the heating.

As described above, the column 1 may be provided with the heating means 31 and the column 1 and the heating tank 3 may be a single tank. However, when the leaching reaction proceeds rapidly, it is difficult to rapidly reduce the temperature of the leaching solution in the column 1 even if the heating means 31 is stopped, and the leaching reaction may further progress. is there.
On the other hand, since the acid leaching apparatus A of the present embodiment is provided with the heating tank 3 separately from the column 1, even when the leaching reaction proceeds abruptly, the pump 4 is stopped to circulate the leachate. If stopped, the heated leachate can be stopped from flowing into the column 1 and the leach reaction can be suppressed, which is safe.

  Further, when the leaching reaction proceeds rapidly and the hydrogen gas concentration approaches the explosion limit, the valves V1 and V2 may be operated to connect the bottom of the column 1 to the upper part of the storage tank 2. If it does so, all the leaching liquids in the column 1 can be discharged | emitted to the storage tank 2, and since a raw material stops contacting with a leaching liquid, a leaching reaction can be stopped rapidly. Thus, even when the leaching reaction proceeds rapidly, it is safe because the leaching reaction can be stopped by discharging the leaching solution by the discharging means of the column 1.

  The supply of sulfuric acid to the storage tank 2 is stopped after supplying a predetermined amount of sulfuric acid. Here, the amount of sulfuric acid is determined in advance based on the amount of leaching solution and the acid concentration necessary for leaching the target metal from the raw material to be added.

Even after the supply of sulfuric acid to the storage tank 2 is stopped, the leaching reaction continues with the remaining raw material, and the raw material gradually decreases. If it does so, reaction of the said Chemical formula 1 will decrease and hydrogen gas concentration will become low. Utilizing this, the concentration of hydrogen gas generated in the column 1 is measured by the hydrogen concentration meter 6, and when the hydrogen gas concentration falls below the threshold value, it is determined as the end point of the leaching reaction, and the process is terminated. Here, the threshold value of the hydrogen gas concentration is set to 0.1%, for example.
Thus, since the process is terminated when the hydrogen gas concentration falls below the threshold value, the process can be terminated at the end point of the leaching reaction, and an efficient operation cycle is possible.

  Further, when the leaching reaction proceeds and the raw material decreases, the metal as the reducing agent decreases, so that the oxidation-reduction potential of the leaching solution increases. By utilizing this, the oxidation-reduction potential of the leaching solution is measured by the oxidation-reduction potentiometer 7, and when the oxidation-reduction potential exceeds the threshold value, it is determined as the end point of the leaching reaction, and the processing may be terminated. Here, when the raw material is a nickel metal hydride battery or a lithium ion battery, the threshold of the oxidation-reduction potential is set to, for example, +100 mV (silver-silver chloride electrode).

Further, when the leaching reaction is completed and all the target metal contained in the raw material is dissolved in the leaching solution, the oxidation-reduction potential of the leaching solution does not change with time thereafter. Using this, the oxidation-reduction potential of the leaching solution is measured by the oxidation-reduction potentiometer 7, and when the oxidation-reduction potential does not change with time, it is determined as the end point of the leaching reaction, and the processing may be terminated.
Thus, since the process is terminated based on the oxidation-reduction potential, the process can be terminated at the end point of the leaching reaction, and an efficient operation cycle is possible.

  In addition, since the leaching reaction is weakened after the supply of sulfuric acid to the storage tank 2 is stopped, it may take time to reach the threshold even if the hydrogen gas concentration decreases and the oxidation-reduction potential increases. . That is, it may take time for the leaching reaction to reach the end point. In such a case, the treatment time can be shortened by accelerating the leaching reaction by increasing the circulation flow rate of the leaching solution.

  After determining that the end point of the leaching reaction has been reached, the valves V1 and V2 are operated to connect the bottom of the column 1 to the upper part of the storage tank 2, and the leached liquid in the column 1 is discharged to the storage tank 2. . And the liquid after leaching in the storage tank 2 is discharged | emitted from the acid leaching apparatus A through the piping 45, and is supplied to a post process.

  Thereafter, the leach residue remaining in the column 1 is recovered. If the leaching residue is not insoluble and can be leached, it may be left in the column 1 as it is. Even in this case, the leaching process can be performed as a part of the raw material of the next batch.

  The end point of the leaching reaction may not be the time when the target metal contained in the raw material is completely dissolved in the leaching solution, but may be a state where the target metal remains in the leaching residue. The determination of the end point of the leaching reaction is determined in consideration of the leaching efficiency and the operating efficiency of the apparatus.

  As described above, since the acid leaching apparatus A includes the hydrogen concentration meter 6 and the oxidation-reduction potentiometer 7, the progress of the leaching reaction can be confirmed from the hydrogen gas concentration and the oxidation-reduction potential. In addition, the end point of the leaching reaction is known, and an efficient operation cycle is possible.

Example 1
Acid leaching was performed using the acid leaching apparatus A. The side filter 15b and the bottom filter 15c of the filter device 15 were made of a polypropylene hard net (Takiron Co., Ltd. Tricarnet (registered trademark)) having an opening of 3 mm. As a raw material, foamed nickel (Celmet (registered trademark) manufactured by Sumitomo Electric Industries, Ltd.), which is a positive electrode material obtained by disassembling a used nickel-metal hydride battery, was used.

  The column 1 was charged with 24 kg of foamed nickel as a raw material, and then 240 L of water was supplied to the storage tank 2 to fill the column 1 with water. Next, supply of sulfuric acid having a concentration of 59% was started, and leaching treatment was started. The target value of hydrogen gas concentration during the leaching process was set to 0.5%. The exudate circulation flow rate was 25 L / min unless otherwise adjusted. The circulating flow rate is obtained from the measurement result obtained by measuring the linear velocity in the column 1.

  Immediately after the start of the leaching process, there was a plate-like metal piece in the raw material, and the generation of hydrogen gas was active. Therefore, the tendency for the metal piece to collect at the overflow port 13 was confirmed. However, the metal piece did not flow out of the overflow port 13 by the filter device 15. And the leaching process could be continued stably without the overflow port 13 being blocked. As the leaching reaction progressed, the metal piece melted and the shape became smaller, the buoyancy decreased, and the metal piece lift itself decreased.

FIG. 3A shows changes with time in the hydrogen gas concentration and the oxidation-reduction potential (silver-silver chloride electrode) in Example 1. FIG.
The hydrogen gas concentration has increased immediately after the start of the leaching process. Since the hydrogen gas concentration exceeded 0.5% at 10:09, the pump 4 was stopped at 10:12. As a result, the hydrogen gas concentration immediately dropped, and at 10:49, the hydrogen gas concentration again fell below 0.5%. Therefore, the pump 4 was driven at 10:49, and the circulation flow rate was again set to 25 L / min. Moreover, the heating by the heating tank 3 was started from 10:58, and it controlled to maintain the liquid temperature of a leaching solution at 75 degreeC.
From the above, it was confirmed that the hydrogen gas concentration can be controlled and the explosion limit can be prevented by increasing or decreasing the circulation rate of the leachate.

The supply of sulfuric acid to the storage tank 2 was completed at 11:40. The supply amount of sulfuric acid is 130L. Thereafter, the hydrogen gas concentration began to decrease around 13:30, and the oxidation-reduction potential exceeded +50 mV (silver-silver chloride electrode). This shows that the metal component which remains in the raw material is reduced.
Thus, the progress of the leaching reaction could be confirmed from the hydrogen gas concentration and the oxidation-reduction potential.

At 16:40 when the hydrogen gas concentration was below 0.1%, the end point of the leaching reaction was judged, and the treatment was terminated. After discharging the leachate from the column 1, the leach residue was recovered and its weight was measured to be 0.6 kg. It was confirmed that the leaching reaction was completed, as it was sufficiently smaller than the input amount of 24 kg.
From the above, it was confirmed that the end point of the leaching reaction can be determined based on the hydrogen gas concentration.

(Example 2)
In Example 1, the leaching process was performed by reducing the circulation flow rate of the leachate. The other conditions are the same as in Example 1.
FIG. 3B shows changes with time in the hydrogen gas concentration and the oxidation-reduction potential (silver-silver chloride electrode) in Example 2.

The circulation flow rate of the leachate was 25 L / min from the start of the leaching process to about 10:30, and gradually decreased from about 10:30 to 17 L / min at 11:00. Thereafter, 17 L / min was maintained until 14:15. During this time, the hydrogen gas concentration increases and decreases as the circulating flow rate increases and decreases. It can be seen that when the circulation flow rate is 17 L / min, the hydrogen gas concentration does not increase or decrease near 0.1%, and the leaching reaction is weak and a long time has passed. When the circulation flow rate was increased at 14:15, it was confirmed that the hydrogen gas concentration increased and the leaching reaction became active.
From the above, it was confirmed that the progress of the leaching reaction can be controlled by increasing / decreasing the circulation flow rate of the leachate.

(Comparative example)
In Example 1, instead of the filter device 15, a filter cloth (Saran (registered trademark) filter cloth (product number NF-711) manufactured by Asahi Kasei Co., Ltd.) was wound around the overflow port 13. The air permeability of the filter cloth is a catalog value of 32 cm / sec. The other conditions are the same as in Example 1.

When the leaching process was started, the metal piece in the raw material floated and adhered to the filter cloth, and the overflow port 13 was blocked. Further, an increase in the level of the leachate in the column 1 was also observed. As a result, it was necessary to stop the pump 4 and manually remove the material attached to the filter cloth.
From the above, it was confirmed that according to the filter device 15 in the above embodiment, the overflow port 13 can be blocked.

A Acid leaching device 1 Column 2 Reservoir 3 Heating bath 4 Pump 5 Condenser 6 Hydrogen concentration meter 7 Oxidation reduction potential meter 8 Thermometer 11 Raw material input port 12 Support plate 13 Overflow port 14 Air port 15 Filter device 15a Top plate 15b Side filter 15c Bottom filter

Claims (8)

An acid leaching apparatus for acid leaching a target metal from a waste battery or a battery-treated product as a raw material,
A column which the material is introduced,
A leachate circulation means for circulating an acidic aqueous solution as a leachate to the column;
A metal acid leaching apparatus comprising: a hydrogen concentration meter that measures a concentration of hydrogen gas generated in the column; and / or a redox potential meter that measures a redox potential of the leachate. 2. The metal acid leaching apparatus according to claim 1, wherein the leachate circulation means includes a heating tank capable of heating the leachate. 3. The metal acid leaching apparatus according to claim 1, wherein the leachate circulating means includes a storage tank for storing the leachate. 4. The metal acid leaching apparatus according to claim 1, 2, or 3, wherein the column is provided with a discharge means capable of discharging the leachate in the column. The column is provided with an overflow port for overflowing the leachate in the column,
A filter device for preventing the outflow of the raw material is attached to the overflow port,
The filter device comprises:
A filter material provided projecting around the overflow port;
5. The metal acid leaching apparatus according to claim 1, comprising a closing member for closing an upper surface of the filter material. A column waste battery or battery treated is turned on, by circulating the acidic aqueous solution as a leachate, a method for acid leaching the purpose metal,
Measure the concentration of hydrogen gas generated in the column,
A metal acid leaching method, wherein the treatment is terminated when the concentration of the hydrogen gas falls below a threshold value. A column waste battery or battery treated is turned on, by circulating the acidic aqueous solution as a leachate, a method for acid leaching the purpose metal,
Measure the concentration of hydrogen gas generated in the column,
A metal acid leaching method, wherein the leaching conditions are controlled so that the concentration of the hydrogen gas becomes a predetermined target value. A column waste battery or battery treated is turned on, by circulating the acidic aqueous solution as a leachate, a method for acid leaching the purpose metal,
Measure the redox potential of the leachate,
A process for acid leaching of a metal, characterized in that the treatment is terminated when the oxidation-reduction potential exceeds a threshold value or when it does not change over time.