JP2006241558A - Apparatus and method for eluting indium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an indium-eluting apparatus which continuously elutes indium included in a sand blast wasted powder containing indium oxide into an aqueous solution containing a low concentration of acid, and thereby efficiently collects indium. <P>SOLUTION: The eluting apparatus 1 comprises: the first elution tank 4a, the first stirrer 6a and the like for agitating the first suspension 5 in which the sand blast wasted powder 2 and the first aqueous acidic solution 3 are mixed; the first settling tank 10 for naturally settling the first suspension 5 to separate it into the first eluate 8 and a non-eluting residue 9; a residue-transferring pump 15 for transferring the non-eluting residue 9 to the second elution tank 12a; the second elution tank 12a, the second stirrer 17a and the like for agitating the second suspension 16 in which the non-eluting residue 9 and the second aqueous acidic solution 11 are mixed; the second settling tank 20 for naturally settling the second suspension; a vacuum filter 25 for filtering the sediment; and a solution transfer pump 28 for transferring a filtrate and the second eluate 26 which is a supernatant liquid in the second settling tank 20, to the first elution tank 4a. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an indium eluting apparatus and an indium eluting method, and more particularly to an indium eluting apparatus for eluting indium into an acid aqueous solution from sandblast waste powder containing indium oxide.

  Conventionally, a sandblast cleaning of a sputtering apparatus used to form an ITO thin film has been performed. Here, ITO is indium oxide containing tin oxide, and since the thin film is excellent in electroconductivity and translucency, it is widely used for the transparent electrode etc. of a liquid crystal display. This ITO thin film is mainly formed by sputtering using an ITO sintered body as a target, but ITO is scattered and adhered inside the sputtering apparatus used at this time. Therefore, as a maintenance of the sputtering apparatus, sandblast cleaning is performed in which an abrasive such as silica sand is sprayed with compressed air, and the adhered ITO is peeled off and removed. Therefore, the sandblast waste powder after the cleaning operation contains indium oxide.

  Here, indium is contained in a very small amount in zinc ore and is produced as a by-product in the process of zinc refining, so that the production amount is limited. However, in recent years, the demand for indium has rapidly increased with the expansion of use and demand for liquid crystal displays, and as a rare valuable metal, it has been required to recover and reuse indium from waste containing indium. Therefore, attempts have been made to recover indium not only from waste containing high-purity indium such as ITO target scrap, but also from low-grade waste containing a large amount of impurities such as used sandblast powder. Yes. For example, a method has been attempted in which indium is eluted and recovered from sandblast waste powder in an acid aqueous solution.

  The above prior art is publicly implemented, and the applicant has not found a document describing this prior art at the time of filing this application.

  However, since the solubility of indium oxide increases as the acid concentration increases, the conventional method uses the high concentration acid, and thus has the following problems. That is, since the waste liquid after the recovery of indium contains a high concentration of acid, a great deal of labor is required for the neutralization operation. In addition, there is a problem that the cost burden is large because the amount of the neutralizing agent used is large. Further, neutralization of high-concentration acid and disposal has been a problem in terms of acid use efficiency. Furthermore, since the indium content of the sandblast waste powder is small, in order to increase the yield of indium, a large amount of sandblast waste powder will be processed, and accordingly, the amount of high-concentration acid used becomes enormous. The above problem was made big.

  In addition, since the conventional method was a batch method, a large amount of high-concentration acid was used for each indium elution treatment, and a large amount of waste was disposed of. And the problem of acid use efficiency was made more serious.

  In addition, since a high concentration acid is used, a container for eluting indium or the like is eroded by the acid, which may cause impurities to be mixed. In order to prevent the contamination of the impurities, a container using a material having excellent acid resistance must be used, which causes a problem that the apparatus itself is expensive.

  Furthermore, silica, which is the main component of silica sand used as sandblast powder, may become colloidal when treated with a high concentration of acid. This is because the pure crystalline silica (quartz) has excellent acid resistance, while silica sand is a crushed rock (silica) containing silica as the main component, so the crystal structure changes due to pulverization. Thus, it is considered that colloids are formed by being affected by high concentration of acid. Further, this silica colloid causes clogging of the filter, and there is also a problem that it takes a long time for filtration when the acid aqueous solution after elution of indium is solid-liquid separated.

  Moreover, in the conventional elution treatment using a batch method using a high concentration of acid, there is a problem that the yield of indium is generally low and remains at 70 to 80%.

  Therefore, in view of the above circumstances, the present invention can elute indium using a low-concentration acid aqueous solution when recovering indium using acid from sandblast waste powder containing indium oxide. It is an object of the present invention to provide an indium elution apparatus and method that can efficiently recover indium by a typical elution process.

  In order to solve the above-mentioned problems, an indium elution apparatus according to the present invention includes a “first elution tank for mixing an indium oxide-containing sandblast waste powder and a first acid aqueous solution, the sandblast waste powder, and the first acid. First stirring means for stirring the first suspension mixed with the aqueous solution to promote elution of indium, and separating the first suspension into solid and liquid, the first elution solution from which indium is eluted, and uneluting indium A first separation means for separating the non-eluting residue, a second elution tank for mixing the non-eluting residue and a second acid aqueous solution having a higher acid concentration than the first acid aqueous solution, and first separation of the non-eluting residue. Means for transferring residue from the means to the second elution tank, second stirring means for stirring the second suspension in which the non-eluting residue and the second acid aqueous solution are mixed, and promoting elution of indium; Two suspensions A second separation means for separating the liquid into a second elution solution from which indium has been eluted and a post-elution residue after elution of indium; and an elution solution transfer for transferring the second elution solution from the second separation means to the first elution tank. It is mainly provided with “means”.

  Here, sandblasting powder is a blast cleaning that uses sprayed air or centrifugal force to spray abrasives at high speed and peels rust, dirt, film, etc. by the impact force, peening after welding, after machining It is a grinding material used for blasting for deburring. Mainly used is artificial silica sand that is made by grinding and sieving silica such as white silica, and the main component is silica. Using this sand blast powder, as described above, the sand blast waste powder after the sand blast cleaning that peels and removes the ITO scattered and adhered in the sputtering apparatus for forming the ITO thin film is several indium. Contains wt% indium oxide. Since this indium oxide is dissolved in an acid and silica is hardly dissolved in an acid, it is possible to recover indium as an aqueous acid solution. Here, hydrochloric acid, nitric acid, sulfuric acid, mixed acid, aqua regia and the like can be used as the acid.

  In addition, the shape and structure of the first stirring means and the second stirring means are not particularly limited as long as both the acid aqueous solution and the sandblast waste powder or the non-eluting residue can be mixed and stirred. For example, a rotating shaft is inserted from the top of the elution tank, and the stirring blade installed around the rotating shaft is rotated by a driving motor, and the stirring blade installed at the bottom of the elution tank is rotated by a driving motor Is exemplified. Further, the stirring blades may be provided in multiple stages depending on the liquid depth of the suspension to be stirred, and it is desirable to have a mechanism for changing the rotation speed depending on the concentration and viscosity of the suspension.

  Furthermore, the first separation means and the second separation means are not particularly limited as long as they can separate solid and liquid. Here, examples of solid-liquid separation include natural sedimentation, vacuum filtration, pressure filtration, and centrifugal separation. For example, considering the processing of a large amount of sandblast waste powder, it is inefficient to filter the entire suspension mixed with the solid content and the liquid content, so that the sedimentation property of the solid content is good. It is simple and efficient to set such conditions so that the solid content is allowed to settle naturally, only the sediment containing the liquid content is filtered, and the filtrate and supernatant are recovered as the liquid content.

  Moreover, if a residue transfer means transfers the solid part isolate | separated from the liquid part by solid-liquid separation, a structure, a structure, etc. will not be specifically limited. For example, the residue separated by vacuum filtration or pressure filtration is transferred to a conveyor, or the sediment that has naturally settled in the settling tank is discharged from a discharge port provided at the bottom of the tank, and this is discharged to a pump or conveyor. What is transported using is mentioned.

  Further, in the second elution tank, the non-eluting residue transferred by the residue transfer means is mixed with the second acid aqueous solution having a higher acid concentration than the first acid aqueous solution, stirred by the second stirring means, and further indium is eluted. The At this time, the introduction of the second acid aqueous solution into the second elution tank can be performed manually intermittently, but continuously using a discharge machine or the like that automatically discharges the acid solution. It is desirable to do.

  The elution solution transfer means is a means for transferring the liquid component that has been solid-liquid separated in the second separation means, that is, the second elution solution from which indium has been eluted, to the first elution tank. The suspension after vacuum filtration and pressure filtration of the two suspensions is transferred to the first elution tank by a pump, solid-liquid separation is performed by natural sedimentation by the second separation means, and the supernatant is introduced into the first elution tank. And the like. In addition, the solid content separated from the liquid component, that is, the post-elution residue containing almost no indium, can be used as, for example, a cement raw material after being washed. However, in this case, a small amount of indium is dissolved in the washing solution. Therefore, this washing solution may be introduced into the first elution tank together with the second elution solution.

  Here, the second elution solution transferred to the first elution tank by the elution solution transfer means still contains a large amount of unreacted acid that has not been used for dissolution of indium. Used as a first acid aqueous solution for dissolving the sandblast waste powder introduced. As a result, the first elution solution separated from the non-eluting residue by the first separating means was eluted from the indium eluted from the non-eluting residue in the second elution tank and the sandblast waste powder newly introduced in the first elution tank. It will contain both indium. And this 1st elution solution becomes a raw material for reproducing | regenerating indium as aqueous solution containing an indium.

  The means for transferring the first suspension from the first elution tank to the first separation means and the means for transferring the second suspension from the second elution tank to the second separation means are not particularly limited. For example, the suspension may be transferred to a filter as a separation means using a pump. Further, when the separation means is a sedimentation tank that allows natural sedimentation, a difference in height may be provided between the installation positions of the elution tank and the sedimentation tank, and the suspension may overflow from the elution tank and flow into the sedimentation tank. In addition, when using a sedimentation tank, it is possible to use the first and second dissolution tanks as a first sedimentation tank and a second sedimentation tank, respectively, but in order to continuously process a large amount of sandblast waste powder. Is preferably a separate body.

  Therefore, according to the indium elution apparatus of the present invention, the sandblast waste powder containing indium oxide is stirred for a predetermined time in a used acid aqueous solution (first acid aqueous solution) having a low acid concentration, and the indium is first acid aqueous solution. After elution in part, the solution is separated into solid and liquid, and the undissolved residue containing undissolved indium is stirred in an acid aqueous solution (second acid solution) newly introduced with a higher acid concentration than the first acid aqueous solution. Further, indium is dissolved. That is, indium is eluted in two stages. This makes it possible to improve the yield of indium even when the concentration of the acid used is lower than that of the prior art. In addition, problems such as the effort and cost of neutralization, contamination of impurities due to acid corrosion of equipment, deterioration of filterability due to the formation of silica colloids, etc., which have conventionally occurred due to the use of high-concentration acid, are greatly reduced. The

  In addition, by reusing the second elution solution containing unreacted acid as the first acid aqueous solution, it is possible to effectively use the acid that was previously disposed of after each treatment without waste. It becomes. Then, as described above, the solid content separated by the first separation means is introduced into the second elution tank, and the solution content separated by the second separation means is introduced into the first elution tank. As described above, when a series of treatments are continuously circulated, the acid can be effectively used, and indium can be efficiently recovered with a low concentration of acid.

  Further, in addition to the above configuration, the indium elution apparatus according to the present invention includes at least one of a pH meter that measures the hydrogen ion concentration of the first suspension and an acid concentration meter that measures the acid concentration of the second suspension. One "may be provided.

  Here, it is desirable that the hydrogen ion concentration of the first suspension is set to a condition in which indium is efficiently eluted and solid-liquid separation by the first separation means is easy. It is desirable to have a pH meter that measures the hydrogen ion concentration of the suspension. The hydrogen ion concentration of the first suspension can be adjusted by adding an alkaline aqueous solution, but it can also be adjusted by changing the acid concentration of the second suspension. In this case, it is necessary to provide an acid concentration meter for measuring the acid concentration of the second acid suspension. And the means which can control the density | concentration of 2nd acid aqueous solution or the introduction amount to the 2nd elution tank of 2nd acid aqueous solution may be further provided with the detected value.

  Moreover, since the amount of indium contained in the sandblast waste powder can be predicted to some extent, it is possible to set the concentration of the second acid aqueous solution by calculation, but more indium that could not be eluted in the first elution tank In order for the two-step elution process of further eluting with a second acid aqueous solution having a high acid concentration to be performed optimally, the acid concentrations of the first suspension and the second suspension must be known at all times. desirable.

  Here, as the pH meter and the acid concentration meter, a known measuring device such as a pH meter based on a glass electrode method or an acid concentration measuring device based on automatic titration can be used. In addition, it is desirable to provide a means for easily monitoring the hydrogen ion concentration or the acid concentration, such as intermittently or continuously automatically measuring and outputting to a monitor or printer.

  Therefore, according to the indium eluting apparatus of the present invention, it is possible to maintain a hydrogen ion concentration or an acid concentration suitable for eluting indium, and to efficiently elute indium. In addition, in order to improve the yield of indium, indium that could not be eluted in the first elution tank is eluted in the second elution tank using a higher concentration acid. It is possible to maintain optimum conditions.

  Furthermore, the indium elution apparatus according to the present invention has, in addition to the above-described configuration, “a temperature for controlling the liquid temperature of at least one of the first suspension and the second suspension to be 70 ° C. or higher and 90 ° C. or lower. Control means "may be included.

  In general, the solubility and dissolution rate of a metal oxide in an acid increases with increasing temperature. Therefore, by maintaining the liquid temperature of the first suspension and the second suspension in the above temperature range, it is possible to promote the elution of indium and further improve the yield.

  Here, the temperature control means only needs to be able to appropriately detect the temperature of the suspension and control the heating based on the result, and can be used in combination with known thermometers, controllers, heaters, and the like. is there. The heating may be performed by heating the elution tank itself with a heater or the like, putting a heater into the suspension, or heating the acid aqueous solution before being introduced into the elution tank.

  Therefore, according to the indium elution apparatus of the present invention, it becomes possible to maintain the liquid temperature of the suspension in the elution tank at a temperature condition suitable for elution of indium, promoting the elution of indium and increasing the yield. It can be improved further.

  In addition, the indium elution method according to the present invention is described as follows: “The first suspension in which the sandblast waste powder containing indium oxide and the first acid aqueous solution are mixed is stirred, and indium is partially eluted in the first acid aqueous solution. A first elution step, a first separation step of solid-liquid separation of the first suspension and separation into a first elution solution in which elution of indium and an unelution residue containing uneluted indium, and the non-elution residue And a second elution step in which a second suspension in which a second acid aqueous solution having a higher acid concentration than the first acid aqueous solution is mixed is stirred to further elute indium into the second acid aqueous solution, and the second suspension. The liquid is separated into solid and liquid, and the second elution solution from which indium has been eluted and the second separation step to separate the indium after elution are used, and the second elution solution is used as the first acid aqueous solution. The main features It is.

  Therefore, according to the indium elution method of the present invention, the used acid aqueous solution is used as the first acid aqueous solution to partially elute indium in the sandblast waste powder, and then the uneluted residue containing uneluted indium is solidified. The liquid was separated, and the uneluted residue was stirred in a second acid aqueous solution, which is a new acid aqueous solution having a higher acid concentration than the first acid aqueous solution to further elute indium, followed by solid-liquid separation to elute indium. An elution solution is obtained, and this is reused as a first aqueous solution to elute indium from the newly added sandblast waste powder with the remaining unused acid, and it is solid-liquid separated from the uneluted residue to obtain a second elution tank and a second elution solution. The first elution tank containing indium eluted in both of the elution tanks is recovered as an indium-containing aqueous solution, and the uneluted residue is treated with the second acid aqueous solution to further elute indium, and so on. It is possible to perform the cycle of the processing of communicating continuously.

  Further, in addition to the above configuration, the indium elution method according to the present invention may be “the hydrogen ion concentration of the first suspension is maintained in the range of pH 0.5 or more and 2.0 or less”. Absent.

  Here, since indium produces | generates a hydroxide and precipitates at pH 2 or more, it cannot isolate | separate from the silica which is a main component of silica sand. Further, it has been found that at a pH of 0.5 or less, solid-liquid separation after elution of indium has poor sedimentation of the solid content. Therefore, it is effective to carry out elution of indium in the first elution step while maintaining the pH of the first suspension in the range of 0.5 to 2.0. The hydrogen ion concentration can be adjusted by adding an alkaline aqueous solution, but can be easily adjusted by the amount of sandblast waste powder to be treated in the first elution step. That is, when the indium content of the sandblast waste powder is higher than originally expected, and the pH value of the first suspension falls below the above setting range due to acid consumption, the amount of sandblast waste powder to be added to the first acid aqueous solution If the indium content is lower than originally expected, the amount of sandblast waste powder to be added is increased. Thereby, an alkali metal etc. do not mix like the case where pH adjustment is carried out by alkali addition. Moreover, the acid concentration of the second elution solution used as the first acid aqueous solution is changed by changing the concentration of the second acid aqueous solution (for example, 1N to 5N) and changing the acid concentration of the second suspension. It is also possible to make adjustments.

  Further, the first elution solution obtained by solid-liquid separation of the first suspension in the first separation step is composed of indium eluted from the non-eluting residue in the second elution step, and sandblast waste powder in the first elution step. It contains both the eluted indium and becomes a raw material for regenerating indium as an indium-containing aqueous solution. Here, indium regeneration from an indium-containing aqueous solution includes adding an alkali to an acid aqueous solution in which indium is dissolved, precipitating indium as a hydroxide, and firing it into indium oxide, or by electrolysis. There are a method of precipitating simple indium, a cementation method of precipitating by replacing zinc and the like, and the like. In the electrolysis method and the cementation method, it is necessary to adjust the electrolytic solution to a pH of about 0.5 or more and about 2.0. The first elution solution is suitable for use as an electrolytic solution or a cementation solution because there is no need to adjust the pH during the regeneration of indium by these methods.

  Therefore, according to the method for eluting indium according to the present invention, it is possible to prevent the formation of indium hydroxide and maintain a pH range in which the sedimentation of solids during solid-liquid separation has a good pH range. It becomes possible to elute.

  Moreover, since the first elution solution is already adjusted to a pH range suitable for the electrolysis method and the cementation method, it is particularly suitable for the regeneration of indium by these methods. And since it is not necessary to neutralize the acid aqueous solution after indium elution, it becomes possible to eliminate the problem regarding the neutralization in the conventional method.

  The indium elution method according to the present invention includes, in addition to the above configuration, “the liquid temperature of at least one of the first suspension and the second suspension is controlled to be 70 ° C. or higher and 90 ° C. or lower”. It doesn't matter.

  Here, the solubility and dissolution rate of a metal oxide in an acid generally increase with an increase in temperature. However, for example, when hydrochloric acid is used as the acid, the boiling point of the specified hydrochloric acid is a few hundred degrees Celsius, so if it exceeds 100 degrees Celsius, it evaporates into hydrogen chloride gas, causing problems in the working environment.

  Therefore, according to the indium elution method of the present invention, the temperature of the first suspension and the second suspension is set to a temperature range of 70 ° C. or higher and 90 ° C. or lower so as not to burden the environment. The elution of indium can be promoted within the range, and the yield can be further improved.

  As described above, according to the indium elution apparatus and the indium elution method of the present invention, a used low-concentration acid and an acid aqueous solution having a higher acid concentration are used to remove sandblast waste powder containing indium oxide. By eluting indium in two steps, it becomes possible to elute indium and recover it with a high yield using a lower concentration of acid than in the past. Further, by reusing the second elution solution as the first acid aqueous solution and continuously performing a series of treatments, it is possible to increase the use efficiency of the acid.

  Hereinafter, an indium eluting apparatus and an indium eluting method using the apparatus according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. Here, FIG. 1 is an explanatory view showing a schematic configuration of an indium elution apparatus (hereinafter simply referred to as “elution apparatus”) of the present embodiment, and FIG. 2 is an indium elution method (hereinafter, “elution apparatus”) using the elution apparatus of FIG. FIG. 6 is a process diagram illustrating a flow of processing of simply “elution method”.

  As shown in FIG. 1, the elution apparatus 1 of the present embodiment includes first elution tanks 4 a and 4 b for mixing the sandblast waste powder 2 and the first acid aqueous solution 3, and the sandblast waste powder 2 and the first acid aqueous solution 3. A first stirrer 6a, 6b that stirs the mixed first suspension 5, a first settling tank 10 that spontaneously settles the first suspension 5 and separates it into a first elution solution 8 and an uneluting residue 9, Second elution tanks 12a and 12b that contain the uneluting residue 9 and the second acid aqueous solution 11, a residue transfer pump 15 that transfers the uneluting residue 9 from the first sedimentation tank 10 to the second elution tank 12a, and an uneluting residue 9 and the second stirrer 17a and 17b that stir the second suspension 16 mixed with the second acid aqueous solution 11, the second settling tank 20 that naturally settles the second suspension, and the filtrate by filtering the sediment. Vacuum filter 25 to separate residue 21 after elution, filtrate and second sedimentation It is mainly constituted by a second elution solution 26 which is supernatant 20 such solution transfer pump 28 for transferring the first elution tank 4a.

  More specifically, the first elution tank includes two elution tanks 4a and 4b, and the first suspension 5 is sequentially stirred in the first elution tanks 4a and 4b. Thus, by providing two elution tanks, the time for stirring the suspension in the elution tank to elute indium can be made twice as long as the time required for natural sedimentation in the settling tank. And with respect to each of the 1st elution tank 4a, 4b, the 1st suspension 5 in a tank is stirred with the stirring blade, The 1st stirrer 6a provided with the mechanism which can control the rotation speed of this stirring blade 6b is provided. Similarly, the second elution tank is also composed of two elution tanks 12a and 12b, and a second stirrer 17a for stirring the second suspension 16 in the tank with respect to each of the second elution tanks 12a and 12b. , 17b. Here, the first stirrers 6a and 6b correspond to the first stirring means in the present invention, and the second stirrers 17a and 17b correspond to the second stirring means in the present invention. The capacities of the first elution tanks 4a and 4b and the second elution tanks 12a and 12b are all 120 liters (effective capacity 90 liters).

  Further, the pH meter 30 is at a position where the pH of the first suspension 5 in the first elution tank 4a can be measured, and the acid concentration of the second suspension 16 in the second elution tank 12a can be measured. An acid concentration meter 31 is provided. In addition, in this embodiment, the discharger 35 which discharges the 2nd acid aqueous solution continuously to the 2nd elution tank 12a is provided.

  Further, for each of the first elution tanks 4a and 4b and the second elution tanks 12a and 12b, the temperature of the heater 36 for heating the elution tank and the suspension in the tank is measured, and the temperature is set to a predetermined value. A temperature controller 37 that controls the heating of the heater 36 is provided to maintain the temperature range. Here, the heater 36 and the temperature controller 37 correspond to the temperature control means in the present invention.

  Moreover, both the 1st sedimentation tank 10 and the 2nd sedimentation tank 20 are made into the funnel shape, It is set as the structure which makes a suspension settle naturally and discharges a sediment from the discharge port 40 of a bottom part to a receiving container. . Moreover, the bottom part in each tank is equipped with the rake (not shown) which attracts sediment. In addition, the capacity | capacitance of the 1st sedimentation tank 10 and the 2nd sedimentation tank 20 is 120 liters (effective capacity 90 liters) similarly to the elution tanks 4a, 4b, 12a, and 12b.

  Furthermore, the residue transfer pump 15 transfers the sediment that naturally settled in the first sedimentation tank 10 and discharged from the discharge port 40 to the receiving container to the second elution tank 12a. Here, the first sedimentation tank 10 corresponds to the first separation means of the present invention, and the residue transfer pump 15 corresponds to the residue transfer means of the present invention.

  Moreover, the vacuum filter 25 filters the sediment settled in the 2nd sedimentation tank 20, and isolate | separates into the residue 21 after a filtrate and elution. The separated filtrate and the supernatant of the second settling tank 20 are both a second elution solution 26 in which indium is dissolved in the second acid aqueous solution 11. Here, the filtrate is transferred to the first elution tank 4a by the solution transfer pump 28, and the supernatant liquid overflows from the second sedimentation tank 20 and flows into the first elution tank 4a. Here, the second sedimentation tank 20 and the vacuum filter 25 correspond to the second separation means of the present invention, so that the supernatant liquid overflowing from the solution transfer pump 28 and the second sedimentation tank 20 flows into the first elution tank 4a. The structure in which both tanks are connected with a difference in height corresponds to the elution solution transfer means of the present invention. In addition, the supernatant liquid of the 2nd sedimentation tank 20 is good also as transferring to the 1st elution tank 4a using a pump.

  In this embodiment, the first suspension 5 is transferred from the first elution tank 4a through the first elution tank 4b to the first sedimentation tank 10, and the second elution tank 12a is moved from the second elution tank 12a. The transfer of the second suspension 16 to the second settling tank 20 is connected to each tank with a difference in height, and the suspension overflows from one end of the upper edge of the tank and flows into the next tank. It is done by doing.

  Next, the elution method 50 using the elution apparatus 1 of this embodiment is demonstrated using FIG.1 and FIG.2. First, untreated sandblast waste powder 2 containing indium oxide is charged into a first acid aqueous solution 3 (that is, a second elution solution 26) that is a used acid aqueous solution introduced into the first elution tank 4a. The first suspension solution 5 mixed with is stirred by the first stirrer 6a. Then, the first suspension solution 5 stirred and overflowed in the first elution tank 4a flows into the second elution tank 4b, and is similarly stirred by the first stirrer 6b. At this time, the stirring speed by the first stirrers 6a and 6b is adjusted to about 350 rpm. By stirring in the first elution tanks 4a and 4b, indium oxide contained in the sandblast waste powder 2 is partially dissolved, and indium is eluted in the first acid aqueous solution 3 (first elution step S1).

  At this time, the first elution tanks 4 a and 4 b are heated by the heater 36, and the temperature of the first suspension 5 is maintained at about 80 ° C. under the control of the temperature controller 37, so that indium elution is promoted. ing. Further, the hydrogen ion concentration of the first suspension 5 is measured by the pH meter 30, and the amount of the sandblast waste powder 2 charged is adjusted so that the pH is maintained in the range of 0.5 to 2.0. Thereby, the hydrogen ion concentration of the first suspension 5 is adjusted to a condition in which indium does not precipitate as a hydroxide and the sedimentation property of the solid content in the next step is good.

  Next, the first suspension 5 overflowing from the first elution tank 4b flows into the first sedimentation tank 10, where the first elution solution 8 from which indium has partially eluted and the uneluting indium are separated by natural sedimentation. Solid-liquid separation is performed on the non-eluting residue 9 (first separation step S2). The sediment is raked by the rake and discharged from the discharge port 40 at the bottom of the first sedimentation tank to the receiving container. The sediment at this time is in a state in which the uneluting residue 9 contains the first eluting solution 8, and this may be filtered to transfer only the uneluting residue 9 to the second eluting tank 12a. In the embodiment, the residue is transferred to the second elution tank 12a using the residue transfer pump 15 as it is.

  The non-eluting residue 9 thus transferred to the second elution tank 12a is mixed with the second acid aqueous solution 11 introduced into the second elution tank 12a to become a second suspension 16. Here, in the present embodiment, hydrochloric acid prepared to about 4N is used as the second acid aqueous solution 11, and is continuously introduced into the second elution tank 12a by the discharger 35. Then, the second suspension 16 is stirred by the second stirrer 17a, and subsequently stirred by the second stirrer 17b in the second elution tank 12b. The stirring speed by the second stirrers 17 and 17b at this time is adjusted to about 350 rpm similarly to the first stirrers 6a and 6b, and the liquid temperature of the second suspension 16 is the same as in the case of the first suspension 5. At about 80 ° C. The acid concentration of the second suspension 16 is measured by the acid concentration meter 31 and is maintained at about 3N by adjusting the amount of the second acid aqueous solution 11 added from the discharger 35. As a result, the indium remaining in the non-eluting residue 9 is not dissolved by the first acid aqueous solution 3 having a low concentration, but is dissolved by the second acid aqueous solution 11 having a higher concentration than the first acid aqueous solution 3, and almost all Is eluted in the second acid aqueous solution (second elution step S3).

  Next, the second suspension 16 overflowing from the second elution tank 12b and flowing into the second settling tank 20 is solid-liquid into the second elution solution 26 and the post-elution residue 21 containing almost no indium by natural sedimentation. To be separated. Then, as in the case of the first settling tank 10, the sediment is discharged from the discharge port 40 to the receiving container. Since this precipitate is in a state in which the residue 21 after elution contains the second elution solution 26, it is introduced into the vacuum filter 25 using the pump 27, and is vacuum filtered to obtain the residue 21 and the second elution solution 26 after elution. (Second separation step S4). The post-elution residue 21 separated by filtration here is mostly silica-derived silica, which can be used as a cement raw material after being washed with water.

  The filtrate filtered by the vacuum filter 25 and the supernatant in the second sedimentation tank 20 are both the second elution solution 26. The filtrate is transferred to the first elution tank 4a by the solution transfer pump 28, and the supernatant liquid. Overflows from the second sedimentation tank 20 and flows into the first elution tank 4a. The acid concentration of the second elution solution 26 is lower than the initial acid concentration of the second acid aqueous solution 11 because the acid was consumed to elute indium in the second elution step S3. This second elution solution 26 is used again as the first acid aqueous solution 3 for dissolving the sandblast waste powder 2 newly introduced in the first elution step, and indium is eluted in the same manner as described above (first elution step). Elution step S1).

  Thereafter, as described above, the first elution solution 8 separated from the sediment in the first separation step S2 overflows from the first separation tank 10 and is recovered. This first elution solution 8 contains both indium eluted from the uneluting residue 9 in the second elution step and indium eluted from the sandblast waste powder 2 newly introduced in the first elution step S1, and contains indium. Used as an aqueous solution for the regeneration of indium. In particular, since the pH is adjusted in the range of 0.5 to 2.0 in the first elution step S1, it is used as a solution for recovering indium by electrolysis or cementation.

  Next, the yield of indium in this embodiment is shown. In addition to the above conditions (temperature, pH, stirring speed), sandblast waste powder 2 containing 2.4 wt% indium was added to the 60 kg first elution tank 4a per hour, and 45 liters per hour The second acid aqueous solution 11 (4N hydrochloric acid) is introduced into the second elution tank 12a, the second elution solution 26 is introduced into the first elution tank 4a at 60 liters per hour, the first settling tank 10, the second settling tank In this case, the settling time in the tank 20 is 1 hour, the stirring time in each of the first elution tanks 4a and 4b and the second elution tanks 12a and 12b is 1 hour, and a series of steps are continuously performed. If the indium contained in the untreated sandblast waste powder 2 is 100% under the above conditions, 21.7% of indium remains in the uneluting residue 9 that has undergone the first elution step S1, and can be recovered. The indium remaining in the residue 21 after elution was 2.1%. That is, 19.6% of indium 21.7% contained in the non-eluting residue 9 was eluted in the second elution step S3. Therefore, indium could be finally recovered from the sandblast waste powder 2 with a high yield of 97.9%.

  As described above, according to the elution apparatus 1 and the elution method 50 of the present embodiment, a used acid aqueous solution (first acid aqueous solution 3) having a low acid concentration is used from the sandblast waste powder 2 containing indium oxide. Using a lower concentration of acid than in the past, elution is carried out in two steps, in which indium is further dissolved by the second acid solution 11 having a higher acid concentration after partially eluting the indium. Even so, indium can be recovered with good yield. In addition, by reusing the second elution solution 26 containing unreacted acid as the first acid aqueous solution 3, it is possible to effectively use the acid that has conventionally been disposed of after each treatment without waste. Is possible.

  Then, the solid component separated in the first sedimentation tank 10 is introduced into the second elution tank 12a, and the solution component separated in the second sedimentation tank 20 is introduced into the first elution tank 4a. Thus, a series of treatments are performed in a circulating manner, and it is possible to recover the indium continuously and efficiently using the acid effectively.

  In addition, by adjusting the first suspension 5 to a pH range of 0.5 to 2.0, conditions suitable for efficient elution of indium, that is, generation of indium hydroxide are prevented. In addition, the conditions under which the sedimentation property of the solid content is good during the solid-liquid separation (first separation step S2) are maintained. In addition, the indium-containing aqueous solution (first elution solution 8) adjusted to such a pH range is suitable for indium regeneration by electrolysis or cementation. In addition, the problem of neutralization after the elution treatment, which was a problem of the conventional method, can be solved. Furthermore, the elution of indium is promoted by maintaining the liquid temperature of the suspensions 5 and 16 in the elution tank at about 80 ° C.

  As a result, indium with a very high yield of about 98% using a low concentration of acid, compared to the conventional elution apparatus and elution method, which remained at a yield of 70 to 80% even when a high concentration of acid was used. Can be recovered.

  The present invention has been described with reference to preferred embodiments. However, the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the present invention as described below. And design changes are possible.

  For example, in order to sufficiently elute indium, in this embodiment, two each of the first elution tank and the second elution tank are provided, and the time for stirring the suspension and eluting indium is determined by the natural sedimentation in the sedimentation tank. However, it is possible to connect more elution tanks to make the elution stage multi-stage and to make the elution process longer. Moreover, the same effect can be acquired also by making each elution tank larger than a sedimentation tank and enlarging a capacity | capacitance.

  In addition, solid-liquid separation of the suspension is performed by natural sedimentation in this embodiment, but may be forcibly separated by vacuum filtration, pressure filtration, or the like.

  Further, in this embodiment, the suspension is transferred between the elution tanks and from the elution tank to the settling tank without using electric power, and connected to each tank with a difference in height, and suspended from the upper part of the tank. Although the turbid liquid is transferred to the next tank by gravity, it can be transferred regardless of the distance or height between the tanks using a pump or the like.

It is explanatory drawing which shows schematic structure of the elution apparatus which is one Embodiment of this invention. It is process drawing which shows the flow of a process of the elution method by the elution apparatus of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Elution apparatus 2 Sandblast waste powder 3 1st acid aqueous solution 4a, 4b 1st elution tank 5 1st suspension 6a, 6b 1st stirrer (1st stirring means)
8 First elution solution 9 Non-elution residue 10 First sedimentation tank (first separation means)
11 Second acid aqueous solution 12a, 12b Second elution tank 15 Residue transfer pump (residue transfer means)
16 Second suspension 17a, 17b Second stirrer (second stirring means)
20 Second sedimentation tank (second separation means)
21 Residue after elution 25 Vacuum filter (second separation means)
26 Second Elution Solution 28 Solution Transfer Pump (Elution Solution Transfer Means)
30 pH meter 31 Acid concentration meter 50 Elution method

Claims (6)

A first elution tank for mixing the sandblast waste powder containing indium oxide and the first acid aqueous solution;
A first stirring means for stirring the first suspension in which the sandblast waste powder and the first acid aqueous solution are mixed, and promoting elution of indium;
A first separation means for separating the first suspension into a solid and liquid, and separating the first suspension into an undissolved residue containing an undissolved insoluble first eluting solution and undissolved indium;
A second elution tank for mixing the non-eluting residue and the second acid aqueous solution having a higher acid concentration than the first acid aqueous solution;
A residue transfer means for transferring the uneluted residue from the first separation means to the second elution tank;
A second agitation means for agitating the second suspension in which the non-eluting residue and the second acid aqueous solution are mixed, and promoting elution of indium;
A second separation means for solid-liquid separation of the second suspension and separating into a second elution solution from which indium has been eluted and a residue after elution after indium elution; and
An indium elution apparatus comprising elution solution transfer means for transferring the second elution solution from the second separation means to the first elution tank.   The apparatus according to claim 1, further comprising at least one of a pH meter for measuring a hydrogen ion concentration of the first suspension and an acid concentration meter for measuring an acid concentration of the second suspension. Indium elution device.   The temperature control means for controlling the liquid temperature of at least any one of a 1st suspension and a 2nd suspension to 70 degreeC or more and 90 degrees C or less is further provided, The claim 1 or Claim characterized by the above-mentioned. 2. The indium elution apparatus according to 2. A first elution step of stirring the first suspension in which the sandblasting waste powder containing indium oxide and the first acid aqueous solution are mixed, and partially eluting indium into the first acid aqueous solution;
A first separation step in which the first suspension is solid-liquid separated and separated into a first eluting solution in which indium is eluted and an uneluting residue containing insoluble eluting indium;
A second elution step of stirring the second suspension in which the non-eluting residue and the second acid aqueous solution having a higher acid concentration than the first acid aqueous solution are mixed, and further eluting indium into the second acid aqueous solution;
Solid-liquid separation of the second suspension, and a second separation step of separating into a second elution solution eluting indium and a residue after elution after indium elution,
The indium elution method, wherein the second elution solution is used as a first acid aqueous solution.   5. The indium elution method according to claim 4, wherein the hydrogen ion concentration of the first suspension is maintained in a range of pH 0.5 or more and 2.0 or less.   6. The indium elution method according to claim 4, wherein the temperature of at least one of the first suspension and the second suspension is controlled to be 70 ° C. or higher and 90 ° C. or lower. .

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