Metal extraction method

Abstract

To provide a technique which suppresses adsorption of impurity metal to a chelate resin in ion exchange treatment using a chelate resin to a solution containing extraction object metal and impurity metal, and effectively adsorbs the extraction object metal.SOLUTION: A method for extracting extraction object metal M from a solution containing extraction object metal M and impurity metal N performs ion exchange treatment including a step of passing a solution through a chelate resin and adsorbing the extraction object metal M to the chelate resin, wherein in the ion exchange treatment, when an adsorption amount of the extraction object metal M to the chelate resin is represented by qM and a maximum adsorption amount is represented by qmax,M, a value of a liquid passage amount BV having qM / qmax,M of 0.5 is defined as a lower limit value, and smaller one of a value of the liquid passage amount BV having the maximum adsorption amount qmax,M of the extraction object metal M and a value of the liquid passage amount BV having an apparent separation coefficient αapp,NM defined by a relation between the extraction object metal M and the impurity metal N of 1 is defined as an upper limit value, the liquid passage amount BV of the solution is set to be in the range between the lower limit value and the upper limit value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for extracting metals, and more particularly to a method for extracting metals by subjecting a solution containing the metal to be extracted and impurities to an ion exchange treatment using a chelating resin. [Background technology]

[0002] As a method for extracting and separating a target metal from a solution containing the target metal and predetermined impurity metals, for example, an ion exchange treatment using a chelating resin is carried out.

[0003] Ion exchange treatment using a chelating resin is an extraction method that utilizes the property of forming a chelate between the chelating resin and the metal ion to be extracted, thereby selectively capturing the metal.

[0004] In the field of metal smelting, for example, ion exchange treatment using chelating resins is carried out as a method for extracting specific valuable metals from acidic solutions obtained by subjecting nickel oxide ores to a hydrometallurgical process.

[0005] More specifically, nickel oxide ores, such as laterite and limonite, contain trace amounts of scandium, and the acidic solution obtained by hydrometallurgical processing of the nickel oxide ores contains scandium. Scandium is a valuable metal that is highly valued as an additive for high-strength aluminum alloys and as an electrode material for fuel cells.

[0006] However, the scandium separated from nickel oxide ore through the hydrometallurgical process is dilute and contains a wide variety of impurity metals, so further purification is required to separate and recover the valuable scandium metal.

[0007] In this case, for example, an ion exchange treatment using a chelating resin can be applied as the purification treatment.

[0008] For example, Patent Document 1 discloses a technique in which nickel and scandium are first selectively leached from nickel oxide ore in an acidic solution under high temperature and pressure in an oxidizing atmosphere to obtain a leachate, the pH of the leachate is then adjusted to 2 to 4, and nickel is selectively precipitated and recovered as a sulfide using a sulfiding agent, and the resulting post-sulfiding solution after nickel recovery is then brought into contact with a chelating resin to adsorb scandium, the chelating resin is washed with a dilute acid, and then the chelating resin is brought into contact with a strong acid after washing to elute the scandium.

[0009] Nickel oxide ore is known to contain impurity metals such as iron, aluminum, chromium, manganese, magnesium, etc., although the type and amount vary depending on the region where it is mined. In particular, the impurity metal chromium behaves similarly to scandium and is characterized by its tendency to be easily adsorbed by chelating resins.

[0010] Therefore, Patent Document 2 discloses a technique for increasing the amount of scandium recovered by contacting an acidic solution containing scandium and chromium with a chelating resin at a predetermined temperature to reduce the amount of chromium adsorbed. This method is useful because it can reduce the amount of impurity metals, including chromium, adsorbed to the chelating resin.

[0011] In this way, by performing ion exchange treatment using a chelating resin on a solution containing a target metal such as scandium and an impurity metal such as chromium, a solution can be obtained in which the target metal has been selectively extracted.

[0012] However, there is still room for improvement in ion exchange processes using chelating resins, and there is a need for technology that can more effectively suppress the adsorption of impurity metals onto chelating resins when treating solutions containing the metals to be extracted and impurity metals. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] Japanese Patent Application Publication No. 9-194211 [Patent Document 2] Japanese Patent Publication No. 2021-050378 Summary of the Invention [Problem to be solved by the invention]

[0014] Therefore, the present invention aims to provide a metal extraction method that can suppress the adsorption of impurity metals to the chelating resin during ion exchange treatment of a solution containing the metal to be extracted and a specified impurity metal, thereby more effectively adsorbing and extracting the metal to be extracted. [Means for solving the problem]

[0015] The inventors focused on the amount of liquid passed through the chelating resin in an ion exchange treatment using a chelating resin packed in a column, and discovered that there is an optimal range of the amount of liquid passed through in relation to the amount of metal M to be extracted adsorbed onto the chelating resin, thereby completing the present invention.

[0016] (1) The first aspect of the present invention is a method for extracting a metal from a solution containing a target metal M and a predetermined impurity metal N, the method comprising: passing the solution through a column packed with a chelating resin to perform an ion exchange treatment including an adsorption step in which the target metal M contained in the solution is adsorbed onto the chelating resin; and in the ion exchange treatment, the amount of the target metal M adsorbed onto the chelating resin is determined as q M The maximum adsorption amount of the target metal M to be extracted onto the chelating resin is q max,M When M / q max,M The value of the flow rate BV of the solution at which the value of q = 0.5 is set as the lower limit, and the maximum adsorption amount q of the target metal M to be extracted onto the chelating resin is set as the max,Mor the apparent separation coefficient α defined as follows in the relationship between the target metal M and the predetermined impurity metal N contained in the solution: app,N M and the value of the solution flow rate BV at which the apparent separation factor α is 1, whichever is smaller, are set as upper limits, and the solution flow rate BV is set within a range from the lower limit to the upper limit. app,N M is the apparent distribution ratio D of the target metal M and the specified impurity metal N. app,i Therefore, α app,N M =D app,M / D app,N The apparent distribution rate D app,i is the amount of adsorption onto the chelating resin, q i and the concentration C in the solution after passing through the column. ef,i By this, D app,i =q i / C ef,i It is expressed as:

[0017] (2) The second invention of the present invention is a metal extraction method in which, in the first invention, the leakage rate, expressed as the ratio of the metal concentration in the solution after passing through the column to the metal concentration in the solution before passing through the column, of the target metal M to be extracted is smaller than the leakage rate of the specified impurity metal N.

[0018] (3) A third aspect of the present invention is the method for extracting metals according to the first or second aspect of the present invention, wherein the chelating resin is an iminodiacetic acid type chelating resin.

[0019] (4) A fourth aspect of the present invention is the method for extracting a metal according to the first or second aspect of the present invention, wherein the concentration of the metal M to be extracted contained in the solution is 1 mg / L or more. [Effects of the Invention]

[0020] According to the present invention, in an ion exchange treatment using a chelating resin on a solution containing a target metal M and a specified impurity metal N, the adsorption of the impurity metal N to the chelating resin can be suppressed, and the target metal M can be more effectively adsorbed and extracted. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a graph showing the relationship between the metal ion concentration in the eluate recovered from the column after passing the solution to be treated through a chelating resin, and the amount of metal ions adsorbed onto the chelating resin, based on the results of a test example of ion exchange treatment. [Figure 2] Similar to Figure 1, this graph shows the relationship between the metal ion concentration in the eluate and the amount of metal ions adsorbed onto the chelating resin, where the temperature condition was 60°C and the solution flow rate BV was 15, 35, and 50. [Figure 3A] 1 is a graph showing a breakthrough curve based on the measurement results of the scandium leakage rate under treatment conditions of a liquid flow rate BV=35 and a liquid flow rate BV=50 in a test example of ion exchange treatment. [Figure 3B] 3A, this is a graph of breakthrough curves based on the measurement results of scandium leakage rates under each treatment condition of liquid flow rates BV=35 and 50. [Figure 4] 1 is a graph showing the relationship between the apparent separation coefficient between scandium and chromium and the adsorption efficiency of scandium versus the solution flow rate BV in a test example of ion exchange treatment. [Figure 5A] 1 is a graph showing breakthrough curves showing the relationship between the leakage rates of scandium and chromium and the amount of solution passed through BV when the solution was passed through a chelating resin at a temperature of 23°C in a test example of ion exchange treatment. [Figure 5B] 1 is a graph showing the breakthrough curves of the leakage rates of scandium and chromium relative to the solution flow rate BV when the solution was passed through a chelating resin at a temperature of 60°C in a test example of ion exchange treatment. DETAILED DESCRIPTION OF THE INVENTION

[0022] Specific embodiments of the present invention will be described in detail below, but the present invention is not limited to the following embodiments and can be implemented with various modifications within the scope of the present invention. In this specification, the expression "X to Y" (X and Y are arbitrary numerical values) means "at least X and at most Y."

[0023] ≪1. Overview of metal extraction methods≫ The metal extraction method according to this embodiment is a method for extracting a target metal from a solution containing the target metal and a predetermined impurity metal by ion exchange treatment using a chelating resin. For ease of explanation, the metal to be extracted will be referred to as "target metal M," and the predetermined impurity metal contained together with the target metal M in the solution to be treated will be referred to as "impurity metal N."

[0024] As described above, the solution to be treated contains the metal M to be extracted and the impurity metal N. The solution may also contain impurities other than the impurity metal N. As will be described in detail later, the method according to the present embodiment can be particularly suitably applied if the metal M to be extracted and the impurity metal N contained in the solution to be treated have similar ionic valences, or otherwise exhibit similar behavior with respect to the chelating resin used.

[0025] Specifically, the method according to this embodiment involves an ion exchange process that includes an adsorption step in which the solution to be treated is passed through a column filled with a chelating resin, thereby adsorbing the metal M to be extracted contained in the solution onto the chelating resin.

[0026] The ion exchange treatment is characterized in that the range of the flow rate BV of the solution passed through the chelating resin packed in the column is set as follows, and the target metal M to be extracted is adsorbed onto the chelating resin.

[0027] That is, first, the amount of the target metal M adsorbed on the chelating resin is q M The maximum adsorption amount of the target metal M on the chelating resin is q max,M When q M / q max,M The lower limit is the value of the solution flow rate BV at which the maximum adsorption amount q of the target metal M to be extracted onto the chelating resin is reached. max,M The apparent separation coefficient α is defined as the relationship between the target metal M and the specified impurity metal N contained in the solution. app,N M The smaller value is the amount of solution passed through BV at which the value of ρ becomes 1. Therefore, the amount of solution passed through the chelating resin is set to be in the range from the set lower limit value to the set upper limit value.

[0028] The volume of solution passed through the chelating resin (BV) is a unit that expresses the amount of solution passed through the chelating resin as a multiple of the volume of the chelating resin in the column. For example, if the amount of solution passed through is 450 mL and the volume of chelating resin in the column is 15 mL, then BV = 450 mL / 15 mL = 30.

[0029] In addition, the apparent separation factor α app,N M " is the apparent distribution ratio D of the target metal M and the specified impurity metal N. app,i By this, "α app,N M =D app,M / D app,N " Also, "apparent distribution rate D app,i " is the amount of metal adsorbed on the chelating resin, q i and the metal concentration C in the solution after passing the solution to be treated through the chelating resin. ef,i By doing so, "D app, i =q i / C ef,i " is defined as follows.

[0030] As described above, in the method according to the present embodiment, in the ion exchange treatment, the flow rate BV of the solution passed through the chelating resin is set within a range from a specific lower limit to an upper limit based on the adsorption amount of the target metal M and the apparent separation coefficient between the target metal M and the impurity metal N. This effectively prevents the impurity metal N contained in the solution from being adsorbed onto the chelating resin, and allows the target metal M to be more effectively adsorbed onto the chelating resin and extracted.

[0031] 2. Solution to be treated Before describing the ion exchange treatment in the method according to the present embodiment in more detail, the solution to be treated will be described. The solution to be treated is a solution containing a target metal M to be extracted and recovered by adsorption onto a chelating resin in the ion exchange treatment step. The solution also contains at least an impurity metal N.

[0032] The solution to be treated is not particularly limited, but preferably has a concentration of the metal M to be extracted of 1 mg / L or more. If the solution has a metal M to be extracted of 1 mg / L or more, the ion exchange treatment described below can be suitably applied. Furthermore, the concentration of the impurity metal N in the solution is not particularly limited, but preferably has a concentration of 0.1 mg / L or more and 500 mg / L or less.

[0033] The metal M to be extracted contained in the solution to be treated is not particularly limited. Examples include gold, silver, copper, platinum, scandium, nickel, cobalt, palladium, iridium, ruthenium, and rhodium. The impurity metal N is also not particularly limited, but the method according to the present embodiment is particularly preferably applicable to metals that exhibit similar behavior to the metal M to be extracted with respect to the chelating resin used, such as having the same ionic valence as the metal M to be extracted.

[0034] Specifically, the solution to be treated may contain, for example, scandium (Sc) as the metal M to be extracted and chromium (Cr) as the impurity metal N. Scandium and chromium are metals in the form of trivalent ions, and exhibit similar adsorption behavior with respect to chelating resins such as iminodiacetic acid-type chelating resins.

[0035] The solution containing scandium and chromium-containing impurities is an acidic solution obtained by leaching nickel oxide ore with a sulfuric acid solution, adding a sulfiding agent to the resulting leachate, and separating nickel sulfide. Nickel oxide ore contains scandium, as well as other elements such as chromium, iron, aluminum, manganese, and magnesium.

[0036] 3. Ion exchange treatment The method of this embodiment involves an ion exchange process that includes an adsorption step in which a solution containing a target metal M and a specified impurity metal N is passed through a column filled with a chelating resin, thereby adsorbing the target metal M contained in the solution onto the chelating resin.

[0037] Specifically, the ion exchange process includes at least an adsorption process in which the solution to be treated is passed through a chelating resin packed in a column, thereby adsorbing the metal M to be extracted in the solution onto the chelating resin, and an elution process in which the metal M to be extracted is eluted from the chelating resin to obtain an eluate.

[0038] <3-1. Adsorption process> The adsorption process is a process in which a solution containing the metal to be extracted M and a specified impurity metal N is passed through a chelating resin packed in a column to bring it into contact with the chelating resin, and the metal to be extracted M in the solution is adsorbed onto the chelating resin and extracted.

[0039] The chelating resin used is not particularly limited. It is preferable to use a chelating resin that can selectively adsorb the target metal M depending on the type of the target metal M. Specifically, for example, an iminodiacetic acid type chelating resin having iminodiacetic acid as a functional group can be used. The iminodiacetic acid type chelating resin has higher selectivity when the metal ion to be adsorbed is a multivalent ion.

[0040] Here, taking a solution containing scandium as the metal to be extracted M and chromium as the predetermined impurity metal N as an example, by passing this solution through an iminodiacetic acid type chelating resin, trivalent scandium ions (Sc 3+ ) with high selectivity. However, on the other hand, iminodiacetic acid type chelating resins have a high selectivity for adsorbing trivalent chromium ions (Cr 3+ The selectivity of chromium in the form of Cr is also relatively high. Therefore, chromium may be adsorbed to the adsorption sites before scandium, resulting in a decrease in the amount of scandium adsorbed. Also, scandium adsorbed on the chelating resin may begin to be replaced by chromium during treatment.

[0041] As a result of investigations by the present inventors, focusing on the amount of solution passed through the chelating resin BV, which was previously determined empirically, it was found that there is an optimal range of the amount of solution passed through the chelating resin BV in relation to the amount of the target metal M adsorbed onto the chelating resin. Therefore, in the method according to the present embodiment, as will be described in detail later, lower and upper limits are set for the amount of solution passed through the chelating resin BV in the ion exchange treatment, and the amount of solution passed through the chelating resin BV is set within the range from the lower limit to the upper limit.

[0042] Specifically, the lower limit of the amount of solution passed through the chelating resin, BV, is the amount of adsorption of the target metal M to the chelating resin, qM, and the maximum amount of adsorption of the target metal M to the chelating resin, q max,M When q M / q max,M = 0.5 is the value of the solution flow rate BV.

[0043] The upper limit of the solution flow rate BV to the chelating resin is determined by the maximum adsorption amount q of the target metal M to be extracted onto the chelating resin. max,M The apparent separation coefficient α is defined as the relationship between the target metal M and the specified impurity metal N contained in the solution. app,N M The value of the volume of solution passed through BV at which the value of the volume of solution passed through BV becomes 1, whichever is smaller.

[0044] [Setting the lower and upper limits of the liquid flow rate BV] Here, we will explain a test example of ion exchange treatment using a solution containing scandium as the metal M to be extracted and chromium as the predetermined impurity metal N as the solution to be treated. A solution containing scandium and chromium with the composition shown in Table 1 below was prepared. Then, an ion exchange treatment was performed in which the solution was passed through an iminodiacetic acid type chelating resin to adsorb scandium onto the chelating resin. [Table 1]

[0045] As test conditions, the iminodiacetic acid type chelating resin used was Diaion CR11 manufactured by Mitsubishi Chemical Corporation, and 15 mL of the chelating resin was packed into the column. The pH of the solution to be treated was set to 2.0, and SV=4 h -1 The flow rate BV was set to 15 to 50. The temperature of the solution when passing through the chelating resin was set to two conditions: 23°C and 60°C, and tests were conducted at each condition. SV is a unit that represents the amount of solution passing through per hour as a multiple of the volume of the chelating resin in the column.

[0046] Figure 1 is a graph showing the relationship between the metal ion concentration in the eluate recovered from the column after passing a solution through the chelating resin at a flow rate BV of 50, and the amount of metal ions adsorbed onto the chelating resin, based on the results of an ion exchange treatment test. app,i" is defined as the "apparent distribution coefficient" of metal ion (i), and the metal ion concentration in the eluate is expressed as C ef,i The amount of metal ions adsorbed onto the chelating resin is q i When "D app,i =q i / C ef,i The eluate is a solution that comes out of the column after the solution to be treated has been passed through the chelating resin, and is also called the post-passage liquid.

[0047] In the graph of Figure 1, the metal ions located in the upper left corner have an apparent distribution ratio D app,i This means that the selectivity to the chelating resin is high. The test results shown in the graph in Figure 1 show that scandium (Sc) has the highest selectivity to the chelating resin at a temperature of 23°C, and chromium (Cr) has the highest selectivity to the chelating resin at a temperature of 60°C.

[0048] From these results, the apparent separation factor (α) between scandium (Sc), which is the target of adsorption to the chelating resin, and other metal ions (i), such as chromium, can be calculated as follows: app,i Sc(III) ) can be defined. That is, the apparent separation factor can be calculated by the above-mentioned apparent distribution ratio. app,i Sc(III) =D app,Sc(III) / D app,i When this apparent separation factor is greater than 1, it means that the selectivity for scandium is higher than that for other metal ions such as chromium.

[0049] Similar to the graph in Figure 1, Figure 2 is a graph showing the relationship between the metal ion concentration in the recovered eluate and the amount of metal ions adsorbed onto the chelating resin. The temperature of the solution when passing through the chelating resin was set to 60°C, and the solution flow rate BV was set to BV = 15, 35, and 50.

[0050] As shown in the graph in Figure 2, under the temperature condition of 60°C, when the solution flow rate BV to the chelating resin is BV = 15, 35, the apparent separation factor (α app,Cr(III) Sc(III) ) is greater than 1. This means that scandium has a higher selectivity for the chelating resin than chromium, and therefore it is possible to increase the amount of scandium adsorbed while effectively suppressing the adsorption of chromium.

[0051] In addition, in the ion exchange process, the scandium leakage rate from the chelating resin can be measured from the scandium concentration in the solution before adsorption of scandium onto the chelating resin and the scandium concentration in the eluate after adsorption of scandium onto the chelating resin. That is, the scandium leakage rate can be expressed as "Leakage rate (%) = scandium concentration in eluate after adsorption / scandium concentration in solution before adsorption × 100," and refers to the proportion of scandium that migrates into the eluate without being adsorbed by the chelating resin.

[0052] Based on this leakage rate, the amount of scandium adsorbed to the chelating resin can be determined from a breakthrough curve that shows the relationship between the leakage rate at that time and the amount of solution passed through BV in the ion exchange treatment.

[0053] FIG. 3A is a graph obtained from the above-mentioned ion exchange treatment test, and is a graph of breakthrough curves based on the measurement results of the scandium leakage rate under treatment conditions where the liquid flow rate BV is 35 and the measurement results of the scandium leakage rate under treatment conditions where the liquid flow rate BV is 50. As shown in the graph of FIG. 3A, when the liquid flow rate BV is 50, the leakage rate is 100%, and the shaded area in the graph is the maximum amount of scandium adsorbed to the chelating resin. The maximum amount of adsorption is referred to as "q max,Sc " is expressed as ".

[0054] Similarly to FIG. 3A, FIG. 3B is a graph of the breakthrough curve based on the measurement results of the scandium leakage rate under each treatment condition where the flow rate BV is 35 and 50. The shaded area in the graph indicates the amount of adsorption up to the flow rate BV of 35. The amount of adsorption of scandium up to the flow rate BV of 35 is referred to as "q Sc (35)".

[0055] As shown in the graphs of Figures 3A and 3B, the amount of scandium adsorbed onto the chelating resin depends on the flow rate BV of the solution. From this, it is possible to determine the adsorption efficiency of scandium onto the chelating resin under treatment conditions with a predetermined flow rate BV. In other words, the maximum adsorption amount of scandium (q max,Sc ) for the scandium adsorption amount (q Sc The adsorption efficiency of scandium onto the chelating resin can be determined from the ratio of q Sc / q max,Sc The higher the ratio, the higher the scandium adsorption efficiency.

[0056] In the ion exchange process where the target metal M, such as scandium, is adsorbed onto a chelating resin, the maximum adsorption amount (q max,M ) for the adsorption amount (q M It is preferable to set the flow rate BV so that the ratio of (BV) is 0.5 or more.

[0057] Therefore, in the method according to the present embodiment, in the ion exchange treatment, q M / q max,M The value of the solution flow rate BV at which β = 0.5 is set as the lower limit, and the solution flow rate BV is set to be equal to or greater than the lower limit. This makes it possible to increase the adsorption efficiency of the target metal M such as scandium.

[0058] FIG. 4 is a graph obtained from the above-mentioned ion exchange treatment test, showing the apparent separation coefficient (α) between scandium and chromium versus the solution flow rate BV. app,Cr(III) Sc(III) ) and scandium adsorption efficiency (q Sc / q max,Sc 4 is a graph showing the relationship between the apparent separation factor and the scandium adsorption efficiency. In the graph of FIG. 4, the solid line shows the apparent separation factor, and the dashed line shows the scandium adsorption efficiency.

[0059] As mentioned above, the apparent separation factor (α app,Cr(III) Sc(III) ) is greater than 1, scandium has a higher selectivity for the chelating resin than chromium, suppressing the adsorption of chromium and increasing the amount of scandium adsorbed. On the other hand, in the region where the apparent separation factor is smaller than 1, the selectivity for chromium for the chelating resin is higher than that for scandium, resulting in preferential adsorption of chromium. As shown in the graph in Figure 4, the apparent separation factor depends on the solution flow rate BV, and in the region where the flow rate BV is greater than 35, the apparent separation factor becomes smaller than 1. In other words, chromium has a higher selectivity for the chelating resin than scandium.

[0060] For this reason, in the method according to the present embodiment, in the ion exchange treatment, the apparent separation factor (α app,N M The upper limit of the solution flow rate BV is the value at which the ratio (%) becomes 1, and the flow rate BV is set to be up to that upper limit. This allows the treatment to be carried out while maintaining a state in which the chelating resin has a higher selectivity for the target metal M than for the impurity metal N, and effectively suppresses adsorption of the impurity metal N.

[0061] 5A is a graph of the breakthrough curves showing the relationship between the leakage rates of scandium and chromium and the amount of solution passed through BV when the solution was passed through the chelating resin at a temperature of 23° C. in the ion exchange test described above. Similarly, FIG. 5B is a graph of the breakthrough curves when the solution was passed through the chelating resin at a temperature of 60° C.

[0062] As shown in the graph in Figure 5A, at a temperature of 23°C, the leakage rate of scandium is low and the amount of scandium adsorbed to the chelating resin is large, regardless of the flow rate BV. On the other hand, the leakage rate of chromium is high and the amount of scandium adsorbed to the chelating resin is small. Therefore, at a temperature of 23°C, scandium is preferentially adsorbed to the chelating resin over the impurity chromium, regardless of the flow rate BV.

[0063] In contrast, as shown in the graph in Figure 5B, under the temperature condition of 60°C, the leakage rate of scandium is low and the amount of adsorption to the chelating resin is high in the region where the solution flow rate BV is low, but the leakage rate of chromium is also low and the amount of chromium adsorption to the chelating resin is high compared to the temperature condition of 23°C. Furthermore, the graph in Figure 5B shows that when the solution flow rate BV is around BV = 35, the leakage rates of scandium and chromium are reversed, and chromium is preferentially adsorbed to the chelating resin. In this case, it is necessary to terminate the solution flow when the solution flow rate BV is around BV = 35.

[0064] Thus, in ion exchange treatment, the amount of target metal M (e.g., scandium) and impurity metal N (e.g., chromium) adsorbed to the chelating resin at a given flow rate BV varies depending on the temperature of the solution during flow. From this perspective, it is preferable to set the temperature of the solution during flow and to set an upper limit for the flow rate BV of the solution according to the temperature. Specifically, it is preferable to set the flow rate BV so that the leakage rate of target metal M is smaller than the leakage rate of impurity metal N.

[0065] As shown in the graph of Fig. 5B, the temperature conditions during liquid passage that cause a reversal between the leakage rate of the target metal M and the leakage rate of the impurity metal N depending on the condition of the liquid flow rate BV are in the range of more than 40°C and not more than 70°C, or in the range of 45°C or more and not more than 70°C.

[0066] When the temperature condition of the solution during the solution passage is in the range of more than 40°C and not more than 70°C, the upper limit of the volume BV of the solution passed through the chelating resin is, as described above, the apparent separation coefficient (α app,N M ) can be taken as the value of the solution flow rate BV at which 1.

[0067] 5A, the temperature condition during liquid passage that results in a small leakage rate of the target metal M and a large amount of adsorption to the chelating resin, regardless of the liquid passage volume BV, is in the range of 15° C. to 40° C. Preferably, the temperature is in the range of 20° C. to 40° C., and more preferably, in the range of 23° C. to 40° C.

[0068] When the temperature condition of the solution during the solution passage is in the range of 15°C to 40°C, the upper limit of the amount of solution passed through the chelating resin (BV) is the maximum adsorption amount q of the target metal M to be extracted onto the chelating resin. max,M As described above, when the temperature condition during the solution passage is in the range of 15°C to 40°C, the amount of the target metal M adsorbed to the chelating resin is large regardless of the amount of solution BV passed, and the target metal M is adsorbed to the chelating resin preferentially over the impurity metal N. Therefore, as shown in Figures 3A and 3B, the maximum adsorption amount q of the target metal M adsorbed to the chelating resin is max,M From the viewpoint of adsorption efficiency, it is effective to pass the solution up to a flow rate BV at which the adsorption efficiency is improved.

[0069] Therefore, in the method according to the present embodiment, the maximum adsorption amount q of the target metal M to be extracted onto the chelating resin is calculated based on the results of the graph shown in FIG. 4 and the graphs shown in FIGS. 5A and 5B. max,MThe apparent separation coefficient α is defined as the relationship between the target metal M and the specified impurity metal N contained in the solution. app,N M The upper limit of the solution flow rate BV for the chelating resin is the smaller of the two values.

[0070] Regarding the upper limit of the amount of solution passed through the chelating resin, BV, the maximum adsorption amount of the target metal M, q max,M The value of the flow rate BV or the apparent separation coefficient α app,N M By using the smaller of either the value of the flow rate BV of the solution at which M is 1, it is possible to maintain a high extraction efficiency of the target metal M while suppressing the preferential adsorption of impurity metal N onto the chelating resin, thereby effectively adsorbing and extracting the target metal M onto the chelating resin.

[0071] <3-2. Elution step> The elution step is a step of eluting the target metal M adsorbed to the chelating resin. Specifically, in the elution step, the target metal M is eluted by contacting the chelating resin that has adsorbed the target metal M with, for example, a sulfuric acid solution. By eluting the target metal M from the chelating resin in this manner, the target metal M adsorbed to the chelating resin and extracted from the solution to be treated can be recovered. The resulting eluate is a solution containing the target metal M at a high concentration.

[0072] For example, as shown in the above-mentioned test example, when scandium is adsorbed onto a chelating resin as the metal M to be extracted, scandium can be efficiently eluted and a scandium eluate can be obtained by contacting the chelating resin with the adsorbed scandium with a sulfuric acid solution having a normality in the range of 0.3N to 3.0N.

Claims

1. A metal extraction method for extracting a target metal M from a solution containing the target metal M and a predetermined impurity metal N, comprising: an ion exchange treatment including an adsorption step of passing the solution through a column filled with a chelating resin, thereby adsorbing the target metal M contained in the solution onto the chelating resin; In the ion exchange treatment, The amount of the metal M to be extracted adsorbed on the chelating resin is q Ｍ The maximum adsorption amount of the target metal M to be extracted onto the chelating resin is q ｍａｘ,Ｍ When that happens, q Ｍ / q ｍａｘ,Ｍ = 0.5 is set as the lower limit value, The maximum adsorption amount q of the target metal M to be extracted onto the chelating resin ｍａｘ,Ｍ or the apparent separation coefficient α defined as follows in the relationship between the target metal M and the predetermined impurity metal N contained in the solution: ａｐｐ，Ｎ Ｍ the value of the solution flow rate BV at which the value of The flow rate BV of the solution is set to be in the range from the lower limit value to the upper limit value. Methods of metal extraction. (wherein the apparent separation factor α ａｐｐ，Ｎ Ｍ is the apparent distribution ratio D of the target metal M and the specified impurity metal N. ａｐｐ，ｉ Therefore, α ａｐｐ，Ｎ Ｍ =D ａｐｐ，Ｍ / D ａｐｐ，Ｎ and the apparent distribution rate D ａｐｐ，ｉ is the amount of adsorption to the chelating resin q ｉ and the concentration C in the post-passage solution after the solution is passed through the column. ｅｆ，ｉ Therefore, D ａｐｐ，ｉ =q ｉ / C ｅｆ，ｉ It is expressed as

2. Regarding the leakage rate, which is expressed as the ratio of the metal concentration in the solution after passing the solution through the column to the metal concentration in the solution before passing the solution through the column, The leakage rate of the target metal M is smaller than the leakage rate of the predetermined impurity metal N.

2. The method for extracting metals according to claim 1.

3. The chelating resin is an iminodiacetic acid type chelating resin.

3. The method for extracting metals according to claim 1 or 2.

4. The concentration of the metal M to be extracted contained in the solution is 1 mg / L or more.

3. The method for extracting metals according to claim 1 or 2.

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