Metal Recovery Agent, Metal Compound Recovery Agent, and Method for Recovering Metal or Metal Compound

Abstract

The present disclosure relates to a method for recovering a metal or a metal compound, using genus Galdieria.

Claims

1-8. (canceled)

9. A method for recovering a metal or a metal compound, comprising: adding, to a metal solution, a dried matter of a cell of red algae belonging to the genus Galdieria or a dried matter of a cell derivative of red algae belonging to the genus Galdieria.

10. The method according to claim 9, wherein an amount of the dried matter added is 0.001 mg or more with respect to 100 ml of the metal solution.

11. The method according to claim 9, wherein the amount of the dried matter added is 100 g or less per 100 ml of the metal solution.

12. The method according to claim 9, wherein at least one metal selected from the group consisting of gold, palladium, ruthenium, platinum, iridium, rhodium and osmium contained in the metal solution is selectively adsorbed.

13. The method according to claim 9, wherein the solution is an acid solution comprising hydrochloric acid or aqua regia.

14. The method according to claim 9, wherein an acid concentration of the metal solution is 0.5 mmol/L or more.

15. The method according to claim 9, wherein an acid concentration of the solution is 0.5 M or more and 6 M or less.

16. The method according to claim 9, wherein the adsorption step is a step of recovering a gold cyanide complex contained in the metal solution.

17. The method according to claim 9, further comprising refining the metal or the metal compound adsorbed onto the cell derived from the dried matter, or the cell derivative derived from the dried matter.

18. The method according to claim 9, further comprising eluting the metal or the metal compound adsorbed onto the cell derived from the dried matter or the cell derivative derived from the dried matter.

19. The method according to claim 18, wherein the adsorbed metal or the metal compound is eluted using ammonia and an ammonium salt.

20. The method according to claim 18, wherein the absorbed metal or the metal compound is eluted using an acid solution.

21. The method according to claim 18, wherein the absorbed metal or the metal compound is eluted using an alkaline solution.

Description

EXAMPLES

[0050] Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited thereto.

[0051] In the following description, recovery rate refers to a value calculated by Formula (1). In addition, the cell non-addition test in Formula (1) refers to a test conducted without adding any of the dry powder produced from live cells of G. sulphuraria and cells of G sulphuraria. In addition, the cell addition test in Formula (1) refers to a test conducted by adding the dry powder produced from the live cells of G. sulphuraria or the cells of G. sulphuraria.

[Formula 1]

Recovery rate (%)=(metal concentration of supernatant in cell non-addition test)(metal concentration of supernatant in cell addition test)/(metal concentration of supernatant in cell addition test)100 (1)

Example 1

[0052] As Example 1, a selective recovery test of gold and palladium from a hydrochloric acid solution (0.5 to 6 M) was conducted using a spray-dried sample.

[0053] (Production of Spray-Dried Sample)

[0054] Cells of G. sulphuraria grown to the stationary phase were recovered by centrifugation. Next, using a spray dryer, a spray-dried sample (dry powder) was produced from the recovered cells under the conditions of an inlet temperature of 120 degrees Celsius, an outlet temperature of 77 to 82 degrees Celsius, a hot air flow rate of 0.6 m.sup.3/min, and a spray pressure of 100 kPa. In the following description, the spray-dried sample refers to a sample produced according to the above-described method.

[0055] (Test Nos. 1-1 and 1-2)

[0056] First, 10 mg of the spray-dried sample was added to 1 ml of a 0.5 M hydrochloric acid solution containing 5 ppm each of Au.sup.3+, Pd.sup.2+, and Cu.sup.2+, and stirred at room temperature for 15 minutes. Next, the hydrochloric acid solution was centrifuged (12,000 rpm, 1 minute), and the metal concentration of the obtained supernatant was measured using ICP-MS (Test No. 1-2).

[0057] In addition, as a control test, the same test as Test No. 1-2 was conducted except that the spray-dried sample was not added, and the metal concentration of the supernatant was measured (Test No. 1-1). Next, the recovery rate in Test No. 1-2 was calculated from the difference between the metal concentrations of Test No. 1-1 and Test No. 1-2 measured above. The measured metal concentration and the recovery rate are shown in Table 1. The metal concentrations and the recovery rates shown in Table 1 are the mean value of three independent testsSD (standard deviation). In Tables 1 to 8 below, powder + indicates that the spray-dried sample or a freeze-dried sample was added, and powder indicates that no spray-dried sample or freeze-dried sample was added.

[0058] (Test Nos. 1-3 to 1-14)

[0059] Test Nos. 1-3 to 1-14 were conducted in the same manner as in Test No. 1-1 or 1-2 except that the concentration of the hydrochloric acid solution was changed to the concentration shown in Table 1. For each test, the measured metal concentration and the recovery rate are shown in Table 1.

TABLE-US-00001 TABLE 1 HCl Metal concentration of Recovery Test concentration supernatant (ppm) rate (%) No. (mol/L) Powder Au.sup.3+ Pd.sup.2+ Cu.sup.2+ Au.sup.3+ Pd.sup.2+ 1-1 0.5 2.24 2.24 2.24 0.54 0.56 0.58 1-2 0.5 + 2.25 0.02 2.84 93 100 0.10 0.03 0.07 3.7 0.6 1-3 1.0 2.41 2.03 3.61 0.54 0.48 0.44 1-4 1.0 + 0.09 0.01 3.04 98 100 0.03 0.01 0.35 1.1 0.3 1-5 2.0 2.37 2.02 3.52 0.53 0.42 0.57 1-6 2.0 + 0.08 0.01 3.07 98 100 0.03 0.01 0.35 0.8 0.2 1-7 3.0 2.32 2.04 3.54 0.67 0.27 0.16 1-8 3.0 + 0.07 0.01 3.21 98 100 0.03 0.01 0.44 0.7 0.2 1-9 4.0 3.26 3.40 4.57 2.27 1.64 2.22 1-10 4.0 + 0.08 0.01 4.01 98 100 0.02 0.01 1.76 0.9 0.2 1-11 5.0 3.14 3.36 4.45 2.36 1.75 2.26 1-12 5.0 + 0.08 0.01 3.97 98 100 0.02 0.01 1.77 0.8 0.2 1-13 6.0 2.38 2.01 3.59 0.59 0.27 0.42 1-14 6.0 + 0.09 0.01 3.13 98 100 0.03 0.01 0.41 0.8 0.3

Example 2

[0060] As Example 2, a selective recovery test of gold and palladium from a hydrochloric acid solution (0.5 to 6 M) was conducted using a freeze-dried sample.

[0061] (Test Nos. 2-1 and 2-2)

[0062] Cells of G. sulphuraria grown to the stationary phase were recovered by centrifugation. Next, the recovered cells were frozen by liquid nitrogen and subjected to a vacuum freeze-drying treatment, thereby producing a freeze-dried sample (dry powder). Next, 10 mg of the freeze-dried sample produced above was added to 1 ml of a 0.5 M hydrochloric acid solution containing 5 ppm each of Au.sup.3+, Pd.sup.2+, and Cu.sup.2+, and stirred at room temperature for 15 minutes. Next, the hydrochloric acid solution was centrifuged (12,000 rpm, 1 minute), and the metal concentration of the obtained supernatant was measured using ICP-MS (Test No. 2-2).

[0063] In addition, as a control test, the same test as Test No. 2-2 was conducted except that the freeze-dried sample was not added, and the metal concentration of the supernatant was measured (Test No. 2-1). Next, the recovery rate in Test No. 2-2 was calculated from the difference between the metal concentrations of Test No. 2-1 and Test No. 2-2 measured above. The measured metal concentration and the recovery rate are shown in Table 2. The metal concentrations and the recovery rates shown in Table 2 are the mean value of three independent testsSD (standard deviation).

[0064] (Test Nos. 2-3 to 2-14)

[0065] Test Nos. 2-3 to 2-14 were conducted in the same manner as in Test No. 2-1 or 2-2 except that the concentration of the hydrochloric acid solution was changed to the concentration shown in Table 2. For each test, the measured metal concentration and the recovery rate are shown in Table 2.

TABLE-US-00002 TABLE 2 HCl Metal concen- concentration of Recovery Test tration supernatant (ppm) rate (%) No. (mol/L) Powder Au.sup.3+ Pd.sup.2+ Cu.sup.2+ Au.sup.3+ Pd.sup.2+ 2-1 0.5 4.58 4.15 4.71 0.45 0.73 0.76 2-2 0.5 + 0.01 0.07 4.61 99.67 98.10 0.01 0.05 0.68 0.58 0.79 2-3 1 4.28 3.11 3.37 1.13 0.59 0.64 2-4 1 + 0.08 0.01 3.36 97.78 99.23 0.10 0.00 2.89 2.12 0.39 2-5 2 4.05 3.28 3.70 0.12 0.34 0.40 2-6 2 + 0.16 0.02 3.88 96.33 99.49 0.14 0.02 1.05 3.67 0.64 2-7 3 4.22 3.37 3.84 0.06 0.21 0.30 2-8 3 + 0.06 0.02 4.50 98.81 99.60 0.08 0.02 1.03 2.07 0.68 2-9 4 7.71 6.35 7.60 0.10 0.04 0.05 2-10 4 + 0.03 0.02 9.32 99.67 100.00 0.01 0.00 0.14 0.58 0.00 2-11 5 7.16 6.10 7.30 0.17 0.18 0.15 2-12 5 + 0.08 0.03 9.26 98.67 99.67 0.07 0.01 0.14 0.58 0.58 2-13 6 7.74 6.19 7.28 0.08 0.18 0.20 2-14 6 + 0.27 0.03 9.25 96.57 99.15 0.32 0.00 0.19 4.22 0.26

Example 3

[0066] As Example 3, a selective recovery test of gold and palladium from 4 M aqua regia was conducted using the spray-dried sample.

[0067] (Test Nos. 3-1 and 3-2)

[0068] First, 15 mg of the spray-dried sample was added to 1 ml of a 4 M aqua regia solution containing 5 ppm each of Au.sup.3+, Pd.sup.2+, and Cu.sup.2+ and stirred at room temperature for 30 minutes. Next, the aqua regia solution was centrifuged (12,000 rpm, 1 minute), and the metal concentration of the obtained supernatant was measured using ICP-MS (Test No. 3-2).

[0069] In addition, as a control test, the same test as Test No. 3-2 was conducted except that the spray-dried sample was not added, and the metal concentration of the supernatant was measured (Test No. 3-1). Next, the recovery rate in Test No. 3-2 was calculated from the difference between the metal concentrations of Test No. 3-1 and Test No. 3-2 measured above. The measured metal concentration and the recovery rate are shown in Table 3. The metal concentrations and the recovery rates shown in Table 3 are the mean value of three independent testsSD (standard deviation).

TABLE-US-00003 TABLE 3 Test Metal concentration of supernatant Recovery rate (%) No. Powder Au.sup.3+ Pd.sup.2+ Cu.sup.2+ Au.sup.3+ Pd.sup.2+ 3-1 4.93 4.71 4.49 1.55 1.44 1.27 3-2 + 0.69 0.04 3.80 87.00 99.33 0.44 0.02 0.98 4.36 0.58

Example 4

[0070] As Example 4, an elution test of gold and palladium was conducted using the spray-dried sample by which gold and palladium were selectively recovered from a 4 M aqua regia solution.

[0071] (Test Nos. 4-1 and 4-2)

[0072] First, 20 mg of the spray-dried sample was added to 1 ml of a 4 M aqua regia solution containing 0.5 ppm each of Au.sup.3+, Pd.sup.2+, and Cu.sup.2+, and stirred at room temperature for 30 minutes. Next, the aqua regia solution was centrifuged (12,000 rpm, 1 minute), and the metal concentration of the obtained supernatant was measured using ICP-MS (Test No. 4-2). The measured metal concentration of the supernatant is shown in Table 4.

[0073] In addition, as a control test, the same test as Test No. 4-2 was conducted except that the spray-dried sample was not added, and the metal concentration of the supernatant was measured (Test No. 4-1). Next, from the difference between the metal concentrations of Test No. 4-1 and Test No. 4-2 measured above, the metal concentration recovered by the spray-dried sample in Test No. 4-2 was calculated. The measured metal concentration of the supernatant and the metal concentration recovered by the spray-dried sample are shown in Table 4.

[0074] Next, a spray-dried sample fraction (precipitated fraction) recovered by centrifugation in Test No. 4-2 was dissolved in 1 ml of a 4 M aqua regia solution and was washed by performing centrifugation (12,000 rpm, 1 minute) on the aqua regia solution. Next, 1 ml of a 0.2 M NH.sub.4Cl/2.8% NH.sub.3 solution (pH 11) was added as a metal elution solution to the spray-dried sample fraction (precipitated fraction) obtained by centrifugation of the aqua regia solution, and stirred at room temperature for 30 minutes. The solution was again centrifuged (12,000 rpm, 1 minute), and the metal concentration of the obtained supernatant was measured using ICP-MS. The measured value is shown in Table 4 as the metal concentration of the eluate.

[0075] In addition, the elution rate in Test No. 4-2 was calculated using Formula (2). The calculated elution rate is shown in Table 4.

[Formula 2]

Elution rate (%)=metal concentration of cluate/metal concentration recovered by spray-dried sample100(2)

[0076] (Test Nos. 4-3 to 4-10)

[0077] Test Nos. 4-3 to 4-10 were conducted in the same manner as in Test No. 4-1 or 4-2 except that the concentration of each metal contained in the 4 M aqua regia solution was changed to the concentration shown in Table 4. For each test, the metal concentration of the supernatant, the metal concentration recovered by the spray-dried sample, the metal concentration of the eluate, and the elution rate are shown in Table 4.

TABLE-US-00004 TABLE 4 Initial metal Metal concentration of Recovered metal Metal concentration Elution Test concentration supernatant (ppm) concentration (ppm) of eluate (ppm) rate (%) No. (ppm) Powder Au.sup.3+ Pd.sup.2+ Cu.sup.2+ Au.sup.3+ Pd.sup.2+ Cu.sup.2+ Au.sup.3+ Pd.sup.2+ Cu.sup.2+ Au.sup.3+ Pd.sup.2+ 4-1 0.5 0.4 0.4 0.4 4-2 0.5 + 0.07 0.0 0.5 0.3 0.4 0.0 0.3 0.2 0.0 91 58 4-3 5 5.4 3.7 3.8 4-4 5 + 0.5 0.02 3.6 4.9 3.7 0.2 1.1 2.4 0.0 23 66 4-5 10 9.8 7.1 7.3 4-6 10 + 1.3 0.08 6.9 8.5 7.0 0.4 1.6 5.7 0.0 19 81 4-7 25 25 18 19 4-8 25 + 4.5 0.9 16 21 17 2.8 3.2 12 0.0 16 71 4-9 50 50 32 36 4-10 50 + 20 5.6 57 31 26 0.0 7.0 21 0.0 23 81

Example 5

[0078] As Example 5, a recovery test of gold from a 0.1 mM KOH solution (pH 10) containing cyan and gold was conducted using the spray-dried sample. In the 0.1 mM KOH solution, Au.sup.3+ ions are stably present as a cyanide complex.

[0079] (Test Nos. 5-1 and 5-2)

[0080] First, 15 mg of the spray-dried sample was added to 1 ml of 0.1 mM KOH (pH 10) containing 1 ppm of gold and stirred at room temperature for 30 minutes. Next, the KOH solution was centrifuged (12,000 rpm, 1 minute), and the metal concentration of the obtained supernatant was measured using ICP-MS (Test No. 5-2).

[0081] In addition, as a control test, the same test as Test No. 5-2 was conducted except that the spray-dried sample was not added, and the metal concentration of the supernatant was measured (Test No. 5-1). Next, the recovery rate in Test No. 5-2 was calculated from the difference between the metal concentrations of Test No. 5-1 and Test No. 5-2 measured above. The measured metal concentration and the recovery rate are shown in Table 5. The metal concentrations and the recovery rates shown in Table 5 are the mean value of two independent tests.

TABLE-US-00005 TABLE 5 Aus.sup.3+ concentration of Recovery rate Test No. Powder supernatant (ppm) (%) 5-1 1.0 5-2 + 0.23 77

Example 6

[0082] As Example 6, a selective recovery test of platinum, gold, palladium, and osmium from a hydrochloric acid solution (1 to 4 M) was conducted using the spray-dried sample.

[0083] (Test Nos. 6-1 and 6-2)

[0084] First, 10 mg of the spray-dried sample was added to 1 ml of a 1 M hydrochloric acid solution containing 10 ppm each of Rh.sup.3+, Pd.sup.2+, Os.sup.4+, Pt.sup.2+, Au.sup.3+, and Ir.sup.3+, and stirred overnight at room temperature. Next, the hydrochloric acid solution was centrifuged (12,000 rpm, 1 minute), and the metal concentration of the obtained supernatant was measured using ICP-MS (Test No. 6-2). In addition, as a control test, the same test as Test No. 6-2 was conducted except that the spray-dried sample was not added, and the metal concentration of the supernatant was measured (Test No. 6-1). The measured metal concentrations are shown in Table 6.

[0085] Next, the recovery rate in Test No. 6-2 was calculated from the difference between the metal concentrations of Test No. 6-1 and Test No. 6-2 measured above. The calculated recovery rate is shown in Table 7. The metal concentrations shown in Table 6 and the recovery rates shown in Table 7 are the mean value of three independent testsSD (standard deviation).

[0086] (Test Nos. 6-3 to 6-8)

[0087] Test Nos. 6-3 to 6-8 were conducted in the same manner as in Test No. 6-1 or 6-2 except that the concentration of the hydrochloric acid solution was changed to the concentration shown in Tables 6 and 7. For each test, the measured metal concentration is shown in Table 6, and the recovery rate is shown in Table 7.

TABLE-US-00006 TABLE 6 HCl Metal concentration Test concentration of supernatant (ppm) No. (mol/L powder Rh.sup.3+ Pd.sup.2+ Os.sup.4+ Pt.sup.2+ Au.sup.3+ Ir.sup.3+ 6-1 1 11.0 10.0 11.0 10.0 10.0 10.0 1.8 1.8 1.6 1.8 1.9 1.6 6-2 1 + 8.3 0.0 4.3 0.6 0.1 6.7 10.1 0.2 0.1 0.1 0.1 0.3 6-3 2 10.0 10.0 10.0 10.0 10.0 10.0 1.4 1.4 1.3 1.4 1.4 1.3 6-4 2 + 9.1 0.0 6.2 4.5 0.1 8.7 0.1 0.6 0.5 0.4 0.1 0.9 6-5 3 11 11.0 10.7 11.0 11.0 11.0 1.7 1.7 1.5 1.7 1.7 1.6 6-6 3 + 9.3 0.0 6.6 5.9 0.1 9.1 0.1 0.8 0.6 0.8 0.1 1.0 6-7 4 10.0 10.0 10.0 10.0 10.0 10.0 1.2 1.2 1.1 1.1 1.2 1.1 6-8 4 + 9.0 0.0 6.5 6.1 0.1 8.7 0.1 0.6 0.4 0.9 0.1 0.6

TABLE-US-00007 TABLE 7 HCl Test concentration Recovery rate (%) No. (mol/L) powder Rh.sup.3+ Pd.sup.2+ Os.sup.4+ Pt.sup.2+ Au.sup.3+ Ir.sup.3+ 6-2 1 + 19 100 59 95 99 35 12 0.6 6.2 1.4 0.5 8.3 6-4 2 + 12 100 41 56 99 16 2.4 0.6 1.8 2.1 0.7 1.6 6-6 3 + 14 100 38 46 100 16 8.7 0.5 6.1 4.3 0.7 8.4 6-8 4 + 12 100 35 39 99 13 6.2 0.5 4.8 7.3 0.8 6.0

Example 7

[0088] As Example 7, a selective recovery test of ruthenium from a hydrochloric acid solution (1 or 2 M) was conducted using the spray-dried sample.

[0089] (Test Nos. 7-1 and 7-2)

[0090] First, 20 mg of the spray-dried sample was added to 1 ml of a 1 M hydrochloric acid solution containing 10 ppm of Ru.sup.3+ and stirred overnight at room temperature. Next, the hydrochloric acid solution was centrifuged (12,000 rpm, 1 minute), and the metal concentration of the obtained supernatant was measured using ICP-MS (Test No. 7-2). In addition, as a control test, the same test as Test No. 7-2 was conducted except that the spray-dried sample was not added, and the metal concentration of the supernatant was measured (Test No. 7-1). The measured metal concentration is shown in Table 8.

[0091] Next, the recovery rate in Test No. 7-2 was calculated from the difference between the metal concentrations of Test No. 7-1 and Test No. 7-2 measured above. The calculated recovery rate is shown in Table 8. The metal concentrations and the recovery rates shown in Table 8 are the mean value of three independent testsSD (standard deviation).

[0092] (Test Nos. 7-3 to 7-4)

[0093] Test Nos. 7-3 and 7-4 were conducted in the same manner as in Test No. 7-1 or 7-2 except that the concentration of the hydrochloric acid solution was changed to the concentration shown Table 8. For each test, the measured metal concentration and the recovery rate are shown in Table 8.

TABLE-US-00008 TABLE 8 Ru.sup.3+ concen- HCl tration of concentration supernatant Ru.sup.3+ recovery Test No. (mol/L) powder (ppm) rate (%) 7-1 1 10.3 0.2 7-2 1 + 5.6 0.2 45.6 2.3 7-3 2 10.5 0.2 7-4 2 + 5.5 0.3 47.9 2.6

Comparative Example 1

[0094] As Comparative Example 1, a selective recovery test of metal from 0.43 M aqua regia was conducted using live cells of G. sulphuraria.

[0095] (Test Nos. C1-1 and C1-2)

[0096] First, 14 mg (dry weight) of live cells of G. sulphuraria were added to 1 ml of a 0.43 M aqua regia solution containing 871 ppm of Au.sup.3+, 86 ppm of Fe.sup.2+/.sup.3+, 107 ppm of Cu.sup.2+, 4.5 ppm of Pt.sup.4+, 262 ppm of Ni.sup.2+, and 24 ppm of Sn.sup.2+, and stirred at room temperature for 30 minutes. Next, the aqua regia solution was centrifuged (12,000 rpm, 1 minute), and the metal concentration of the obtained supernatant was measured using ICP-MS (Test No. C1-2).

[0097] In addition, as a control test, the same test as Test No. C1-2 was conducted except that live cells of G. sulphuraria were not added, and the metal concentration of the supernatant was measured (Test No. C1-1). Next, the recovery rate in Test No. C1-2 was calculated from the difference between the metal concentrations of Test No. C1-1 and Test No. C1-2 measured above. The measured metal concentration and the recovery rate are shown in Table 9. The metal concentrations and the recovery rates shown in Table 9 are the mean value of three independent testsSD (standard deviation).

TABLE-US-00009 TABLE 9 Metal concentration of supernatant (ppm) Recovery rate (%) Test Fe.sup.2+/ Fe.sup.2+/ No. Cells Fe.sup.3+ Cu.sup.2+ Pt.sup.4+ Au.sup.3+ Ni.sup.2+ Sn.sup.2+ Fe.sup.3+ Cu.sup.2+ Pt.sup.4+ Au.sup.3+ Ni.sup.2+ Sn.sup.2+ C1-1 86 107 4.5 871 262 24 14 44 0.6 86 48 3.5 C1-2 + 63 73 3.7 299 223 18 26 28 17 66 14 23 7.6 11 0.3 108 19 1.3

Comparative Example 2

[0098] As Comparative Example 2, a selective recovery test of metal from 4 M aqua regia was conducted using live cells of G. sulphuraria.

[0099] (Test Nos. C2-1 and C2-2)

[0100] First, 14 mg (dry weight) of live cells of G. sulphuraria were added to 1 ml of a 4 M aqua regia solution containing 87 ppm of Fe.sup.2+/.sup.3+, 56 ppm of Cu.sup.2+, 9 ppm of Sn.sup.2+, 3 ppm of Pt.sup.4+, and 912 ppm of Au.sup.3+, and stirred at room temperature for 30 minutes. Next, the aqua regia solution was centrifuged (12,000 rpm, 1 minute), and the metal concentration of the obtained supernatant was measured using ICP-MS (Test No. C2-2).

[0101] In addition, as a control test, the same test as Test No. C2-2 was conducted except that live cells of G. sulphuraria were not added, and the metal concentration of the supernatant was measured (Test No. C2-1). Next, the recovery rate in Test No. C2-2 was calculated from the difference between the metal concentrations of Test No. C2-1 and Test No. C2-2 measured above. The measured metal concentration and the recovery rate are shown in Table 10.

TABLE-US-00010 TABLE 10 Metal concentration Test of supernatant (ppm) Recovery rate (%) No. Cells Fe.sup.2+/Fe.sup.3+ Cu.sup.2+ Sn.sup.2+ Pt.sup.4+ Au.sup.3+ Fe.sup.2+/Fe.sup.3+ Cu.sup.2+ Sn.sup.2+ Pt.sup.4+ Au.sup.3+ C2-1 87 56 9 3 912 C2-2 + 120 60 10 4 794 0 0 0 0 13

Example 8

[0102] As Example 8, an elution test of gold was conducted using the spray-dried sample by which gold was recovered from a 4 M aqua regia solution and an ion exchange resin.

[0103] (Test No. 8-1)

[0104] First, 20 mg of the spray-dried sample was added to 1 ml of a 4 M aqua regia solution containing 10 ppm of Au.sup.3+, and stirred at room temperature for 30 minutes. Next, the aqua regia solution was centrifuged (12,000 rpm, 1 minute), and the metal concentration of the obtained supernatant was measured using ICP-MS (Test No. 8-1). In addition, the same test as Test No. 8-1 was conducted except that spray-dried sample was not added, and the metal concentration of the supernatant was measured (Test No. 8-1-control). Next, from the difference between the metal concentrations of Test No. 8-1 and Test No. 8-1-control measured above, the metal concentration recovered by the spray-dried sample in Test No. 8-1 was calculated.

[0105] Next, a spray-dried sample fraction (precipitated fraction) recovered by centrifugation in Test No. 8-1 was dissolved in 1 ml of a 4 M aqua regia solution and was washed by performing centrifugation (12,000 rpm, 1 minute) on the aqua regia solution. Next, 1 ml of 4 M HCl was added as a metal elution solution to the spray-dried sample fraction (precipitated fraction) obtained by centrifugation of the aqua regia solution, and stirred at room temperature for 30 minutes. The solution was again centrifuged (12,000 rpm, 1 minute), and the metal concentration of the obtained supernatant was measured using ICP-MS. The measured value was used as the metal concentration of the eluate.

[0106] Next, the elution rate in Test No. 8-1 was calculated using Formula (2). The calculated elution rate is shown in Table 11. The elution rates of Test Nos. 8-1 to 8-5 shown in Table 11 are the mean value of three independent testsSD (standard deviation).

[0107] (Test Nos. 8-2 to 8-5)

[0108] Test Nos. 8-2 to 8-5 were conducted in the same manner as in Test No. 8-1 except that as the metal elution solution, instead of 4 M HC, 0.5 M EDTA (pH 8) (Test No. 8-2), 1 M Thiourea/0.1 M HCl (Test No. 8-3), 1 M KOH (Test No. 8-4), and 6 M aqua regia (Test No. 8-5) were used. For each test, the elution rate is shown in Table 11.

[0109] (Test Nos. 8-6 to 8-10)

[0110] Test Nos. 8-6 to 8-10 were conducted in the same manner as in Test No. 8-1 except that an ion exchange resin (SA10A, manufactured by Mitsubishi Chemical Corporation) was used as the metal recovery agent instead of the spray-dried sample, and one those shown in Table 11 were used as the metal elution solutions. For each test, the elution rate is shown in Table 11.

TABLE-US-00011 TABLE 11 Metal recovery Recovery Test No. Metal elution solution agent rate (%) 8-1 4M HCI Spray-dried 25 2.2 8-2 0.5M EDTA (pH 8) sample 20 6.4 8-3 1M Thiourea/0.1M 93 5.7 HCI 8-4 1M KOH 67 5.3 8-5 6M aqua regia 60 12 8-6 4M HCI Ion exchange 0 8-7 0.5M EDTA (pH 8) resin 1.1 8-8 1M Thiourea/0.1M 72 HCI 8-9 1M KOH 12 8-10 6M aqua regia 5.4

Example 9

[0111] As Example 9, an elution test of palladium was conducted using the freeze-dried sample by which palladium was selectively recovered from a 5 M aqua regia solution.

[0112] (Test Nos. 9-1 and 9-2)

[0113] First, 120 mg of the freeze-dried sample was added to 30 ml of a 5 M aqua regia solution containing 10 ppm each of Pd.sup.2+, Al.sup.3+, Cd.sup.2+, Fe.sup.2+/.sup.3+, Mn.sup.2+, Pb.sup.2+, and Zn.sup.2+, and stirred at room temperature for 30 minutes. Next, the aqua regia solution was divided into 10 ml (Test No. 9-1, concentration ratio 10 times) and 20 ml (Test No. 9-2, concentration ratio 20 times) and centrifuged (12,000 rpm, 1 minute), and the metal concentration of each of the obtained supernatants was measured using ICP-MS (Test Nos. 9-1 and 9-2). In addition, the same test as Test Nos. 9-1 and 9-2 was conducted except that the freeze-dried sample was not added, and the metal concentration of the supernatant was measured (Test Nos 9-1-control and 9-2-control). Next, from the difference between the metal concentrations of Test No. 9-1 and Test No. 9-1-control measured above, the metal concentration recovered by the freeze-dried sample in Test No. 9-1 was calculated. Similarly, from the difference between the metal concentrations of Test No. 9-2 and Test No. 9-2-control measured above, the metal concentration recovered by the freeze-dried sample in Test No. 9-2 was calculated.

[0114] Next, freeze-dried sample fractions (precipitated fractions) recovered by centrifugation in Test Nos. 9-1 and 9-2 were each dissolved in 1 ml of a 5 M aqua regia solution and were washed by performing centrifugation (12,000 rpm, 1 minute) on the aqua regia solution. Next, 1 ml of 6 M aqua regia was added as a metal elution solution to each of the freeze-dried sample fractions (precipitated fractions) obtained by centrifugation of the aqua regia solution, and stirred overnight at room temperature. The solution was again centrifuged (12,000 rpm, 1 minute), and the metal concentration of each of the obtained supernatants was measured using ICP-MS. The measured values are shown in Table 12 as the metal concentrations of the eluates.

[0115] Next, the elution rates in Test Nos. 9-1 and 9-2 were calculated using Formula (2). The calculated elution rates are shown in Table 13.

TABLE-US-00012 TABLE 12 Metal concentration of eluate (ppm) Test Concentration Fe.sup.2+/ No. ratio Pd.sup.2+ Al.sup.3+ Cd.sup.2+ Fe.sup.3+ Mn.sup.2+ Pb.sup.2+ Zn.sup.2+ 9-1 10 times 51 2.9 0.3 0 0.2 0 0.8 9-2 20 times 87 1.8 0.2 0.1 0.2 0 0.6

TABLE-US-00013 TABLE 13 Test Concentration Elution rate No. ratio (%) 9-1 10 times 99 9-2 20 times 85

Example 10

[0116] As Example 10, a selective recovery test of iridium from a hydrochloric acid solution (0.1 to 1 M) was conducted using the spray-dried sample.

[0117] (Test No. 10-1)

[0118] First, 20 mg of the spray-dried sample was added to 1 ml of a 0.1 M hydrochloric acid solution containing 10 ppm of Ir.sup.3+, and stirred overnight at room temperature. Next, the hydrochloric acid solution was centrifuged (12,000 rpm, 1 minute), and the metal concentration of the obtained supernatant was measured using ICP-MS (Test No. 10-1). In addition, as a control test, the same test as Test No. 10-1 was conducted except that the spray-dried sample was not added, and the metal concentration of the supernatant was measured (Test No. 10-1-control). Next, the recovery rate in Test No. 10-1 was calculated from the difference between the metal concentrations of Test No. 10-1 and Test No. 10-1-control measured above. The calculated recovery rate is shown in Table 14. The recovery rate shown in Table 14 is the mean value of three independent testsSD (standard deviation).

[0119] (Test Nos. 10-2 to 10-4)

[0120] Test Nos. 10-2 to 10-4 were conducted in the same manner as in Test No. 10-1 except that the concentration of the hydrochloric acid solution was changed to the concentration shown Table 14. For each test, the calculated recovery rate is shown in Table 14.

TABLE-US-00014 TABLE 14 HCl concentration Recovery rate Test No. (mol/l) (%) 10-1 0.1 87.0 0.90 10-2 0.2 78.9 0.72 10-3 0.5 55.3 0.31 10-4 1 31.9 6.40