Method for recovering scandium oxide from scandium-containing intermediate product

Abstract

The invention provides a method for recovering scandium oxide from a scandium-containing intermediate product. A method for recovering scandium oxide from a scandium-containing intermediate product comprises the following steps that acid leaching is conducted, specifically, the scandium-containing intermediate product is leached through first acid liquor, the concentration of the first acid liquor is 5-6 mol / L, and scandium-containing acid leaching liquor is obtained; extracting: adding an organic extracting agent into the scandium-containing pickle liquor to obtain a loaded organic phase and raffinate; the organic extraction agent comprises C272 and kerosene, the volume of C272 accounts for 20%-30% of the volume of the organic extraction agent, the balance is kerosene, and the ratio of O to A is 2: (1-1.25); pickling: adding the loaded organic phase into a second acid solution for washing to obtain a scandium-rich organic phase and a pickling solution; precipitating: mixing the scandium-rich organic phase with a precipitating agent, separating scandium-containing precipitate, and washing; and calcining: calcining the scandium-containing precipitate to obtain scandium oxide, wherein the purity of the scandium oxide is greater than 99.95%. According to the method, a scandium oxide product with the purity being greater than 99.95% can be obtained.

Description

Technical Field

[0001] The invention relates to the technical field of hydrometallurgy, and in particular to a method for recovering scandium oxide from a scandium-containing intermediate product. Background Art

[0002] Scandium is a very important strategic metal. Metal scandium and its compounds and alloys are widely used in metallurgy, aerospace, ships, superconductors, lasers, nuclear energy, electronics and other fields. Since the scandium content in the scandium-containing intermediate is low and highly dispersed, the conventional P204 / P507 scandium extraction process has the problems of poor separation of scandium from iron, nickel, cobalt, etc., difficult stripping, easy emulsification, etc., and only crude scandium products can be obtained. In addition, the existing technology has high energy consumption and long process, and does not involve the separation of impurities such as rare earth and thorium. Therefore, the present invention is proposed. Summary of the invention

[0003] The object of the present invention is to provide a method for recovering scandium oxide from a scandium-containing intermediate product, which meets the industrial requirement for high purity scandium oxide and is further applicable to clean, efficient separation and extraction of low-concentration scandium elements.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] A method for recovering scandium oxide from a scandium-containing intermediate product comprises the following steps:

[0006] Acid leaching: leaching the scandium-containing intermediate product through a first acid solution, wherein the concentration of the first acid solution is 5-6 mol / L, to obtain an acid leaching solution containing scandium;

[0007] Extraction: adding an organic extractant to the scandium acid leaching solution to obtain a loaded organic phase and a raffinate; the organic extractant comprises C272 and kerosene, the volume of C272 accounts for 20%-30% of the volume of the organic extractant, the balance is kerosene, the phase O:A ratio is 2:(1-1.25), and C272 is bis(2,4,4-trimethylpentyl)phosphonic acid;

[0008] Acid washing: adding a second acid solution to the loaded organic phase for washing to obtain a scandium-rich organic phase and an acid washing solution;

[0009] Precipitation: mixing the scandium-rich organic phase with a precipitant, separating and washing the scandium-containing precipitate;

[0010] Calcination: calcining the scandium-containing precipitate to obtain the scandium oxide, the purity of which is greater than 99.95%.

[0011] Preferably, the scandium content of the scandium-containing intermediate product is 15%-20%. The scandium content refers to the mass fraction of scandium in the scandium-containing intermediate product.

[0012] Preferably, the scandium concentration in the scandium-containing acid leaching solution in the acid leaching step is 4-5 g / L, and the first acid solution is hydrochloric acid.

[0013] Preferably, the leaching temperature in the acid leaching step is 40-90°C.

[0014] Preferably, the extraction temperature in the extraction step is 40-60°C.

[0015] Preferably, the second acid solution in the pickling step is hydrochloric acid.

[0016] Preferably, the acid washing is carried out by cross-flow washing.

[0017] Preferably, in the precipitation step, the scandium-rich organic phase is mixed with the precipitant at 60-80° C., and the precipitant is an oxalic acid aqueous solution with a concentration of 80-120 g / L.

[0018] Preferably, in the precipitation step, the separated scandium-containing precipitate is first washed with hydrochloric acid and then washed with ultrapure water.

[0019] Preferably, in the calcination step, the calcination temperature is 800-1000° C. and the calcination time is 3-6 hours.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention provides a method for recovering scandium oxide from a scandium-containing intermediate product. After acid leaching, extraction, pickling, precipitation, and calcination, the purity of scandium oxide is significantly improved, and a scandium oxide product with a purity of >99.95% can be obtained. The process flow is simple, the extractant has a good scandium extraction effect, the rare earth impurity removal rate is high, and the difficult-to-separate impurity thorium has a good removal effect. The present invention has low environmental pollution and can meet the industrial requirements for high-purity scandium oxide, such as solid oxide fuel cells, 5G communications and other fields.

[0022] The organic extractant used in the present invention has higher selectivity for the extraction of scandium.

[0023] The method of the present invention can effectively separate and purify the scandium-containing intermediate product even when the scandium concentration is low, thereby obtaining high-purity scandium oxide. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the embodiment of the present invention. The embodiment described below is exemplary and is intended to be used to explain the present invention, and cannot be understood as limiting the present invention.

[0025] In the present invention, the scandium-containing intermediate product refers to the intermediate product after preliminary enrichment of scandium.

[0026] A method for recovering scandium oxide from a scandium-containing intermediate product (containing 15%-20% scandium), comprising the following steps:

[0027] 1. Acid leaching: The scandium-containing intermediate product is leached through the first acid solution to obtain a scandium-containing acid leaching solution. The scandium concentration in the scandium-containing acid leaching solution is 4-5 g / L, the concentration of the first acid solution is 5-6 mol / L, and the first acid solution is hydrochloric acid. The leaching temperature is 40-90°C, which can be 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, etc.

[0028] 2. Extraction: Add an organic extractant to the scandium-containing acid leaching solution to obtain a loaded organic phase and a raffinate; the organic extractant includes C272 and kerosene, the volume of C272 accounts for 20%-30% of the volume of the organic extractant, and the balance is kerosene, the phase O:A is 2: (1-1.25), and the extraction temperature is 40-60°C, which can be 40°C, 50°C, 60°C, etc. There are other extractants in the field, such as P204, which have the problems of poor separation effect of scandium from iron, nickel, cobalt, etc., difficult stripping, and easy emulsification.

[0029] 3. Pickling: The loaded organic phase is washed with a second acid solution in a cross-flow manner to obtain a scandium-rich organic phase and an acid washing solution. The second acid solution is hydrochloric acid with a concentration of 4.5-6.5 mol / L.

[0030] 4. Precipitation: Mix the scandium-rich organic phase with a precipitant at 60-80°C, wherein the precipitant is an oxalic acid aqueous solution with a concentration of 80-120 g / L. The present invention adopts precipitation treatment, which can form a scandium-containing precipitate more efficiently. The stripping rate of conventional stripping treatment is about 85%, which is lower than 94%, and cannot achieve the ideal treatment effect. After keeping warm for a period of time, separate the scandium-containing precipitate and wash it. First, wash it with hydrochloric acid with a concentration of 10-20 g / L to remove oxalate impurities, and then wash it with ultrapure water to clean the residual acid on the surface of scandium oxalate, wash away the acidified substances and residual acid on the surface of scandium oxalate, improve product quality, and protect the equipment at the same time.

[0031] 5. Calcination: Calcinate the scandium-containing precipitate at a temperature of 800-1000° C. for 3-6 hours to obtain scandium oxide with a purity of >99.95%.

[0032] The purity of scandium oxide obtained by the method of the present invention is significantly improved, Sc2O3>99.95%, Sc2O3 / REO>99.99%. It is difficult to achieve the above purity level with the existing technology in the field.

[0033] Example 1

[0034] The composition of the scandium-containing intermediate product of this embodiment is shown in Table 1 and Table 2.

[0035] Table 1

[0036] Element content(%) <![CDATA[Sc2O3]]> 33.52 <![CDATA[Fe2O3]]> 1.60 CaO <0.0001 <![CDATA[ZrO2]]> <0.0001 <![CDATA[Al2O3]]> 0.0006 <![CDATA[TiO2]]> 0.098 CuO <0.0001 <![CDATA[V2O5]]> <0.0001 MgO <0.0001 <![CDATA[Na2O]]> 0.0015 <![CDATA[SiO2]]> 0.0013

[0037] Table 2

[0038]

[0039] A method for recovering scandium oxide from a scandium-containing intermediate product (containing 15% scandium) comprises the following steps:

[0040] 1. Acid leaching: stir and mix the scandium-containing intermediate with 5 mol / L hydrochloric acid in a beaker, keep the leaching temperature at 40°C for 1 hour, and obtain a scandium-containing acid leaching solution with a scandium concentration of 4 g / L.

[0041] 2. Extraction: Add an organic extractant to the scandium acid leaching solution, the ratio of organic phase to water is 2:1, the extraction temperature is 40°C, and a loaded organic phase and a raffinate are obtained. The organic extractant includes C272 and kerosene, the volume of C272 accounts for 25% of the volume of the organic extractant, and the volume of kerosene accounts for 75% of the volume of the organic extractant.

[0042] 3. Pickling: Add 5 mol / L hydrochloric acid to the loaded organic phase for cross-flow washing to obtain a scandium-rich organic phase and a pickling solution.

[0043] 4. Precipitation: Mix the scandium-rich organic phase with an oxalic acid aqueous solution with a concentration of 80 g / L at 60°C. Keep warm for 3 hours, separate the scandium-containing precipitate and wash it, first wash it with hydrochloric acid with a concentration of 10 g / L to remove oxalate impurities, and then wash it with ultrapure water to clean the residual acid on the surface of the scandium oxalate. When the conductivity of the washing liquid is measured by a conductivity meter and is less than 100 us / cm, stop washing and filter press to obtain the scandium oxalate solid.

[0044] 5. Calcination: The scandium-containing precipitate was heated to 850° C. in a muffle furnace for calcination for 4 hours to obtain high-purity scandium oxide with a purity of 99.97%. The composition of scandium oxide was tested, and the results are shown in Tables 3 and 4.

[0045] Table 3

[0046]

[0047]

[0048] Table 4

[0049]

[0050] It can be seen from Table 3 and Table 4 that the absolute purity of Sc2O3 prepared by the present invention is 99.97%, Sc2O3 / REO>99.9995%, and the removal rate of rare earth impurities is high.

[0051] Example 2

[0052] The composition of the scandium-containing intermediate product of this embodiment is shown in Table 5 and Table 6.

[0053] Table 5

[0054] Element content(%) <![CDATA[Sc2O3]]> 29.80 <![CDATA[Fe2O3]]> 1.30 CaO <0.0001 <![CDATA[ZrO2]]> 0.0035 <![CDATA[Al2O3]]> 0.0017 <![CDATA[TiO2]]> 0.12 CuO 0.0003 <![CDATA[V2O5]]> <0.0001 MgO <0.0001 <![CDATA[Na2O]]> <0.0001 <![CDATA[SiO2]]> <0.0001

[0055] Table 6

[0056]

[0057] A method for recovering scandium oxide from a scandium-containing intermediate product (containing 18% scandium) comprises the following steps:

[0058] 1. Acid leaching: stir and mix the scandium-containing intermediate with 5.5 mol / L hydrochloric acid in a beaker, keep the leaching temperature at 70°C for 1 hour, and obtain a scandium-containing acid leaching solution with a scandium concentration of 4.5 g / L.

[0059] 2. Extraction: Add an organic extractant to the scandium acid leaching solution, the ratio of organic phase to water is 2:1.12, the extraction temperature is 50°C, and a loaded organic phase and a raffinate are obtained. The organic extractant includes C272 and kerosene, the volume of C272 accounts for 20% of the volume of the organic extractant, and the volume of kerosene accounts for 80% of the volume of the organic extractant.

[0060] 3. Pickling: Add 4.6 mol / L hydrochloric acid to the loaded organic phase for cross-flow washing to obtain a scandium-rich organic phase and a pickling solution.

[0061] 4. Precipitation: Mix the scandium-rich organic phase with an aqueous solution of oxalic acid at a concentration of 90 g / L at 65°C. Keep warm for 3 hours, separate the scandium-containing precipitate and wash it, first wash it with hydrochloric acid at a concentration of 15 g / L to remove oxalate impurities, then wash it with ultrapure water to clean the residual acid on the surface of the scandium oxalate. When the conductivity of the washing liquid is measured by a conductivity meter and is less than 100 us / cm, stop washing and filter press to obtain the scandium oxalate solid.

[0062] 5. Calcination: The scandium-containing precipitate was heated to 800° C. in a muffle furnace for calcination for 6 hours to obtain high-purity scandium oxide with a purity of 99.98%. The composition of scandium oxide was tested, and the results are shown in Tables 7 and 8.

[0063] Table 7

[0064] Element content(%) <![CDATA[Sc2O3]]> 99.98 <![CDATA[Sc2O3 / REO(%)]]> ≥99.9995 <![CDATA[Fe2O3]]> 0.0030 CaO 0.0069 <![CDATA[ZrO2]]> <0.0001 <![CDATA[Al2O3]]> <0.0001 <![CDATA[TiO2]]> <0.0001 CuO <0.0001 <![CDATA[V2O5]]> <0.0001 MgO 0.0022 NiO 0.0076 <![CDATA[Na2O]]> 0.0070 <![CDATA[SiO2]]> 0.0009 <![CDATA[ThO2]]> <0.0001

[0065] Table 8

[0066]

[0067] It can be seen from Tables 7 and 8 that the absolute purity of Sc2O3 prepared by the present invention is 99.98%, Sc2O3 / REO>99.9995%, and the removal rate of rare earth impurities is high.

[0068] Example 3

[0069] The composition of the scandium-containing intermediate product of this embodiment is shown in Tables 9 and 10.

[0070] Table 9

[0071] Element content(%) <![CDATA[Sc2O3]]> 29.98 <![CDATA[Fe2O3]]> 2.35 CaO 0.0028 <![CDATA[ZrO2]]> 0.0001 <![CDATA[Al2O3]]> 0.0032 <![CDATA[TiO2]]> 0.057 CuO <0.0001 <![CDATA[V2O5]]> <0.0001 MgO <0.0001 <![CDATA[Na2O]]> <0.0001 <![CDATA[SiO2]]> <0.0001

[0072] Table 10

[0073]

[0074] A method for recovering scandium oxide from a scandium-containing intermediate product (containing 20% ​​scandium) comprises the following steps:

[0075] 1. Acid leaching: stir and mix the scandium-containing intermediate and 6 mol / L hydrochloric acid in a beaker, keep the leaching temperature at 90°C for 1 hour, and obtain a scandium-containing acid leaching solution with a scandium concentration of 5 g / L.

[0076] 2. Extraction: Add an organic extractant to the scandium acid leaching solution, the ratio of organic phase to water is 2:1.25, the extraction temperature is 60°C, and a loaded organic phase and a raffinate are obtained. The organic extractant includes C272 and kerosene, the volume of C272 accounts for 30% of the volume of the organic extractant, and the volume of kerosene accounts for 70% of the volume of the organic extractant.

[0077] 3. Pickling: Add 5 mol / L hydrochloric acid to the loaded organic phase for cross-flow washing to obtain a scandium-rich organic phase and a pickling solution.

[0078] 4. Precipitation: Mix the scandium-rich organic phase with an aqueous solution of oxalic acid at a concentration of 120 g / L at 80°C. Keep warm for 3 hours, separate the scandium-containing precipitate and wash it, first wash it with hydrochloric acid at a concentration of 20 g / L to remove oxalate impurities, then wash it with ultrapure water to clean the residual acid on the surface of the scandium oxalate. When the conductivity of the washing liquid is measured by a conductivity meter and is less than 100 us / cm, stop washing and filter press to obtain the scandium oxalate solid.

[0079] 5. Calcination: The scandium-containing precipitate was heated to 1000° C. in a muffle furnace for calcination for 3 hours to obtain high-purity scandium oxide with a purity of 99.96%. The composition of scandium oxide was tested, and the results are shown in Tables 11 and 12.

[0080] Table 11

[0081] Element content(%) <![CDATA[Sc2O3]]> 99.96 <![CDATA[Sc2O3 / REO(%)]]> ≥99.9995 <![CDATA[Fe2O3]]> 0.00047 CaO 0.0079 <![CDATA[ZrO2]]> 0.00065 <![CDATA[Al2O3]]> <0.0009 <![CDATA[TiO2]]> <0.0003 CuO 0.00041 <![CDATA[V2O5]]> 0.00031 MgO 0.00032 NiO 0.0003 <![CDATA[Na2O]]> 0.031 <![CDATA[SiO2]]> 0.0068 <![CDATA[ThO2]]> 0.0003

[0082] Table 12

[0083]

[0084] It can be seen from Tables 11 and 12 that the absolute purity of Sc2O3 prepared by the present invention is 99.96%, Sc2O3 / REO>99.9995%, and the removal rate of rare earth impurities is high.

[0085] Comparative Example 1

[0086] The scandium-containing intermediate (containing 15% scandium) was stirred and mixed with 4 mol / L hydrochloric acid in a beaker at a leaching temperature of 40°C. After keeping warm for 1 hour, the scandium-containing intermediate was not completely dissolved. Therefore, the acid concentration of 4 mol / L was too low, resulting in incomplete reaction.

[0087] Comparative Example 2

[0088] The composition of the scandium-containing intermediate product in this comparative example is the same as that in Example 2.

[0089] A method for recovering scandium oxide from a scandium-containing intermediate product (containing 18% scandium) comprises the following steps:

[0090] 1. Acid leaching: Stir and dissolve the scandium-containing intermediate with nitric acid in a beaker.

[0091] 2. Extraction: Add an organic extractant to the scandium acid leaching solution, the ratio of organic phase to water is 2:1.12, the extraction temperature is 50°C, and a loaded organic phase and a raffinate are obtained. The organic extractant is 20% C272, 10% TPB and kerosene.

[0092] 3. Pickling: same as Example 2.

[0093] 4. Stripping: Strip the scandium-rich organic phase with 90 g / L oxalic acid aqueous solution, the phase O / A ratio is 3:1, the stripping temperature is 80°C, and the scandium oxalate precipitate is obtained after filtration.

[0094] 5. Calcination: The scandium oxalate precipitate was heated to 800°C for calcination to obtain scandium oxide with a purity of 97.16%. The scandium oxide was tested for its composition, and the results are shown in Tables 13 and 14.

[0095] Table 13

[0096] Element content(%) <![CDATA[Sc2O3]]> 97.16 <![CDATA[Sc2O3 / REO(%)]]> ≥99.9 <![CDATA[Fe2O3]]> 0.011 CaO 0.02 <![CDATA[ZrO2]]> 0.01 <![CDATA[Al2O3]]> 0.009 <![CDATA[TiO2]]> 0.02 CuO 0.01 <![CDATA[V2O5]]> 0.005 MgO 0.0049 NiO 0.01 <![CDATA[Na2O]]> 0.08 <![CDATA[SiO2]]> 0.01 <![CDATA[ThO2]]> 0.04

[0097] Table 14

[0098]

[0099] It can be seen from Table 13 and Table 14 that the absolute purity of Sc2O3 prepared in Comparative Example 2 is 97.16%, and Sc2O3 / REO>99.9%. Comparative Example 2 not only has more steps but also has lower purity.

[0100] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. It is understandable that those skilled in the art can change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention.

Claims

1. A method for recovering scandium oxide from a scandium-containing intermediate product, characterized in that: The following steps are involved: Acid leaching: leaching the scandium-containing intermediate product through a first acid solution, wherein the concentration of the first acid solution is 5-6 mol / L, to obtain an acid leaching solution containing scandium; Extraction: adding an organic extractant to the scandium-containing acid leaching solution to obtain a loaded organic phase and a raffinate; the organic extractant comprises C272 and kerosene, the volume of C272 accounts for 20%-30% of the volume of the organic extractant, the remainder is kerosene, and the phase ratio O:A is 2:(1-1.25); Acid washing: adding a second acid solution to the loaded organic phase for washing to obtain a scandium-rich organic phase and an acid washing solution; Precipitation: mixing the scandium-rich organic phase with a precipitant, separating and washing the scandium-containing precipitate; Calcination: calcining the scandium-containing precipitate to obtain the scandium oxide, the purity of which is greater than 99.95%.

2. The method for recovering scandium oxide from a scandium-containing intermediate product according to claim 1, characterized in that: The scandium content of the scandium-containing intermediate product is 15%-20%.

3. The method for recovering scandium oxide from a scandium-containing intermediate product according to claim 1, characterized in that: The scandium concentration in the scandium-containing acid leaching solution in the acid leaching step is 4-5 g / L, and the first acid solution is hydrochloric acid.

4. The method for recovering scandium oxide from a scandium-containing intermediate product according to claim 1, characterized in that: The leaching temperature in the acid leaching step is 40-90°C.

5. The method for recovering scandium oxide from a scandium-containing intermediate product according to claim 1, characterized in that: The extraction temperature in the extraction step is 40-60°C.

6. The method for recovering scandium oxide from a scandium-containing intermediate product according to claim 1, characterized in that: The second acid solution in the pickling step is hydrochloric acid.

7. The method for recovering scandium oxide from a scandium-containing intermediate product according to claim 1, characterized in that: The pickling is carried out by cross-current washing.

8. The method for recovering scandium oxide from a scandium-containing intermediate product according to claim 1, characterized in that: In the precipitation step, the scandium-rich organic phase is mixed with the precipitant at 60-80° C., and the precipitant is an oxalic acid aqueous solution with a concentration of 80-120 g / L.

9. The method for recovering scandium oxide from a scandium-containing intermediate product according to claim 1, characterized in that: In the precipitation step, the separated scandium-containing precipitate is first washed with hydrochloric acid and then washed with ultrapure water.

10. The method for recovering scandium oxide from a scandium-containing intermediate product according to claim 1, characterized in that: In the calcination step, the calcination temperature is 800-1000° C. and the calcination time is 3-6 hours.

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