Method for recovering scandium oxide from zirconium oxychloride mother liquor and application of scandium oxide

Abstract

The invention relates to the field of recycling of zirconium oxychloride mother liquor, in particular to a method for recycling scandium oxide from the zirconium oxychloride mother liquor and application of the method. The method for recovering scandium oxide from the zirconium oxychloride mother liquor comprises the following steps: (a) mixing the zirconium oxychloride mother liquor and a flocculating agent, and then carrying out solid-liquid separation to obtain purified liquor; (b) extracting the purified liquid to obtain a loaded organic phase and raffinate; and (c) carrying out first acid pickling, second acid pickling and back extraction on the loaded organic phase to obtain scandium oxalate. The method for recovering scandium oxide from the zirconium oxychloride mother liquor has the advantages of simple process flow, high comprehensive recovery rate of valuable metals, few reagents, low cost, environmental friendliness and the like, and the recovered scandium oxide is good in quality and low in impurity content.

Description

Technical Field

[0001] The invention relates to the field of recycling zirconium oxychloride mother liquor, and in particular to a method for recycling scandium oxide from zirconium oxychloride mother liquor and application thereof. Background Art

[0002] Zirconium oxychloride mother liquor generally refers to a solution containing zirconium element produced in the process of preparing zirconium oxychloride or other zirconium compounds. This mother liquor is an intermediate product in industrial production. In addition to the target product zirconium oxychloride, it may also contain other impurities, unreacted raw materials, solvents and by-products. For example, zirconium oxychloride mother liquor contains a large amount of scandium. Effectively treating and utilizing zirconium oxychloride mother liquor is of great significance for improving production efficiency, reducing costs and protecting the environment. With the continuous improvement of environmental protection requirements, the treatment and recovery of zirconium oxychloride mother liquor are also receiving increasing attention.

[0003] In the prior art, the method of recovering scandium oxide from zirconium oxychloride mother liquor is to use N235 to remove iron, then use P204 to extract scandium, wash with mixed acid, and extract with liquid alkali to obtain a scandium enrichment, and then roast the acid-soluble straw precipitate to prepare scandium oxide. The stripping solution of N235 is ammonia water, and the washing water of P204 is a mixed acid containing hydrofluoric acid, which has the problems of ammonia nitrogen wastewater and fluorine-containing wastewater discharge and equipment corrosion protection. Multiple extraction agents are used for extraction, the process is cumbersome, and the comprehensive recovery rate of valuable elements is low.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The object of the present invention is to provide a method for recovering scandium oxide from zirconium oxychloride mother liquor and its application. The method for recovering scandium oxide from zirconium oxychloride mother liquor has the advantages of simple process flow, high comprehensive recovery rate of valuable metals, less reagents used, low cost, and environmental friendliness.

[0006] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0007] One aspect of the present invention relates to a method for recovering scandium oxide from zirconium oxychloride mother liquor, comprising the following steps:

[0008] (a) mixing a zirconium oxychloride mother solution and a flocculant and performing solid-liquid separation to obtain a purified solution;

[0009] (b) extracting the purified liquid to obtain a loaded organic phase and a raffinate;

[0010] (c) subjecting the loaded organic phase to a first acid wash, a second acid wash and stripping to obtain scandium oxalate.

[0011] The method for recovering scandium oxide from zirconium oxychloride mother liquor has the advantages of simple process flow, high comprehensive recovery rate of valuable metals, less reagents used, low cost, and environmental friendliness.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] The method for recovering scandium oxide from zirconium oxychloride mother liquor provided by the present invention is to extract with Cyanex272, wash thorium with sulfuric acid, wash iron with hydrochloric acid, and then recover scandium oxide by high-concentration oxalic acid back extraction + impurity removal. The process flow is reduced by one extraction, and no additional ammonia nitrogen and fluorine-containing reagents are added. The recovered scandium oxide has good quality and low impurity content. The raffinate can be used to recover rare earth enrichment by adjusting pH. The method has high comprehensive recovery rate of valuable metals, less reagents, low cost, and is environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0015] Figure 1 A flow chart of a method for recovering scandium oxide from zirconium oxychloride mother liquor provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0016] The technical scheme of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0017] One aspect of the present invention relates to a method for recovering scandium oxide from zirconium oxychloride mother liquor, comprising the following steps:

[0018] (a) mixing a zirconium oxychloride mother solution and a flocculant and performing solid-liquid separation to obtain a purified solution;

[0019] (b) extracting the purified liquid to obtain a loaded organic phase and a raffinate;

[0020] (c) subjecting the loaded organic phase to a first acid wash, a second acid wash and stripping to obtain scandium oxalate.

[0021] The method for recovering scandium oxide from zirconium oxychloride mother liquor comprises the following steps: adding a flocculant to the zirconium oxychloride mother liquor for pretreatment to remove silicon in the mother liquor; extracting the purified liquid to separate rare earth elements; removing thorium and titanium by two acid washes; and finally performing back extraction to obtain a scandium oxalate precipitate and an oxalic acid solution containing zirconium. The process is simpler and more efficient, and the recovered scandium oxide has good quality and less impurity content.

[0022] The present invention utilizes a flocculant to remove suspended particles such as crystallized zirconium oxychloride in zirconium oxychloride mother liquor, thereby reducing the silicon content in the mother liquor to below 10 mg / L.

[0023] Furthermore, the flocculant is added in the form of a solution, and the volume of the flocculant solution is 0.5% to 5% of the volume of the zirconium oxychloride mother solution, including but not limited to any point value of 0.5%, 1%, 2%, 3%, 4% or 5% or a range value between any two of them.

[0024] Furthermore, the mass concentration of the flocculant solution is 0.5‰ to 2‰, including but not limited to any point value of 0.5‰, 0.8‰, 1.0‰, 1.3‰, 1.5‰, 1.8‰ or 2‰, or a range value between any two of them.

[0025] Furthermore, the flocculant includes but is not limited to: at least one of polyaluminium sulfate or polyferric sulfate.

[0026] The addition ratio of the flocculant is limited to a certain range, which can ensure that the crystallized zirconium oxychloride and silicon are effectively removed.

[0027] The present invention utilizes the extractant Cyanex272 for extraction to achieve the separation of scandium and other rare earth elements.

[0028] Furthermore, the extraction agent of the extraction includes: Cyanex272.

[0029] Furthermore, the chemical composition of Cyanex272 is bis(2,4,4-trimethylpentyl)phosphonic acid. This extractant can completely separate rare earth from scandium, titanium, zirconium, etc. under high acid conditions.

[0030] Furthermore, the organic phase of the extraction comprises: 10 vol% to 20 vol% of Cyanex272, 5 vol% to 10 vol% of isooctyl alcohol and 70 vol% to 85 vol% of sulfonated kerosene.

[0031] In some specific embodiments, in the organic phase of the extraction, Cyanex272 may be, for example, but not limited to, 10 vol%, 12 vol%, 14 vol%, 16 vol%, 18 vol% or 20 vol%; isooctyl alcohol may be, for example, but not limited to, 5 vol%, 6 vol%, 7 vol%, 8 vol%, 9 vol% or 10 vol%; sulfonated kerosene may be, for example, but not limited to, 70 vol%, 73 vol%, 75 vol%, 78 vol%, 80 vol%, 83 vol% or 85 vol%.

[0032] C272 is used as an extractant to synthesize an extractant with scandium, thereby transferring it from the aqueous phase to the organic phase, and plays a major role in the extraction process; isooctyl alcohol is used as an additive to inhibit emulsification, but excessive use will affect the extraction performance of the extractant; sulfonated kerosene is used as a diluent, which is an inert organic reagent that does not participate in the reaction and facilitates the separation and flow of the aqueous phase and the oil phase.

[0033] Furthermore, the extraction phase ratio of the extraction is O / A=1:2-10, including but not limited to 1:2, 1:4, 1:5, 1:6 or 1:10.

[0034] Furthermore, the extraction is 6 to 8 levels of countercurrent extraction.

[0035] The present invention can remove impurities such as titanium, zirconium and thorium through the first acid washing.

[0036] Furthermore, the acid solution for the first pickling includes a sulfuric acid solution and hydrogen peroxide in a volume ratio of 100:0.5-2 (for example, but not limited to 100:0.5, 100:1, 100:1.5 or 100:2).

[0037] Further, the concentration of the sulfuric acid solution is 4-6M, including but not limited to any point value of 4M, 4.5M, 4.8M, 5.0M, 5.3M or 6M or a range value between any two of them.

[0038] Furthermore, the mass concentration of the hydrogen peroxide is 25% to 35%, including but not limited to any point value of 25%, 27%, 29%, 31%, 33% or 35% or a range value between any two of them.

[0039] The pickling solution of the first pickling with a specific composition can effectively remove impurities such as titanium, zirconium and thorium.

[0040] Furthermore, the wash ratio of the first acid wash is O / A=4 to 8:1, including but not limited to 5:1, 6:1 or 7:1.

[0041] Furthermore, the temperature of the first pickling is 35-45°C, including but not limited to any point value of 35°C, 38°C, 39°C, 40°C, 41°C or 45°C or a range value between any two of them.

[0042] Furthermore, the first pickling is 4 to 6 stages of countercurrent washing.

[0043] The present invention removes impurities such as iron and thorium through the second pickling.

[0044] Furthermore, the acid solution for the second pickling includes hydrochloric acid with a concentration of 3 to 5 M (for example, it can be, but is not limited to, any one of 3 M, 4 M or 5 M or a range between any two of them).

[0045] Furthermore, the washing phase ratio of the second acid wash is O / A=(4-8):1, including but not limited to 4:1, 5:1, 6:1, 7:1 or 8:1.

[0046] Furthermore, the temperature of the second pickling is 35-45°C, including but not limited to any point value of 35°C, 38°C, 39°C, 40°C, 41°C or 45°C, or a range value between any two of them.

[0047] Furthermore, the second pickling is 4 to 6 stages of countercurrent washing.

[0048] The stripping of the present invention is to strip by oxalic acid solution at high temperature to directly obtain scandium oxalate precipitation, eliminating the steps of alkali stripping-acid dissolution-oxalate precipitation. Since the concentration of oxalic acid solution is relatively high, impurities such as zirconium and titanium can be separated from scandium by forming soluble oxalates with oxalic acid.

[0049] Furthermore, the stripping agent for stripping includes 3-5M (for example, but not limited to, any one of 3M, 4M or 5M or a range between any two) oxalic acid solution. If the concentration of oxalic acid is not within a reasonable range, it will affect the stripping rate of scandium.

[0050] Furthermore, the stripping is single-stage stripping.

[0051] Furthermore, the stripping phase ratio of the stripping is O / A=2 to 4:1, including but not limited to 2:1, 3:1 or 4:1.

[0052] Further, the stripping temperature is 60-80°C, including but not limited to any point value of 60°C, 65°C, 70°C, 75°C or 80°C or any range value between two of them. If the stripping temperature is too low, the stripping time is too long; if the temperature is too high, the cost is too high and the organic phase volatilizes too much. The stripping temperature will affect the stripping rate and the time to reach the maximum stripping rate.

[0053] Furthermore, the stripping time is 20 to 30 min, including but not limited to any one of 20 min, 22 min, 24 min, 26 min, 28 min or 30 min or a range between any two of them.

[0054] Furthermore, the scandium oxalate is calcined to obtain scandium oxide.

[0055] Furthermore, the calcination temperature is 850-1050°C, including but not limited to any point value of 850°C, 880°C, 900°C, 930°C, 950°C, 980°C, 1000°C, 1030°C or 1050°C or a range value between any two of them.

[0056] Furthermore, the calcination time is 4 to 12 hours, including but not limited to any one of 4 hours, 6 hours, 8 hours, 10 hours or 12 hours or a range between any two of them.

[0057] Furthermore, the method for recovering scandium oxide from zirconium oxychloride mother liquor further comprises:

[0058] (d) After removing impurities from the raffinate, the pH value of the raffinate is adjusted to 8-9 to obtain a rare earth enriched product.

[0059] Furthermore, the impurity removal process includes:

[0060] The pH of the raffinate is adjusted to 2 to 3. The impurities such as titanium and zirconium are removed by impurity removal treatment.

[0061] The embodiments of the present invention will be described in detail below in conjunction with the examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. If no specific conditions are specified in the examples, the conditions are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be obtained commercially.

[0062] During the process of preparing zirconium oxychloride from zircon sand, scandium will be enriched in the concentrated crystallization mother liquor. The composition of the zirconium oxychloride mother liquor involved in the following examples is shown in Table 1.

[0063] Table 1

[0064] Element (g / L) Sc Ti Zr Th U Fe Re Zirconium mother solution 0.5-1 10-15 20-40 1-3 1-3 10-20 5-10

[0065] Example 1

[0066] The method for recovering scandium oxide from zirconium oxychloride mother liquor provided in this embodiment is as follows: Figure 1 As shown, the following steps are included:

[0067] 1. Pretreatment: prepare a flocculant solution with a mass concentration of 1‰ with pure water, then add 1% of the volume of the zirconium oxychloride mother liquor to the zirconium oxychloride mother liquor, stir and filter to obtain a purified liquid, remove suspended particles such as crystallized zirconium oxychloride in the mother liquor and reduce the silicon content to less than 10 mg / L;

[0068] 2. C272 extraction: The purified liquid is directly extracted into the extraction tank, and the organic phase is the extractant Cyanex272, isooctyl alcohol and sulfonated kerosene in a volume ratio of 20:10:70, the extraction phase ratio O / A=1:5, and the extraction stage is 6-stage countercurrent extraction to obtain the loaded organic phase and the raffinate;

[0069] 3. Sulfuric acid washing: A mixed solution of 5M sulfuric acid and 30% hydrogen peroxide with a volume ratio of 100:0.5 is prepared to wash the loaded organic phase. The washing ratio O / A=6:1, the washing temperature is 40°C, and the washing stage is 4-stage countercurrent, mainly separating impurities such as titanium, zirconium, and thorium;

[0070] 4. Hydrochloric acid washing: 4M hydrochloric acid is used to wash the loaded organic phase, the washing phase ratio O / A=6:1, the washing temperature is 40°C, the washing stage is 4-stage countercurrent, mainly separating impurities such as iron and thorium;

[0071] 5. Oxalic acid stripping: pure water is used to prepare 4M oxalic acid solution, and the loaded organic phase after two-step acid washing is subjected to single-stage stripping, the stripping phase ratio O / A=3:1, the stripping temperature is 70°C, and the stripping time is 20 minutes; finally, scandium oxalate precipitate, organic phase after stripping, and oxalic acid mother liquor containing impurities such as zirconium are obtained;

[0072] 6. Calcination: Scandium oxalate is directly calcined at high temperature to prepare scandium oxide. The calcination temperature is 950°C and the calcination time is 6 hours.

[0073] 7. Preparation of rare earth enriched products: The Cyanex272 raffinate was first adjusted to pH = 2.5 with liquid alkali to remove titanium and zirconium, and then adjusted to pH = 8.5 to prepare rare earth enriched products.

[0074] Example 2

[0075] The method for recovering scandium oxide from zirconium oxychloride mother liquor provided in this embodiment comprises the following steps:

[0076] 1. Pretreatment: prepare a flocculant solution with a mass concentration of 1‰ with pure water, then add 2% of the volume of the zirconium oxychloride mother liquor to the zirconium oxychloride mother liquor, stir and filter to obtain a purified liquid, remove suspended particles such as crystallized zirconium oxychloride in the mother liquor and reduce the silicon content to less than 10 mg / L;

[0077] 2. C272 extraction: The purified liquid is directly extracted into the extraction tank, and the organic phase is the extractant Cyanex272, isooctyl alcohol and sulfonated kerosene in a volume ratio of 20:8:72, the extraction phase ratio O / A=1:5, and the extraction stage is 6-stage countercurrent extraction to obtain the loaded organic phase and the raffinate;

[0078] 3. Sulfuric acid washing: A mixed solution of 5.5M sulfuric acid and 30% hydrogen peroxide in a volume ratio of 100:0.8 is prepared to wash the loaded organic phase. The washing ratio O / A=6:1, the washing temperature is 42°C, and the washing stage is 4-stage countercurrent, mainly separating impurities such as titanium, zirconium, and thorium;

[0079] 4. Hydrochloric acid washing: 5M hydrochloric acid is used to wash the loaded organic phase, the washing phase ratio O / A=6:1, the washing temperature is 42°C, the washing stage is 4-stage countercurrent, mainly separating impurities such as iron and thorium;

[0080] 5. Oxalic acid stripping: pure water is used to prepare 5M oxalic acid solution, and the loaded organic phase after two-step acid washing is subjected to single-stage stripping, the stripping phase ratio O / A=3:1, the stripping temperature is 72°C, and the stripping time is 22 minutes; finally, scandium oxalate precipitate, organic phase after stripping, and oxalic acid mother liquor containing impurities such as zirconium are obtained;

[0081] 6. Calcination: Scandium oxalate is directly calcined at high temperature to prepare scandium oxide. The calcination temperature is 950°C and the calcination time is 6 hours.

[0082] 7. Preparation of rare earth enriched products: The Cyanex272 raffinate was first adjusted to pH = 2 with liquid alkali to remove titanium and zirconium, and then adjusted to pH = 9 to prepare rare earth enriched products.

[0083] Example 3

[0084] The method for recovering scandium oxide from zirconium oxychloride mother liquor provided in this embodiment comprises the following steps:

[0085] 1. Pretreatment: prepare a flocculant solution with a mass concentration of 1‰ with pure water, then add 0.5% of the volume of the zirconium oxychloride mother liquor to the zirconium oxychloride mother liquor, stir and filter to obtain a purified liquid, remove suspended particles such as crystallized zirconium oxychloride in the mother liquor and reduce the silicon content to less than 10 mg / L;

[0086] 2. C272 extraction: The purified liquid is directly extracted into the extraction tank, and the organic phase is the extractant Cyanex272, isooctyl alcohol and sulfonated kerosene in a volume ratio of 10:5:85, the extraction phase ratio O / A=1:5, and the extraction stage is 6-stage countercurrent extraction to obtain the loaded organic phase and the raffinate;

[0087] 3. Sulfuric acid washing: A mixed solution of 4.5M sulfuric acid and 30% hydrogen peroxide in a volume ratio of 100:1.2 is prepared to wash the loaded organic phase. The washing ratio O / A=6:1, the washing temperature is 38°C, and the washing stage is 4-stage countercurrent, mainly separating impurities such as titanium, zirconium, and thorium;

[0088] 4. Hydrochloric acid washing: 6M hydrochloric acid is used to wash the loaded organic phase, the washing phase ratio O / A=6:1, the washing temperature is 38°C, the washing stage is 4-stage countercurrent, mainly separating impurities such as iron and thorium;

[0089] 5. Oxalic acid stripping: 3M oxalic acid solution is prepared with pure water, and the loaded organic phase after two-step acid washing is subjected to single-stage stripping, the stripping phase ratio O / A=3:1, the stripping temperature is 68°C, and the stripping time is 30 minutes; finally, scandium oxalate precipitate, organic phase after stripping, and oxalic acid mother liquor containing impurities such as zirconium are obtained;

[0090] 6. Calcination: Scandium oxalate is directly calcined at high temperature to prepare scandium oxide. The calcination temperature is 950°C and the calcination time is 6 hours.

[0091] 7. Preparation of rare earth enriched products: The Cyanex272 raffinate was first adjusted to pH=3 with liquid alkali to remove titanium and zirconium, and then adjusted to pH=8 to prepare rare earth enriched products.

[0092] Example 4

[0093] The method for recovering scandium oxide from zirconium oxychloride mother liquor provided in this embodiment comprises the following steps:

[0094] 1. Pretreatment: prepare a flocculant solution with a mass concentration of 1‰ with pure water, then add 3% of the volume of the zirconium oxychloride mother liquor to the zirconium oxychloride mother liquor, stir and filter to obtain a purified liquid, remove suspended particles such as crystallized zirconium oxychloride in the mother liquor and reduce the silicon content to less than 10 mg / L;

[0095] 2. C272 extraction: The purified liquid is directly extracted into the extraction tank, and the organic phase is the extractant Cyanex272, isooctyl alcohol and sulfonated kerosene in a volume ratio of 13:7:80, the extraction phase ratio O / A=1:5, and the extraction stage is 6-stage countercurrent extraction to obtain the loaded organic phase and the raffinate;

[0096] 3. Sulfuric acid washing: A mixed solution of 4.8M sulfuric acid and 30% hydrogen peroxide in a volume ratio of 100:1.6 is prepared to wash the loaded organic phase. The washing ratio O / A=6:1, the washing temperature is 39°C, and the washing stage is 4-stage countercurrent, mainly separating impurities such as titanium, zirconium, and thorium;

[0097] 4. Hydrochloric acid washing: 4.5M hydrochloric acid is prepared to wash the loaded organic phase, the washing phase ratio O / A=6:1, the washing temperature is 39°C, the washing stage is 4-stage countercurrent, mainly separating impurities such as iron and thorium;

[0098] 5. Oxalic acid stripping: pure water is used to prepare 4.5M oxalic acid solution, and the loaded organic phase after two-step acid washing is subjected to single-stage stripping, the stripping phase ratio O / A=3:1, the stripping temperature is 60°C, and the stripping time is 29 minutes; finally, scandium oxalate precipitate, organic phase after stripping, and oxalic acid mother liquor containing impurities such as zirconium are obtained;

[0099] 6. Calcination: Scandium oxalate is directly calcined at high temperature to prepare scandium oxide. The calcination temperature is 950°C and the calcination time is 6 hours.

[0100] 7. Preparation of rare earth enriched products: The Cyanex272 raffinate was first adjusted to pH = 2-3 with liquid alkali to remove titanium and zirconium, and then adjusted to pH = 8-9 to prepare rare earth enriched products.

[0101] Example 5

[0102] The method for recovering scandium oxide from zirconium oxychloride mother liquor provided in this embodiment comprises the following steps:

[0103] 1. Pretreatment: prepare a flocculant solution with a mass concentration of 1‰ with pure water, then add 5% of the volume of the zirconium oxychloride mother liquor to the zirconium oxychloride mother liquor, stir and filter to obtain a purified liquid, remove suspended particles such as crystallized zirconium oxychloride in the mother liquor and reduce the silicon content to less than 10 mg / L;

[0104] 2. C272 extraction: The purified liquid is directly extracted into the extraction tank, and the organic phase is the extractant Cyanex272, isooctyl alcohol and sulfonated kerosene in a volume ratio of 17:10:73, the extraction phase ratio O / A=1:5, and the extraction stage is 6-stage countercurrent extraction to obtain the loaded organic phase and the raffinate;

[0105] 3. Sulfuric acid washing: A mixed solution of 5.2M sulfuric acid and 30% hydrogen peroxide in a volume ratio of 100:2 is prepared to wash the loaded organic phase. The washing ratio O / A=6:1, the washing temperature is 41°C, and the washing stage is 4-stage countercurrent, mainly separating impurities such as titanium, zirconium, and thorium;

[0106] 4. Hydrochloric acid washing: 6M hydrochloric acid is used to wash the loaded organic phase, the washing phase ratio O / A=6:1, the washing temperature is 41°C, the washing stage is 4-stage countercurrent, mainly separating impurities such as iron and thorium;

[0107] 5. Oxalic acid stripping: pure water is used to prepare 4.5M oxalic acid solution, and the loaded organic phase after two-step acid washing is subjected to single-stage stripping, the stripping phase ratio O / A=3:1, the stripping temperature is 80°C, and the stripping time is 21 minutes; finally, scandium oxalate precipitate, organic phase after stripping, and oxalic acid mother liquor containing impurities such as zirconium are obtained;

[0108] 6. Calcination: Scandium oxalate is directly calcined at high temperature to prepare scandium oxide. The calcination temperature is 950°C and the calcination time is 6 hours.

[0109] 7. Preparation of rare earth enriched products: The Cyanex272 raffinate was first adjusted to pH = 2-3 with liquid alkali to remove titanium and zirconium, and then adjusted to pH = 8-9 to prepare rare earth enriched products.

[0110] Comparative Example 1

[0111] The difference between this comparative example and Example 1 is that no flocculant is added in step (1).

[0112] In this comparative example, no flocculant was added in the pretreatment stage, resulting in severe emulsification during the extraction process, making it impossible to proceed to the subsequent steps.

[0113] Comparative Example 2

[0114] The difference between this comparative example and Example 1 is that in step 1, a flocculant solution in an amount of 0.1% of the volume of the zirconium oxychloride mother solution is added to the zirconium oxychloride mother solution.

[0115] The amount of flocculant added in this comparative example is less than that in Example 1, and severe emulsification occurs during the extraction process, making it impossible to carry out subsequent steps.

[0116] Comparative Example 3

[0117] The difference between this comparative example and Example 1 is that in step 2, the organic phase is an extractant Cyanex 272, isooctyl alcohol and sulfonated kerosene in a volume ratio of 35:5:60.

[0118] Comparative Example 4

[0119] The difference between this comparative example and Example 1 is that in step 3, the concentration of sulfuric acid is 5M, the concentration of hydrogen peroxide is 30%, and the volume ratio of sulfuric acid to hydrogen peroxide is 100:0.3.

[0120] Comparative Example 5

[0121] The difference between this comparative example and Example 1 is that step 4 is omitted.

[0122] Comparative Example 6

[0123] The difference between this comparative example and Example 1 is that step 3 is omitted.

[0124] Experimental example

[0125] The components in the purified liquid obtained in the examples and comparative examples were tested, and the results are shown in Table 1.

[0126] Table 1

[0127] Element (g / L) Sc Ti Zr Th U Fe Si Re Remark Zirconium mother solution 0.74 14.21 36.48 2.44 1.87 15.44 0.34 7.59 Example 1 0.71 14.11 35.54 2.31 1.87 15.12 0.0087 7.24 No emulsification Example 2 0.72 14.08 35.45 2.42 1.87 15.15 0.0075 7.44 No emulsification Example 3 0.72 14.09 35.55 2.22 1.87 15.22 0.010 7.14 No emulsification Example 4 0.71 14.01 35.25 2.12 1.87 15.01 0.0035 7.46 No emulsification Example 5 0.73 14.22 35.17 2.10 1.87 15.01 0.0015 7.34 No emulsification Comparative Example 1 0.74 14.21 36.48 2.44 1.87 15.44 0.34 7.59 Severe emulsification Comparative Example 2 0.73 14.13 35.12 2.44 1.87 15.01 0.14 7.54 Severe emulsification

[0128] As can be seen from Table 1, when the amount of flocculant added is less than 0.5%, the silicon in the zirconium mother liquor cannot be reduced to the required value, which will result in excessive emulsions during the extraction process and make subsequent processes impossible. Too much flocculant will result in excessive viscosity of the feed liquid, which will also lead to extraction emulsification and increase production costs.

[0129] As can be seen from Table 1, due to the serious emulsification during the extraction process of Comparative Examples 1 and 2, the raffinate was not analyzed. The extraction rate of scandium in Examples 1-5 increased with the increase of C272, but at the same time, the extraction rates of impurities such as titanium and zirconium also increased. Silicon was basically extracted into the organic phase.

[0130] The raffinate components of the embodiment and the comparative example were tested, and the results are shown in Table 2.

[0131] Table 2

[0132]

[0133]

[0134] As can be seen from Table 2, in Comparative Example 3, due to the increase in the content of the extractant in the organic phase, the viscosity of the organic phase increased, the fluidity decreased, and there was a slight emulsification phenomenon during the extraction process, which affected the continuity of the overall extraction process. At the same time, excessive extractant would also increase the product cost.

[0135] The impurity content of the scandium oxide prepared in the embodiment and the comparative example was tested, and the results are shown in Table 3.

[0136] Table 3

[0137]

[0138] It can be seen from Table 3 that the scandium oxide products produced by Examples 1 to 5 all meet the standard requirements. Comparative Example 4 reduces the amount of hydrogen peroxide used, resulting in serious excess of titanium and thorium, indicating that hydrogen peroxide can promote the washing of titanium and thorium. Comparative Examples 5 and 6 lack hydrochloric acid washing and sulfuric acid washing, respectively, and the zirconium, iron, titanium and thorium in the products are high, indicating that washing can significantly reduce impurities such as titanium, zirconium, iron, and thorium in the organic phase.

[0139] Although the present invention has been illustrated and described with specific embodiments, it should be appreciated that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents without departing from the spirit and scope of the present invention. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention. Therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A method for recovering scandium oxide from zirconium oxychloride mother liquor, characterized in that: The following steps are involved: (a) mixing a zirconium oxychloride mother solution and a flocculant and performing solid-liquid separation to obtain a purified solution; (b) extracting the purified liquid to obtain a loaded organic phase and a raffinate; (c) subjecting the loaded organic phase to a first acid wash, a second acid wash and stripping to obtain scandium oxalate.

2. The method for recovering scandium oxide from zirconium oxychloride mother liquor according to claim 1, characterized in that: Includes at least one of the following technical features: (1) The flocculant is added in the form of a flocculant solution, the volume of the flocculant solution being 0.5% to 5% of the volume of the zirconium oxychloride mother solution; (2) The flocculant includes at least one of polyacrylamide, polyaluminium sulfate or polyferric sulfate.

3. The method for recovering scandium oxide from zirconium oxychloride mother liquor according to claim 1, characterized in that: Includes at least one of the following technical features: (1) The extraction agent of the extraction comprises: Cyanex272; (2) The organic phase of the extraction comprises: 10 vol% to 20 vol% of Cyanex272, 5 vol% to 10 vol% of isooctyl alcohol and 70 vol% to 85 vol% of sulfonated kerosene.

4. The method for recovering scandium oxide from zirconium oxychloride mother liquor according to claim 1, characterized in that: Includes at least one of the following technical features: (1) The first pickling acid solution includes a sulfuric acid solution and a hydrogen peroxide solution in a volume ratio of 100:0.5-2; (2) The concentration of the sulfuric acid solution is 4 to 6 M; (3) The mass concentration of the hydrogen peroxide is 25% to 35%; (4) The temperature of the first pickling is 35-45°C.

5. The method for recovering scandium oxide from zirconium oxychloride mother liquor according to claim 1, characterized in that: Includes at least one of the following technical features: (1) the acid solution of the second pickling comprises hydrochloric acid with a concentration of 4 to 6 M; (2) The temperature of the second pickling is 35-45°C.

6. The method for recovering scandium oxide from zirconium oxychloride mother liquor according to claim 1, characterized in that: Includes at least one of the following technical features: (1) The stripping agent of the stripping includes a 3-5M oxalic acid solution; (2) The stripping temperature is 60 to 80° C. (3) The stripping time is 20 to 30 minutes.

7. The method for recovering scandium oxide from zirconium oxychloride mother liquor according to claim 1, characterized in that: Includes at least one of the following technical features: (1) calcining the scandium oxalate to obtain scandium oxide; (2) The calcination temperature is 850-1050° C.; (3) The calcination time is 4 to 12 hours.

8. The method for recovering scandium oxide from zirconium oxychloride mother liquor according to any one of claims 1 to 7, characterized in that: The method for recovering scandium oxide from zirconium oxychloride mother liquor also includes: (d) After removing impurities from the raffinate, the pH of the raffinate is adjusted to 8-9 to obtain a rare earth enriched product.

9. The method for recovering scandium oxide from zirconium oxychloride mother liquor according to claim 8, characterized in that: The impurity removal process comprises: The pH of the raffinate is adjusted to 2-3.

10. A method for recycling zirconium oxychloride mother liquor, characterized in that: The invention comprises the method for recovering scandium oxide from zirconium oxychloride mother liquor as described in any one of claims 1 to 9.

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