CN111961849B - Method for extracting and separating scandium - Google Patents

Abstract

The invention belongs to the technical field of extraction and purification of scandium, and in particular relates to a method for separating scandium and other impurities by utilizing an amide pod ether extractant. The invention adopts N,N,N',N'-tetracyclohexyl-3-oxoglutaramide as extractant to separate scandium from nitric acid medium, has high selectivity to scandium, and has high selectivity to Fe, Mg, Ti, Ba, Al , Zr, Mn and other impurities have poor extraction ability, and realize the separation of scandium and impurity elements. The technology is simple in operation, low in pollution and low in equipment requirements.

Description

A kind of method of extracting and separating scandium

technical field

The invention belongs to the technical field of hydrometallurgy, in particular to a method for separating scandium and other impurities by utilizing an amide pod ether extraction agent.

Background technique

The excellent properties of scandium make it play an important role in the fields of electric light source, aerospace, electronic industry, nuclear technology, superconducting technology, etc. However, as a rare earth element, scandium is scattered and independent deposits are extremely rare. Crude scandium oxide contains impurities Fe, Mg, Ti, Ba, Al, Zr, Mn, etc., and the content of Sc ₂ O ₃ is 80-90%. In the process of extracting scandium, how to enrich scandium with low cost and then obtain high-purity scandium oxide is an industrial problem.

Chinese patent CN108754156A) discloses a method for separating iron and scandium in red mud acid leaching solution by an extraction method. The iron complex ions are extracted and separated by using a long-chain alkyl quaternary ammonium salt extractant, so that the scandium ions remain in the leaching solution to realize The separation of iron and scandium. The iron removal rate of this method is greater than 95%, indicating that a certain amount of iron remains in the leaching solution, which affects the purity of scandium. Chinese patent (publication number CN109022810B) discloses a method for separating and recovering valuable metals iron, manganese and scandium from tungsten slag, using P204 to extract the leaching solution of sulfuric acid, and the single-stage extraction rates of iron, manganese and scandium in the leaching solution are 86.1% respectively , 82.4% and 97.7%, it is difficult to obtain high-purity scandium products by using different stripping solutions to strip metals. Chinese patent (publication number CN109022839A) discloses a method for enriching scandium, using different extractants to enrich scandium, respectively using neutral, alkaline, organic chelating extractant scandium for extraction and back-extraction. Separation of impurities. Chinese patent (publication number CN1844421A) discloses a kind of method for extracting scandium from red mud, adopts P204 extraction and reclaims scandium in red mud, and needs to use 2.5 mol/L concentrated sulfuric acid to first purify the loaded organic phase before stripping, resulting in Large amounts of concentrated acid with low iron content are difficult to handle. Chinese patent (publication number CN101182601A) uses concentrated hydrochloric acid of different mass fractions to impregnate red mud twice, and uses P204 to extract scandium from the second leaching solution. The organic phase contains a small amount of impurity iron, which affects the purity of scandium.

Phosphorus-containing extractants (P204, etc.) are commonly used in the above-mentioned extraction and separation, and alkali is added during the extraction process, resulting in waste water containing salt and ammonia nitrogen, which is difficult to handle, and solid waste remains after combustion.

SUMMARY OF THE INVENTION

The content of Sc ₂ O ₃ in crude scandium oxide is 80-90%, and phosphorus-containing extractants are commonly used to purify scandium, which pollutes the environment. The present invention designs and synthesizes N,N,N',N'-tetracyclohexyl-3-oxoglutaramide extractant, which has a large molecular weight, is almost insoluble in water, does not require saponification in the extraction process, and is environmentally friendly. The extractant has a strong ability to extract scandium in nitric acid and the coexisting solution of nitric acid and nitrate, but has a low ability to extract coexisting impurity ions. The high separation coefficient of the extractant to scandium and other impurities can effectively separate scandium and other impurities. other impurity elements.

The above technical features of the present invention are implemented through the following technical solutions, and a method for extracting and separating scandium is composed of the following steps:

(1) Dissolve the scandium sample with nitric acid to obtain an aqueous solution with impurities including Fe, Mg, Ti, Ba, Al, Zr, and Mn. The concentration of nitric acid in the aqueous phase is 0.01~5 mol/L, or the concentration of nitric acid is 0.01~1 mol/L and nitrate concentrations were 0.01-4 mol/L, of which the total scandium concentration was 1-200 g/L.

(2) Weigh a certain mass of N,N,N',N'-tetracyclohexyl-3-oxoglutaramide extractant, and dilute it with a diluent to a certain concentration to form the organic phase, wherein the diluent is toluene, xylene , one of dichloromethane, chloroform or carbon tetrachloride; the concentration of extractant is 0.01~2 mol/L.

(3) Mix and stir the aqueous phase and the organic phase in a certain volume ratio (1:10~10:1) for 10~120 min, and the extraction temperature is 5~60 ^o C.

(4) The mixed solution after extraction is left to stand for 1-5 minutes to separate phases, and becomes two clear and transparent phases, namely the organic phase loaded with scandium, and the impurities remain in the aqueous phase of the raffinate.

(5) Take a certain volume concentration of 0.1~1.0 mol/L oxalic acid or oxalate aqueous solution and mix it with the organic phase loaded with scandium, the stirring time is 5~100 min, the temperature is 5~60 ^o C, stand to separate the organic phase, filter The aqueous phase was precipitated, dried at 120 ^o C for 2 hours, and calcined at 600 ^o C for 2 hours to obtain scandium oxide. The organic phase after standing and layering can be reused.

Compared with the prior art, the present invention has the following characteristics and beneficial effects:

(1) The extractant used in the present invention has high identification ability for scandium, and has a large separation coefficient for scandium and impurity elements, which is beneficial to the effective separation of scandium and impurities.

(2) The extractant used in the present invention has good thermal stability, low volatility, low water solubility, good physical and chemical stability, and can be reused.

(3) Compared with the phosphoric acid extractant, the extractant used in the present invention does not need saponification, and belongs to the environment-friendly extractant.

(4) The present invention is easy to operate, has low requirements for equipment, and is easy to realize continuous industrial production.

Specific implementation method

The extraction rate (E) represents the ratio of metal concentrations in the aqueous phase before and after extraction. The concentrations of metals Sc, Fe, Mg, Ti, Ba, Al, Zr, Mn in this patent were determined by ICP-AES.

Weigh 36g of scandium oxide product with a purity of 85%, and heat the scandium sample with nitric acid to dissolve the scandium sample. The following working solutions are all diluted with this solution.

Example 1

(1) The concentration of Sc in the aqueous phase is 5 g/L, and the concentration of nitric acid is 0.6 mol/L.

(2) Using toluene as the diluent, prepare 0.5 mol/L N,N,N',N'-tetracyclohexyl-3-oxoglutaramide as the organic phase.

(3) The aqueous phase and the organic phase were mixed with 20 mL each, the stirring time was 30 min, the extraction temperature was 10 ^o C, the concentration of Sc in the raffinate was measured, and the extraction rate was 99.89%.

(4) Mix 20 mL of oxalic acid aqueous solution with a concentration of 0.5 mol/L with the organic phase after extraction, stir for 30 min, and at a temperature of 30 ^o C, stand to separate the organic phase, filter the aqueous phase to obtain a precipitate, and dry at 120 ^o C for 2 calcination at 600 ^o C for 2 hours to obtain scandium oxide. The recovery rate of scandium is over 98%, and the purity of scandium is over 99.8%.

Example 2

(1) The concentration of Sc in the aqueous phase is 5 g/L, and the concentration of nitric acid is 0.6 mol/L.

(2) Using toluene as the diluent, prepare 0.5 mol/L N,N,N',N'-tetracyclohexyl-3-oxoglutaramide as the organic phase.

(3) The aqueous phase and the organic phase were mixed with 20 mL each, the stirring time was 30 min, the extraction temperature was 40 ^o C, the concentration of Sc in the raffinate was measured, and the extraction rate was 98.85%.

(4) Take 20 mL of oxalate aqueous solution with a concentration of 0.5 mol/L and mix it with the organic phase after extraction, stir for 30 minutes, and set the temperature to 30 ^o C, stand to separate the organic phase, filter the aqueous phase to obtain a precipitate, and bake at 120 ^o C. Dry for 2 hours and calcined at 600 ^o C for 2 hours to obtain scandium oxide. The recovery rate of scandium is over 97%, and the purity of scandium is over 99.3%.

Example 3

(1) The concentration of Sc in the aqueous phase is 10 g/L, and the concentration of nitric acid is 3.0 mol/L.

(2) Using toluene as the diluent, prepare 1 mol/L N,N,N',N'-tetracyclohexyl-3-oxoglutaramide as the organic phase.

(3) The aqueous phase and the organic phase were mixed with 20 mL each, the stirring time was 30 min, the extraction temperature was 20 ^o C, the concentration of Sc in the raffinate was measured, and the extraction rate was 99.98%.

(4) Mix 20 mL of oxalic acid aqueous solution with a concentration of 0.5 mol/L with the organic phase after extraction, stir for 30 min, and at a temperature of 30 ^o C, stand to separate the organic phase, filter the aqueous phase to obtain a precipitate, and dry at 120 ^o C for 2 calcination at 600 ^o C for 2 hours to obtain scandium oxide. The recovery rate of scandium is over 98%, and the purity of scandium is over 99.9%.

Example 4

(1) The concentration of Sc in the aqueous phase is 10 g/L, the concentration of nitric acid is 0.2 mol/L, and the concentration of lithium nitrate is 0.4 mol/L.

(2) Using toluene as the diluent, prepare 1 mol/L N,N,N',N'-tetracyclohexyl-3-oxoglutaramide as the organic phase.

(3) The aqueous phase and the organic phase were mixed with 20 mL each, the stirring time was 30 min, the extraction temperature was 20 ^o C, and the concentration of Sc in the raffinate was measured, and the extraction rate was 86.96%.

(4) Take 20 mL of oxalate aqueous solution with a concentration of 1.0 mol/L and mix it with the organic phase after extraction. The stirring time is 30 min and the temperature is 30 ^o C. The organic phase is separated by standing, and the aqueous phase is filtered to obtain a precipitate. Dry at 120 ^o C. Dry for 2 hours and calcined at 600 ^o C for 2 hours to obtain scandium oxide. The recovery rate of scandium is over 85%, and the purity of scandium is over 99.7%.

Example 5

(1) The concentration of Sc in the aqueous phase is 10 g/L, the concentration of nitric acid is 0.2 mol/L, and the concentration of lithium nitrate is 3 mol/L.

(2) Using toluene as the diluent, prepare 1 mol/L of N,N,N',N'-tetracyclohexyl-3-oxoglutaramide as the organic phase.

(3) The aqueous phase and the organic phase were mixed with 20 mL each, the stirring time was 30 min, the extraction temperature was 20 ^o C, the concentration of Sc in the raffinate was measured, and the extraction rate was 99.68%.

(4) Mix 20 mL of oxalic acid aqueous solution with a concentration of 0.5 mol/L with the organic phase after extraction, stir for 30 min, and at a temperature of 30 ^o C, stand to separate the organic phase, filter the aqueous phase to obtain a precipitate, and dry at 120 ^o C for 2 calcination at 600 ^o C for 2 hours to obtain scandium oxide. The recovery rate of scandium is over 98%, and the purity of scandium is over 99.7%.

Example 6

(1) The concentration of Sc in the aqueous phase is 5 g/L, the concentration of nitric acid is 0.2 mol/L, and the concentration of lithium nitrate is 3 mol/L.

(2) Using toluene as the diluent, prepare 0.5 mol/L N,N,N',N'-tetracyclohexyl-3-oxoglutaramide as the organic phase.

(3) The aqueous phase and the organic phase were mixed with 20 mL each, the stirring time was 60 min, the extraction temperature was 20 ^o C, and the concentration of Sc in the raffinate was measured, and the extraction rate was 99.98%.

(4) Mix 20 mL of oxalic acid aqueous solution with a concentration of 0.5 mol/L with the organic phase after extraction, stir for 30 min, and at a temperature of 30 ^o C, stand to separate the organic phase, filter the aqueous phase to obtain a precipitate, and dry at 120 ^o C for 2 calcination at 600 ^o C for 2 hours to obtain scandium oxide. The recovery rate of scandium is over 98%, and the purity of scandium is over 99.6%.

Example 7

(1) The concentration of Sc in the aqueous phase is 10 g/L, and the concentration of nitric acid is 1 mol/L.

(2) Using toluene as the diluent, prepare 0.5 mol/L N,N,N',N'-tetracyclohexyl-3-oxoglutaramide as the organic phase.

(3) Mix 20 mL of the aqueous phase and 40 mL of the organic phase, the stirring time is 30 min, the extraction temperature is 20 ^o C, the concentration of Sc in the raffinate is determined, and the extraction rate is 98.32%.

(4) Take 40 mL of oxalic acid aqueous solution with a concentration of 0.5 mol/L and mix it with the organic phase after extraction. The stirring time is 30 minutes and the temperature is 30 ^o C. The organic phase is separated by standing, and the aqueous phase is filtered to obtain a precipitate, and dried at 120 ^o C for 2 calcination at 600 ^o C for 2 hours to obtain scandium oxide. The recovery rate of scandium is over 97%, and the purity of scandium is over 99.6%.

Example 8

(1) The concentration of Sc in the aqueous phase is 5 g/L, and the concentration of nitric acid is 1 mol/L.

(2) Using toluene as the diluent, prepare 0.5 mol/L N,N,N',N'-tetracyclohexyl-3-oxoglutaramide as the organic phase.

(3) Mix 40 mL of the aqueous phase and 20 mL of the organic phase, the stirring time is 30 min, the extraction temperature is 20 ^o C, the concentration of Sc in the raffinate is determined, and the extraction rate is 72.56%.

(4) Mix 20 mL of oxalic acid aqueous solution with a concentration of 0.5 mol/L with the organic phase after extraction, stir for 30 min, and at a temperature of 30 ^o C, stand to separate the organic phase, filter the aqueous phase to obtain a precipitate, and dry at 120 ^o C for 2 calcination at 600 ^o C for 2 hours to obtain scandium oxide. The recovery rate of scandium is over 70%, and the purity of scandium is over 99.7%.

Example 9

(1) The concentration of Sc in the aqueous phase is 5 g/L, and the concentration of nitric acid is 2 mol/L.

(2) Using toluene as the diluent, prepare 0.5 mol/L N,N,N',N'-tetracyclohexyl-3-oxoglutaramide as the organic phase.

(3) Mix 80 mL of the aqueous phase and 20 mL of the organic phase, the stirring time is 30 min, the extraction temperature is 30 ^o C, the concentration of Sc in the raffinate is determined, and the extraction rate is 45.80%.

(4) Mix 20 mL of oxalic acid aqueous solution with a concentration of 0.5 mol/L with the organic phase after extraction, stir for 30 min, and at a temperature of 30 ^o C, stand to separate the organic phase, filter the aqueous phase to obtain a precipitate, and dry at 120 ^o C for 2 calcination at 600 ^o C for 2 hours to obtain scandium oxide. The recovery rate of scandium is over 44%, and the purity of scandium is over 99.8%.

Example 10

(1) The concentration of Sc in the aqueous phase is 5 g/L, and the concentration of nitric acid is 0.6 mol/L.

(2) Using carbon tetrachloride as the diluent, prepare 0.5 mol/L N,N,N',N'-tetracyclohexyl-3-oxoglutaramide as the organic phase.

(3) The aqueous phase and the organic phase were mixed with 20 mL each, the stirring time was 30 min, the extraction temperature was 10 ^o C, and the concentration of Sc in the raffinate was measured. The extraction rate was 98.76%.

(4) Mix 20 mL of oxalic acid aqueous solution with a concentration of 0.5 mol/L with the organic phase after extraction, stir for 30 min, and at a temperature of 30 ^o C, stand to separate the organic phase, filter the aqueous phase to obtain a precipitate, and dry at 120 ^o C for 2 calcination at 600 ^o C for 2 hours to obtain scandium oxide. The recovery rate of scandium is over 97%, and the purity of scandium is over 99.8%.

Claims (5)

1. a method for extracting and separating scandium, is characterized in that the extraction agent used is N,N,N',N'-tetracyclohexyl-3-oxoglutaramide, after diluting with diluent, as extraction organic phase, One or both of nitric acid and nitrate are added to the extraction water phase, and high-purity scandium is obtained through extraction and back-extraction, wherein the step of extracting and purifying scandium comprises: (1) Dissolve the scandium sample with nitric acid to obtain an aqueous solution of impurities including Fe, Mg, Ti, Ba, Al, Zr, Mn, and add one or both of nitric acid and nitrate to the aqueous phase, wherein the total concentration of scandium is 1~200 g/L, the concentration of nitric acid and nitrate is 0.01~5mol/L; (2) Weigh a certain quality of extractant, dilute it to a certain concentration with a diluent to form the organic phase, wherein the diluent is one of toluene, xylene, dichloromethane, chloroform or carbon tetrachloride; the concentration of the extractant is 0.01 ~2 mol/L; (3) Mix and stir a certain volume ratio of the aqueous phase and the organic phase for 10-120 min, and the extraction temperature is 5-60 ^o C; (4) The mixed solution after extraction is left to stand for phase separation to obtain a scandium-loaded organic phase, and impurities remain in the raffinate; (5) Take a certain volume concentration of 0.1~1.0 mol/L oxalic acid or oxalate aqueous solution and mix it with the organic phase loaded with scandium in step (4), the stirring time is 5~100 min, the temperature is 5~60 ^o C, stand for separation The organic phase is filtered and the aqueous phase is filtered to obtain a precipitate, dried at 120 ^o C for 2 hours, and calcined at 600 ^o C for 2 hours to obtain scandium oxide, and the organic phase after standing and layering can be reused. 2. a kind of method for extracting and separating scandium according to claim 1, is characterized in that, in described step (3), water phase and organic phase mixing volume ratio is 1:10～10:1. 3. a kind of method for extracting and separating scandium according to claim 1, is characterized in that, in described step (3), extraction time is 20～60 min, and extraction temperature is 10～50 ^℃ . 4 . The method for extracting and separating scandium according to claim 1 , wherein in the step (4), the standing time is 1 to 5 min, and the mixed solution becomes clear and transparent two-phase. 5 . 5. The method for extracting and separating scandium according to claim 1, wherein in the step (5), the back-extraction agent is oxalic acid or an oxalate solution, and the back-extraction time is 10 to 30 min. The extracted organic phase can be reused.