Method for recovering hafnium and impurity metals from hafnium-containing waste residue

1 . A method for recovering hafnium and impurity metals from a hafnium-containing waste residue, comprising the following steps:

(1) adjusting acidity of an acidic solution of the hafnium-containing waste residue to 1 mol/L to 3 mol/L, removing a resulting residue through filtration, and adding a complexing agent to a resulting mother liquor to obtain a material solution;

(2) conducting extraction with a mixture of an acidic phosphorus extractant, sulfonated kerosene, and sec-octanol as an organic phase and the material solution obtained in step (1) as an aqueous phase to obtain a hafnium-loaded organic phase and an impurity metal ions-containing aqueous phase; purifying the hafnium-loaded organic phase with a sulfuric acid solution; and subjecting a purified hafnium-loaded organic phase to stripping with a stripping liquid to obtain a hafnium-containing stripping solution;

(3) adding a precipitating agent to the hafnium-containing stripping solution obtained in step (2), filtering to obtain a precipitate, and washing and burning the precipitate to obtain hafnium oxide;

(4) precipitating the impurity metal ions-containing aqueous phase obtained in step (2) with a strong alkali; washing a resulting precipitate to remove the complexing agent to obtain precipitates of the impurity metal ions; and adding a sulfuric acid solution to adjust acidity of a resulting solution from the precipitates of the impurity metal ions and the sulfuric acid solution to 1 mol/L to 5 mol/L and to obtain a solution of the impurity metal ions;

(5) conducting extraction with a mixture of an acidic phosphorus extractant, sulfonated kerosene, and sec-octanol as an organic phase and the solution of the impurity metal ions obtained in step (4) as an aqueous phase to obtain an impurity metal ions-loaded organic phase; purifying the impurity metal ions-loaded organic phase with a sulfuric acid solution;

and subjecting a purified impurity metal ions-loaded organic phase to stripping with a stripping liquid to obtain an impurity metal ions-containing stripping solution; and

(6) adding a precipitating agent to the impurity metal ions-containing stripping solution obtained in step (5), filtering to obtain a precipitate, and washing and burning the precipitate to obtain oxides of the impurity metals;

wherein in step (1), the acidic solution of the hafnium-containing waste residue is obtained by dissolving the hafnium-containing waste residue in sulfuric acid and ammonium sulfate; and

in step (2), the stripping liquid is at least one selected from the group consisting of an oxalic acid solution, a sodium carbonate solution, and an ammonium bicarbonate solution.

2 . The method for recovering hafnium and impurity metals from a hafnium-containing waste residue according to claim 1 , wherein the method comprising at least one selected from the group consisting of the following items:

in step (1), the complexing agent is ammonium sulfate or an organic acid; and

in step (2), the acidic phosphorus extractant is P204 and/or P507.

3 . The method for recovering hafnium and impurity metals from a hafnium-containing waste residue according to claim 2 , wherein the method comprising at least one selected from the group consisting of the following items:

in step (1), the acidic solution is obtained by mixing the hafnium-containing waste residue with concentrated sulfuric acid and ammonium sulfate and conducting a complete reaction at 200° C. to 300° C.; and

the organic acid is one or more selected from the group consisting of oxalic acid, acetic acid, and citric acid.

4 . The method for recovering hafnium and impurity metals from a hafnium-containing waste residue according to claim 3 , wherein the hafnium-containing waste residue, the concentrated sulfuric acid, and the ammonium sulfate are mixed in a mass ratio of 1:(2-5):(0.8-1.5).

5 . The method for recovering hafnium and impurity metals from a hafnium-containing waste residue according to claim 1 , wherein the method comprising at least one selected from the group consisting of the following items:

in step (1), a volume of the complexing agent is 1% to 5% of a volume of the mother liquor;

in step (2), the acidic phosphorus extractant, the sulfonated kerosene, and the sec-octanol in the organic phase are in a volume ratio of (1-8):(10-18):(1-2);

in step (2), a volume ratio of the organic phase to the aqueous phase is 1: (0.2-5);

in step (2), the purification is conducted by adjusting pH of a resulting purifying system with sulfuric acid to 1 to 5;

in step (2), the stripping liquid has a concentration of 0.25 mol/L to 6 mol/L; and

in step (2), a volume ratio of the purified hafnium-loaded organic phase to the stripping liquid is (3-6):1.

6 . The method for recovering hafnium and impurity metals from a hafnium-containing waste residue according to claim 5 , wherein in step (2), the purification is conducted by adjusting the pH of the resulting purifying system with the sulfuric acid to 3.

7 . The method for recovering hafnium and impurity metals from a hafnium-containing waste residue according to claim 2 , wherein when the stripping liquid in step (2) is an oxalic acid solution, in step (3), the precipitating agent is ammonia water and a resulting solution from the hafnium-containing stripping solution and the precipitating agent has an endpoint pH ranging from 8 to 10; and when the stripping liquid in step (2) is a sodium carbonate and/or ammonium bicarbonate solution, in step (3), the precipitating agent is hydrochloric acid and a resulting solution from the hafnium-containing stripping solution and the precipitating agent has an endpoint pH ranging from 1 to 5, and temperature is controlled at 50° C. to 120° C.

8 . The method for recovering hafnium and impurity metals from a hafnium-containing waste residue according to claim 7 , wherein when the stripping liquid in step (2) is a sodium carbonate or ammonium bicarbonate solution, in step (3), the precipitating agent is hydrochloric acid and the resulting solution from the hafnium-containing stripping solution and the precipitating agent has an endpoint pH ranging from 1 to 3, and the temperature is controlled at 60° C. to 100° C.

9 . The method for recovering hafnium and impurity metals from a hafnium- containing waste residue according to claim 1 , wherein the method comprising at least one selected from the group consisting of the following items:

in step (3), the burning is conducted at 700° C. to 1,200° C.; and

in step (6), the burning is conducted at 700° C. to 1,200° C.

10 . The method for recovering hafnium and impurity metals from a hafnium- containing waste residue according to claim 1 , wherein the method comprising at least one selected from the group consisting of the following items:

in step (5), the acidic phosphorus extractant is P204 and/or P507; and

in step (5), the stripping liquid is at least one selected from the group consisting of an oxalic acid solution, a sodium carbonate solution, and an ammonium bicarbonate solution.

11 . The method for recovering hafnium and impurity metals from a hafnium- containing waste residue according to claim 10 , wherein in step (5), the stripping liquid is at least one selected from the group consisting of a mass percentage of 1% to 18% oxalic acid solution, a mass percentage of 3% to 25% sodium carbonate solution, and a mass percentage of 3% to 25% ammonium bicarbonate solution.

12 . The method for recovering hafnium and impurity metals from a hafnium- containing waste residue according to claim 1 , wherein the method comprising at least one selected from the group consisting of the following items:

in step (5), a volume ratio of the organic phase to the aqueous phase is 1:(0.1-8);

in step (5), the sulfuric acid solution has an acidity of 3 mol/L to 8 mol/L;

in step (5), a volume ratio of the impurity metal ions-loaded organic phase to the sulfuric acid solution is (2-8):1; and

in step (5), a volume ratio of the purified impurity metal ions-loaded organic phase to the stripping liquid is (2-8):1.

13 . The method for recovering hafnium and impurity metals from a hafnium-containing waste residue according to claim 1 , wherein in step (5), the acidic phosphorus extractant, the sulfonated kerosene, and the sec-octanol in the organic phase are in a volume ratio of (1-10):(8-20):(1-3).

14 . The method for recovering hafnium and impurity metals from a hafnium-containing waste residue according to claim 2 , wherein,

when the stripping liquid in step (5) is an oxalic acid solution, in step (6), the precipitating agent is ammonia water and a resulting solution from the impurity metal ions-containging stripping solution and the precipitating agent has an endpoint pH ranging from 8 to 10; and

when the stripping liquid in step (5) is a sodium carbonate or ammonium bicarbonate solution, in step (6), the precipitating agent is hydrochloric acid and a resulting solution from the impurity metal ions-containging stripping solution and the precipitating agent has an endpoint pH ranging from from 1 to 5, and temperature is controlled at 50° C. to 120° C.

15 . The method for recovering hafnium and impurity metals from a hafnium-containing waste residue according to claim 14 , wherein when the stripping liquid in step (5) is a sodium carbonate or ammonium bicarbonate solution, in step (6), the precipitating agent is hydrochloric acid and the resulting solution from the impurity metal ions-containging stripping solution and the precipitating agent has an endpoint pH ranging from 1 to 3, and the temperature is controlled at 60° C. to 100° C.

16 . The method for recovering hafnium and impurity metals from a hafnium-containing waste residue according to claim 2 , wherein the method comprising at least one selected from the group consisting of the following items:

in step (4), the precipitate is washed with water to remove the complexing agent; and

in step (4), the acidity is adjusted with water or a sulfuric acid solution.

17 . The method for recovering hafnium and impurity metals from a hafnium-containing waste residue according to claim 2 , wherein in steps (2) and (5), the extraction refers to 3-5 stage countercurrent extraction, the purification refers to 3-4 stage countercurrent purification, and the stripping refers to 3-4 stage countercurrent stripping.