Method for selective recovery of valuable metal from waste denitrification catalyst through alkali fusion

Patent metadata

Field	Value
Publication number	US-12037659-B2
Application number	US-201816633257-A
Country	US
Kind code	B2
Filing date	Jul 27, 2018
Priority date	Jul 27, 2017
Publication date	Jul 16, 2024
Grant date	Jul 16, 2024

Abstract

The present invention provides a method for selective recovery of a valuable metal from a waste denitrification catalyst through alkali fusion, the method comprising the steps of: (a) adding an alkali metal to a waste denitrification catalyst, followed by mixing and alkali fusion, to generate a calcination product; (b) subjecting the calcination product to water-leaching to recover an alkali leachate and a residue; (c) adding a precipitator to the alkali leachate, followed by stirring, to recover calcium metavanadate (Ca(VO 3 ) 2 ) or calcium tungstate (CaWO 4 ) through precipitation; and (d) subjecting the recovered calcium tungstate to acid decomposition to prepare tungstic acid. Therefore, vanadium and tungsten can be recovered at high efficiency by a method in which a precipitator is added to a leachate, which is obtained by adding an excess amount of an alkali metal to a waste denitrification catalyst and carrying out calcination and water-leaching, and then a reaction rate is controlled.

First claim

The invention claimed is:

1. A method for selectively recovering valuable metals from a waste denitrification catalyst through alkali fusion, the method comprising:
(a) adding an alkali metal to the waste denitrification catalyst, followed by mixing and alkali fusion, to generate a calcination product;
(b) subjecting the calcination product to water-leaching to recover an alkali leachate and a residue;
(c) adding a precipitator to the alkali leachate, followed by stirring, to recover calcium metavanadate (Ca(VO 3 ) 2 ) and calcium tungstate (CaWO 4 ) through precipitation; and
(d) when the calcium tungstate is recovered in step (c), subjecting the recovered calcium tungstate to acid decomposition to prepare tungstic acid,
wherein the method further comprising:
recovering the residue of step (b), and
(i) acid-leaching by adding sulfuric acid or hydrochloric acid to the residue;
(ii) adding sodium hydroxide to the acid leachate to precipitate metatitanic acid (TiO(OH)2); and
(iii) calcining the metatitanic acid to recover titanium dioxide.

2. The method for selectively recovering the valuable metals from the waste denitrification catalyst through the alkali fusion of claim 1 , wherein the alkali metal is sodium carbonate (Na 2 CO 3 ) or sodium hydroxide (NaOH).

3. The method for selectively recovering the valuable metals from the waste denitrification catalyst through the alkali fusion of claim 1 , wherein, during alkali fusion, calcination is performed at an output of 1 kW per 100 g of the waste denitrification catalyst using a microwave.

4. The method for selectively recovering the valuable metals from the waste denitrification catalyst through the alkali fusion of claim 1 , wherein, during the alkali fusion, the calcination is performed for 20 to 60 minutes at 900° C. to 1000° C.

5. The method for selectively recovering the valuable metals from the waste denitrification catalyst through the alkali fusion of claim 1 , wherein the precipitator is calcium chloride (CaCl 2 ).

6. The method for selectively recovering the valuable metals from the waste denitrification catalyst through the alkali fusion of claim 1 , wherein the precipitator is added and a strong alkaline calcium hydroxide [Ca(OH) 2 ] is further added to adjust pH.

7. The method for selectively recovering the valuable metals from the waste denitrification catalyst through the alkali fusion of claim 1 , wherein stirring after addition of the precipitator is performed at 200 to 600 rpm for 30 minutes to 2 hours.

8. The method for selectively recovering the valuable metals from the waste denitrification catalyst through the alkali fusion of claim 5 , wherein, when the alkali metal is sodium hydroxide and the sodium hydroxide in the alkali leachate has a concentration of 0.5 to 0.75 mol/L, 1.0 to 1.5 equivalents of the calcium precipitator are added to precipitate calcium metavanadate with a precipitation efficiency of 99% or more,
wherein the 1 equivalent the calcium precipitator is a sum of amount of calcium precipitator used for the precipitation of vanadium and tungsten by the following Reaction formula 8:
2NaVO3(aq)+CaCl2(aq)→Ca(VO3)2(s)↓+2NaCl(aq)

Na2WO4(aq)+CaCl2(aq)→CaWO4(s)↓+2NaCl(aq).  [Reaction formula 8]

9. The method for selectively recovering the valuable metals from the waste denitrification catalyst through the alkali fusion of claim 1 , wherein, when the alkali metal is sodium hydroxide and sodium hydroxide in the alkaline leachate has a concentration of 0.5 to 1.0 mol/L, 0.5 to 1.0 equivalent of the calcium precipitator are added to precipitate calcium tungstate with 1% or less of a recovery rate,
wherein the 1 equivalent the calcium precipitator is a sum of amount of calcium precipitator used for the precipitation of vanadium and tungsten by the following Reaction formula 8:
2NaVO3(aq)+CaCl2(aq)→Ca(VO3)2(s)↓+2NaCl(aq)

Na2WO4(aq)+CaCl2(aq)→CaWO4(s)↓+2NaCl(aq).  [Reaction formula 8]

10. The method for selectively recovering the valuable metals from the waste denitrification catalyst through the alkali fusion of claim 1 , wherein
the precipitator is added to the alkaline leachate, stirred to be reacted,
the reaction is performed at 333 K to 353 K for 15 minutes or less to precipitate calcium metavanadate, and
calcium tungstate is precipitated by reacting at 313 K to 353 K for one hour to two hour.

11. The method for selectively recovering the valuable metals from the waste denitrification catalyst through the alkali fusion of claim 1 , wherein the acid leaching is performed for two or three hours at 323 K to 333 K.

12. The method for selectively recovering the valuable metals from the waste denitrification catalyst through the alkali fusion of claim 1 , wherein a leaching rate is 99% or more by adjusting pH to be 2 or less in the step of adding and reacting the sodium hydroxide.

13. The method for selectively recovering the valuable metals from the waste denitrification catalyst through the alkali fusion of claim 1 , wherein the calcination of step (iii) is performed for four to five hours at 850 K to 900 K.

Assignees

• Korea Inst Geoscience & Mineral Resources

Inventors

• Lee Jin-Young
• Kang Jung-Shin
• Kang Hee-Nam

Classifications

• C22B34/124

  using acidic solutions or liquors · CPC title

• C22B7/009

  General processes for recovering metals or metallic compounds from spent catalysts (for recovering specific metals C22B11/00 - C22B61/00) · CPC title

• C22B7/008

  by an alkaline or ammoniacal leaching · CPC title

• C22B3/12

  in inorganic alkaline solutions · CPC title

• C22B1/16

  Sintering; Agglomerating · CPC title