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

Patent metadata

Field	Value
Publication number	US-2021130928-A1
Application number	US-201816633257-A
Country	US
Kind code	A1
Filing date	Jul 27, 2018
Priority date	Jul 27, 2017
Publication date	May 6, 2021
Grant date	—

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(VO3)2) or calcium tungstate (CaWO4) 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

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 ) or calcium tungstate (CaWO 4 ) through precipitation; and (d) subjecting the recovered calcium tungstate to acid decomposition to prepare tungstic acid.

2 . The method for selectively recovering the valuable metals from the waste denitrification catalyst through the alkali fusion of claim 1 , wherein 1.1 to 1.2 equivalents of alkali metal is added with respect to 1 equivalent of the waste denitrification catalyst.

3 . 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).

4 . 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 when a microwave is used.

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

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 calcium chloride (CaCl 2 ).

7 . 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.

8 . 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.

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 the sodium hydroxide in the alkaline leachate has a concentration of 0.5 to 0.75 mol/L, the precipitator is added in order for 1.0 to 1.5 equivalents of calcium to be added, and is reacted to precipitate calcium metavanadate with a precipitation efficiency of 99% or more.

10 . 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 mol/L or less, the precipitator is added in order for 1.0 equivalent or less of calcium to be added, and is reacted to precipitate calcium tungstate with 1% or less of a recovery rate.

11 . The method for selectively recovering the valuable metals from the waste denitrification catalyst through the alkali fusion of claim 1 , therein
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.

12 . The method for selectively recovering the valuable metals from the waste denitrification catalyst through the alkali fusion of claim 1 , the method further comprising:
recovering the residue, (i) acid-leaching by adding sulfuric acid or hydrochloric acid to the residue; (ii) adding sodium hydroxide to the acid leachate and reacting to precipitate metatitanic acid (TiO(OH) 2 ); and (iii) calcining the metatitanic acid to recover titanium dioxide.

13 . The method for selectively recovering the valuable metals from the waste denitrification catalyst through the alkali fusion of claim 12 , wherein the acid leaching is performed for two or three hours at 323 K to 333 K.

14 . The method for selectively recovering the valuable metals from the waste denitrification catalyst through the alkali fusion of claim 12 , 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.

15 . The method for selectively recovering the valuable metals from the waste denitrification catalyst through the alkali fusion of claim 12 , wherein the calcination 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

• C22B34/225

  from spent catalysts · CPC title

• C22B1/02 Primary

  Roasting processes (C22B1/16 takes precedence) · CPC title

• C22B3/12

  in inorganic alkaline solutions · CPC title

• C22B1/16

  Sintering; Agglomerating · CPC title

• Y02P10/20

  Recycling · CPC title