Sodium tungstate production method

Patent metadata

Field	Value
Publication number	US-10011890-B2
Application number	US-201414775824-A
Country	US
Kind code	B2
Filing date	Mar 6, 2014
Priority date	Mar 15, 2013
Publication date	Jul 3, 2018
Grant date	Jul 3, 2018

Abstract

A method of producing sodium tungstate of this invention including allowing cemented carbide scrap containing tungsten to react with a molten salt containing sodium sulfate and having added thereto a metal oxide, to thereby obtain sodium tungstate.

First claim

The invention claimed is:

1. A method of producing sodium tungstate, the method comprising allowing cemented carbide scrap containing tungsten to react with a molten salt containing sodium sulfate and having added thereto a metal oxide, to thereby obtain sodium tungstate.

2. The method of producing sodium tungstate according to claim 1 , the method comprising:
(a) generating a molten salt of sodium tungstate through a reaction between sodium sulfate in the molten salt containing the sodium sulfate and tungsten carbide in the cemented carbide scrap; and
(b) immobilizing a sulfide ion to be generated during the reaction between the sodium sulfate and the tungsten carbide by allowing the sulfide ion to react with the metal oxide.

3. The method of producing sodium tungstate according to claim 2 , the method further comprising (c) dissolving the generated sodium tungstate in water to obtain an aqueous solution of sodium tungstate.

4. The method of producing sodium tungstate according to claim 1 , wherein the metal oxide is added before or after the generating a molten salt.

5. The method of producing sodium tungstate according to claim 1 , wherein the metal oxide is added in an amount of 5 wt % or more and less than 30 wt % with respect to a weight of the cemented carbide scrap.

6. The method of producing sodium tungstate according to claim 1 , wherein the metal oxide is added in an amount of 5 wt % or more and less than 20 wt % with respect to a weight of the cemented carbide scrap.

7. The method of producing sodium tungstate according to claim 3 , wherein the dissolving comprises dissolving the generated sodium tungstate in water, to thereby obtain an aqueous solution of sodium tungstate having a mixing ratio (%) of a sulfide ion of 0.2% or less.

8. The method of producing sodium tungstate according to claim 1 , wherein the sodium sulfate is added in an amount of 70 wt % or more and 150 wt % or less with respect to a weight of the cemented carbide scrap.

9. The method of producing sodium tungstate according to claim 1 , wherein the sodium sulfate is added in an amount of 70 wt % or more and 100 wt % or less with respect to a weight of the cemented carbide scrap.

10. The method of producing sodium tungstate according to claim 1 , wherein:
the cemented carbide scrap contains chromium; and
an oxidation number of the chromium is set to a valence of less than 6 when the sodium tungstate is obtained.

11. The method of producing sodium tungstate according to claim 1 , wherein the metal oxide comprises a transition metal oxide.

12. The method of producing sodium tungstate according to claim 1 , wherein the metal oxide comprises an oxide containing iron oxide, nickel oxide, cobalt oxide, cobalt tungstate, and tungsten trioxide.

13. The method of producing sodium tungstate according to claim 1 , wherein:
the cemented carbide scrap contains cobalt; and
the cemented carbide scrap is roasted to obtain cobalt tungstate or tungsten trioxide, and the obtained cobalt tungstate or the obtained tungsten trioxide is used as the metal oxide.

14. The method of producing sodium tungstate according to claim 13 , further comprising immobilizing a water-soluble sulfide, which is a byproduct, by adding, as the metal oxide, cobalt tungstate or tungsten trioxide in an amount of 14 wt % or more and less than 20 wt % with respect to a weight of the cemented carbide scrap.

15. The method of producing sodium tungstate according to claim 1 , wherein:
the cemented carbide scrap contains cobalt; and
the metal oxide is obtained by oxidizing and roasting a residue containing cobalt as a main component, the residue being generated when the sodium tungstate is obtained.

16. The method of producing sodium tungstate according to claim 15 , further comprising immobilizing a water-soluble sulfide, which is a byproduct, by adding the metal oxide, which is obtained by oxidizing and roasting the residue containing cobalt as a main component, in an amount of 14 wt % or more and less than 20 wt % with respect to a weight of the cemented carbide scrap.

17. The method of producing sodium tungstate according to claim 2 , wherein the reaction is performed at a temperature of 900° C. or more and 1,100° C. or less.

18. The method of producing sodium tungstate according to claim 3 , wherein the reaction is performed at a temperature of 900° C. or more and 1,000° C. or less.

19. The method of producing sodium tungstate according to claim 2 , wherein the immobilizing comprises immobilizing a sulfide ion to be generated during the reaction between the sodium sulfate and the tungsten by allowing the sulfide ion to react with the metal oxide while stirring the molten salt.

Assignees

• Almt Corp

Inventors

• Itakura Takeshi
• Ikegaya Akihiko
• Yamamoto Yoshiharu

Classifications

• Y02P10/214

  Cross-Sectional Technologies · mapped topic

• C22B7/001

  Dry processes · CPC title

• C22B7/00

  Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; {Methods of a general interest or applied to the winning of more than two metals (briquetting of scrap C22B1/248; preliminary treatment of scrap C22B1/005)} · CPC title

• C01G41/00

  Compounds of tungsten · CPC title

• Y02P10/234

  Cross-Sectional Technologies · mapped topic