Scandium recovery method

Patent metadata

Field	Value
Publication number	US-9963762-B2
Application number	US-201515115030-A
Country	US
Kind code	B2
Filing date	Jan 21, 2015
Priority date	Jan 31, 2014
Publication date	May 8, 2018
Grant date	May 8, 2018

Abstract

In order to recover high-quality scandium from nickel oxide ores efficiently, this method comprises: a step (S 1 ) for feeding Ni oxide ores and sulfuric acid into a pressure vessel, and subjecting the mixture to solid-liquid separation to form a leachate and a leach residue; a step (S 2 ) for adding a neutralizing agent to the leachate, and thus forming a neutralization sediment and a post-neutralization fluid; a step (S 3 ) for adding a sulfurizing agent to the post-neutralization fluid, and separating the obtained mixture into Ni sulfide and a post-sulfurization fluid; a step (S 4 ) for bringing the post-sulfurization fluid into contact with a chelating resin, making Sc adsorbed on the chelating resin, and forming an Sc eluent; a step (S 6 ) for bringing the Sc eluent into contact with an extracting agent, adding a back-extraction agent to the extract, and forming back-extracted matter; and a step (S 8 ) for roasting the back-extracted matter, and forming Sc oxide.

First claim

The invention claimed is:

1. A method of recovering scandium, the method comprising: a leaching step of introducing nickel oxide ore containing scandium, aluminum and chromium into a pressure vessel along with sulfuric acid to perform solid-liquid separation into a leachate and a leach residue under high temperature and high pressure;
a neutralization step of adding a neutralizing agent to the leachate to obtain a neutralized precipitate and a post-neutralization solution;
a sulfuration step of adding a sulphidizing agent to the post-neutralization solution to allow separation into nickel sulfide and a post-sulfuration solution;
an ion exchange step of bringing the post-sulfuration solution into contact with a chelating resin to allow adsorption of the scandium by the chelating resin, thereby obtaining a scandium eluent;
a concentration step of generating a scandium-containing precipitate from the scandium eluent after the ion exchange step, and acid-dissolving the precipitate to obtain a scandium concentrate,
a solvent extraction step of bringing the scandium concentrate into contact with an extracting agent to obtain an extract liquid where scandium is extracted into the extracting agent, and adding a backward extracting agent to the extract liquid to obtain a backward extract material; and
a roasting step of calcining the backward extract material to obtain scandium oxide.

2. The method of recovering scandium according to claim 1 , wherein the concentration step comprises:
a step of adjusting pH to a range of between 8 or more and 9 or less by adding a neutralizing agent to the scandium eluent to produce a neutralized material; and
a step of acid-dissolving the neutralized material in sulfuric acid or hydrochloric acid.

3. The method of recovering scandium according to claim 1 , wherein the concentration step comprises:
a step of adding oxalic acid to the scandium eluent to generate crystals of scandium oxalate; and a step of acid-dissolving the crystals of scandium oxalate in sulfuric acid or hydrochloric acid.

4. The method of recovering scandium according to claim 1 , wherein the extracting agent is an acidic extracting agent.

5. The method of recovering scandium according to claim 4 , wherein the acidic extracting agent is di-2-ethylhexyl phosphoric acid.

6. The method of recovering scandium according to claim 1 , wherein
the backward extracting agent is sodium hydroxide with a concentration of 5 mol/l or more to 8 mol/l or less, and the backward extract material is a precipitate of scandium hydroxide.

7. The method of recovering scandium according to claim 1 , wherein the solvent extraction step comprises:
an extraction step of mixing the scandium eluent with the extracting agent to allow separation into a post-extraction organic solvent containing extracted scandium and a raffinate liquid, the extracting agent being an organic solvent;
a scrubbing step of mixing the post-extraction organic solvent with a hydrochloric acid solution with a concentration of 5.0 mol/l or more to 7.0 mol/l or less or a sulfuric acid solution with a concentration of 2.5 mol/l or more to 3.5 mol/l or less to separate impurities from the post-extraction organic solvent, thereby obtaining a post-washing organic solvent; and
a backward extraction step of adding the backward extracting agent to the post-washing organic solvent to perform backward extraction of scandium from the post-washing organic solvent, thereby obtaining the backward extract material.

8. The method of recovering scandium according to claim 4 , wherein the acidic extracting agent is 2-ethylhexyl phosphoric acid-mono-2-ethylhexyl.

9. The method of recovering scandium according to claim 8 , comprising:
an extraction step of mixing the scandium eluent with the extracting agent to allow separation into a post-extraction organic solvent containing extracted scandium and a raffinate liquid, the extracting agent being an organic solvent;
a scrubbing step of mixing the post-extraction organic solvent with a hydrochloric acid solution with a concentration of 5.0 mol/l or more to 7.0 mol/l or less or a sulfuric acid solution with a concentration of 2.0 mol/l or more to 5.0 mol/l or less to separate impurities from the post-extraction organic solvent, thereby obtaining a post-washing organic solvent; and
a step of adding 5 mol/l or more to 8 mol/l or less of sodium hydroxide to a post-scrubbing organic solvent obtained from the scrubbing step to obtain a scandium hydroxide precipitate.

10. The method of recovering scandium according to claim 1 , further comprising: a scandium precipitation step of dissolving the backward extract material in hydrochloric acid after the solvent extraction step, and adding oxalic acid to a hydrochloric acid solution obtained from the dissolution to obtain crystals of scandium oxalate,
wherein the roasting step comprises calcining the crystals of scandium oxalate.

Assignees

• Sumitomo Metal Mining Co

Inventors

• Higaki Tatsuya
• Ozaki Yoshitomo
• Matsumoto Shin-Ya
• Matsuoka Itsumi
• Nagai Hidemasa
• Nagakura Toshihiko
• Kudo Keiji

Classifications

• C22B21/0015

  by wet processes (C22B21/02, C22B21/04 and C22B21/06 take precedence) · CPC title

• C22B3/44

  by chemical processes (treatment or purification of solutions by liquid-liquid extraction C22B3/26, by ion-exchange extraction C22B3/42) · CPC title

• C22B34/32

  Obtaining chromium · CPC title

• C22B59/00 Primary

  Obtaining rare earth metals · CPC title

• C22B3/42

  by ion-exchange extraction · CPC title