Generation of rare earth elements from organically-associated leach solutions
A method for recovering rare earth elements (REE) from a leach solution. The method includes determining the concentration of a first plurality of contaminates in the leach solution, adding a first amount of oxalic acid to the leach solution and allowing it to react for a first period of time to form a first precipitant and a first liquor, maintaining the pH of the first liquor between 1.5 and 3 by the addition of an alkali base, removing the first precipitant, adding a second amount of oxalic acid to the first liquor and allowing it to react for a second period of time to form a second precipitant and a second liquor, maintaining the pH of the second liquor between 1.5 and 3 by the addition of the alkali base, and removing the second precipitant.
1. A method for recovering rare earth elements (REE) from a leach solution, the method comprising:
determining a total concentration of a first plurality of contaminates present in the leach solution, the first plurality of contaminates comprising iron, aluminum, vanadium, or a combination thereof, and including any iron, aluminum, and vanadium present in the leach solution,
adding a first amount of oxalic acid to the leach solution and allowing it to react for a first period of time to form a first precipitant and a first liquor,
maintaining the pH of the first liquor between 1.5 and 3 by the addition of an alkali base,
removing the first precipitant,
adding a second amount of oxalic acid to the first liquor and allowing it to react for a second period of time to form a second precipitant and a second liquor,
maintaining the pH of the second liquor between 1.5 and 3 by the addition of the alkali base, and
removing the second precipitant,
wherein the first amount of oxalic acid is between 0.05 mol/L and 0.4 mol/L greater than the total concentration of the first plurality of contaminates in the leach solution.
2. The method of claim 1 , further comprising the steps of:
adding a third amount of oxalic acid to the second liquor and allowing it to react for a third period of time to form a third precipitant and a third liquor,
maintaining the pH of the third liquor between 1.5 and 3 by the addition of the alkali base, and
removing the third precipitant.
3. The method of claim 2 wherein the third amount of oxalic acid is less than 0.2 mol/L.
4. The method of claim 2 wherein the third precipitant comprises scandium, cobalt, gallium, or a combination thereof.
5. The method of claim 2 wherein the third period of time is between 30 minutes to 3 hours.
6. The method of claim 1 wherein the first precipitant comprises europium, gadolinium, or a combination thereof.
7. The method of claim 1 further comprising the step of determining the concentration of a second plurality of contaminates in the leach solution, wherein the second amount of oxalic acid is between 0.05 mol/L and 0.4 mol/L greater than the concentration of the second plurality of contaminates in the leach solution.
8. The method of claim 7 wherein the second plurality of contaminates comprises calcium, magnesium, or a combination thereof.
9. The method of claim 7 wherein the second precipitant comprises ytterbium, cerium, or a combination thereof.
10. The method of claim 1 wherein the pH of the first liquor is continuously monitored.
11. The method of claim 1 wherein the alkali base comprises sodium carbonate, sodium hydroxide, potassium carbonate, potassium hydroxide, or a combination thereof.
12. The method of claim 11 wherein the alkali base is a powder.
13. The method of claim 1 wherein the oxalic acid is a powder.
14. The method of claim 1 wherein the first period of time is between 1 hour and 12 hours.
15. The method of claim 1 wherein the second period of time is between 30 minutes to 3 hours.
16. The method of claim 1 wherein the leach solution has a total suspended solids density, and wherein the step of determining the concentration of a first plurality of contaminates in the leach solutions comprises measuring the total suspended solids density.