Refining agents for alkaline earth production
Hydrometallurgical systems, methods, and compositions are described in which organic amine-based lixiviants are utilized in the selective recovery of alkaline earth elements. The lixiviant can be regenerated and recycled for use in subsequent iterations of the process. Multiple alkaline earth elements can be recovered from a sample in parallel or in serial applications of the disclosed methods.
1. A method for extracting an alkaline earth element, comprising:
contacting a sample comprising a first alkaline earth element with an uncharged first lixiviant precursor comprising an uncharged organic amine;
mixing the sample with the first lixiviant precursor;
after mixing the sample with the first lixiviant precursor, generating a first lixiviant comprising a first organic amine cation and a first counterion from the first lixiviant precursor by addition of an acid form of the first counterion;
forming a depleted sample and a first supernatant comprising a first uncharged organic amine, and a first soluble complex comprising a cation of the first alkaline earth element and the first counterion;
transferring the first alkaline earth element cation from the first supernatant; and
regenerating the first organic amine cation by the addition of a first precipitant, wherein the first organic amine cation comprises carbon.
2. The method of claim 1 , wherein the pH during regeneration of the organic amine cation is less than about 7.
3. The method of claim 1 , wherein the pH during regeneration of the organic amine cation is greater than 6 and less than 7.
4. The method of claim 1 , wherein the organic amine has a pKa between 8 and 14.
5. The method of claim 4 , wherein the organic amine cation is derived from a biological source.
6. The method of claim 1 , wherein the lixiviant is formed by adding an acid to the first lixiviant precursor in the presence of the sample.
7. The method of claim 1 , wherein the regenerated organic amine cation is treated using a multi-effect evaporator.
8. The method of claim 1 , further comprising a step of using at least a portion of the regenerated organic amine cation to contact a sample comprising an alkaline earth element.
9. The method of claim 1 , wherein the first precipitant is carbon dioxide or carbonic acid.
10. A method of claim 1 , wherein the sample comprises a second alkaline earth element, and comprising the additional steps of:
contacting the depleted sample with a second lixiviant, the second lixiviant comprising a second organic amine cation and a second counterion and wherein the second lixiviant is selective for the second alkaline earth element;
forming a second supernatant comprising an uncharged second organic amine and a second complex comprising a second alkaline earth element cation and the second counterion; and,
transferring the second alkaline earth cation from the depleted sample; and,
regenerating the second organic amine cation by the addition of a second precipitant.
11. The method of claim 10 , wherein the first alkaline earth element is precipitated by the first precipitant.
12. The method of claim 10 , wherein the first precipitant is carbon dioxide or carbonic acid.
13. The method of claim 10 wherein the second alkaline earth element is precipitated by the second precipitant.
14. A method for extracting alkaline earth elements, comprising:
contacting a sample comprising a first alkaline earth element and a second alkaline earth element with a lixiviant, the lixiviant comprising a first organic amine cation, a second organic amine cation, and a counterion, wherein the first organic amine cation is selective for the first alkaline earth element and the second organic amine cation is selective for the second alkaline earth element;
forming a first supernatant comprising an uncharged first organic amine, an uncharged second organic amine, a first complex comprising a first alkaline earth metal cation and the counterion, and a second complex comprising a second alkaline earth metal cation and the counterion;
transferring the first alkaline earth metal cation from the first supernatant to form a second supernatant;
transferring the second alkaline earth metal cation from the second supernatant and,
regenerating the first organic amine cation and the second organic amine cation from the second supernatant,
wherein the first organic amine cation is regenerated by the addition of a first precipitant.
15. The method of claim 14 , wherein the first organic amine cation and the second organic amine cation are different species.
16. The method of claim 14 , wherein the first alkaline earth element is precipitated from the first supernatant by the addition of the first precipitant.
17. The method of claim 14 , wherein the second alkaline earth element is precipitated from the second supernatant by the addition of a second precipitant.
18. The method of claim 17 , wherein the second precipitant is CO 2 or carbonic acid.