Influence of P and Ti on Phase Formation at Solidification of Synthetic Slag Containing Li, Zr, La, and Ta
In the future, it will become increasingly important to recover critical elements from waste materials. For many of these elements, purely mechanical processing is not efficient enough. An already established method is pyrometallurgical processing, with which many of the technologically important el...
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MDPI AG
2022-02-01
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| Series: | Minerals |
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| Online Access: | https://www.mdpi.com/2075-163X/12/3/310 |
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| author | Thomas Schirmer Hao Qiu Daniel Goldmann Christin Stallmeister Bernd Friedrich |
| author_facet | Thomas Schirmer Hao Qiu Daniel Goldmann Christin Stallmeister Bernd Friedrich |
| author_sort | Thomas Schirmer |
| collection | DOAJ |
| description | In the future, it will become increasingly important to recover critical elements from waste materials. For many of these elements, purely mechanical processing is not efficient enough. An already established method is pyrometallurgical processing, with which many of the technologically important elements, such as Cu or Co, can be recovered in the metal phase. Ignoble elements, such as Li, are known to be found in the slag. Even relatively base or highly redox-sensitive elements, such as Zr, REEs, or Ta, can be expected to accumulate in the slag. In this manuscript, the methods for determining the phase formation and the incorporation of these elements were developed and optimized, and the obtained results are discussed. For this purpose, oxide slags were synthesized with Al, Si, Ca, and the additives, P and Ti. To this synthetic slag were added the elements, Zr and La (which can be considered proxies for the light REEs), as well as Ta. On the basis of the obtained results, it can be concluded that Ti or P can have strong influences on the phase formation. In the presence of Ti, La, and Ta, predominantly scavenged by perovskite (Ca<sub>1−w</sub>La<sub>2/3w</sub>Ti<sub>1−(x+y+z)</sub>Al<sub>4/3x</sub>Zr<sub>y</sub>Ta<sub>4/5z</sub>O<sub>3</sub>), and Zr predominantly as zirconate (Ca<sub>1−w</sub>La<sub>2/3w</sub>Zr<sub>4−(x+y+z)</sub>Al<sub>4/3x</sub>Ti<sub>y</sub>Ta<sub>4/5z</sub>O<sub>9</sub>), with the P having no effect on this behavior. Without Ti, the Zr and Ta are incorporated into the pyrochlore (La<sub>2−x</sub>Ca<sub>3/2x−y</sub>Zr<sub>2+2/4y−z</sub>Ta<sub>4/5z</sub>O<sub>7</sub>), regardless of the presence of phosphorus. In addition to pyrochlore, La accumulates primarily in britholite-type La oxy- or phosphosilicates. Without P and Ti, similar behavior is observed, except that the britholite-like La silicates do not contain P, and the scavenging of La is less efficient. Lithium, on the other hand, forms its own compounds, such as LiAlO<sub>2</sub>(Si), LiAl<sub>5</sub>O<sub>8</sub>, eucryptite, and Li silicate. Additionally, in the presence of P, Li<sub>3</sub>PO<sub>4</sub> is formed, and the eucryptite incorporates P, which indicates an additional P-rich eutectic melt. |
| first_indexed | 2024-03-09T13:14:03Z |
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| last_indexed | 2024-03-09T13:14:03Z |
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| spelling | doaj.art-c6bbb62c42784ecc968a6f384bab54532023-11-30T21:38:20ZengMDPI AGMinerals2075-163X2022-02-0112331010.3390/min12030310Influence of P and Ti on Phase Formation at Solidification of Synthetic Slag Containing Li, Zr, La, and TaThomas Schirmer0Hao Qiu1Daniel Goldmann2Christin Stallmeister3Bernd Friedrich4Department of Mineralogy, Geochemistry, Salt Deposits, Institute of Disposal Research, Clausthal University of Technology, Adolph-Roemer-Str. 2A, 38678 Clausthal-Zellerfeld, GermanyDepartment of Mineral and Waste Processing, Institute of Mineral and Waste Processing, Waste Disposal and Geomechanics, Clausthal University of Technology, Walther-Nernst-Str. 9, 38678 Clausthal-Zellerfeld, GermanyDepartment of Mineral and Waste Processing, Institute of Mineral and Waste Processing, Waste Disposal and Geomechanics, Clausthal University of Technology, Walther-Nernst-Str. 9, 38678 Clausthal-Zellerfeld, GermanyInstitute of Process Metallurgy and Metal Recycling, RWTH Aachen University, Intzestr. 3, 52056 Aachen, GermanyInstitute of Process Metallurgy and Metal Recycling, RWTH Aachen University, Intzestr. 3, 52056 Aachen, GermanyIn the future, it will become increasingly important to recover critical elements from waste materials. For many of these elements, purely mechanical processing is not efficient enough. An already established method is pyrometallurgical processing, with which many of the technologically important elements, such as Cu or Co, can be recovered in the metal phase. Ignoble elements, such as Li, are known to be found in the slag. Even relatively base or highly redox-sensitive elements, such as Zr, REEs, or Ta, can be expected to accumulate in the slag. In this manuscript, the methods for determining the phase formation and the incorporation of these elements were developed and optimized, and the obtained results are discussed. For this purpose, oxide slags were synthesized with Al, Si, Ca, and the additives, P and Ti. To this synthetic slag were added the elements, Zr and La (which can be considered proxies for the light REEs), as well as Ta. On the basis of the obtained results, it can be concluded that Ti or P can have strong influences on the phase formation. In the presence of Ti, La, and Ta, predominantly scavenged by perovskite (Ca<sub>1−w</sub>La<sub>2/3w</sub>Ti<sub>1−(x+y+z)</sub>Al<sub>4/3x</sub>Zr<sub>y</sub>Ta<sub>4/5z</sub>O<sub>3</sub>), and Zr predominantly as zirconate (Ca<sub>1−w</sub>La<sub>2/3w</sub>Zr<sub>4−(x+y+z)</sub>Al<sub>4/3x</sub>Ti<sub>y</sub>Ta<sub>4/5z</sub>O<sub>9</sub>), with the P having no effect on this behavior. Without Ti, the Zr and Ta are incorporated into the pyrochlore (La<sub>2−x</sub>Ca<sub>3/2x−y</sub>Zr<sub>2+2/4y−z</sub>Ta<sub>4/5z</sub>O<sub>7</sub>), regardless of the presence of phosphorus. In addition to pyrochlore, La accumulates primarily in britholite-type La oxy- or phosphosilicates. Without P and Ti, similar behavior is observed, except that the britholite-like La silicates do not contain P, and the scavenging of La is less efficient. Lithium, on the other hand, forms its own compounds, such as LiAlO<sub>2</sub>(Si), LiAl<sub>5</sub>O<sub>8</sub>, eucryptite, and Li silicate. Additionally, in the presence of P, Li<sub>3</sub>PO<sub>4</sub> is formed, and the eucryptite incorporates P, which indicates an additional P-rich eutectic melt.https://www.mdpi.com/2075-163X/12/3/310lithiumtitaniumzirconiumlanthanumtantalumengineered artificial minerals (EnAM) |
| spellingShingle | Thomas Schirmer Hao Qiu Daniel Goldmann Christin Stallmeister Bernd Friedrich Influence of P and Ti on Phase Formation at Solidification of Synthetic Slag Containing Li, Zr, La, and Ta Minerals lithium titanium zirconium lanthanum tantalum engineered artificial minerals (EnAM) |
| title | Influence of P and Ti on Phase Formation at Solidification of Synthetic Slag Containing Li, Zr, La, and Ta |
| title_full | Influence of P and Ti on Phase Formation at Solidification of Synthetic Slag Containing Li, Zr, La, and Ta |
| title_fullStr | Influence of P and Ti on Phase Formation at Solidification of Synthetic Slag Containing Li, Zr, La, and Ta |
| title_full_unstemmed | Influence of P and Ti on Phase Formation at Solidification of Synthetic Slag Containing Li, Zr, La, and Ta |
| title_short | Influence of P and Ti on Phase Formation at Solidification of Synthetic Slag Containing Li, Zr, La, and Ta |
| title_sort | influence of p and ti on phase formation at solidification of synthetic slag containing li zr la and ta |
| topic | lithium titanium zirconium lanthanum tantalum engineered artificial minerals (EnAM) |
| url | https://www.mdpi.com/2075-163X/12/3/310 |
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