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@ARTICLE{Zhu:904030,
author = {Zhu, Mengyi and Yue, Shengying and Wu, Guixuan and Tang,
Kai and Xu, Yijiang and Safarian, Jafar},
title = {{P} removal from {S}i by {S}i-{C}a-{A}l alloying-leaching
refining: {E}ffect of {A}l and the {C}a{A}l2{S}i2 phase},
journal = {Separation and purification technology},
volume = {271},
issn = {1383-5866},
address = {Amsterdam [u.a.]},
publisher = {Elsevier Science},
reportid = {FZJ-2021-05600},
pages = {118675 -},
year = {2021},
abstract = {Phosphorus (P) is a critical impurity in
metallurgical-grade Si that needed to be removed for
solar-grade Si production. The Si-Ca-Al-P system is one of
the most crucial alloy systems for Si refining, where P can
be separated by either the Si-Al solvent refining or the
Si-Ca alloying-leaching process. In this work, a series of
Si-Ca-Al alloys were obtained to investigate the role of
alloy composition and the CaAl2Si2 phase in P segregation
and separation. The used alumina crucible led to heavy Al
contamination and resulted in unexpected Si-Ca-Al alloy
compositions. CaAl2Si2 and CaSi2 were found as the main
precipitates, and relatively higher P content was detected
in the CaAl2Si2 phase. Leaching experiments indicate that P
removal degree increases with increasing Ca/Al ratio and
increasing total alloying amount (Ca + Al). Effects of alloy
composition were further analyzed by statistical methods,
which indicates Ca firmly plays a strong, positive, and
monotonic role in P removal while no strong attraction
between Al and P. Theoretical P removal model for the
Si-Ca-Al system was established and in good agreement with
measured results. Interaction coefficients of Ca and Al to P
were fitted as and , which further confirms Ca is the
essential driving force for P segregation. Finally, the
possibility of P solid solution formation was verified by
first-principle simulations that both CaAl2Si2 and CaSi2 are
able to dissolve P, especially through the Si site, but the
CaAl2Si2 phase is more favourable for P dissolution than
CaSi2, which explains the reason of the often detected high
P content in CaAl2Si2.},
cin = {IEK-2},
ddc = {540},
cid = {I:(DE-Juel1)IEK-2-20101013},
pnm = {1231 - Electrochemistry for Hydrogen (POF4-123)},
pid = {G:(DE-HGF)POF4-1231},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000656879100003},
doi = {10.1016/j.seppur.2021.118675},
url = {https://juser.fz-juelich.de/record/904030},
}