US 12,344,530 B2
Method for purifying silicon by means of phase separation dealloying reaction
Kaifu Huo, Hubei (CN); Biao Gao, Hubei (CN); and Weili An, Hubei (CN)
Assigned to WUHAN UNIVERSITY OF SCIENCE AND TECHNOLOGY, Hubei (CN)
Appl. No. 17/600,611
Filed by WUHAN UNIVERSITY OF SCIENCE AND TECHNOLOGY, Hubei (CN)
PCT Filed Jun. 18, 2019, PCT No. PCT/CN2019/091750
§ 371(c)(1), (2) Date Oct. 1, 2021,
PCT Pub. No. WO2020/199366, PCT Pub. Date Oct. 8, 2020.
Claims priority of application No. 201910272586.X (CN), filed on Apr. 4, 2019.
Prior Publication US 2022/0177316 A1, Jun. 9, 2022
Int. Cl. C01B 33/039 (2006.01)
CPC C01B 33/039 (2013.01) [C01P 2002/72 (2013.01); C01P 2004/04 (2013.01); C01P 2006/80 (2013.01)] 8 Claims
OG exemplary drawing
 
1. A method for purifying silicon by means of phase separation dealloying reaction, comprising the following steps:
step 1, a silicon raw material containing impurities is mixed with magnesium powder and then fully reacted under an inert atmosphere so that silicon atoms in the silicon raw material react with magnesium to be converted into magnesium silicide, wherein the impurities in the silicon raw material are simultaneously separated from silicon, so as to obtain a first product;
step 2, the first product is placed in a nitrogen-containing atmosphere to undergo a nitriding reaction, in a process of the nitriding reaction, the magnesium silicide in the first product is converted into a liquid-phase magnesium nitride, while silicon is precipitated and crystallized from the liquid-phase magnesium nitride to form a three-dimensional porous silicon having a nano-skeleton structure and magnesium nitride distributed in pore channels of the three-dimensional porous silicon so as to obtain a second product; wherein silicon is further separated from the impurities in step 1 during the precipitation and crystallization of silicon; and
step 3, the second product is treated by using acid-pickling, wherein magnesium nitride and the impurities in step 1 are dissolved and converted into a solution, and a solid product is collected to obtain a high-purity porous silicon, wherein a purity of the high-purity porous silicon is 99% or higher,
wherein the nitrogen-containing atmosphere in step 2 comprises one or more of nitrogen, nitrogen plasma and a nitrogen-containing organic substance,
wherein the high-purity porous silicon obtained in step 3 is used as the impurity-containing silicon raw material described in step 1, and step 1 to step 3 are performed repeatedly to further purify the high-purity porous silicon.