Method for purifying silicon by means of phase separation dealloying reaction

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.