Method of purifying silicon utilizing cascading process
View Patent ↗The present invention relates to a method of purifying a material using a metallic solvent. The present invention includes a method of purifying silicon utilizing a cascade process. In a cascade process, as the silicon moves through the purification process, it contacts increasingly pure solvent metal that is moving through the process in an opposite direction.
1. A method for purifying silicon, comprising:
(a) contacting a first silicon with a second mother liquor, to provide a first mixture;
(b) melting the first mixture, to provide a first molten mixture;
(c) cooling the first molten mixture to form first silicon crystals and a third mother liquor;
(d) separating the first silicon crystals and the third mother liquor;
(e) contacting the first silicon crystals and a first mother liquor, to provide a second mixture;
(f) melting the second mixture, to provide a second molten mixture;
(g) cooling the second molten mixture to form second silicon crystals and a second mother liquor;
(h) separating the second silicon crystals and the second mother liquor;
(i) contacting the second silicon crystals with a first solvent metal, to provide a third mixture;
(j) melting the third mixture, to provide a third molten mixture;
(k) cooling the third molten mixture to form third silicon crystals and a first mother liquor; and
(l) separating the third silicon crystals and the first mother liquor,
wherein the mother liquors and the first solvent metal comprise a solvent metal and further comprising combining the second mother liquor with at least a portion of the third mother liquor prior to contacting the second mother liquor with the first silicon.
2. The method of claim 1 , further comprising combining the first mother liquor with at least a portion of the second mother liquor prior to contacting the first mother liquor with the first silicon crystals.
3. The method of claim 2 , wherein the first mother liquor contains more of the solvent metal, compared to the second mother liquor.
4. The method of claim 1 , further comprising removing at least a portion of the solvent metal from the third silicon crystals.
5. The method of claim 1 , further comprising mechanically removing a powder, the solvent metal, a contaminate, or some combination thereof from the third silicon crystals.
6. The method of claim 1 , further comprising melting the third silicon crystals.
7. The method of claim 6 , further comprising contacting a gas, slag molten silicon or some combination thereof to the molten third silicon crystals.
8. The method of claim 7 , further comprising directionally solidifying silicon from the molten third silicon crystals, to form an ingot.
9. The method of claim 8 , further comprising removing a portion of the ingot.
10. The method of claim 9 , wherein the steps of directionally solidifying and removing at least a portion of the ingot are repeated one or more times.
11. The method of claim 1 , wherein steps (a)-(d) are repeated one or more times.
12. The method of claim 1 , wherein steps (e)-(h) are repeated one or more times.
13. The method of claim 1 , wherein one or more of the mother liquors or the molten mixtures or a combination thereof are cleaned using a ceramic foam filter or gas injection containing chlorine.
14. The method of claim 7 , further comprising cleaning the molten silicon with a ceramic foam filter or gas injection containing chlorine.
15. The method of claim 1 , wherein the solvent metal comprises aluminum.
16. The method of claim 4 , wherein removing comprises dissolving or reacting or a combination thereof with acid, base or other chemical.
17. The method of claim 7 , wherein the gas comprises oxygen.
18. A method for purifying silicon, comprising:
(a) contacting a first silicon with a second mother liquor, to provide a first mixture;
(b) melting the first mixture, to provide a first molten mixture;
(c) cooling the first molten liquid to form first silicon crystals and a third mother liquor;
(d) separating the first silicon crystals and the third mother liquor;
(e) contacting the first silicon crystals and a first mother liquor, to provide a second mixture;
(f) melting the second mixture, to provide a second molten mixture;
(g) cooling the second molten liquid to form second silicon crystals and a second mother liquor;
(h) separating the second silicon crystals and the second mother liquor;
(i) contacting the second silicon crystals with a first solvent metal, to provide a third mixture;
(j) melting the third mixture, to provide a third molten mixture;
(k) cooling the third molten liquid to form third silicon crystals and a first mother liquor;
(l) separating the third silicon crystals and the first mother liquor;
(m) melting the third silicon crystals, to provide melted third crystals;
(n) directionally solidifying the melted third crystals, to provide a solidified silicon; and
(o) removing at least a portion of the solidified silicon,
wherein the mother liquors and the first solvent metal comprise a solvent metal, and
wherein the solvent metal comprises aluminum and further comprising combining the second mother liquor with at least a portion of the third mother liquor prior to contacting the second mother liquor with the first silicon.
19. The method of claim 18 , further comprising, prior to step (n), contacting the melted third crystals with at least one of a gas or slag molten silicon.
20. The method of claim 18 , further comprising repeating step (m) through (o) one or more times.
21. A method for purifying silicon, comprising:
(a) contacting a silicon A with a third mother liquor, to provide a mixture A;
(b) melting the mixture A, to provide a molten mixture A;
(c) cooling the molten liquid A to form a first silicon and a fourth mother liquor;
(d) separating the first silicon and the fourth mother liquor;
(e) contacting the first silicon with a second mother liquor, to provide a first mixture;
(f) melting the first mixture, to provide a first molten mixture;
(g) cooling the first molten liquid to form first silicon crystals and a third mother liquor;
(h) separating the first silicon crystals and the third mother liquor;
(i) contacting the first silicon crystals and a first mother liquor, to provide a second mixture;
(j) melting the second mixture, to provide a second molten mixture;
(k) cooling the second molten liquid to form second silicon crystals and a second mother liquor;
(l) separating the second silicon crystals and the second mother liquor;
(m) contacting the second silicon crystals with a first solvent metal, to provide a third mixture;
(n) melting the third mixture, to provide a third molten mixture;
(o) cooling the third molten liquid to form third silicon crystals and a first mother liquor;
(p) separating the third silicon crystals and the first mother liquor;
(q) melting the third silicon crystals, to provide melted third crystals;
(r) directionally solidifying the melted third crystals, to provide a solidified silicon;
(s) removing at least a portion of the solidified silicon;
wherein the mother liquors and the first solvent metal comprise a solvent metal,
wherein the solvent metal comprises aluminum,
wherein steps (a)-(d) are repeated zero times, once, or twice,
wherein steps (e)-(h) are repeated zero times, once, or twice,
wherein steps (i)-(l) are repeated zero times, once, or twice,
wherein steps (m)-(p) are repeated zero times, once, or twice,
wherein steps (q)-(s) are repeated zero times, once, or twice and further comprising combining the third mother liquor with at least a portion of the fourth mother liquor prior to contacting the third mother liquor with the silicon A.