Back to results
US 4,304,763 AGranted
Process for purifying metallurgical-grade silicon
AssigneeConsortium fur Elektrochemische Industrie GmbH
InventorsJosef Dietl, Michael Wohlschlager
Life of this patent
Estimating the term…
Abstract
A process is provided for purifying metallurgical-grade silicon for the manufacture of solar cells, wherein the acid treatment of the silicon, known per se, is combined with vacuum evaporation. This may be optionally combined with slag extraction and directional solidification.
Claims11
In a process for purifying metallurgical-grade silicon for the manufacture of solar cells by leaching with an acid solution, the improvement comprising the steps of:
- combining said chemical purification step of leaching with an acid solution which is known per se with vacuum evaporation at 1500.degree. to 1700.degree. C. under a pressure of from 10.sup.-6 to 10.sup.-4 bar.
A process for purifying metallurgical grade silicon for the manufacture of solar cells, comprising the steps of:
- (a) subjecting said metallurgical grade silicon to a single chemical purification operation by leaching with an acid solution selected from the group consisting of aqueous hydrocloric acid, aqueous hydrofluoric acid and an admixture thereof;
- (b) subjecting said metallurgical grade silicon to a single vacuum evaporation operation at 1500.degree. to 1700.degree. C. under a pressure of from 10.sup.-6 to 10.sup.-4 bar for a period of about 0.5 to 2 hours;
- and
- (c) following steps (a) and (b) directly recovering solar cell grade silicon.
1 more element
Dependencies are inferred from the claim text.