Patent ID: 8216539

Claim:
A method for increasing the purity of silicon, comprising: combining a first silicon-aluminum complex with a first acid solution to allow the first complex to react at least partially with the first acid solution, to provide a first mixture; separating the first mixture, to provide a third silicon-aluminum complex and the first acid solution; combining the third silicon-aluminum complex with a second acid solution to allow the third complex to react at least partially with the second acid solution, to provide a third mixture, wherein the second acid solution is stronger than the first acid solution; separating the third mixture, to provide a first silicon and the second acid solution; transferring portions of the second acid solution to the first acid solution to maintain the pH of the first acid solution, the volume of the first acid solution, the specific gravity of the first acid solution, or a combination thereof; combining the first silicon with a first rinse solution, to provide a fourth mixture; separating the fourth mixture, to provide a wet purified silicon and the first rinse solution; drying the wet purified silicon, sufficient to provide a dry purified silicon.