Purified silicon, devices and systems for producing same

A device for purifying silicon comprising:

• a vessel having a top end, an opposing bottom end, and a sidewall extending between the opposing ends and defining a chamber;
• a silicon inlet at a top portion of the vessel for introducing molten silicon into the chamber;
• a gas injection structure at a bottom portion of the vessel, the gas injection structure having a plurality of orifices for introducing a gas comprising oxygen into the chamber in the form of bubbles, where introduction of the gas bubbles into the molten silicon oxidizes silicon at the outside of the bubbles and produces a plurality of in situ silica-walled gas filled beads in the chamber;
• a countercurrent exchange section located between the silicon inlet and the gas injection structure, the countercurrent exchange section comprising
• (1) a controlled downward flow of the molten silicon;
• (2) a controlled upward flow of the beads;
• wherein the countercurrent flow between the molten silicon and the silica-walled gas filled beads provides intimate high area contact between the down-flowing molten silicon and the up-flowing beads that enables impurities present in the molten silicon to transfer into the up-flowing silica walled gas filled beads so that the down-flowing molten silicon is purified.