Exploration of boron removal from molten silicon by introducing oxygen resources into ammonia blowing treatment

Ammonia gas blowing has been successfully applied to the silicon refining process for boron removal. Molten iron catalyst could effectively promote the boron removal ratio in the progress. It inspired the attempt of combining ammonia blowing with other refining treatments. Oxygen resources were introduced into the process in order to further decrease the boron content in silicon. However, neither slagging + ammonia blowing nor humidification + ammonia blowing shows a significant positive improvement in the silicon refining process, respectively. The experimental results implied that the introduction of oxygen sources into the ammonia system would decrease boron nitride activity or produce Si2N2O which retard the efficient generation of boron-bearing volatiles.