Modified sedimentation system for improving separation of silicon and silicon carbide in recycling of sawing waste

Recycling kerf silicon from sawing waste may be a good solution to overcoming the shortage of silicon feedstock in photovoltaic industries. This study reports the application of a horizontal electrical field to a sedimentation cell. Due to the small size, low density, and high negative charges in a solution of pH 7, the electrical field enhanced the displacement of Si more than SiC particles, leading to a Si distribution on the bottom of sedimentation cell. Separation performance was not enhanced efficiently by increasing the operation time or the strength of the electrical field, but was improved obviously by baffle plates, which reduced the dispersion between particles and easily captured the tiny Si particles. The minimum SiC content was obtained near the cell outlet, and only 7.6 wt% SiC remaining in the mixture. The recovered material with high Si content can be transferred to an induction furnace to generate solar-grade Si.