Recovery of silicon powder from silicon wiresawing slurries by tuning the particle surface potential combined with centrifugation

• A novel process for silicon recovery without using any toxic reagents.
• Zeta potential used for the effective separation of Si and SiC particles.
• Higher separation efficiency can be obtained with this method.
• Si and SiC can be recovered simultaneously with high separation ratios.
• The whole process was very rapid, taking just a few minutes.

A novel recovery process for effective separation of silicon and silicon carbide micropowders from the wiresawing slurry was proposed, based on the difference in their size and surface charging state. The surface charging levels of silicon and silicon carbide particles were found to be obviously different by tuning the solution pH values, so the pre-dispersed mixed particles in the suspension will be subject to different static electrical repulsion and particle mass. Under the same centrifugation filed, Si and SiC particles will have distinctly different separation tendency. Experimental results show that the silicon microparticles tend to suspend in the upper part of the vessels whereas the silicon carbide particles will settle down to the bottom quickly, leading to the effective separation of above powders. The optimal results show that Si content can reach 91.8% in the Si-rich powder and 4.8% in the SiC-rich powder by separating the mixed powder with Si 24.9% and SiC 70.1% as the raw material.