Experimental Study on the Sedimentation of Silicon Particles Under the Interference of Flocculants

Silicon separation from diamond wire saw waste slurry is the primary step for silicon resource recovery, yet the relatively low recovery rate in current processes indicates inadequate separation efficiency. This study focuses on the sedimentation behavior of particle groups and investigates the interference sedimentation mechanism under the action of flocculants. Experimental results show that CPAM (Cationic Polyacrylamide) is the optimal flocculant for promoting interference sedimentation. For 3.72 μm silicon particles, the best effect is achieved with a CPAM concentration of 0.2% and a dosage of 0.34 g/L, while 0.59 μm silicon particles require a higher CPAM concentration of 0.4% and a dosage of 0.68 g/L due to their larger specific surface area and more surface voids, which demand more flocculant. The addition of PDDA(Polydiallyldimethylammonium chloride) can reduce the contact angle between particles and CPAM, improve the overall hydrophilicity of the suspension, and enhance flocculation efficiency. Specifically, 2.35 g/L PDDA is suitable for 3.72 μm particles, and 7.05 g/L PDDA is needed for 0.59 μm particles. This study reveals the influence of flocculant concentration and particle size on sedimentation, providing a theoretical basis for enhancing solid–liquid separation in silicon waste slurry recovery.