Separation Between Silicon and Aluminum Powders Contained Within Pulverized Scraped Silicon-Based Waste Solar Cells by Flotation Method

There are few study examples on the separation of metals by floating method. In this study, separation of silicon and aluminum, which are the main components of silicon-based solar cell module, was carried out by floating method in order to purify silicon from waste solar cell module. The selection of surfactant, control of electric charge, wettability of the solid particles, surface tensions, and bubble surface area are important for separation of solids by floating method. Sodium dodecyl sulfate (SDS) can increase the hydrophobicity of aluminum powder due to the difference of surface potentials between silicon and aluminum. SDS behaves as a collector of aluminum as well as a frothing agent to decrease the bubble size. At a SDS concentration of 2 g/L and sample dipping time of 10 min, 80.1 mass% of aluminum was floated and separated, and the sedimentary silicon reached a purity of 90.7% from a mixture of 50 mass% aluminum and 50 mass% silicon. Finally, at a pH value of 7.0, SDS concentration between 1.0 and 2.5 g/L and air flow rate of 2.5 L/min (STP) were suitable experimental conditions to purify silicon from a mixture of silicon and aluminum by flotation separation method.