Oxidation Behaviors of Dusts Generated in Different Cutting Processes of Silicon Ingots

Abstract

Large amounts of silicon dusts, including band saw dusts, grinding dusts and wire saw dusts were generated in photovoltaic industry. Recovery of pure silicon from the dusts is of great value to industry, and understanding their oxidation behaviors is essential for such recovery. The present paper reports our investigations into the oxidation status of the as-generated dusts and their oxidation kinetics in further exposure. Hand-ground multi-crystalline silicon fine powders from broken wafers were used as reference. And the oxidation behaviors of the reference silicon powders were also discussed. The results show that severe oxidation on the surface of the band saw and grinding dusts occurs due to the existence of the aqueous medium. With the storage time prolonged, the oxidation increases rapidly in the aqueous medium in the ambient temperature initially, and then it drives to stabilize. While no obvious oxidation appears in the wire saw dusts due to the protection of PEG (polyethylene glycol). With the PEG concentration in the liquid medium increased, the oxidation degrees of the multi-crystalline silicon fine powders are decreased. Based on above knowledge, an efficient suppression of oxidation of band saw and grinding dusts was proposed lastly.