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The surface oxide layer (SiO 2 layer) is still one of the main limitations of the recovery and purification of silicon kerf waste (SKW). Herein, to recycle SKW as the low-boron silicon ingot, an effective combination strategy that digests the surface oxide layer by pretreatment and then removes impurity boron by slag treatment is proposed. In the pretreatment part, the surface oxide layer of SKW was successfully digested into a liquid phase after mixing 10.5 wt% cryolite and sintering at 1400 °C, and the obtained SKW-ceramic has a dense structure. Moreover, when holding at 1400 °C for 2 h, the boron concentration in SKW-ceramic was decreased to 5.75 ppmw, and the removal rate reaches 14.18%. In the slag treatment part, CaO and SiO 2 are selected as slag agents. The CaO/SiO 2 mass ratio and reaction temperature were determined to be 2 and 1600 °C based on thermodynamic simulation. Besides, Na 2 O formed due to the dissociation of cryolite, which can enhance the oxygen ion activity and boron-absorbing capacity of the slag. The experimental result exhibited that the boron removal efficiency reached 86.56%. The simplicity and scalability of this strategy provide a better alternative for the recovery of SKW. [Display omitted] • Hazardous silicon kerf waste is recycled into a useful low-boron silicon ingot. • Mixing cryolite to digest SiO 2 surface layer of silicon kerf waste. • SKW-ceramic sintering can remove impurity boron to a certain extent. • The formed Na 2 O enhanced the boron-absorbing and boron-holding of the slag. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mixing sintering aids to digest SiO 2 surface-layer of silicon kerf waste. • The addition range of sintering aids was designed by thermodynamic simulation. • The emerged liquid slag phase has a positive effect on the separation of B. • After a few sintering aids mixed, the removal efficiency of B reached 45.32%. • The mechanism of removing B in silicon kerf waste was discussed in detail. Removing the SiO 2 surface-layer and impurity boron in diamond wire saw silicon powder waste (DWSSP) are two difficulties in the field of photovoltaic waste recycling. Aiming at the two difficulties, this paper proposes a method of mixing sintering aids to digest the SiO 2 layer and remove impurity boron. Firstly, sintering aids Al 2 O 3 and CaO were mixed into DWSSP, and DWSSP-ceramics were prepared by pressure-less sintering. The mixed sintering aids reacted with the SiO 2 surface-layer of DWSSP, and the formed liquid slag phase plays a role in promoting the densification of DWSSP-ceramics (the relative density reached 85.97% when sintered at 1300 °C). Secondly, to obtain low-boron silicon, the slag phase was separated from DWSSP-ceramics by smelting treatment. The results showed that an optimal boron removal effect of 45.32% was reached after only 10.11 wt% sintering aids were mixed into DWSSP. The mechanism that the liquid slag phase gathered impurity boron during the sintering process, and then promoted boron to remove from silicon was reasonably deduced. The method of mixing sintering aids to remove the SiO 2 surface-layer and impurity boron provides a novel insight into purification and recovery of DWSSP. [ABSTRACT FROM AUTHOR]