Rapid recovery of polycrystalline silicon from kerf loss slurry using double-layer organic solvent sedimentation method

Abstract

The rapid development of photovoltaic (PV) industries has led to a shortage of silicon feedstock. However, more than 40% silicon goes into slurry wastes due to the kerf loss in the wafer slicing process. To effectively recycle polycrystalline silicon from the kerf loss slurry, an innovative double-layer organic solvent sedimentation process was presented in the paper. The sedimentation velocities of Si and SiC particles in some organic solvents were investigated. Considering the polarity, viscosity, and density of solvents, the chloroepoxy propane and carbon tetrachloride were selected to separate Si and SiC particles. It is found that Si and SiC particles in the slurry waste can be successfully separated by the double-layer organic solvent sedimentation method, which can greatly reduce the sedimentation time and improve the purity of obtained Si-rich and SiC-rich powders. The obtained Si-rich powders consist of 95.04% Si, and the cast Si ingot has 99.06% Si.

Keywords

silicon / purification / sedimentation / organic solvents / waste utilization

References

[1] Goetzberger A, Hebling C. Photovoltaic materials, past, present, future. Sol. Energy Mater. Sol. Cells, 2000, 62(1–2): 1

[2] Smestad GP, Lampert CM. Solar power 2006, San José, CA. Sol. Energy Mater. Sol. Cells, 2007, 91(5): 440.

[3] Zhao YW, industry T f o P, materials S-S. Phys. Status Solidi C, 2009, 6(3): 744.

[4] Compaan AD. Photovoltaics: Clean power for the 21st century. Sol. Energy Mater. Sol. Cells, 2006, 90(15): 2170.

[5] Woditsch P, Koch W. Solar grade silicon feedstock supply for PV industry. Sol. Energy Mater. Sol. Cells, 2002, 72(1–4): 11

[6] Sarti D, Einhaus R. Silicon feedstock for the multicrystalline photovoltaic industry. Sol. Energy Mater. Sol. Cells, 2002, 72(1–4): 27

[7] Neesse T. Review on SiC-recycling in wafer sawing operations. Interceram, 2006, 55(6): 430

[8] Horio M. Recycling System of Wire Saw Abrasive Grain Slurry and Centrifugal Separators, 2003

[9] Zavatttari C, Fragiacomo G, Portaluppi E. Method for Treating an Exhausted Glycol-based Slurry, 2007

[10] Nishijima S, Izumi Y, Takeda SI, Suemoto H, Nakahira A, Horie SI. Recycling of abrasives from wasted slurry by superconducting magnetic separation. IEEE Trans. Appl. Supercond., 2003, 13(2): 1596.

[11] Billiet RL, Nguyen HT. Photovoltaics from Silicon Kerf, 2004

[12] Wang TY, Lin YC, Tai CY, Sivakumar R, Rai DK, Lan CW. A novel approach for recycling of kerf loss silicon from cutting slurry waste for solar cell applications. J. Cryst. Growth, 2008, 310(15): 3403.

[13] Wang TY, Lin YC, Tai CY, Fei CC, Tseng MY, Lan CW. Recovery of silicon from kerf loss slurry waste for photovoltaic applications. Prog. Photovoltaics, 2009, 17(3): 155.

[14] Lin YC, Wang TY, Lan CW, Tai CY. Recovery of silicon powder from kerf loss slurry by centrifugation. Powder Technol., 2010, 200, 216.

[15] Wu YF, Chen YM. Separation of silicon and silicon carbide using an electrical field. Sep. Purif. Technol., 2009, 68(1): 70.

[16] Lin YC, Tai CY. Recovery of silicon powder from kerfs loss slurry using phase-transfer separation method. Sep. Purif. Technol., 2010, 74, 170.

[17] Tsai TH. Modified sedimentation system for improving separation of silicon and silicon carbide in recycling of sawing waste. Sep. Purif. Technol., 2011, 78, 16.

[18] Tsai TH. Silicon sawing waste treatment by electrophoresis and gravitational settling. J. Hazard. Mater., 2011, 189(1–2): 526-530.

[19] Ren J, Shen J, Lu SC. The Science and Technology of Particles Dispersion, 2005, Beijing, Chemical Industry Press

[20] Guo J. Recycling of Silicon and Silicon Carbide from SOG-Crystalline Silicon Cutting Loss Slurry, 2011, Shenyang, Northeastern University, 67