A Low-Cost and Facile Method to Recycle Silicon Carbide Particles from the Solar Grade Silicon Slicing Wastes
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ORIGINAL PAPER
A Low-Cost and Facile Method to Recycle Silicon Carbide Particles from the Solar Grade Silicon Slicing Wastes Jing Guo 1 & Yang Liu 2 & Lu Liu 3 & Jia Liu 3 & Jian Kong 3 & Shuai Wang 3 & Shengnan Jiang 3 & Pengfei Xing 3 Received: 19 June 2019 / Accepted: 25 November 2019 # Springer Nature B.V. 2020
Abstract Solar grade silicon slicing wastes (SoG-Siw) are the byproducts of the photovoltaic industry, which are the precious sources of SiC particles and high-purity silicon. Herein, we report a low-cost and facile approach to recover the SiC particles by the methods of physical sedimentation and chemical technique. The effects of reaction time, reaction temperature, acid concentration, stirring speed and liquid-solid ratio on the purity of SiC were discussed in details. The results indicated that the optimal reaction conditions were as follows: mixed acid solution of 5 wt% HF and 8 wt% HNO3, reaction time of 2 h, temperature of 60 °C and liquid-solid ratio of 5:2. SiC particles with the purity of 98.54 wt% with grain sizes of 1.2 ~ 11.4 μm were obtained, which could match the standards of SiC abrasives. It is promising that the current work could provide a low-cost and facile method for recycling SiC particles from SoG-Siw, which could also reduce the cost for solar cells and facilitate the recycling of high-purity silicon from SoG-Siw. Keywords Slicing wastes . Silicon carbide . Recycling . Physical sedimentation . Chemical technique
1 Introduction The rapid developments of photovoltaic industry result in a lot of solar grade silicon (SoG-Si) slicing wastes (SoG-Siw) [1, 2]. SoG-Siw are the byproducts derived from the slicing process of polysilicon ingots, which are composed of kerf loss silicon (Sik) particles, abrasive silicon carbide (SiC) particles, metal impurities from the iron cutting wires and polyethylene glycol solution (PEG) [3]. These materials not only cause the environmental burden, but also increase the cost of silicon solar cells [4, 5]. Recycling Sik from SoG-Siw is regarded as an effective way to overcome the silicon feedstock shortages [6], however, it is difficult to separate the SiC particles from the SoG-Siw completely. In addition, the strict chemical composition standard of silicon for solar cells make it difficult to recycle the Sik * Jing Guo [email protected] 1
College of Materials and Metallurgy, University of Science and Technology Liaoning, Anshan 114051, People’s Republic of China
2
School of Resource and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China
3
College of Metallurgy, Northeastern University, Shenyang 110004, People’s Republic of China
particles directly. Metal impurities and PEG can be removed easily and recycled [7]. Therefore, it is necessary to remove and recycle the SiC particles. SiC is applied as a mediator during the silicon slicing process, and the fragmenting SiC and silicon tend to mix with the cutting system due to the collision and friction of SiC particle and silicon rod. As a result, 25
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