Xiamen Key Laboratory of Electronic Ceramic Materials and Devices, College of Materials, Xiamen University, Xiamen 361005, PR China; Shenzhen Research Institute of Xiamen University, Shenzhen 518063, PR China.
Xiamen Key Laboratory of Electronic Ceramic Materials and Devices, College of Materials, Xiamen University, Xiamen 361005, PR China; Shenzhen Research Institute of Xiamen University, Shenzhen 518063, PR China.
Waste Manag. 2023 Aug 1;168:107-115. doi: 10.1016/j.wasman.2023.05.046. Epub 2023 Jun 7.
Recycling diamond wire sawing silicon powders (DWSSP) from photovoltaic (PV) silicon wafers production has become an urgent problem. The challenge of recovery is the surface oxidation and contamination of the ultra-fine powder with impurities during the sawing and collection process. In this study, a clean recovery strategy of NaCO-assisted sintering and acid leaching was proposed. Due to the Al contamination from the perlite filter aid, the introduced NaCO sintering aid can react with the SiO shell of DWSSP to form a slag phase with accumulated impurity Al during the pressure-less sintering process. Meanwhile, the evaporation of CO contributed to the formation of ring-like pores surrounded by a slag phase, which can be easily removed by acid leaching. When 15 % NaCO was added, the content of impurity Al in DWSSP could be reduced to 0.07 ppm with a removal rate of 99.9 % after acid leaching. The mechanism suggested that the addition of NaCO can trigger the liquid phase sintering (LPS) process of the powders, and the cohesive force and liquid pressures difference generated during the process facilitated the transportation of impurity Al from the SiO shell of DWSSP to the formed liquid slag phase. The efficient silicon recovery and impurity removal of this strategy demonstrated its potential for solid waste resource utilization in the PV industry.
回收光伏（PV）硅片生产中的金刚石线锯硅粉（DWSSP）已成为当务之急。回收的难点在于锯切和收集过程中超细粉末的表面氧化和杂质污染。在本研究中，提出了一种 NaCO 辅助烧结和酸浸的清洁回收策略。由于珍珠岩助滤剂中的 Al 污染，引入的 NaCO 烧结助剂可以与 DWSSP 的 SiO 壳反应，在无压烧结过程中形成含有累积杂质 Al 的渣相。同时，CO 的蒸发有助于形成由渣相包围的环状孔，这可以通过酸浸很容易地去除。当添加 15%的 NaCO 时，酸浸后 DWSSP 中的杂质 Al 含量可降低至 0.07ppm，去除率达到 99.9%。该机制表明，NaCO 的添加可以引发粉末的液相烧结（LPS）过程，在该过程中产生的粘合力和液体压力差有助于杂质 Al 从 DWSSP 的 SiO 壳转移到形成的液态渣相中。该策略在硅的高效回收和杂质去除方面表现出了其在光伏产业中固体废料资源利用方面的潜力。
