Separation and recovery of high-purity Si powder from kerf-loss Si slurry waste is a critical challenge for the photovoltaic industry. A green surfactant poly (propylene glycol) bis (2-aminopropyl ether) (PEA) was employed as a collector to facilitate the separation of Si and SiC from kerf-loss Si waste during flotation process. Single flotation tests of Si and SiC were conducted using 5 × 10 −6 mol/L PEA, respectively. The separation efficiencies of Si and SiC in conjunction with PEA adsorption mechanism were investigated. It was found that the maximum recoveries rate of SiC and Si were 90.59% (pH 9.00) and 80.93% (pH 1.96), respectively. Furthermore, the maximum Si grade was determined as 92.31% at pH 8.95 for the sinking part of the mixture generating excellent floatability and selectivity. Zeta potential measurements, FT-IR spectra, and XPS analyses demonstrated that PEA was present on the surface of Si and SiC through electrostatic and hydrogen-bond interactions. The adsorption mechanism was explained based on the results. This research provides an efficient and environmentally friendly route for the separation and recovery of high purity silicon from kerf-loss Si waste.
Minpeng Lei,Yun Lei,Shiding Wang,Dongfang Yang,Shaoyuan Li,Wenhui Ma
Spent nickel-metal hydride (NiMH) batteries are a significant secondary resource for recovering rare earth elements (REEs), particularly lanthanum (La). However, extracting La from the La 2 O 3 -containing oxide slag generated during pyrometallurgical recycling remains a major challenge. This study proposes a novel approach to address this issue by synergistically extracting La from La 2 O 3 -containing oxide slag while simultaneously upgrading metallurgical-grade silicon (MG-Si, 99.2%) to high-purity Si (99.991%). The process begins with the extraction of La from the La 2 O 3 -containing oxide slag using MG-Si as a reductant, yielding a useful Si-La alloy. This is followed by a three-stage leaching process to further separate the Si-La alloy and purify the Si powder. In the primary leaching stage, the Si-La alloy powder is separated into a La-containing acidic solution and residual Si powder using HCl solution. In the secondary leaching stage, Fe impurities in the residual Si powder are removed using a mixed acids solution of HF and HCl. In the tertiary leaching stage, the Si powder is further purified to 99.991% using HCl. Finally, the La ions in the La-containing acidic solution are selectively precipitated using hydrofluoric acid (HF) and ammonia (NH 3 ·H 2 O), respectively, resulting in high-purity LaF 3 (96.2%) and LaOCl (99.4%). This new method simultaneously recovers La from La 2 O 3 -containing oxide slag and enhances Si purity from 99.2 to 99.991%.
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