National Engineering Laboratory for Vacuum Metallurgy/Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093, China.
National Engineering Laboratory for Vacuum Metallurgy/Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093, China; State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, Kunming 650093, China.
Waste Manag. 2021 Feb 1;120:820-827. doi: 10.1016/j.wasman.2020.11.005. Epub 2020 Nov 29.
Silicon recovery from diamond wire saw silicon powder (DWSSP) waste is of great significance for increasing production profits and alleviating hazardous effects on the ecological environment. The purity of recovered silicon powder is determined by the purification efficiency during acid leaching pretreatment. Because the metallic impurities present in DWSSP are mostly physically mixed rather than chemically bound, the reaction rate is very fast in the initial stage of acid leaching, whereas it is difficult to dissolve the retained impurities in the later stage with the depletion of metal fragments adhered on the surface of the silicon matrix. Many prior studies have failed to consider the retained metallic impurities that reside in the inner silicon particle surfaces. Therefore, this study investigates the dissolution behavior of retained impurities via the dissolution of Al in HCl solution as an example. Thermodynamic results indicate that the Al dissolution process is dominated by entropic changes (ΔS), rather than enthalpic changes (ΔH). Furthermore, the dissolution behavior of Al is in accordance with the diffusion-controlled step in the Avrami mode, and the kinetic parameters were found to be A=5.85×10, E=49.27kJ·mol, and m<1. The determined dissolution behavior provides a clear understanding of the removal of retained metallic impurities from DWSSP via an acid leaching pretreatment. This study provides enlightenment for the further purification of silicon recovered from DWSSP waste.
从金刚石线锯硅粉 (DWSSP) 废料中回收硅具有提高生产利润和减轻对生态环境危害的重要意义。回收硅粉的纯度取决于酸浸预处理过程中的净化效率。由于 DWSSP 中存在的金属杂质大多是物理混合而不是化学结合，因此在酸浸的初始阶段反应速率非常快，而随着硅基体表面附着的金属碎片的消耗，后期溶解残留的杂质变得困难。许多先前的研究都没有考虑到残留在硅颗粒内部表面的残留金属杂质。因此，本研究以 Al 在 HCl 溶液中的溶解为例，研究了残留杂质的溶解行为。热力学结果表明，Al 的溶解过程主要受熵变 (ΔS) 控制，而不是焓变 (ΔH)。此外，Al 的溶解行为符合阿仑尼乌斯模式中的扩散控制步骤，并且发现动力学参数为 A=5.85×10，E=49.27kJ·mol，m<1。确定的溶解行为为通过酸浸预处理从 DWSSP 去除残留金属杂质提供了清晰的认识。本研究为进一步纯化从 DWSSP 废料中回收的硅提供了启示。
