A novel method for refining photovoltaic waste silicon powder using photovoltaic waste glass: Pulsed direct current-assisted refining

Abstract

Photovoltaic waste silicon powder (PWSP), as the by-products during the solar cell production, and how to achieve its effective recycling and reuse has become the focus of industry research. In this work, focused on the oxidation of PWSP during the refining process, a novel method was proposed. Based on the concept of slag refining, photovoltaic waste glass (PWG) was used to react with the oxide layer, and pulsed direct current was introduced to assist. Compared with the traditional process, the pulsed direct current assisted refining method does not introduce impurities, but also reduces the amount of chemical reagents, and the operation is very simple. Under the influence of pulsed direct current, network destructors such as Ca²⁺, Na⁺, and Al³⁺ in the PWG were cyclically utilized, effectively disrupting the SiO₂ network structure. The Joule heating effect generated by the current increased the melt temperature and reduced the slag phase viscosity, creating an ideal microenvironment for silicon separation. Furthermore, the stirring effect induced by the pulsed direct current enhanced particle collisions, further accelerating the reaction between the network destructors and the oxide layer. Compared to the non-current application, the introduction of pulsed direct current significantly improved the silicon recovery rate from 77.0 % to 93.3 %. This study pioneered a pulsed direct current-assisted refining method for PWSP using PWG, providing a green and clean potential solution for the photovoltaic industry’s development.