posted on 2024-03-07, 10:05authored byLuisa Blaesing, Alexander Walnsch, Sebastian Hippmann, Christian Modrzynski, Claudia Weidlich, Sandra Pavón, Martin Bertau
The increasing importance of recycling end-of-life photovoltaic
modules is demonstrated by the rising quantity of discarded crystalline
silicon solar cells that contain valuable metals. Despite advanced
recycling methods, the surplus of broken Si wafers poses challenges
for reintegration into new module manufacturing. The present study
introduces a novel recycling process that addresses this issue and
promotes sustainable waste processing, focusing on the untapped resources
of Si wafer breakage and environmentally harmful red mud. The proposed
method uses these two critical waste materials to enable a silicothermal
reduction, yielding ferrosilicon-based alloys. To comprehensively
analyze the influence of the iron oxide source on alloy composition,
a readily available iron oxide pigment (Bayferrox 110) is implemented
as a reference material. Fe–Si-based alloys containing 15 to
65 wt % Si are produced by the silicothermal reduction with soda ash
as a flux, at a temperature of 1600 °C. The use of Bayferrox
as an iron oxide source facilitates the production of Fe–Si
alloys that are free from additional impurities. Moreover, the use
of red mud as the source of iron oxide leads to the production of
Fe–Si–Ti alloys, containing up to 8.6 wt % of Ti. The
inclusion of Ti in the ferrosilicon-based alloy elevates the market
value of the resulting products, emphasizing the commercial viability
of the suggested recycling process. By simultaneously utilizing two
critical waste materials, namely, red mud and Si wafer breakage, this
novel recycling strategy demonstrates significant potential, especially
in view of a circular and holistic waste management.