Substance Flow Analysis of Antimony in Japan Focused on Recycling of Used Flame Retardant Assistant

Antimony has been long used for battery and flame retardant, yet, not highlighted as a critical metal so far, because of its diffusion into common consumption resulting in feeling of ubiquitousness. Now, in transformation to sustainable energy, its value is increasing due to demand for new technologies such as solar power and recent Chinese export control. Antimony trioxide, the biggest demand of antimony, is mainly used as flame retardant assistant which is contained in automobiles and electric appliances. The newest law for recycling of such products, “act on promotion of recycling of small waste electrical and electronic equipment” (came into effect in 2013) mentions collection of end-of-life products and recycling of useful metals. According to this law, collection of used small electrical and electronic equipment (SEEE) and recycling of metals contained in SEEE are progressing, while recycling of antimony is still uncertain. In this study, we conducted a substance flow analysis (SFA) of antimony in Japan to analyze the present condition of recycling of antimony as flame retardant assistant. In addition, we evaluated obtainable amount and economical effect by antimony recycling focused on SEEE, as well as environmental effects including other metals contained in board of SEEE. The result of SFA showed that in 2020, antimony as flame retardant assistant, sharing more than 70% of whole amount of end-of-life antimony in Japan, were all discarded into landfill through incineration/smelting or directly, except export. Furthermore, we revealed that recycling of antimony in SEEE might have remarkable benefit economically and environmentally. Based on these results, it is suggested that domestically recycling of antimony from end-of-life product in Japan should be more promoted.