Leaching behavior and toxicity of solid waste from ore-based lithium extraction: Implications for safe storage and...

The rapid expansion of lithium-ion battery (LIB) production has led to a substantial increase in the generation of solid waste, which poses potential environmental risks. However, the environmental behavior and potential adverse effects of lithium (Li)-derived solid waste remain poorly understood. This study systematically compared leaching behavior and toxicity of Li ores, tailings, and slags from ore-based Li extraction industries. The results revealed distinct physicochemical properties across the materials, with slags exhibiting significantly higher levels of toxic elements. Notably, thallium (Tl) leaching from slags reached 13-14 μg/L (pH 3-8), exceeding drinking water standards by 6.5 to 7 times, while beryllium (Be) release from tailings at pH 3 exceeded the safety limit by a factor of three. The leaching mechanisms differed substantially: ores and tailings exhibited strong pH dependence, whereas slag leaching was pH-independent for key elements across the pH range of 3 to 8. Toxicity assessments showed that slag leachate induced complete mortality in zebrafish embryos, while all leachates caused significant developmental abnormalities, including reduced heart rate and body length. These findings underscore the need for waste-specific management strategies, with slags requiring impermeable containment due to their persistent leaching properties and high toxicity potential, providing essential insights for the environmentally sound disposal of Li processing wastes.