有色金属(冶炼部分)

电动汽车快速推广将引发锂离子电池退役潮，为避免污染环境与资源浪费，从废旧正极材料中高效回收Li至关重要。针对传统工艺高能耗与污染等局限，本文提出微波辅助加热强化硫酸化焙烧的新方法。该工艺利用废旧正极材料优异的微波吸收特性实现快速整体加热，并基于Li与过渡金属硫酸盐的热稳定性差异，促使Li优先转化为易溶于水的硫酸盐。本文以失效三元正极材料为对象，采用微波强化硫酸铵焙烧工艺。结果表明，在焙烧温度650℃、焙烧时间30 min、硫酸铵添加量n(SO₄^2-)/n(Li)=1.8的最佳条件下，Li的水浸浸出率达到95.1%，过渡金属以难溶氧化物形式留在浸出渣中，成功实现Li的高效选择性回收。研究结果证实，微波辅助硫酸铵焙烧具备低能耗、反应快、Li提取选择性高的优势，为废旧锂离子电池绿色高效回收提供了新的技术路径与理论依据。

To combat global climate change and resource scarcity, the rapid proliferation of electric vehicles has triggered a massive wave of decommissioned power batteries. Improper disposal of these spent lithium-ion batteries poses severe threats to environmental safety and leads to significant resource depletion. Consequently, achieving the efficient and selective recovery of scarce lithium(Li) from cathode materials is paramount for a sustainable circular economy. Currently, lithium-ion battery recycling primarily relies on traditional thermal treatment technology. However, this process faces significant bottlenecks at both the macroscopic heat transfer and microscopic reaction levels. Traditional heating relies on external thermal conduction, often resulting in low thermal efficiency, high energy consumption, and uneven temperature distribution, which can easily lead to localized sintering. Furthermore, due to the difficulty of effectively enhancing mass transfer at the reaction interface in traditional thermal fields, the conversion efficiency during the roasting process is severely constrained by the interface reaction rate. Therefore, developing a novel recovery process capable of precisely inducing phase transformations and significantly enhancing interfacial activity has become a critical breakthrough for achieving efficient metal extraction and synergistic resource recovery. Facing the increasingly severe pressure of battery waste disposal and resource security challenges, developing green and low-carbon recycling technology is both an environmental imperative and a strategic necessity. To break through these bottlenecks, this study introduces microwave heating technology, leveraging its unique advantages such as rapid response, volumetric heating, and selective activation, to enhance the sulfation roasting process, aiming to achieve low-energy consumption and high-efficiency selective Li recovery from spent ternary lithium-ion batteries. The effects of roasting temperature from 200 ℃ to 650 ℃, duration from 5 min to 90 min, and ammonium sulfate dosage n(SO₄^2-)/n(Li) from 1.0 to 2.6 on Li leaching efficiency were systematically investigated. The results demonstrate that the reaction is initiated through direct interaction between(NH₄)₂ SO₄ and spent cathode materials in the low-temperature region at 200 ℃. The(NH₄)₂ SO₄ reacts with the spent ternary cathode material first, converting part of the Li into water-soluble sulfate. As the temperature rises to 280 ℃, both Li and transition metals undergo sequential sulfation transformations. When the temperature further escalates to 650 ℃, the unstable transition metal sulfates decompose into stable metal oxides. This decomposition releases sulfur-containing species that synergistically promote the complete conversion of remaining Li into water-soluble Li₂ SO₄, ultimately inducing its in-situ growth into large-scale crystals. The Li leaching efficiency reaches 95.1% under the optimal parameters including roasting temperature of 650 ℃, roasting duration of 30 min, and(NH₄)₂ SO₄ dosage of n(SO₄^2-)/n(Li)=1.8.