从废磷铁渣中回收磷酸铁和石墨的工艺研究

A Study on the Process of Recovering Iron Phosphate and Graphite from Waste Iron Phosphorus Residue

摘要: 目前，退役旧磷酸铁锂电池经放电和物理分选得到金属及正负极材料的混合物黑粉，工业生产通常采用硫酸浸取黑粉以回收高价值锂资源后产生大量的废磷铁渣，这些磷铁渣堆积在仓库里无法消纳。为了实现退役磷酸铁锂电池全组分回收，避免堆存的废磷铁渣对环境潜在危害，本文采用氧化焙烧+浮选的工艺从废磷铁渣中回收磷酸铁和石墨资源。首先，在400℃~550℃条件下进行有氧焙烧以去除了其中的粘接剂和导电炭黑，然后对焙烧样品进行浮选处理，结果显示，在焙烧温度为400℃，在煤油添加量30 mg/L和MIBC添加量40 mg/L的浮选条件下，获得精矿为石墨，其回收率为91.7%，尾矿为无定形磷酸铁，其回收率为95.2%，经表征分析磷酸铁和石墨产品具有作为磷酸铁锂电池生产材料的潜力，合成的磷酸铁锂初始放电比容量为143.7 mAh∙g⁻¹，30轮后衰减至137.2 mAh∙g⁻¹。实现了废磷铁渣的简单、高效分离回收。

Abstract: At present, decommissioned lithium iron phosphate batteries are discharged and physically separated to obtain black powder of metal, cathode and anode electrode materials, and industrial production usually uses sulfuric acid to leach the black powder to recover high-value lithium resources, produces a large number of waste phosphorus iron slag. In order to realize the recovery of all components of decommissioned lithium iron phosphate batteries and avoid the potential harm of accumulated waste iron phosphate slag to the environment, the process of oxidation calcination + flotation was used to recover iron phosphate and graphite resources from waste iron phosphate slag. Firstly, the adhesive and conductive carbon black were removed by aerobic calcination at 400˚C ~550˚C, and then the samples were processed by flotation. The results showed that under the flotation conditions of 30 mg/L kerosene and 40 mg/L MIBC at a calcination temperature of 400˚C, the concentrate was graphite, and the recovery was 91.7%. The tailings are amorphous iron phosphate with a recovery of 95.2%. The characterization analysis shows that iron phosphate and graphite products have the potential as materials for lithium iron phosphate batteries, the initial specific discharge capacity of the synthesized lithium iron phosphate was 143.7 mAh∙g⁻¹, which attenuated to 137.2 mAh∙g⁻¹ after 30 rounds. The separation and recovery of waste phosphorus and iron slag is simple and efficient.