再生铜和再生黄铜原料的金属回收率研究

Study on Metal Recovery of Regenerated Copper and Regenerated Brass Raw Materials

金属回收率是评价再生金属资源品质的重要参数。然而再生铜原料及再生黄铜原料的国家标准GB/T 38471—2019和GB/T 38470—2019中并未对金属回收率实验的技术内容作出明确规定,致使各实验室对金属回收率实验的结果不一。通过考察不同种类的再生铜原料及再生黄铜原料的回收率影响因素,重点探索样品成分、检验设备的差异及对应的不同熔炼功率、不同种类除渣剂的影响等因素所导致样品的回收率偏移,并以镀白紫铜为案例使用扫描电子显微镜观察与分析了金属回收率副产物的形貌及组成。结果表明:再生铜原料及再生黄铜原料中的合金成分是影响金属回收率数据的主要因素,再生纯铜原料中铜含量较高且结构简单,因此在实验中干扰因素较少,纯铜回收率比合金、镀金类铜更稳定更高,且波动较少;含低熔点合金元素的铜合金中低熔点金属易发生烧损,金属回收率易偏低、含高熔点合金元素的铜合金由于高熔点合金元素不能完全熔化,金属回收率易偏高;多种除渣剂中,除渣效果较好的有硼酸、生石灰及炼钢用打渣剂火山灰,其中后两者效果表现优良。熔炼所得的粉尘和氧化物结块成分以金属氧化物为主,不宜作为可利用的金属加入到金属回收率的计算。

The metal recovery is an important parameter to evaluate the quality of recycled metal resources.However,the national standards GB/T 38471—2019 and GB/T 38470—2019 for recycled copper raw materials and recycled brass raw materials do not provide clear regulations on the technical content of the metal recovery rate experiments,resulting in inconsistent results on the metal recovery experiments by various laboratories.This study discussed the factors affecting the recovery of different types of recycled copper raw materials and recycled brass raw materials.The focus was on exploring the influences of sample chemical compositions,the different testing equipment and the corresponding different melting power,and different deslagging agent types on the deviation of sample recovery.And a raw white copper plating was a study case by using scanning electron microscopy to observe and analyze the morphology and composition of the metal recovery testing by-products.The results showed that the alloy composition in the recycled copper raw materials and recycled brass raw materials were the main factors affecting the metal recovery data.The relatively high copper content and simple structure in the recycled pure copper raw materials lead to fewer interfering factors in the experiment.The results also indicated that the pure copper recovery was more stable and higher than that of alloy and gold-plated copper with less fluctuation.The low melting point metals in the copper alloys containing low melting point alloying elements were prone to burnout,resulting in lower metal recoveries.The copper alloys containing high melting point alloying elements were prone to higher metal recovery due to high melting point alloying elements could not be completely melted.Among a variety of slagging agent,boric acid,lime and steelmaking slagging agent volcanic ash performed better slag removal effects,and the latter two showed excellent performance.The resulting dust and oxide caking composition obtained from smelting were mainly composed of metal oxides,and should not be used as available metal added to the calculation of metal recovery.