摘要
有氧韧铜是制作压延铜箔的重要原料,杂质的存在会直接影响铜的导电率,影响其在电子电路行业的应用。根据硼化钙(CaB_(6))与杂质元素Fe、P、S的热力学反应可行性,开展除杂试验研究。结果表明,在CaB_(6)和O2的协同作用下,熔体中杂质元素出现明显降低。当温度为1250℃、反应时间为120 min、CaB_(6)加入量为理论计算值的1.2倍时,杂质元素Fe、P和S的分离率皆超过80%,满足产品的成分要求。杂质分离后的铸锭导电率达到99.98%IACS,满足产品的导电率要求。研究结果为高品质的有氧韧铜铸锭生产提供了解决方案,是制造极端规格化产品的基础。
The rolled copper foil is produced through the plastic processing principle,involving repeated rolling and annealing processes of copper ingots,resulting in a lamellar crystalline structure within.Due to its excellent ductility,electrical conductivity,and high flexibility,the rolled copper foil is widely used in industries such as printed circuit boards(PCBs),copper-clad laminates(CCLs),and lithium-ion battery manufacturing.Oxygen-tough pitch copper ingots serve as a crucial raw material for the production of rolled copper foil.The most common impurity elements are Fe,P and S.The source of Fe impurities in oxygen-tough pitch copper melt may originate from copper ores,which naturally contain iron,such as chalcopyrite(CuFeS_(2)),a common form of copper ore.During the smelting process,Fe is easily reduced and enters the crude copper.Additionally,during the electrolytic refining of crude copper,Fe,being more reactive than Cu,preferentially dissolves at the anode and may not be completely separated,ultimately remaining in the cathode copper.Impurity element S may also stem from sulfide copper ores,where sulfides (like CuFeS_(2)) partially fail to be completely desulfurized during smelting, leading to residues like Cu2S in the cathode copper. The use of new scrap copper in copper foil production workshops can lead to an increase in P content due to improper process management, resulting in the incorporation of oxygen-free copper materials, which also introduces impurity elements Fe and S. The aggregation and precipitation of these three elements in the copper matrix significantly impairs the electrical conductivity of copper, further affecting its application in the electronic circuit industry. Calcium hexaboride (CaB_(6)) is an exceptional refining agent widely used in the copper industry. Based on the thermodynamic feasibility of reactions between CaB_(6) and impurity elements Fe, P and S in oxygen-tough pitch copper melts, laboratory experiments were conducted. In the presence of CaB_(6), the oxidation processes of Fe, P, and S are promoted, and CaB_(6) also directly participates in binding reactions with the impurity elements. According to thermodynamic analysis, to achieve complete separation of Fe, the theoretically required addition mass ratio of refining agent CaB_(6) to copper melt is 0.2%. The laboratory experimental results indicate that, under the synergistic effect of CaB_(6) and O_(2), the impurity elements Fe, P and S in the melt significantly decrease. When the reaction temperature is 1 250 ℃, the reaction time is 120 minutes, and the addition amount of refining agent CaB_(6) is 1.2 times of the theoretical value, the separation rates of impurity elements Fe, P and S all exceed 80%. Meanwhile, the contents of elements Ca and B in the ingot does not exceed 0.0002%, meeting the product's compositional requirements. The electrical conductivity of the oxygen-tough pitch copper ingot after impurity separation reaches 99.98% IACS, satisfying the product's electrical conductivity requirements. To observe the micromorphology, the inclusions in samples under optimal reaction conditions (reaction temperature of 1 250 ℃, reaction time of 30 minutes, and refining agent addition amount of 1.5 times of the theoretical value) were selected. Compositional analysis reveals aggregations of elements P/O, Ca/P/O, Fe/B, and Ca/S/O. Combining the thermodynamic results, it is determined that calcium sulfate (CaSO4), calcium phosphate (Ca_(3)(PO_(4))_(2)), and iron boride (FeB) existe in the incompletely floated melt, along with P2O5 that has not yet floated or participated in other reactions. Therefore, the refining agent demonstrates a significant separation effect on Fe in the melt. In the presence of O_(2), the oxidation of P and O elements is promoted, with some combining with the refining agent to form intermediate compounds Ca_(3)(PO_(4))_(2) and CaSO4. The refining agent CaB_(6) and O_(2) jointly facilitated the separation of impurity elements Fe, P and S from the oxygen-tough pitch copper melt, reducing their contents to within the compositional requirements for downstream products. Furthermore, X-ray diffraction analysis of the slag reveals, in addition to copper oxides (CuO, Cu2O), residual charcoal (C), and ash in the charcoal (SiO_(2)), the presence of CaSO4, Ca_(3)(PO_(4))_(2) and FeB. Only copper phases are presented in the residual copper ingots after refining. The characterization results of these reaction products provide strong evidence supporting the thermodynamic simulations. This study expands the scope of impurity removal by redox methods in copper and copper alloy melts, providing a solution for the production of high-quality oxygen-tough pitch copper ingots, which is foundational for manufacturing highly specialized products.
作者
魏迎辉
刘伟
柴胜利
张健宇
李晓丹
WEI Yinghui;LIU Wei;CHAI Shengli;ZHANG Jianyu;LI Xiaodan(Shanxi Key Laboratory of Copper-Based New Materials,Yuncheng 044000,Shanxi,China;Shanxi North Copper New Material Technology Co.,Ltd.,Yuncheng 044000,Shanxi,China)
出处
《有色金属(冶炼部分)》
北大核心
2025年第8期165-174,共10页
Nonferrous Metals(Extractive Metallurgy)
关键词
有氧韧铜
精炼剂
杂质元素
导电率
压延铜箔
oxygen-tough pitch copper
refining agent
impurity elements
conductivity
rolled copper foil
