摘要
铜粉是粉末冶金工业的基础原材料之一,也是我国大量生产和消费的有色金属粉末,在现代工业生产中发挥着不可替代的作用。以硫酸铜为原料,采用不溶阳极电积的方法制备铜粉具有原料成本低、工艺流程短、产品应用领域广等优点。但是在实际生产过程中,所采用的粗硫酸铜原料中As、Sb、Bi等杂质直接造成电积铜粉中杂质含量超标；同时,在不溶阳极电积过程中所使用的阳极为Pb-Ca-Sn合金阳极,阳极板性能的好坏,将直接影响铜粉中铅的含量。
本论文采用氧化-中和-共沉淀法净化粗硫酸铜溶液,研究了硫酸铁与双氧水加入量、终点pH值、氧化时间等对净化效果的影响,确定了净化除杂最佳工艺条件。研究表明：室温下,控制mFe：mAs为13.5、V双氧水：V溶液为1／600、终点pH为3.8、氧化时间为5 min时,除杂效果最佳,原液中Fe脱除率为89.42%,As脱除率为98.03%,Sb脱除率为42.97%,Bi脱除率为35.36%,除杂后的电解液可以达到电积过程高品质铜粉制备的要求。系统研究了电积过程铜电解液组成以及工艺条件对电流效率和产品性能的影响。研究结果表明：Cu2+浓度、硫酸浓度、电解液温度的提高有利于降低槽电压,Cu2+浓度、电解液温度、刮粉周期的增加有利于提高电流效率,提高电流密度、高硫酸浓度、低Cu2+浓度有利于得到粒度小的铜粉；在最佳的工艺条件下,即Cu2+浓度15g/L,硫酸浓度140 g／L,电流密度为1800A/m2,温度为35℃,刮粉周期为30 min,循环流量为14 L／h,极距为4.5 cm,得到的产品质量达到了国家标准GB5246-2007的要求,粒度分布均匀且微观形貌呈树枝状。
采用计时电位法(CP)、循环伏安(CV)、腐蚀速率、线性电位扫描(LSV)等电化学测试手段,研究了Pb-Ag-Ca, Pb-Sn-Ca, Pb-Sn-Sr, Pb-Sb合金阳极的阳极电位与耐腐蚀性能,优选出Pb-Ag-Ca为最佳阳极,为不溶阳极电积铜粉的工业生产提供了依据。
Copper powders play a vital role in modern industry, because it is not only one of the fundamental materials in powder metallurgy industry, but also has the largest yield and comsumption among the non-ferrous metal powders in China. But in the actural process, using copper sulfate as raw materials will directly lead the content of the impurities such as As, Sb, Bi and etc., higher than the standard in the production of copper powder by electro-deposition. In the meantime, the performance of the anode, which is now Pb-Ca-Sn in use, will directly affect the content of Pb in copper powders.
In this study, we carried out the impurities removal experiments by oxidation-neutralization-coprecipitation method, and the optimum conditions were obtained. The results showed that, at room temperature, the removal efficiencies of Fe, As, Sb and Bi could reach 89.42%, 98.03%,42.97% and 35.36%, respectively, by controlling mFe:mAs=13.5 and VH2O2:Vsolution= 1/600 with oxidation 5 min and the solution final pH 3.8. The electrolytes after removal impurities can adapt to the electro-deposition process for high quality copper powders.
The effects of compositions of electrolyte and process conditions on current efficiency and product performance were investigated. The results showed that, increasing Cu2+ concentration, H2SO4 concentration and electrolyte temperature helped to reduce cell voltage; the increase of Cu2+ concentration, electrolyte temperature and scraping interval helped to improve current efficiency; high current density, high H2SO4 concentration and low Cu2+ concentration were beneficial to obtain small particle size powders. The optimum conditions were Cu2+ concentration of 15 g/L, H2SO4 concentration of 140 g/L, current density of 1800 A/m2, electrolyte temperature of 35℃, scraping interval of 30 min, circulation rate of 14 L/h, and interpolar distance of 4.5 cm, respectively. Under the optimum conditions, the content of obtained copper powders could reach the requirement of GB5246-2007 in the national standard. The high quality copper powders were dendritic shape with normal distribution of particle size.
In order to seek for the insoluble anode with low anode potential and corrosion rate, the electrochemistry performance of Pb-Ag-Ca, Pb-Sn-Ca, Pb-Sn-Sr, Pb-Sb by Chronopotentiometry(CP), Cyclic Voltammetry(CV) Corrosion Rate and Linear Sweep Valtammetry(LSV) were studied in this paper. Among these anodes, Pb-Ag-Ca alloy was prior to other alloy anode with lowest stable anode potential and corrosion rate for industry application of preparing copper powder.
引文
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