PCB碱性蚀刻废液高效回收铜粉研究

Efficient recovery of copper powder form PCB alkaline etching wastewater

针对PCB碱性蚀刻废液含铜量高、腐蚀性强等特点,在氮气气氛下采用水合肼液相还原制备高质量铜粉,同时实现蚀刻液再生。研究了液相还原气氛、肼与铜离子的摩尔比、反应温度和反应时间等对沉铜效率以及产物组成的影响。通过电感耦合等离子体质谱(ICP)、X射线衍射仪(XRD)、扫描电子显微镜(SEM)和激光粒度分析仪(LDPA)等对蚀刻液成分、产物物相、形貌结构以及铜粉粒度分布进行表征。实验结果表明:空气气氛下液相还原过程中易产生一价铜,导致产物不纯且沉铜率较低;氮气气氛下肼还原效率显著提高,当肼与铜离子摩尔比≥0.64∶1.00、温度≥90℃时,沉铜率高达99.9%,还原产物以单质铜为主,伴有少量CuCl和Cu_(2)O杂质。经碱洗转化、氢还原后得到的铜粉产品纯度不低于99.9%,粒度均匀,满足工业质量标准。

Considering the characteristics of PCB alkaline etching waste liquid,such as high copper content and strong causticity,this paper proposesa novel way to preparing high-quality copper powder through hydrazine hydrate reduction under a nitrogen atmosphere.This method also enables the regeneration of the etching liquid.The study examined the effects of the reducing atmosphere,the molar ratio of hydrazine to copper ion,reaction temperature,and time oncopper removal efficiency and product composition in detail.The solution composition,phase,morphology and particle size distribution of copper powder were characterized using inductively coupled plasma mass spectrometry(ICP),X-ray diffractometry(XRD),scanning electron microscopy(SEM),and laser particle size analyzer(LDPA).The results showed that monovalent copper was easily produced during the liquid-phase reduction process under an air atmosphere,resulting in impurities and a low copper removal rate.Howecer,conducting the reduction process under a nitrogen atmosphere significantly improved the reduction efficiency of hydrazine hydrate.When the molar ratio of hydrazine to copper ion was≥0.64∶1.00,and the temperature was≥90℃,the copper removal rate reached 99.9%.The resulting product consisted mainly copper,with a small amount of CuCl and Cu_(2)O.Through a combination with alkali transformation and hydrogen reduction treatment,superfine copper powders with high purity(≥99.9%)and uniform granularity were obtained,meeting the industrial quality standards.