Pyrolisis Removal Of Organics And Chloridization Extraction Of Tantalum From Waste Tantalum Capacitors

Tantalum capacitors,due to its superior performance of small size,large capacity and high thermal stability,have become one of the most significant electronic components in printed circuit boards from electrical and electronic equipment.The rapid update of the electronic products has resulted in a large quantity of waste tantalum capacitors(WTCs).The construction and composition of tantalum capacitor are very complex.On the one hand,tantalum capacitors contain valuable metals that the contents are higher than that of ore concentrate,such as Ta,Ag and Fe,which has high recycling value as secondary resource.On the other hand,organic materials tightly cover the tantalum electrodes,which hinders the recovery of tantalum resource and have potential health risk as well as environmental risk.Hence,the recycling of WTCs in an efficient and environmental-friendly way is of significance in resource recycling and environment management.However,at present few studies of waste resource recovery technology of tantalum capacitor at home and abroad have reported,and there are still not mature disposal methods for WTCs,so the topic has an exigently realistic significance.To address the above problems,this study adopted an effective recycling process to recover tantalum and removal organics from waste tantalum capacitors based on pyrolysis and chloride metallurgy.The pyrolysis process of organics from WTCs both in argon gas and vacuum environment were investigated respectively.Pyrolysis mechanism,pyrolysis products and reaction parameters of waste tantalum capacitors at these two kinds of atmospheres were compared.Response surface method was adopted to investigate optimal pyrolysis temperature,system pressure and holding time for pyrolysis reaction.The experiments showed that the optimum pyrolysis condition was 425 ~oC,50 Pa and 30 min,and the organics of the conversion rate can reach 94.32%.The composition and content of pyrolysis products were analyzed,and on this basis the mechanism of vacuum pyrolysis of organic materials of waste tantalum capacitor was proposed combining the theory of chemical bonds.Chlorination process was proposed to extract tantalum and ferrous chloride was added as chlorination agent.The thermodynamic analysis indicated that ferrous chloride reacted with tantalum,which could produce tantalum chloride.The generated tantalum chloride with low boiling point and high vapor pressure then would volatilize in form of gaseous from WTCs.Through single-factor experiment(ferrous chloride content,heating temperature,holding time and sample grain size),the optimum reaction parameters of chlorination were determined:500 ~oC,120 min,ferrous chloride content of 50 wt%and particle size less than 0.24 mm.Under the optimum condition,tantalum recovery and purity of tantalum reached 93.23%and 99%,respectively.Based on the above study,method of vacuum pyrolysis-mechanical physical separation-chlorination tantalum was put forward to recycle waste tantalum capacitors in an effective and environmentally-friendly way.This study provides a theoretical basis and reference for the extraction of rare metals and the removal of organics from WTCs.