消費性電子產品日益蓬勃，許多廢棄印刷電路板大量堆積造成環境汙染，其電路板上含有大量金屬材料，在全球環保回收趨勢中，近日已有相關的金屬回收方式。本論文將針對廢棄印刷電路板上的銲錫材料進行研究，採用市面上多數採用的錫料做為實驗素材，並以微生物做為工具，探討不同的錫料外型長度大小、上清液對錫料的溶濾、不同的溫度環境、不同的培養箱轉速、不同的溶濾溶液體積、不同的錫料重量與超聲波震盪對溶濾的影響，回收溶濾完上清液中的錫、鉛、銅、銀等金屬做為日後循環應用，實驗採用無危害人體的非傳統微生物溶濾錫料的方式。實驗結果以100ml Aspergillus niger上清液在溫度30(_^0)C、轉速200rpm溶濾尺寸3mm、0.5g之含銀銅錫料，經過60小時其溶濾效果達到99%。廢棄印刷電路板溶濾以兩階段處理，以溫度30(_^0)C、轉速200rpm、0.5g廢棄印刷電路基板粉末浸泡在100ml Aspergillus niger上清液中，每12、24小時以超聲波震盪30分鐘，經過144小時以回收鉛、錫金屬。溶濾後之溶液再添加NaCl、NaOH及Hydrogen sulfide以回收銀、錫、銅及鉛金屬。
本實驗首次針對銲料溶濾使用對環境無害的Aspergillus niger進行溶濾，Sn(60%)-Cu(37%)-Ag(3%)錫料溶濾效果在36hr達到97.8%、Sn(63%)-Pb(37%)錫料溶濾效果在144hr達到99.4%。

The increase in use of electrical and electronic equipments (EEE) results in an increase in amount of electronic waste. Solders are used as interconnecting material in electronic packaging. However, metals present in solder can pose negative impacts on both environment and the human body. Pyrometallurgical and hydrometallurgical methods are used for recycling of these waste solders. However, these methods have certain disadvantages, such as consumption of high energy and use of harmful chemicals. There is a need of environmentally benign process to recover metals from waste solders. In the present work bioleaching of lead free and lead containing solders was studied. This was achieved by employing culture supernatants of Acidithiobacillus ferrooxidans (At. ferrooxidans) and Aspergillus niger (A. niger). Two types of lead free solders were used, Sn-Cu and Sn-Cu-Ag. Along with this lead containing (Sn-Pb) solder was also used. It was found that culture supernatant of A. niger removed metals in less time as compared to culture supernatant of At. ferrooxidans. Therefore further bioleaching experiments were carried out with A. niger supernatant to investigate the dissolution behavior of metals under varying process parameters viz. time, temperature, shaking speed, volume of culture supernatant, amount of solder, etc. The results show that for Sn-Cu-Ag solder 99% dissolution was achieved in 60 h, while it required 96 (99%) and 144 (99%) h for Sn-Cu and Sn-Pb solders respectively. For bioleaching experiment 200 rpm shaking speed and 30 oC temperature were found optimum.
In another experiment ultrasonic waves are used along with bioleaching process to recover metals from waste PCB. Also experiments were carried out to recover metals from bioleached solution by adding sodium chloride, sodium hydroxide and hydrogen sulfide gas. These results suggest that it is possible to recover metals from waste solders by applying biohydrometallurgical method.
The current research is original using Aspergillus niger for solder bioleaching. This method is environmentally friendly. Solder leaching effect of Sn-Cu-Ag reached 97.8% after 36hr and solder leaching effect of Sn-Pb reached 99.4% after 144hr.

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