利用超重力旋轉填充床於廢資訊主機板中IC晶片碳化處理製程所排放細懸浮微粒之效能評估

Abstract

隨著科技進步及人們消費模式改變，電子廢棄物日益地增加，不僅造成大量的物質之浪費，且造成許多環境污染議題。本研究利用此類的廢棄物藉由高溫碳化過程，結合使用優勝奈米公司所研發的環保剝金技術進行高效回收金製程。電子廢棄物經過高溫碳化過程中會產生對人體有害之細懸浮微粒，而旋轉填充床藉由高速旋轉，增加微小液滴及液膜，增加與懸浮微粒碰撞的機率，從此提升捕捉效果。本研究之主要目的為優化各製程的操作參數。首先，碳化製程必須考量金最佳提取率及污染排放最小化。從實驗結果，本研究得出優化條件出現於800oC，金之提取率可高達99.8%。除此以外，超重力技術透過反應曲面法可找出最高效率之操作條件，本研究最高去除效率可達至99.2% 當超重力因子為323及氣液比約 4.22。除了實際操作以外，本研究集合多項經驗公式及實際操作條件，透過建立半理論模式進行探討每種去除機制在不同懸浮微粒粒徑分佈下之貢獻量。最後，本研究針對空氣污染物排及能源議題進行整合性分析，因此可得出該整合性技術之實際最佳操作條件。

The urban mining via electronic waste (e-waste) recycling process is a merging industries which several high-value precious metals can be collected to reduce natural degradation and depletion. To obtain those precious metals more effective, the e-waste pretreatments such as carbonization process are inevitable. In this study, the high-gravity rotating packed bed (HiGee RPB) was applied to grade down the air pollution, especially fine-sized particles due to its centrifugal force, also micro-mixing performance between gas and liquid phase. The carbonization process was considered to balance and qualify two conditions, including maximal of gold stripping efficiency with minimal of PM emission. The optimized condition was achieved at 800oC with the gold stripping efficiency reached up to 99.8%. Besides, the countercurrent RPB was operated to proceed on-site experiment under different operating condition such as high gravity factor and gas-to-liquid ratio. By using response surface method (RSM), the maximal achievable removal efficiency (MARE) was identified as 99.2% when high gravity of 323, gas-to-liquid ratio of 4.22. Moreover, empirical and semi-theoretical were developed basing on experiment results as well as several physical variables. Remarkably, the semi-theoretical was established to describe how the Brownian diffusion, inertial impaction as well as interception affect the removal efficiency in different size of particles. The U-shaped curve was determined with a minimum in the region around 1.9 µm. Finally, the concept of particles capture capacity was applied to illustrate the air-energy nexus issue. A motivation toward a cleaner production technology with the integration of carbonization process and high gravity RPB system was described with the expectedly providing a reference for optimizing design, or scaling up, also promising solution for efficient e-waste carbonization as well as particles emission controls in the future.