以具分散反萃取相支撐式液態薄膜分離並回收廢螢光粉內釔離子之研究

Separation and Recovery Yttrium ions from waste fluorescent powder by Supported Liquid Membrane with Strip Dispersion

江慕楓(Mu-Feng Chiang)

指導教授 ： 游勝傑

中原大學/工學院/生物環境工程研究所/碩士(2015年)

https://doi.org/10.6840/cycu201500078

摘要

本研究利用中空纖維膜式的具分散反萃取相支撐式液態薄膜（Supported Liquid Membrane with Strip Dispersion, SLMSD），以兩步驟程序回收及純化濃縮廢螢光粉內的稀土元素釔。近年來，白光發光二極體及電子顯示器是所有螢光粉產業中發展最為迅速的，這也凸顯了螢光粉在光電元件應用上所扮演角色的重要性。由於台灣LED照明光電產業供應鏈完整，其中LED光源產量全球第一，產值第二，市占率僅次於日本，故釔金屬對於我國之產業影響深遠，且台灣本身不出產稀土金屬，其回收與濃縮純化所帶來的經濟效益更加不容小覷。
本研究利用王水消化法溶出廢螢光粉中所含的各金屬離子總量為基礎，利用酸浸法實驗、批次搖瓶實驗（溶劑萃取實驗、反萃取實驗）來獲得SLMSD模場操作前的最佳操作條件，最後利用其參數設定操作SLMSD模場，並計算出該實驗之經濟效益成本及收益。
經由王水消化法可得到每克廢螢光粉可溶出釔離子約237毫克；從酸浸實驗可知，濃度5N的HCl可以在最短的時間內溶出最大量的釔離子；從批次萃取實驗可知，將酸浸液控制在pH範圍1.5~2.0時，萃取劑D2EHPA可得到最高的萃取效率97%；從批次反萃取實驗可知，使用濃度7N之反萃取液HCl，在45分鐘內可以回收最多且純度較高之釔離子。在SLMSD操作廢螢光粉酸浸漬液45分鐘回收釔離子，可將進料濃度1712 mg/L的釔離子提升至5599 mg/L，自酸浸漬液中的回收率為75%、回收總量為178 mg Y/g 廢螢光粉、回收純度為90%、濃縮程度為3.3倍。本研究經簡單經濟評估後，初步計算每噸廢螢光粉之回收利潤約為30萬元。

關鍵字

具分散反萃取相支撐式液態薄膜、釔、萃取、D2EHPA

並列摘要

A rapid increase in demand of rare earth elements (REEs) for High-Technology industries during the last decade led to a growing research interest of new technology for material recovery from electric and electronic wastes. Recycling of these waste materials help to reduce energy usage, reduce the consumption of fresh raw materials and also reduce environmental pollution that may be a result of an inappropriate disposal for the wastes.
This study investigates the potential recovery of yttrium from the waste fluorescent powder (WFP) by solvent extraction and supported liquid membrane with strip dispersion (SLMSD). The polypropylene hollow fiber membrane was used as a solid support for the SLM process and di (2-ethylhexyl) phosphoric acid (D2EHPA) in Isopar-L was used as an extractant. After total leaching of WFP by aqua regia, the selection of mineral acids including HCl, H2SO4, HNO3 for leaching of yttrium from the powder was carried out and the leaching solution was used for the solvent extraction. Effect of pH in the feed solution, extractant concentration, oil and aqueous (O/A) ratio and stripping solution on the extraction behavior of yttrium was evaluated in detail. Concentrations of yttrium ion and co-existed components (Ba, Sr, Ca and Al) in the solution were analyzed by ICP-OES.
Experimental results have shown that one gram of WFP contained 237 mg of yttrium and 5 N of HCl can leach the maximum amount of yttrium ion in the powder within 4 h. The increase of acid concentration did not enhance the leaching rate of metal ions. The optimum conditions for solvent extraction of yttrium ion with the highest extraction efficiency of 97% were that the pH of feed solution was 1.5, D2HEPA concentration was 0.25 mol/L and O/A was 0.5. Hydrochloric acid of 7N can strip all yttrium ions (100% recovery) from the extractant within 10 min at the O/A ratio of 4. In addition, the operation of the hollow fiber SLM-SD under this optimum condition showed a computable result with a recovery of 90% yttrium. The concentration of yttrium the strip solution was around 5599 mg/L while the initial concentration of yttrium in feed solution of 1712 mg/L decreased to 50.8 mg/L after a continuous extraction for 45 min.
The preliminary cost-benefit analysis of yttrium recovery from WFP showed a profit of approximate 300,000 dollars per tons of waste.

並列關鍵字

yttrium ； solvent extraction ； D2EHPA ； SLMSD

參考文獻

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