電解和離子交換法回收含銅廢液及污泥中的銅金屬

Copper Recovery from Copper-Containing Waste Solution and Sludge by Electrolysis and Ion Exchange

羅科顯(Ke H. Lo)

指導教授 ： 林勝雄

元智大學/工程學院/化學工程與材料科學學系/碩士(2004年)

摘要

摘要
在我國經濟發展的過程中，印刷電路板與半導體製造業扮演很重要的角色，這些產業製程中會產生大量且高濃度含銅廢液與污泥，這些廢棄物若處置不當，將會造成嚴重的環境污染問題。本論文針對兩種廢棄物進行實驗與理論研究，含高濃度銅廢液(包括污泥酸洗液)以電解方式回收，低濃度含銅廢水部分則採用離子交換回收。
本研究利用流體化床電解法回收酸性廢液中的銅離子。模擬高濃度含銅廢液的部分，分別以不同的電流、pH值及濃度做變因的討論，觀察其實驗中的溫度、電壓、電解效率及最終的金屬回收率，由實驗結果得知，在pH=1時，電流為8A電解24小時則電解回收率最高，其回收銅的效率在99.9%以上。
本研究也利用實際工廠廢水進行測試，因實驗結果得知，pH變因對廢液最終銅離子濃度的影響很小，因此電流是主要的實驗變因，實驗結果發現電流越大，銅回收速率越快。實驗測試利用兩批不同公司的廢液，電解回收銅的效率都在99.5%以上。
取自現場的污泥，先經由硫酸酸洗萃取污泥中的銅，萃取所需的硫酸體積濃度在20%時，酸洗的效果最佳，由酸洗下來的萃取液再經電解回收，銅的回收率也達99.5%以上。
針對低濃度含銅廢水(即經電解回收銅後之廢液)，利用拜耳公司TP207型離子交換樹脂來進一步回收銅，分別進行批次實驗和管柱實驗，並探討離子交換樹脂的批次脫附。理論研究部分以Langmuir和Freundlich等溫離子交換模式來和實驗數據來進行模擬比較。管柱離子交換實驗中的主要變因主要探討不同進料流速、進料濃度對離子交換系統的影響，並以Simplified Logistic-1和General Logistic模式模擬實際的離子交換情形。最後在批次的脫附再生實驗中，離子交換樹脂經過三次離子交換與再生，再生效率可達94.3%。

關鍵字

電解 ； 離子交換法 ； 銅廢液

並列摘要

Abstract
Printed circuit board (PCB) and semiconductor are two high-tech products that play crucial role in the economic development of this country. In spite of their growing importance, manufacturing of these products leads inherently to production of waste solution and sludge that contain high concentration heavy metals. Proper disposal of these solution and sludge are necessary in order to minimize their negative environmental impact. This research represents an attempt to deal with waste solution and sludge that contain high concentration copper. Electrolysis and ion exchange processes were adopted for this purpose.
In the electrolytic process, both simulated and real waste copper solutions were employed. This process was intended to recover copper from the waste solution by greatly reducing the copper concentration from over 20% to hundreds of ppm. The primary operating variables considered in the test runs included current, initial pH and copper concentration. The effects of these variables on the copper recovery were thoroughly examined. The test results indicated that under the condition of pH<1, a current of 8 A and 24 h of electrolysis, a 99.9% copper recovery could be achieved in this process using the simulated waste solution. For the real plant copper solution obtained from the PCB etching process, the pH effect was found to be relatively small and hence current became the prime control variable. The copper recovery under optimal current condition was found to be quite good, exceeding 99.5%.
For treatment of waste sludge from a PCB plant, the sludge was first broken up into small pieces which in turn were mixed with acid extractant (sulfuric acid). A solution containing 20% sulfuric acid was found to provide the best copper extraction. The sulfuric solution containing over 10% copper was then subject to electrolysis. Again the copper recovery was found to be excellent, being greater than 99.5%.
The residual solution after electrolysis contained a copper concentration under 500 mg/l which was not acceptable for direct discharge. To further reduce the copper concentration, ion exchange was adopted. Both batch equilibrium and column ion exchange experimental tests were performed. The batch equilibrium data were modeled by Langmuir and Freundlich isotherms for optimal model discretion. In the column tests, the main control variables included solution feed rate and inlet copper concentration. The experimental data were employed to verify the ion exchange column model. Both simplified and general logistic models were found to describe the present ion exchange reasonably well. The verified column model could significantly facilitate predictions of the breakthrough time and capacity. The exhuasted ion exchange resins after breakthrough need to be regenerated for reuse for cost reason. Preliminary batch regeneration of exhausted ion exchange resins was performed. Test results indicated that after three ion-exchange/regeneration cycles, an ion exchange capacity of 94.3% was still retained.

並列關鍵字

HASH(0xccf0fd0)

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