利用銦-錫氧化物(ITO)廢料回收高純度銦材

Abstract

內含銦-錫氧化物的ITO酸洗液或ITO汙泥中含有貴金屬銦，本研究將整合濕法冶金與火法冶金，提供一具經濟價值之銦回收方法。銦於溶液中為離子狀態，利用濕法冶金法(電析法或化學置換法)可將銦元素由溶液中取出，另外火法冶金法(造渣技術)可將銦元素由固態廢料中取出，以上所得的粗銦經真空熔煉後可使金屬銦與氧化層分離，可得到3N(99.9%)高純度之銦材。回收後的銦材由感應耦合電漿質譜儀、分析掃描式電子顯微鏡、能量分散光譜儀、光學顯微鏡分析，從銦的顯微組織、成份分析之結果，銦的純度可達到3N。回收ITO酸洗液可以得到純銦17.69g/L，且其純度為3N。回收酸洗液的過程中，以鎂粉當做濕法冶金中的置換劑，其鎂粉的量約為4.67g/L，且操作溫度在室溫下便可。另外氫氧化鈉為火法冶金中的造渣物質，添加量大約6g/L可以得到17.69g/L的純銦。回收ITO汙泥可以得到5.39g/L的純銦，且其純度為99.7%。在回收污泥的過程中，以鋅粉作為濕法冶金中的置換劑，其鋅粉的量約為3g/L，且操作溫度需超過攝氏60度才會反應完全。氫氧化鉀為火法冶金中的造渣物質，添加量大約5.33g/L可以得到5.39g/L的純銦。從濕法冶金中若可置換出越多的海綿銦，則在火法冶金中獲得的銦含量也相對提高一些。在本實驗中，從酸洗廢液置換出的海綿銦，經火法冶金提煉後銦的損失率為33%，由污泥廢料中提煉出的純銦其損失率為24%。 本研究針對銦元素的回收方法、回收效率，結合濕法冶金及火法冶金法，製作出高純度的銦材。另外，本研究亦將藉由此題目，深入探討銦之電化學與熱力學反應特性。

The study was used to establish a method to recycle indium from ITO wasted solution and ITO wasted mud. The economical and efficient method was presented in the processes of hydrometallurgy and pyrometallurgy. In the hydrometallurgy method (chemical replacement), the powder of Mg and Zn were used to be the reducing agents. No matter in the ITO wasted solution or ITO wasted mud, the sponge indium was obtained by hydrometallurgy. In the pyrometallurgy method (slags making), the alkali compounds liked NaOH and KOH were used to make slags. The pure indium with a purity of 99.9% (3N) could be obtained from the sponge indium. The recycled indium was analyzed by Scanning Electron Microscopy, Energy Dispersive X-ray analysis, Inductively Coupled Plasma-mass spectrometry and Optical Microscope. In recycling indium from ITO wasted solution, the addition of Mg was 4.67g/L to replace the sponge indium and the operation temperature was room temperature. Moreover, the addition of NaOH was 6g/L to refine the sponge indium. The amount of pure indium was obtained 17.69g/L with a purity of 3N. In recycling indium from ITO wasted mud, the addition of Zn was 3g/L to replace the sponge indium and the operation temperature was 60℃. Besides the addition of KOH was 5.33g/L to refine the sponge indium. The amount of pure indium was obtained 5.39g/L with a purity of 99.7%. In this article, the recycling process involved electrochemical technology, vacuum smelting technology, thermodynamic theorems and microstructure analysis. Therefore, we detailed to study and discuss the behavior and characterization of indium by electrochemistry and thermodynamics.