Application of Solvent Extraction to the Treatment of Waste Acid Mixture discharged from IT relating Industry

本研究对半导体和液晶显示器生产过程中排放的废酸液的分离技术进行了研究，即溶剂萃取法分离废酸液，并建立了分离工艺。在去年研究成果的基础上，对液晶显示器生产过程中废酸液的分离方法进行了研究。本文以正癸醇、磷酸三丁酯、磷酸三辛酯等为萃取剂，对磷酸、醋酸、硝酸、硫酸、盐酸等六种废酸进行了萃取反萃的基础研究。阐明了这些萃取剂对各酸的萃取机理以及各酸的萃取反萃特性。结果表明，酸在单一组分中的萃取行为与酸在两种或三种组分中的萃取行为有很大的不同。虽然在酸的萃取过程中，一般可以分离酸，但不能浓缩酸，但如果将酸萃取的特性适当地应用于酸混合物，则酸的浓缩和分离是可能的。例如，在稀磷酸废液中加入其它无机酸，可使废液中的磷酸以分离浓缩的形式得到回收。本文在实验基础上，建立了酸分离工艺，并在小型中试装置上进行了示范试验，同时探讨了在保持高纯度的同时提高回收率的方法。

In this study the separation technology of waste acid mixture discharged in the production of semi-conductor and liquid crystal display, namely the separation method of acid mixture with solvent extraction was investigated and the process for separation was established The separation methed of acids from waste acid mixture in the production of liquid crystal display was investigated based on the research results carried out last year, where we found that the solvent extraction was a suitable method to separate each acid from waste acid mixture in the production of semi-conductor,The basic study on extraction and stripping of phosphoric, acetic, nitric, sulphuric and hydrochloric acids was carried out by using decanol, TBP(tri-butyl phosphate), TOP(tri-octyl phosphate) etc. as extractants. We clarified the extraction mechanism of each acid with these extractants as well as the characteristics of extraction and stripping of each acid. It was found that the extraction behavior of acid in single compornent is largely different from that of acid in two or three acid components. Though in the extraction process of acid generally the separation of acids is possible, but the concentration of acid is impossible, the concentration and separation of acids will he possible if the characteristics of acid extraction is suitably applied to the acid mixture. For example, if other mineral acids are intentionally added to dilute phosphoric acid waste, the phosphoric acid is recovered in the separated and concentrated form.Based on the fundamental experimental data, the acid separation process was established and the demonstaration test for the proposed separation process was carried out using a small scale pilot plant At the same time the method to improve the recovery with keepinghigh purity was investigated.