Study on Recovery of Separated Hydrofluoric Acid, Nitric Acid and Acetic Acid Respectively from Mixed Waste Acid Produced during Semiconductor Wafer Process

반도체 웨이퍼 제조공정(製造工程) 중 발생혼합폐산(發生混合廢酸)으로부터 불산, 질산 및 초산의 각 산 회수(回收)에 관한 연구(硏究)

  • Published : 2009.08.27

Abstract

We researched separation of mixed waste acids with HF, $CH_3COOH$, $HNO_3$ that were produced during a semiconductor wafer process to recycle these acids. At first, we manufactured the fluoride compound in form of $Na_2SiF_6$ by precipitating HF using $NaNO_3$ and Si powder. The concentration of HF was reduced from the initial concentration of 127 g/L to 0.5 g/L with an HF recovery ratio of 99.5%. After the manufacture of $Na_2SiF_6$, the concentration of $HNO_3$ and $CH_3COOH$ demonstrated 502 g/L and 117 g/L respectively. Following these findings we added NaOH in this $CH_3COOH/HNO_3$ mixed acid in order to obtain pH=4. Next we separated the $CH_3COOH$ and recoverd it through the use of vaccum evaporation at -440 mmHg, $95^{\circ}C$. The concentration of the recovered $CH_3COOH$ was approximately 15% and the recovery ratio of $CH_3COOH$ was over 85%. We precipitated the $NaNO_3$ by cooling the concentrated solution to $20^{\circ}C$ with a $HNO_3$ recovery ratio of over 93%. We confirmed that only $Na_2SiF_6$ and $NaNO_3$ were manufactured by XRD analysis after drying these precipitants at $90^{\circ}C$. The precipitants demonstrated a purity of approximately 97% and 98% respectively. Therefore, the purity of the precipitants proved to be similar to that of commercial products.

반도체 웨이퍼 제조 공정 중 발생하는 질산, 불산, 초산으로 구성된 혼합폐산을 재활용하기 위한 연구를 수행하였다. 초기에 $NaNO_3$와 Si powder를 사용하여 불산을 $Na_2SiF_6$로 침전시켜 불소화합물을 제조하였고, 이 때 혼산 중 불산의 농도는 초기 127g/L에서 0.5g/L로 낮아져 불산 회수율은 99.5%였다. $Na_2SiF_6$ 제조 후 남은 혼산의 질산과 초산의 농도는 각각 502g/L, 117g/L였고, 이 혼산에 NaOH를 투입하여 pH=4로 맞춘 후 -440 mmHg, $95^{\circ}C에서 증발농축을 하여 초산 분리 회수하였다. 회수된 초산의 농도는 약 15%였고, 회수율은 85.3% 이상이었다. 또한, 농축여액을 $20^{\circ}C$까지 냉각하여 $NaNO_3$ 결정을 석출시킴으로 질산나트륨을 제조하였고, 그 회수율은 약 93%이상이었다. 제조된 $Na_2SiF_6$$NaNO_3$$90^{\circ}C$에서 건조시킨 후, XRD 분석한 결과, 순수 $Na_2SiF_6$$NaNO_3$만 합성된 것을 확인하였고, 그 순도는 각각 약 97%, 98%로 시판용과 유사하였다.

Keywords

References

  1. Yamamoto, A., et aI., 1979: Recovery Process of Nitric and Hydrofluoric Acids from Waste Pickling Solutions for stainless steel, Nissin steel Gihou, 40, pp. 49-54
  2. Kuylerstiema, U. and Otteryun, H., 1974: Solvent Extraction of HNO$_{3}$-HF from Stainless Pickling Solutions, Proceedings from the International Solvent Extraction Conference. 3, pp. 2803-2816
  3. 이향숙, 김준영, 김주엽, 안재우, 소순섭, 정동화, 2006: 반도체 생산 공정에서 배출되는 폐산중 초산과 질산의 혼합산 분리를 위한 기초 연구, 한국자원리싸이클링학회 추계학술대회 (2006. 11), P137-141
  4. Yu, L., Guo, Q., Hao, J., Jiang, Weihua, Y., 2000: Recovery of acetic acid from dilute wastewater by means of bipolar membrane electrodialysis, Desalination, 129(3), pp. 283-288 https://doi.org/10.1016/S0011-9164(00)00068-0
  5. Anasthas, H. M., and Gaikar, V. G, 2001: Adsorption of acetic acid on ion-exchange resins in non-aqueous conditions, Reactive & functional polymers, 47(1), pp. 23-35 https://doi.org/10.1016/S1381-5148(00)00066-3
  6. Tongwen, X., and Weihua, Y., 2003: Industrial recovery of mixed acid (HF +$_{3}$)from the titanium spent leaching solutions by diffusion dialysis with a new series of anion exchange membranes, Journal of membrane science, 220, pp. 89-95 https://doi.org/10.1016/S0376-7388(03)00218-7
  7. Hu Xinglan, Miao Wenjun, and Zhou Rongqi, 2004: Simulation of extrative distillation of acetic acid-water, Computers and applied chemistry(China), 21(6), pp828-830
  8. Zhigang Lei, Chengyue Li, Yingxia Li, and Biaohua Chen, 2004: Separation of acetic acid and water by complex extractive distillation, Separation and Purification Technology, 36, pp13I-138 https://doi.org/10.1016/S1383-5866(03)00208-9
  9. Bock Heiko, Jimoh Mohammed, and Wozny Guenter: Analysis of reactive distillation using the esterfication of acetic acid as an example, Chemical engineering& technology, 20(3), pp182-191
  10. Saha B., Chopade S.P., and Mahajani S.M., 2000: Recovery of dilute acetic acid through esterification in a reactive distillation column, Catalysis Today, 60, pp147-157 https://doi.org/10.1016/S0920-5861(00)00326-6