Resources Recycling (자원리싸이클링)

The Korean Institute of Resources Recycling (한국자원리싸이클링학회)
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Titanium Dioxide Recovery from Soda-roasted Spent SCR Catalysts through Sulphuric Acid Leaching and Hydrolysis Precipitation

소다배소 처리된 탈질 폐촉매로부터 황산침출과 가수분해 침전반응에 의한 TiO2의 회수

  • Kim, Seunghyun (Dept. of Energy & Resources Engineering, Kangwon National University) ;
  • Trinh, Ha Bich (Dept. of Energy & Resources Engineering, Kangwon National University) ;
  • Lee, Jaeryeong (Dept. of Energy & Resources Engineering, Kangwon National University)
  • 김승현 (강원대학교 에너지자원공학과) ;
  • 친빅하 (강원대학교 에너지자원공학과) ;
  • 이재령 (강원대학교 에너지자원공학과)
  • Received : 2020.08.25
  • Accepted : 2020.09.29
  • Published : 2020.10.30
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Abstract

Sulphuric acid (H2SO4) leaching and hydrolysis were experimented for the recovery of titanum dioxide (TiO2) from the water-leached residue followed by soda-roasting spent SCR catalysts. Sulphuric acid leaching of Ti was carried out with leachate concentration (4~8 M) and the others were fixed (temp.: 70 ℃, leaching time: 3 hrs, slurry density: 100 g/L, stirring speed: 500 rpm). For recovering of Ti from the leaching solution, hydrolysis precipitation was conducted at 100 ℃ for 2 hours in various mixing ratio (leached solution:distilled water) of 1:9 to 5:5. The maximum leachability was reached to 95.2 % in 6 M H2SO4 leachate. on the other hand, the leachability of Si decreased dramatically 91.7 to 3.0 % with an increase of H2SO4 concentration. Hydrolysis precipitation of Ti was proceeded with leaching solution of 8 M H2SO4 with the lowest content of Si. The yield of precipitation increased proportionally with a dilution ratio of leaching solution. Moreover, it increased generally by adding 0.2 g TiO2 as a precipitation seed to the diluted leaching solution. Ultimately, 99.8 % of TiO2 can be recovered with the purity of 99.46 % from the 1:9 diluted solution.

소다배소 처리한 탈질폐촉매의 수침출 잔사로부터 TiO2 회수를 위하여 황산침출과 가수분해 반응을 실시하였다. Ti 성분의 황산침출은 70 ℃, 3 시간, 교반속도 500 rpm, 슬러리 농도 100 g/L로 고정하여 실시하였고, 황산농도는 4~8 M로 변화시키며 진행하였다. 침출액으로부터 Ti 성분의 침전회수는 가수분해반응을 이용하였으며, 실험조건은 100 ℃, 반응시간 2 시간으로 고정하였고, Ti 성분의 침전율은 침출액과 증류수의 혼합비와 침전반응 Seed 혼입유무에 따라 비교하였다. Ti의 침출율은 6 M에서 최대 95.2 %까지 도달 후 점차 감소하는 경향을 나타내었고, Si의 침출율은 황산농도 증가에 반비례하여 급격히 감소하여 91.7 %에서 8 M 조건에서는 3.0 %까지 억제되었다. 침출액을 이용한 가수분해는 부성분인 Si의 함량이 가장 낮은 8 M 침출액을 이용하여 진행하였다. 침출액의 혼합비에 의한 Ti의 침전회수율은 반응시간에 비례하였고 혼합비에 반비례하였다. 또한, 침전반응의 가속화를 위해 TiO2(#325~#400 mesh, 0.2 g) seed를 첨가하였을 경우에 모든 혼합조건에서 침전회수율이 상승하였으며, 혼합비(침출액:증류수) 1:9~3:7 구간에서 98.8~99.8 %의 침전율이 달성되었다. 회수된 TiO2의 순도는 침출액 혼합비 1:9~3:7 구간에서 혼합비가 낮을수록 증가하여 최대 99.46 %까지 상승함을 확인하였다.

Keywords

References

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