우라늄 오염 동전기 침출액의 재이용을 위한 침전-여과 방법

Abstract

우라늄 오염토양을 동전기제염 시 많은 양의 동전기 침출액이 발생한다. 발생된 우라늄 침출액을 재이용하기 위한 처리기술이 개발되었다. 동전기제염 시 발생된 우라늄침출액 내의 우라늄농도는 180 ppm이었고, Mg(II), K(I), Fe(II), Al(III) 농도는 20 ppm~1,210 ppm이었다. 우라늄침출액의 최적 처리공정은 혼합, 응집, 침전, 농축, 그리고 여과로 구성된다. 침전액의 pH를 11로 맞추기 위해, calcium hydroxide는 3.0g/100ml 그리고 sodium hydroxide는 2.7g/100ml이 필요했다. 여러 침전실험 결과 NaOH+0.2g alum+0.15g magnetite가 여과를 위한 최적 침전혼합제로 선정되었다. NaOH+0.2g alum+0.15g magnetite 투입 시 침전입자의 평균크기는 <TEX>$600\;{\mu}m$</TEX>이었다. pH=9에서 침전 후 상등액에 총 금속농도가 가장 낮았기 때문에, 최적 침전을 위하여 먼저 0.2g/100ml alum와 0.15g/100ml magnetite 투입한 후 pH=9일 때까지 sodium hydroxide을 투입하여야 한다. A large volume of uranium electrokinetic leachate has been generated during the electrokinetic decontamination to remove uranium from contaminated soil. The treatment technology for the reuse of the uranium leachate was developed. The concentration of uranium in the generated uranium leachate was 180 ppm and concentrations of Mg(II), K(I), Fe(II), and Al(III) ions ranged from 20 ppm to 1,210 ppm. The treatment process for uranium leachate consisted mainly of mixing and cohesion, precipitation, concentration, and filtration. In order to obtain the pH=11 of a precipitate solution, the calcium hydroxide needs to be 3.0g/100ml and the sodium hydroxide needed to be 2.7g/100ml. The results of several precipitation experiments showed that a mixture of NaOH+0.2g alum+0.15g magnetite was an optimal precipitant for filtration. The average particle size of precipitate with NaOH+alum+0.15g magnetite was <TEX>$600\;{\mu}m$</TEX>. Because the total value of metal concentrations in supernatant at pH=9 was the smallest, sodium hydroxide should be added with 0.2g alum and 0.15g magnetite for pH=9 of leachate.