The development of precipitation-filtering technology for uranium electrokinetic leachate

A great volume of uranium electrokinetic leachate has been generated during the operation of the electrokinetic decontamination experiment to remove uranium from radioactive soil. Treatment technology for the reuse of the generated 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 were high. When sodium hydroxide was put in the uranium leachate as a precipitant, the precipitation velocity was shorter and the precipitate particle size was larger than those of calcium hydroxide. The treatment process for uranium leachate consists mainly of mixing and cohesion, precipitation, concentration, and filtration. In order for the pH of a precipitate solution to reach 11, the amount of sodium hydroxide and calcium hydroxide needs to be 2.7–3.0 g/100 ml. In several respects, sodium hydroxide is more efficient as a precipitant than ammonium hydroxide and calcium hydroxide. The results of precipitation experiments show that a mixture of NaOH + 0.2 g alum + 0.15 g magnetite is an optimal precipitant for filtration. The average particle size of precipitate with NaOH + alum + 0.15 g magnetite was 600 μm. Because a pH level of 9 provides the lowest total amount of metal concentrations in the supernatant, sodium hydroxide should be added to 0.2 g alum and 0.15 g magnetite for optimal filtration until the pH of the leachate reaches 9.

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► The concentration of uranium in the generated electrokinetic leachate was 180 ppm.
► NaOH was more profitable than NH4OH and Ca(OH)2.
► A mixture of NaOH + 0.2 g alum + 0.15 g magnetite was an optimal precipitant.
► Sodium hydroxide should be added till the pH of uranium leachate reaches 9.