Evaluation on the Performance of Separation Process for Heavy Metal Contaminated Soils Originating from Millitary Regions using a Reciprocating Shaking Table

초록

This study evaluated the performance of a gravity separation process using a reciprocating shaking table as a pretreatment step to reduce contamination levels before applying soil washing to heavy metal (Pb, Cu, Zn) contaminated soil in a military shooting range. Heavy metals in the shooting range soil existed as a mixture of metal fragments derived from bullets and brass, as well as adsorbed forms on soil particles. In particular, lead (Pb) was found in high concentrations (4,058 similar to 7,141 mg/kg) within the particle size ranges of 2.0 similar to 0.8 mm, 0.8 similar to 0.5 mm, 0.5 similar to 0.15 mm, and 0.15 similar to 0.075 mm, indicating a high necessity for physical separation before soil washing. Based on the experiments to determine the optimal operating conditions for the shaking table (deck slope of 7 degrees and amplitude of 4.5 cm), gravity separation was conducted. The results showed that the maximum concentrations of lead, copper, and zinc in the F6 fraction, where high-density particles were collected, were 50,216 mg/kg, 7,365 mg/kg, and 657 mg/kg, respectively. In contrast, the concentrations in the other fractions (F0 similar to F5) were significantly lower, ranging from 376 similar to 2,093 mg/kg for Pb, 35 similar to 620 mg/kg for Cu, and 47 similar to 88 mg/kg for Zn, confirming the effective separation of bullet and casing fragments. The gravity separation process using a reciprocating shaking table effectively reduced the contamination levels on soils of different particle size ranges. It proved to be cost-effective way that can reduce the burden on the subsequent soil washing process, reducing the required removal efficiency from over 95% to a range of 51.0-84.3%.

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