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 ~ 7,141 mg/kg) within the particle size ranges of 2.0 ~ 0.8 mm, 0.8 ~ 0.5 mm, 0.5 ~ 0.15 mm, and 0.15 ~ 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° 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 ~ F5) were significantly lower, ranging from 376 ~ 2,093 mg/kg for Pb, 35 ~ 620 mg/kg for Cu, and 47 ~ 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 a 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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